CN203931383U - Soild state transmitter panel - Google Patents

Abstract

The present application provides a solid state emitter panel comprising: a submount; a mask on the submount, the mask defining a plurality of pixel regions; an adhesive between the mask and the submount an agent; at least one light emitter located in each of the pixel regions; and an encapsulant portion at least partially covering the at least one light emitter. With the invention, flexibility is allowed in driving each pixel so that it can emit different colors of combinations of light from the LEDs.

Description

Solid State Transmitter Panel

technical field

The utility model relates to a solid-state emitter panel.

Background technique

A light emitting diode (LED) is a solid state device that converts electrical energy into light. A light emitting diode typically includes one or more active layers of semiconductor material between opposing doped layers. When a bias is applied to the doped layer, holes and electrons are injected into the active layer where they recombine to generate light. Light is emitted from the active layer and from all surfaces of the LED.

As a result of technological advances over the past decade or more, LEDs have smaller footprints, improved emission efficiency, and reduced cost. LEDs also have an increased operating lifetime compared to other emitters. For example, the operating life of an LED can exceed 50,000 hours, while the operating life of an incandescent light bulb is about 2,000 hours. LEDs can also be more durable and consume less energy than other light sources. For these and other reasons, LEDs are becoming more popular and are now traditionally used in increasing numbers of applications in the field of incandescent, fluorescent, halogen and other emitters.

To use LED chips in conventional applications, it is known to enclose the LED chips in packages to provide environmental and/or mechanical protection, color selection, light concentration, and the like. The LED package also includes leads, contacts or traces for electrically connecting the LED package to an external circuit. In a typical two-pin LED package/component 10 shown in FIG. 1 , a single LED chip 12 is mounted on a reflective cup 13 by solder adhesive or conductive epoxy. One or more wire bonds connect the resistive contacts of LED chip 12 to leads 15A and/or 15B, which may be attached to or integrally formed with reflective cup 13 . The reflective cup 13 may be filled with an encapsulant material 16 and a wavelength converting material, such as phosphor, which may be included in the entire LED chip or in the encapsulant. Light emitted by the LED at a first wavelength can be absorbed by the phosphor, which can responsively emit light at a second wavelength. The whole assembly can then be enclosed in a transparent protective resin 14 which can be molded into the shape of a lens to direct or shape the light emitted from the LED chip 12 .

A conventional LED package 20, shown in FIG. 2, may be better suited for high power operation, which may generate more heat. In LED package 20 , one or more LED chips 22 are mounted on a carrier such as a printed circuit board (PCB) carrier, substrate or submount 23 . A metal reflector 24 mounted on the submount 23 surrounds the LED chip 22 and reflects light emitted by the LED chip 22 away from the package 20 . The reflector 24 also provides mechanical protection for the LED chip 22 . One or more wire bond connections 21 are formed between resistive contacts on LED chip 22 and electrical traces 25A, 25B on submount 23 . The mounted LED chip 22 is then covered with an encapsulant portion 26 which also acts as a lens while providing environmental and mechanical protection to the chip. Metal reflector 24 is typically attached to the carrier by solder or epoxy adhesive.

FIG. 3 shows yet another LED package 30 comprising a housing 32 and a lead frame 34 at least partially embedded in the housing 32 . A lead frame 34 is provided for surface mounting of the package 30 . Portions of lead frame 34 are exposed through cavities in housing 32 , with three LEDs 36 a - c mounted on portions of lead frame 34 connected by wire bonds 38 to other portions of the lead frame. Different types of LEDs 36a-c can be used, some packages have red, green and blue emitting LEDs. Package 30 includes a pin output structure having six pins 40 , and the lead frame is arranged such that the light emitted by each of LEDs 36a - c through a corresponding pair of pins 40 can be independently controlled. This allows the package to emit multiple color combinations from the LEDs 36a-c.

Different LED packages, such as those shown in Figures 1-3, can be used as light sources for signs and displays (both large and small). Large-screen LED-based displays (often denoted giant screens) are becoming more common in many indoor and outdoor venues, such as at sports arenas, running tracks, concerts, and in large public areas such as Times Square in New York City. With current technology, some of these displays and screens can measure up to 60 inches high and 60 inches wide. As technology advances, it can be expected that larger screens will be developed.

These screens can include millions or hundreds of thousands of "pixels" or "pixel modules," each of which can include one or more LED chips or packages. The pixel modules can use high-efficiency and high-brightness LED chips that allow the display to be visible from relatively long distances even during the day when facing the sun. In some signs, each pixel has a separate LED chip, and the pixel module has as few as three or four LEDs (such as one red, one green, and one blue) that allow the pixel to switch from red, The combination of green and/or blue light emits many different colors of light. Pixel modules can be arranged in a rectangular grid that can include hundreds of thousands of LEDs or LED packages. In one type of display, the grid may be 640 modules wide and 480 modules high, where the size of the screen depends on the actual size of the pixel modules. As the number of pixels increases, so does the interconnection complexity of the display. This interconnection complexity can be one of the major costs of these displays and can be one of the major sources of failure during the manufacture of the display as well as during its operational life.

Utility model content

The utility model provides a solid-state emitter panel, comprising: a base; a mask located on the base, the mask defining a plurality of pixel areas; a mask located between the mask and the base an adhesive; at least one light emitter in each of the pixel regions; and an encapsulant portion at least partially covering the at least one light emitter.

Further, the submount includes an electrical interconnection structure, and each of the light emitters is electrically connected to the submount in the pixel area.

Further, each of the pixel regions includes at least the following three emitters: an emitter that provides red light, an emitter that provides green light, and an emitter that provides blue light.

Further, the abutment is made of ceramic material.

Further, the base platform includes a printed circuit board.

Further, each of the light emitters is electrically connected to the submount by wire bonding.

Further, each of the pixel regions is at least partially filled with an encapsulant material, and the encapsulant material at least partially surrounds the light emitter.

Further, the solid state emitter panel further includes a filling material between the pixel regions on the submount.

Further, each of the pixel areas has a square occupancy area.

Further, the base platform includes a printed circuit board, the mask is made of polyphthalamide, and the adhesive is made of solid epoxy glue.

The invention has the benefit of allowing flexibility in driving each pixel so that it can emit different colors of combinations of light from the LEDs.

Description of drawings

1 is a side view of a conventional light emitting diode package;

2 is a side view of another conventional LED package;

3 is a plan view of another conventional LED package;

4 is a plan view of an embodiment of an LED package according to the present invention;

5 is a side view of the LED package shown in FIG. 4;

6 is another side view of the LED package shown in FIG. 4;

7 is a plan view of an embodiment of the LED display according to the present invention;

Figure 8 is a schematic view showing the interconnection between LEDs in an LED package according to the present invention;

9 is a plan view of another embodiment of the LED package according to the present invention;

10 is a schematic view showing the interconnection between LEDs in another LED package according to the present invention;

Fig. 11 is a plan view of another embodiment of the LED package according to the present invention;

Fig. 12 is a plan view of another embodiment of the LED package according to the present invention;

Fig. 13 is a plan view of another embodiment of the LED package according to the present invention;

Fig. 14 is a plan view of another embodiment of the LED package according to the present invention;

Fig. 15 is a plan view of an embodiment of the LED display according to the present invention;

Fig. 16 is a plan view of another embodiment of the LED display according to the present invention;

Fig. 17 is a perspective view of yet another embodiment of an LED package according to the present invention;

FIG. 18 is a plan view of the LED package shown in FIG. 17 without showing the LEDs in the pixels;

19 is a plan view of one of the pixels in the LED package of FIGS. 17 and 18;

20 is a side view of the LED package shown in FIGS. 17 and 18 taken along section line 20-20;

Figure 21 is a bottom view of the LED package shown in Figures 17 and 18;

Figure 22 is a bottom perspective view of the LED package shown in Figures 17 and 18;

Figure 23 is another bottom view of the LED package shown in Figures 17 and 18 with a pin numbering arrangement;

Fig. 24 is a schematic view of a pin-designated embodiment in an embodiment of an LED package according to the present invention;

FIG. 25 is a schematic view showing the interconnections between LEDs in an LED package according to the present invention and designated by pins shown in FIG. 24;

26 is a plan view of another embodiment of the LED display according to the present invention; and

Fig. 27 is a plan view of another embodiment of the LED display according to the present invention.

Figures 28a-28d illustrate a method for manufacturing an emitter panel according to an embodiment of the invention.

29 is a top plan view of an emitter panel according to an embodiment of the present invention.

30 is a cross-sectional view of a face mask/submount combination in accordance with an embodiment of the present invention.

31 is a perspective view of an emitter panel according to an embodiment of the present invention.

32 is a top plan view of an emitter panel according to an embodiment of the present invention.

33 is a top plan view of a transmitter module according to an embodiment of the present invention.

34 is a top plan view of a pixel according to an embodiment of the invention.

35 is a cross-sectional view of a transmitter module according to an embodiment of the present invention.

36a-36d illustrate a method for manufacturing a light emitter panel according to an embodiment of the invention.

Figure 37 shows a cross-sectional view of a transmitter module during an intermediate manufacturing step according to an embodiment of the invention.

Figure 38 shows a cross-sectional view of a transmitter module during an intermediate manufacturing step according to an embodiment of the invention.

Figure 39 shows a cross-sectional view of a transmitter module during an intermediate manufacturing step according to an embodiment of the invention.

Figures 40a-40c illustrate a method of manufacturing an emitter panel according to an embodiment of the invention.

Figures 41a-41d illustrate a method of manufacturing an emitter panel according to an embodiment of the invention.

Detailed ways

The invention relates to an improved LED package and an LED display utilizing the LED package, and the LED package according to the invention includes a "multi-pixel" package. That is, the package includes more than one pixel, and each of the pixels includes one or more light emitting diodes. Different implementations include different features for applying electrical signals to LEDs in pixels. In some embodiments, corresponding electrical signals can be applied to each of the pixels to control their emission color and/or intensity, while in other embodiments two or more pixels can be controlled by the same electrical signal control. In embodiments where a pixel has multiple LEDs, one or more of the LEDs in each pixel may be controlled by separate signals, while in other embodiments LEDs in different pixels may be controlled by the same signal. In some of these embodiments, the same signal can be used to control the emission of two or more pixels, while in other embodiments each of the pixels can be controlled by a separate signal.

In some embodiments, the term pixel is understood in its ordinary sense, ie as an element of an image, and can be individually processed and controlled in a display system. In some of these embodiments, all or some of the pixels may include red, green, and blue emitting LEDs, and at least some of the pixels are arranged to allow the intensity of each LED in the pixel to be controllable . This allows the color of light emitted by each pixel to be a combination of red, green, and blue light, and allows flexibility in driving each pixel so that it can emit different colors of the combination of light from the LEDs.

In other embodiments, the packages may include pixels capable of emitting a single color of light while these packages are used in different applications, such as lighting or backlighting. In some of these embodiments, the pixel can emit white light and can include at least one blue LED with one or more phosphors, and the LED emits a white combination of blue light and phosphor light. Others of these implementations can allow individual LEDs in each pixel to be controlled, while in other implementations the LEDs can be driven by the same drive signal. In some embodiments, a pixel can include one or more white emitting diodes in combination with red emitting diodes to achieve a desired pixel emission, such as a desired color temperature. In other embodiments, the emission of the LEDs in a pixel can be controlled such that the pixel emits different color temperatures in the cool to warm color temperature spectrum.

Packages according to the invention can comprise many different shapes and sizes, and can be arranged with different numbers of pixels. In some implementations, the package can be square and can have pixels in 2 by 2, 4 by 4, 8 by 8, etc. format. In other embodiments, the package can be rectangular and can have fewer pixels in one direction than in another direction. For example, a package may have a pixel format of 2 by 3, 4, 5, 6, etc., 3 by 4, 5, 6, 7, etc., or 4 by 4, 5, 6, 7, 8, etc. In yet other embodiments, the pixels may be a linear array of pixels 2, 3, 4, 5, etc. in length. These are just some of the shapes of the packages, while others are triangular, circular or irregularly shaped.

LED packages according to the present invention offer several advantages over prior art single pixel packages. LED packages can result in lower cost per pixel by reducing material costs such as lead frame materials. The spacing between adjacent pixels can also be reduced while maintaining a lambertian beam profile. By reducing the pitch between pixels, higher resolution displays can be made. Display manufacturing costs can also be reduced by reducing handling costs as well as picking and placing components. The complexity of interconnecting pixels can also be reduced, thus reducing material costs as well as display manufacturing levels. This will also reduce potential interconnections that could fail over the lifetime of the display.

The invention can relate to many different package types, with some of the following embodiments being surface mount devices. It will be appreciated that the invention can also be used with other package types such as packages with pins for through-hole mounting processes.

LED packages according to the present invention can be used in LED signs and displays, but it will be appreciated that they can be used in many different applications. LED packages are compatible with various industry standards, making them suitable for use in LED substrate signage, channel letter lighting, or general backlighting and lighting applications. Some embodiments may include a flat top emitting surface, making them compatible for mating with light tubes. These are just a few of the many different applications for LED packages according to the present invention.

An LED package according to the present invention may include a single LED chip or multiple LED chips, and can include a reflective cup surrounding one or more LED chips. The upper surface of the housing surrounding each reflective cup may include a material that contrasts with the light emitted by the LED chip. Portions of the housing exposed within the cup, and/or reflective surfaces within the cup may include a material that reflects light from the LED chips. In some of these embodiments, the light emitted from the LED chips may be white light or other wavelength-varying light, and the surface of the submount within the reflective cup, as well as the reflective surface of the cup, may be white or otherwise capable of emitting White light or light of varying wavelengths. The contrasting upper surface of the reflective cup can be a variety of different colors, but in some embodiments is black.

The invention is described herein with reference to particular embodiments, but it will be understood that the invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In particular, a variety of different LED chip, reflective cup and lead frame arrangements can be provided beyond those described above, and the encapsulant portion can provide further features to improve the reliability of the LED package and displays utilizing the same. properties and emission characteristics. Although various embodiments of LED packages are discussed here for use in LED displays, LED packages can also be used in many different lighting applications.

It will be understood that when an element such as a layer, region or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Additionally, relative terms, such as "above" and "beneath", and similar terms, may be used herein to describe the relationship of one layer or another region. It will be understood that these terms are intended to encompass different orientations in addition to the orientation depicted in the figures.

Although the terms first, second, etc. may be used herein to describe various elements, members, regions, layers and/or sections, these elements, members, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Accordingly, a first element, first member, first region, first layer or first section discussed below may also be referred to as a second element, second member, second region, second layer or second section, and not Deviate from the teaching of the utility model.

Embodiments of the present invention described herein refer to schematic cross-sectional views that are schematic diagrams of embodiments of the present invention. Accordingly, the actual thickness of the layers may vary, and variations from the schematic shapes due to, for example, manufacturing techniques and/or tolerances are to be expected. Embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Due to normal manufacturing tolerances, regions illustrated or described as square or rectangular will typically have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the present invention.

4-7 illustrate one embodiment of a multi-pixel emitter package 50 according to the invention, and FIG. 7 shows in more detail a pixel emitter that may be used in some embodiments according to the invention. The package includes four pixels 52a-d arranged in a 2 by 2 format or layout, the package 50 having a substantially square footprint. The package 50 may include features for different mounting methods, and the illustrated embodiment has features that allow for surface mounting. That is, the package 50 includes a surface mount device (SMD) having a pin and lead frame structure with pins and lead frame structures arranged such that the package can be mounted on a structure such as a printed circuit board (PCB) using surface mount technology. on the pin output. As mentioned above, it will be appreciated that the invention can also be applied to other emitter package types than SMDs, such as pin mount emitter packages. Package 50 includes a housing or submount 54 carrying an integral lead frame 56 . Lead frame 56 includes a plurality of conductive connections for conducting electrical signals to the light emitters of the package and also assisting in dissipating heat generated by the emitters.

The housing or submount ("housing") 54 can be formed from a variety of different materials, or a combination of materials, and can have different materials in different portions. An acceptable housing material is electrically insulating, such as a dielectric material. Housing 54 may comprise, at least in part, a ceramic material such as alumina, aluminum nitride, silicon carbide, or a polymer material such as polyamide and polyester. In some embodiments, housing 54 may comprise a dielectric material with relatively high thermal conductivity, such as aluminum nitride and aluminum oxide. In other embodiments, submount 54 may comprise a printed circuit board (PCB), sapphire or silicon or any other suitable material, such as those available from The Bergquist Company of Chanhassen, Minnesota. T-Clad thermally covers insulating substrate materials. For PCB implementation, different PCB types can be used, such as standard FR-4 type PCB, metal core PCB, or any other type of printed circuit board.

The lead frame 56 can be arranged in many different ways and various numbers of parts can be used in different package embodiments. Pixels may have the same emitter or emitters, such as LEDs, and in some implementations, different pixels may have different numbers of LEDs. As best seen in Figure 7, the package 50 may include three LEDs 58a-c per pixel, and in the embodiment shown a lead frame 56 is arranged for applying electrical signals to the LEDs 58a-c. Lead frame 56 includes conductive features for conducting electrical signals from the package mounting surface (eg, PCB) to LEDs 58a-c. The leadframe may also include features for providing mounting stability to the LEDs and for providing auxiliary thermal paths for dissipating heat from the emitters. The lead frame may also include physical features such as holes, cutouts, etc., to increase the stability and reliability of the package, and in some embodiments to help maintain a watertight seal between components. These various features are described in U.S. Patent Application Serial No. 13/192,293, entitled "Water Resistant Surface Mount Device Package," to Chan et al., which is incorporated by reference The whole is included here.

Fabrication of the lead frame 56 may be accomplished by stamping, injection molding, cutting, etching, bending, or by other known methods and/or combinations of methods to achieve the desired configuration. For example, the conductive parts may be produced by partial metal stamping (eg simultaneously stamped from a single sheet of relevant metal), suitably bent, and completely separated or completely separated after all or part of the housing has been formed.

Lead frame 56 may be made of conductive metal or metal alloy, such as copper, copper alloy and/or other suitable low resistance corrosion resistant material or combination of materials. It should be noted that the thermal conductivity of the leads assists somewhat in conducting heat away from the LEDs 58a-c.

Housing 54 can have a variety of different shapes and sizes, and in the illustrated embodiment is generally square or rectangular, with an upper surface 60 and a lower surface 62 (best seen in FIGS. 5 and 6 ), and The first side surface 64 and the second side surface 66 . The upper portion of the housing further includes a groove or cavity 72 that extends from the upper surface 60 , into the body of the housing 54 and to the lead frame 56 . The LEDs 58a - c of each pixel are arranged on the lead frame 56 of a corresponding one of the cavities 72 such that light from the LEDs is emitted from the package 50 through the cavities 72 . Each cavity 72 may have angled side surfaces that form a reflective cup around the LEDs 58a - c to help reflective emitter light exit the package 50 . In some embodiments, a reflective insert or ring (not shown) may be positioned and secured along at least a portion of the side surface 74 of the cavity 72 . The reflective effect of the ring and thus the emission angle of the package can be enhanced by tapering the cavity 72 and the ring is carried within the enclosure inwardly towards the interior of the enclosure. By way of example only, a reflector angle of about 50 degrees provides suitable reflectivity and viewing angles.

In some embodiments, cavity 72 can be at least partially filled with a filler material (or encapsulant portion) that can protect lead frame 56 and LEDs 58a-c and stabilize the position of the lead frame and LEDs. In some embodiments, the filler material may cover the emitters and the portion of the lead frame 56 exposed through the cavity 72 . The fill material can be selected to have predetermined optical properties to enhance projection of light from the LED, and in some embodiments the fill material is substantially transparent to light emitted by the emitter of the package. The filler material may also be flat such that it is approximately at the same level as the upper surface 60, or it may be shaped as a lens, such as a hemisphere or a bullet. Alternatively, the filler material may be fully or partially recessed into one or more cavities 72 . The filler material may be made of resin, epoxy, thermoplastic polycondensate, glass, and/or other suitable materials or combinations of materials. In some embodiments, materials may be added to the fill material to enhance the emission, absorption, and/or transmission of light to and/or from the LED.

Housing 54 may be made of a material that is preferably electrically insulating and thermally conductive. Such materials are well known in the art and may include, but are not limited to, certain ceramics, resins, epoxies, thermoplastics, polycondensates (e.g., polyphthalamide (PPA)), and Glass. The package 50 and its housing 54 may be formed and/or assembled by any of a number of known methods known in the art. For example, housing 54 may be formed or molded around the lead frame, such as by injection molding. Alternatively, the housing may be formed in parts, for example, in a top part and a bottom part, with the conductive parts being formed on the bottom part. The top and bottom sections are then bonded together using known methods and materials, such as epoxy, adhesive or other suitable joining material.

A variety of different emitters can be used with packages according to the invention, package 50 utilizing LEDs 58a-c. Different embodiments may have different LED chips that emit different colors of light, and in the embodiment shown, each pixel in package 50 includes red, green, and blue emitting LED chips that can produce colors including white A mixed color emission of many different wavelengths of light.

LED chip structures, features, and their fabrication and operation are generally known in the art and are only briefly discussed here. LED chips can have many different semiconductor layers arranged in different ways, and can emit different colors. The layers of the LED chip can be fabricated using known processes, a suitable process being the metal organic vapor deposition (MOVCD) fabrication process. The layers of an LED chip generally include an active layer/region sandwiched between opposing first and second doped epitaxial layers, all of which are sequentially formed on a growth substrate or growth wafer. The LED chips formed on the wafer can be monolithic and used in different applications, such as mounted in packages. It will be appreciated that the growth substrate/wafer may remain as part of the final monolithic LED chip, or the growth substrate may be completely or partially removed.

It is also understood that additional layers and components may also be included in the LED chip, including but not limited to buffers, nucleations, contact pads and current distribution layers, and light extraction layers and components. The active region may comprise a single quantum well (SQW), multiple quantum well (MQW), double heterostructure or superlattice structure.

The active region and doped layers can be made of different material systems, one such system is a Group-III nitride based material system. Group III nitrides refer to those semiconductor compounds formed between nitrogen and a group III element of the periodic table, usually aluminum (Al), gallium (Ga), indium (In). These terms also refer to ternary or quaternary compounds, such as aluminum gallium nitride (AlInGaN) and aluminum gallium indium nitride (AlInGaN). In a preferred embodiment, the doped layer is gallium nitride (GaN) and the active region is InGaN. In alternative embodiments, the doped layer may be AlGaN, aluminum gallium arsenide (AlGaAs) or indium gallium aluminum arsenide phosphide (AlGaInAsP) or gallium indium aluminum phosphide (AlInGaP) or zinc oxide (ZnO).

Growth substrates/wafers can be made of many materials such as silicon, glass, sapphire, silicon carbide, aluminum nitride (AlN), gallium nitride (GaN), a suitable substrate can be 4H-type silicon carbide, although other materials including 3C, 6H and 15R types of silicon carbide. Silicon carbide has certain advantages, such as a tighter lattice match to III-nitrides than sapphire, and enables higher-quality III-nitride films. Silicon carbide also has very high thermal conductivity such that the total output power of a Group III nitride-on-silicon carbide device is not limited by the heat dissipation of the substrate (as may be the case with some devices formed on sapphire). SiC substrates are available from the Cree Institute in Durham, New York, and methods of making them are described in scientific literature Re. 34,861, and in US Patent Nos. 4.946,547 and 5,200,022. LEDs can also include additional features, such as conductive distribution structures and current distribution layers, all of which can be deposited from known materials using known methods.

The LEDs 58a-c may be mounted to and electrically coupled to the lead frame by an electrically and thermally conductive bonding material such as solder, adhesive, plating, film, encapsulant, paste, grease, and/or other suitable material 56. In a preferred embodiment, the LEDs can be electrically coupled and secured to their respective pads using solder pads on the bottom of the LEDs such that the solder is not visible from the top. Wire bonds 74 (shown in FIG. 7 ) can be included extending between LEDs 58 a - c and lead frame 56 .

Different embodiments of the invention may have different pin output settings that can depend on different factors, such as the number of LEDs, the interconnection of the LEDs, and each of the pixels and/or each of the LEDs in the pixels. individual levels of separation and independent control. Figure 7 shows a package 50 having 8 pins 76 in its pin output configuration, while Figure 8 shows an embodiment of an interconnect structure 80 according to the present invention that can utilize an 8 pin output . Interconnect structure 80 shows four pixels 52a-d, each including three LEDs 58a-c, and the electrical connection between LEDs 58a-c can be made by lead frame 56 and/or wire bonds shown in FIG. 74 provided. Electrical signals on pins V1 and V2 provide energy to drive the LEDs, V1 driving the first and third pixels 52a, 52c and V2 driving the other two pixels 52b, 52d. Electrical signals R1, G1 and B1 on the needles control the emission of LEDs 58a-c in the first two pixels 52a, 52b, while signals R2, G2 and B2 control the emission of LEDs 58a-c in the last two pixels 52c, 52d. This arrangement allows dynamic control of the pixels 52a-d, each pixel being controlled by a respective combination of drive and control signals. In the illustrated embodiment, V1, R1, G1, and B1 control the emission of the first pixel 52a, and V1, R2, G2, and B2 control the emission of the third pixel 52c. Likewise, V2, R1, G1, and B1 control the emission of the second pixel 52b, and V2, R2, G2, and B2 control the emission of the fourth pixel 52d.

It will be appreciated that different packages may have different numbers of pins in their pin output configurations, and that pixels and LEDs may be interconnected in different ways by different lead frame configurations and wire bonds. Fig. 9 shows another embodiment of an LED package 100 according to the present invention, also having four pixels 102a-d in a 2 by 2 layout. The package further includes a housing 104 and a lead frame 106, each of which can be fabricated using the same methods and materials described above. Each of the pixels 102a-d may also include one or more LEDs, similar to those described above, the embodiment shown having three LEDs 108a-c. Package 100 also includes wire bonds 110 to provide electrical connection between lead frame 106 and LEDs 108a-c in pixels 102a-d.

The package 100 also includes a pin output structure with 16 pins 112. FIG. 10 shows an embodiment of an interconnection structure 120 according to the present invention. The four pixels in the 9 embodiment are used in combination. The interconnect structure 120 is provided by the lead frame 106 and the wire bonds 110 and allows discrete control of the pixels 102a-d. That is, each of the pixels 102a-d has its own pin for providing a respective power signal, and a respective set of pins for providing control over the emission of the LEDs 108a-c in its pixel. For pixel 102a, a power signal may be provided on pin V11, and signals to control the emission of LEDs 108a-c are provided on pins R11, G11, and B11. For pixel 102b, power is provided on pin V12 and LED control is provided on pins R12, G12 and B12. Power and control are identically provided to pixel 102c through V22, R22, G22, and B22, and power and control are provided to pixel 102d through V21, R21, G21, and B21. This arrangement requires more needles 112 than the package 50 described above, but allows for separate control of the emission of each of the pixels 102a-d. These are just two of the many different pin output and interconnection structures that can be provided by packages according to the present invention.

As discussed above, packages according to the present invention may be provided with a variety of different matrix layouts other than those 2 by 2 layouts shown in package 50 and package 100 . Figure 11 shows yet another embodiment of a package 130 having six pixels 132a-f arranged in a 2 by 3 matrix layout. Figure 12 shows yet another embodiment of a package 140 having eight pixels 142a-h arranged in a 2 by 4 matrix layout. Each of the packages 130, 140 includes a housing, with lead frames, pins and wire bonds similar to those described above, but arranged to accommodate a greater number of pixels. Each pixel may include a different number of LEDs, with each pixel shown having three LEDs as described above.

LED packages according to the present invention can also be arranged in an array or a linear layout. Figure 13 shows yet another embodiment of an LED package 150 according to the present invention having two pixels 152a-b arranged in a 2 by 1 linear format. Figure 14 shows yet another embodiment of an LED package 160 according to the present invention having four pixels 162a-d arranged in a 4 by 1 linear format. Each of the packages also includes the above-described housing, lead frame, pins, and wire bonds, and each pixel may include an LED as described above.

Multiple LED packages as described above can be mounted together to form a display, with different sized displays having different numbers of packages. FIG. 15 shows a portion of a display 170 having sixteen of the 2 by 2 LED packages 50 described above, surface mounted to a display panel 172 . Package 50 has eight pins 76 and display panel 172 may have interconnects to allow dynamic driving of pixels 52a-d in each package 50 as described above. The panel may comprise a variety of different structures arranged in many different ways, one embodiment comprising at least in part a printed circuit board (PCB) with conductive traces to which the surface mount package is in electrical contact. It will be appreciated that a typical display may have many more packages to form a display, some displays having enough packages to provide hundreds of thousands of pixels.

The other packages described above can be similarly provided in the display. FIG. 16 shows another portion of a display 180 having sixteen of the 2 by 2 LED packages 100 described above, surface mounted to a display panel 182 . These packages have 16 pins, and the display panel 182 may include the interconnects described above to allow discrete driving of the pixels 102a-d. Panel 182 may at least partially comprise a printed circuit board (PCB) with conductive traces, and a complete display may have as many packages 100 as possible.

By arranging multiple pixels on a single package, the pixels can be placed closer to each other (ie, closer pitch), which will allow for higher resolution LED displays. At the same time, multi-pixel packages allow for reduced complexity in LED displays compared to using single-pixel LED packages. In some embodiments, the LED packages can have a pitch in the range of 0.5 to 3.0 millimeters, while in other embodiments the pitch can be in the range of 1.0 to 2.0 millimeters. In still other embodiments, the pitch between pixels may be about 1.5 millimeters.

Packages may also have footprints of different sizes depending on the number of pixels in the package. For the 2 by 2 LED packages 50, 100 described above, the footprint may be square or rectangular, with some embodiments having sides in the range of 2 to 6 millimeters. In other embodiments, the sides may be in the range of 3 to 5 millimeters. In some generally square embodiments, the sides may be in the range of 3 to 4 mm, while in some generally rectangular embodiments, one side may be in the range of 3-4 mm and the other side Can be in the range of 4-5 mm. It will be appreciated that these are only some of the dimensions of LED packages according to the present invention, which may increase in proportion to the increased number of pixels in the package.

Different embodiments of LED packages according to the present invention may include matrix layouts larger than the 2 by 2 matrix layout described above, including 4 by 4, 5 by 5, 6 by 6, etc. 17-22 illustrate yet another embodiment of an LED package 200 according to the present invention having 16 pixels 202 arranged in a 4 by 4 matrix layout. Package 200, has housing 204, lead frame 206, and wire bonds 208 made from the same materials as those described above by the same process. Each pixel may include one or more LEDs, the embodiment shown has a pixel including three LEDs similar to those described above.

Different embodiments of package 200 may have lead frames with different numbers of pins, lead frames and wire bonds interconnecting the LEDs in different ways. In the illustrated embodiment, the lead frame 206 includes a needle output structure having twenty needles 210 , as best shown in FIGS. 21 and 22 . Pins 210 extend from the side surfaces of the package and are bent under housing 204 to provide convenient surface mounting, such as to a display panel. The bottom surface of package 200 may also include a plurality of polarity indicators that can be used by a pick and place machine to install the package in the correct orientation. Referring now to FIG. 21, a "+" shaped polarity indicator 212 is positioned at a corner of the package 200, but it will be appreciated that the polarity indicator could be in a variety of different shapes and placed in a number of different locations. s position. For example, FIG. 22 places triangular polarity indicators 214 at different corners of package 200 .

Referring to Figure 23, the twenty pins 210 are numbered 1-20 around the perimeter of the package. FIG. 24 shows the functions implemented by electrical signals placed on the different needles 210 . Pins 1-4 are designated R1P, R2P, R3P, and R4P, each providing power to the red LEDs in four pixels. Pins 12-15 are designated GB1P, GB2P, GB3P, and GB4P, each providing power to the green and blue LEDs in the four pixels. Pins 5-8 are designated R1, R2, R3, and R4, each controlling the emission of the red LEDs in the four pixels. Similarly, pins 9-11 and 16 are designated G1, G2, G3 and G4, each controlling the emission of the green LEDs in the four pixels. Finally, pins 17-20 are designated Bl, B2, B3, and B4, each of which controls the emission of the blue LEDs in the four pixels.

FIG. 25 shows one embodiment of an interconnection 240 between LEDs in different pixels when utilizing the pin output designation shown in FIG. 24 . Each electrical signal applied to pins 1-4 (R1P-R4P) applies power to the red LED 208a in the respective row of pixels 202, while the signal applied to pins 5-8 controls the red LED 208a in the column of pixels 202 launch. This row and column setup allows control over the emission of individual red LEDs. For example, the emission of red LED R8 in the second row and in the second column may be controlled by an electrical signal applied to pin 2 (R2P) and pin 6 (R2).

Similar steps can be used to control the lighting of the green LED 208b as well as the blue LED 208c. Electrical signals applied to pins 12 - 15 ( GB1P - GB4P ) apply power to green LED 208 b and blue LED 208 c in respective rows of pixels 202 . Signals applied to pins 9-11 and 16 (G1-G4) control the emission of green LEDs 208b in respective columns of pixels 202, and signals applied to pins 17-20 (B1-B4) control the respective LEDs 208b of pixels 202. The emission of the blue LED 208c in the column. This row and column setup allows control of individual green and blue emissions. For example, the emission of the green LED G8 in the second row and in the second column in the pixel can be controlled by an electrical signal applied to pin 14 (GB2P) and pin 10 (G2). The emission of the blue LED B8 in the second row and second column in the pixel can be controlled by an electrical signal also applied to pin 14 (GB2P) and pin 18 (B2). This interconnection arrangement is only one of many arrangements that can be used in embodiments according to the invention.

As a result of using the packages described above, multiple 4 by 4 LED packages can be mounted together to form a display, where different sized displays have different numbers of packages. FIG. 26 illustrates an embodiment of a display 300 , or a portion of a display, having sixty 4 by 4 packages 200 mounted to a display panel 302 in a 6 by 10 arrangement. The display panel 302 may include interconnections for the 20-pin pin-out structure of the package 200 to allow the driving of the pixels 202 . The display panel 302 may include a number of different structures arranged in a number of different ways, with one embodiment comprising at least in part a printed circuit board (PCB) with conductive traces, wherein the package is surface mounted in electrical connection with the traces.

FIG. 27 shows another embodiment of a display 350 having seventy 4 by 4 LED packages mounted on a display panel 352 in a 6 by 12 arrangement. Panel 352 may include interconnections for the 20-pin pin-out structures of package 200 to allow driving of pixels 202 . It is understood that a typical display will have many more packages to form the display, with some displays having enough packages to provide hundreds of thousands of pixels.

Referring again to FIG. 17 , package 200 may be arranged such that the upper surface of housing 204 has a color that contrasts with the color of light emitted from package 200 through groove/cavity 211 . In most embodiments, the light emitted from cavity 211 may comprise a combination of light emitted by LEDs 208a-208c. In some embodiments, the LED can emit white light and the upper surface of the housing can comprise a color that contrasts with the white light. A number of different colors can be used such as blue, brown, gray, red, green, purple etc., the embodiment shown has black on its upper surface. Black coloration can be applied using a number of different known methods. This black coloration can be applied during the molding process of the housing 204, or at a later step in the package manufacturing process using different methods such as screen printing, inkjet printing, painting, etc. FIG. LEDs with contrasting surfaces are described in U.S. Patent Application Serial No. 12/875,873 to Chen et al., entitled "LED Package With Contrasting Face," the entirety of which Incorporated herein by reference.

Figures 28a to 28d illustrate the method of manufacturing the emitter panel. In FIGS. 28a and 28b barrier 402 is secured to submount 404 using adhesive 406 such that barrier 402 is on or over submount 404 . As material is added to submount 404, an additive process (additive process, additive process) is used to create this array of pixel areas. Barriers 402 are aligned on submount 404 to define a plurality of cavities serving as pixel regions 408, and then at least one light emitter 410 is mounted in each pixel region 408 on mounting surface 411 as shown in FIG. 28c. In this embodiment, 3 LEDs (one red, one green, and one blue) are mounted to mounting surface 411 in pixel area 408 . Finally, in FIG. 28d the cavity of the barrier 402 is filled with material to provide an encapsulant portion 412 which at least partially covers the emitter 410 in the pixel area 408 . In this embodiment, barrier 402 is a mask mounted on the mounting surface of submount 404 . Masks can be manufactured from a variety of different materials including, for example, PPA and PCB. In another embodiment, barrier 402 may be formed from a molded sealant portion secured to abutment mounting surface 411 . In yet another embodiment, barrier 402 may be formed by forming a recess in the submount such that the mounting surface is recessed into the submount and the barrier is above the mounting surface.

Figure 29 is a top view of a mask 500 that may be incorporated into an emitter panel. The mask 500 has square holes cut into the mask that will define the pixel areas when the mask 500 is secured to the submount. Square holes are used because square holes provide the most space-efficient windows for pixels. In some embodiments, where a drill bit is used to create the hole, the corners of the hole may be rounded. In this particular embodiment, mask 500 includes a 6 by 4 array of 4 by 4 base modules 502 for a total of 384 pixel apertures. It is understood that more or fewer base modules can be used to provide the required array size and that base modules other than 4 by 4 in the array can be used as well. As indicated herein, PPA is one suitable material that may be used to fabricate mask 500 . Other materials such as polyester can also be used. Mask 400 can be manufactured using a number of different methods such as, for example, molding, stamping, or drilling. Materials and fabrication methods should be selected to provide a mask 500 that will not deform, have good thermal stability, adhere adequately to silicone/epoxy, have similar thermal expansion to the abutment it will be secured to coefficient (CTE), good hardness with reasonable elongation and preferably non-smooth surface.

Referring again to FIG. 28 , barrier 402 (mask, in this embodiment) may be attached to submount 404 with an adhesive. In one embodiment, a liquid phase glue may be used. A stencil (stencil) can be applied and used in conjunction with a controlled, high-viscosity glue. It is equally possible to apply the glue using various writing methods. In other embodiments, a solid phase glue may be suitable. In this case a stamping method may be used to form the glue into a solid grid (matching the shape of the barrier 402 ) to be applied to the mounting surface 411 of the abutment 404 . The solid glue can also be formed at the same time as the barrier, reducing processing time and improving alignment. A variety of different glues will suffice, a suitable glue will adhere adequately to both barrier 402 and abutment 404 and will ooze minimally after curing. Preferably the glue will have good heat/UV stability. In some embodiments, it is advantageous to use a b-staging process with solid glue. B grading is known in the art and describes a process that utilizes heat or ultraviolet light to remove solvent from the adhesive allowing the structure to be graded. That is, between adhesive application, assembly, and curing, mask barrier 402 and submount 404 can be held for a period of time without having to complete all fabrication steps at once. For example, this would allow immediate deformation of products for shipping or assembly in various locations. Room temperature vulcanizing (RTV) materials can be used as adhesives in this process.

Figure 30 is a cross-sectional view of another embodiment of a barrier/submount combination 600 in which the barrier is a second submount 604 that functions as a mask. In some embodiments, the first and second submounts can be used with a barrier created by mounting the second submount to the first submount. Here a PCB board is used for the first submount 602 , where the top surface is either a PCB core material 606 or a prepreg material 608 . Prepregs are known in the art and describe "pre-impregnated" composite fibers in which a matrix material, such as epoxy resin, has been present. The fibers are often in the form of a weave, and a matrix is used to bond the fibers together to other components during the manufacturing process. In this particular embodiment, the second submount 604 is shaped to function as a mask. The mask material can likewise be a PCB core; in other cases the mask can be a prepreg. Using common PCB materials, the second submount 604 can be produced at the PCB production facility and attached to the mounting surface 610 of the PCB submount 602 . Some other suitable subtractive methods that can be used are drilling, ablation (eg using a laser), or punching.

In other embodiments, the barrier is created with an ablation process (ie, by removing material), wherein material from the top surface of the submount is removed to create a recessed mounting surface. The remaining submount material then defines the barrier and thus the pixel area. Thus, it is possible to provide raised barriers defining pixel areas above the mounting surface using either an additive process or an subtractive process.

31 to 34 show various views of the emitter panel 700: FIG. 31 is a perspective view of the emitter panel 700; FIG. 32 shows a top plan view of the emitter panel 700; FIG. 33 is a 4 by 4 module 704 and FIG. 34 shows a close-up of a single pixel 706. Emitter panel 700 includes PCB submount 702 . Each module 704 includes 16 individual pixels 706 . Light emitters (not yet included) within each pixel are electrically connected within submount 702 . The PCB may include internal power interconnects that provide power and control signals to pixels 706 . A suitable abutment material will have low transparency, good rigidity, similar CTE to the barrier/mask material, good thermal stability, and adhere well to silicone/epoxy. Module 704 is fabricated with PCB submount 702, PPA mask, and solid epoxy adhesive.

FIG. 35 shows a cross-sectional view of module 704 with light emitter 710 mounted and connected to submount 702 . Mask 708 provides a raised barrier above mounting surface 713 that defines pixel region 712 . Light emitter 710 is electrically connected to trace 718 with wire bond 714 on mounting surface 713 of submount 702 . Encapsulant portion 716 material fills pixel region 712 defined by mask 708 and covers light emitter 710 and wire bonds 714 . The encapsulant portion 716 can perform a dual function: it both protects the elements within the pixel area 712 and shapes the outwardly emitted light from the emitter 710 . The encapsulant portion (performed or molded on the submount) can be designed to act as a lens, providing a specific optical output from the pixel.

Another method for manufacturing the solid state emitter panel 800 is shown in FIGS. 36a-36d. In this embodiment, as shown in FIG. 36 a , the light emitter 410 is first mounted on the mounting surface 411 of the submount 404 . An integral encapsulant portion 802 is then molded over the light source 410 to define a pixel 806, as shown in FIG. 36b. Thus, in this embodiment, the barrier is defined by the sidewalls of the encapsulant portion 802 and the light source 410 is located within the barrier on the mounting surface 411 . A number of additive processes can be used including transfer molding, dispense molding, injection molding, and the like. The encapsulant portion material should be selected to provide good light output efficiency, rigidity, uniformity, compact CTE of the submount 404 , and good adhesion to the submount 404 . For example, suitable materials include epoxy and silicone. As previously noted, when the encapsulant portion 802 is attached to the submount 404 , the encapsulant portion may act as a lens with the lensed portion of the lens aligned with the pixel region 806 .

Referring to FIG. 36b, during the molding process, some residual material called "flash" 804 remains on submount 404 in the area between pixels 806. Referring to FIG. As will be discussed below, in FIG. 36c burrs 804 have been removed from the gaps between pixels 806 . Once the burrs 804 are removed, a fill material 808 may be applied over the submount 404, in the gaps between the pixels 806, as shown in FIG. 36d.

FIG. 37 shows a cross-sectional view of an unfinished module 800 in the middle of the manufacturing process (see FIG. 36d ), where burrs 804 are visible on submount mounting surfaces 411 located between pixels 806 . In those applications where accuracy is important, such as in displays, the residual burr 804 remains due to the transmission of light from the emitter 410 between adjacent pixels 806 (as indicated by the arrow) when it acts as a light guide. Flashing 804 is undesirable. This effect is known as pixel crosstalk and can cause blurring and reduce resolution. To minimize crosstalk, burrs 804 should be removed from the surface of submount 404 between pixels 806 .

Burr 804 can be removed from abutment 404 in different ways. For example, portions of flash 804 may be removed mechanically (eg, with a saw), optically (eg, with a laser), or chemically (eg, with etching). When removing the flash 804 it is important not to cut/burn under the abutment 404 . If a PCB submount is used, it may also be advantageous to design the layout of the traces so that the traces do not extend along the area between pixels 806 .

Another approach for minimizing the adverse effects of pixel crosstalk is to introduce discontinuities or isolations in the lightguide path (eg, flash 804 ) to interfere with the transmission between pixels 806 . For example, as shown in FIG. 38 , V-shaped cutouts 810 are formed in the submount between pixels 806 prior to adding encapsulant portion 802 . When the encapsulant portion 802 is applied, the material coats the V-shaped cutout area. V-shaped cutout 810 creates an inactive path for light to travel between pixels 806 to reduce crosstalk. This method of isolation eliminates the need to completely remove flash 804 . If a PCB submount is used, the trace should not extend in the area where the V-cut will be applied. It is also necessary to closely control the amount of sealant portion 802 during application.

FIG. 39 shows a cross-sectional view of a module 800 using yet another method for minimizing pixel crosstalk. This particular embodiment includes spacers 811 to introduce discontinuities or isolations in the lightguide path (eg, flash 804 ) to interfere with transmission between pixels 806 . For example, as shown in FIG. 39 , the light emitter 410 is mounted on a spacer 811 located on the submount mounting surface 411 . Spacers 811 raise pixels 806 a distance away from mounting surface 411 such that the optical path within residual flash 804 is not a straight path from one pixel to another. Kinks in the optical path introduce multiple hard angles and surfaces that significantly reduce the amount of light transmitted between pixels 806 by total internal reflection. The reflector 410 can be electrically connected to the submount 404 through the spacer 811 using the via 813 .

Referring again to FIG. 36d , after the encapsulant portion 802 is applied to the submount 404 and any unwanted burrs 804 are removed, a gap-fill material 808 may be applied over the areas of the submount 404 between pixels 806 . This process should be well controlled to avoid contamination of the pixels 806 . The gap-fill material 808 should be chosen such that it adheres well to the sidewalls of the pixels 806 . The gap fill material 808 should have a dark color. Ideally, the gap-fill material 808 will be black to provide maximum contrast between the emitting surface of the pixel 806 and the area surrounding the pixel. In some embodiments, black paint can be used. A suitable coating will have good flow properties, good heat/UV/humidity stability, and good adhesion to sealant portion 802 and abutment 404 .

Gap-fill material 808 can be applied using a number of different methods. For example, as shown in Figures 40a to 40c, a stencil method may be used. After the encapsulant portion 802 is applied to the submount 404 and any unwanted burrs 80 are removed, a stencil 812 is placed over the stencil 800 such that the emitting surface of the pixel 806 is covered as shown in Figure 40a. Gap-fill material 808 may then be applied across the entire surface of module 800 as indicated by the arrows in FIG. 40b. In FIG. 40c , stencil 812 is removed, leaving pixels 806 uncovered by gap-fill material 808 . A variety of materials can be used for the stencil 812, suitable materials having the following properties: low deformability, good resistance to chemical cleaning, reasonable material hardness to protect the sealant portion 802 during handling.

Another method for applying the gap-fill material 808 is shown in FIGS. 41a-41d. The process includes applying a dark photosensitive gap-fill material 808 over the encapsulant portion 802 and submount 404 (FIG. 41b). Next, as shown in Figure 41c, the gap-fill material 808 is exposed to a specified amount of radiation/light. By closely controlling the amount of radiation, some material 808 in the gaps between pixels 806 will not be removed, depending on the photon penetration properties of the radiation used. As shown in FIG. 41 d , after development, the gap-fill material 808 may be removed to a depth such that the gap-fill material is coplanar with the emitting surface of the pixel 806 . A subsequent baking step may be necessary in order to harden the gap-fill material 808 .

Alternatively, as shown in Figure 41c, the gap-fill material 808 may be removed by mechanical means, such as grinding or cutting, for example. In this case, the gap-fill material 808 does not need to be photosensitive, but can only withstand mechanical stress during removal. It should be understood that a variety of materials can be used as gap fillers and that a variety of different methods can be used to apply and remove gap fillers from modules.

Although the invention has been described in detail with reference to a particular configuration thereof, other forms are possible. Emitter panels can come in many different shapes and sizes, can be arranged in many different ways, and can be made of many different materials. Pixels can be arranged in many different ways and in many different styles. Pixels can be interconnected using a variety of different features and have multiple interconnect structures. Therefore, the spirit and scope of the present invention should not be limited to the forms described above.

Claims (10)

1. A solid-state emitter panel, characterized in that, comprising: abutment; a mask on the submount, the mask defining a plurality of pixel regions; an adhesive between the mask and the submount; at least one light emitter located in each of said pixel regions; and An encapsulant portion at least partially covers the at least one light emitter. 2. The solid state emitter panel of claim 1, wherein the submount comprises an electrical interconnect structure, each of the light emitters being electrically connected to the submount in the pixel region. 3. The solid state emitter panel of claim 1 , wherein each of said pixel areas includes at least three of the following emitters: an emitter providing red light, an emitter providing green light, and an emitter providing blue light device. 4. The solid state emitter panel of claim 1 wherein said submount is comprised of a ceramic material. 5. The solid state emitter panel of claim 1, wherein the submount comprises a printed circuit board. 6. The solid state emitter panel of claim 1, wherein each of said light emitters is electrically connected to said submount by wire bonding. 7. The solid state emitter panel of claim 1, wherein each said pixel area is at least partially filled with an encapsulant material at least partially surrounding said light emitter. 8. The solid state emitter panel of claim 1, further comprising a fill material on the submount between the pixel regions. 9. The solid state emitter panel of claim 1, wherein each of said pixel areas has a square footprint. 10. The solid state emitter panel of claim 1, wherein the submount comprises a printed circuit board, the mask is composed of polyphthalamide, and the adhesive is composed of solid epoxy glue composition.