JP4910953B2 - Electronic component package structure - Google Patents

Description

  The present invention relates to a package structure of an electronic component in which a functional element is sealed in a hollow state, represented by a surface acoustic wave filter used in a high-frequency electronic circuit.

  The package of an element that exhibits a specific electrical function by forming an electrode pattern or a fine structure on the surface of a single crystal wafer, represented by a surface acoustic wave filter, changes its characteristics when the functional part surface is covered with a resin or the like. A hollow structure is employed so that other objects do not come into contact with a particularly functionally important part of the element surface.

  FIG. 4 shows a package structure of a general surface acoustic wave filter (hereinafter referred to as SAW filter).

  For the purpose of reducing package dimensions, so-called flip chip mounting is performed in which a surface acoustic wave element (hereinafter referred to as a SAW element) 104 is mounted on a substrate 101 with a functional surface facing the substrate side, and a material 107 such as a resin is also used. A structure sealed with is generally used. A space part 108 is formed on the surface of the functional part so that the sealing material does not cover it.

  The above structure is a structure in which a SAW element is cut out from a wafer into individual pieces, and then the individual elements are mounted on a substrate. For the purpose of further miniaturization, after forming a hollow sealing structure with a wafer, dicing is performed. A structure in which a package is completed by dividing it into pieces is proposed, and an example thereof is shown in FIG.

  FIG. 5 is a cross-sectional view of the element after being singulated. On the single crystal material 110 on which the functional portion 111 and the electrode 112 are formed, the resin layer 113 for forming the space 116 and the resin layer 113 are formed thereon. The circuit board 114 is bonded, and reference numeral 115 denotes an external connection terminal.

  Compared to the package shown in FIG. 4, the package having such a structure does not have a sealing structure surrounding the SAW element, and therefore can be further reduced in size.

For example, Patent Document 1 is known as a prior art document related to the invention of this application.
Special Table 2002-532934

  The package structure disclosed in the prior art shown in FIG. 5 has a problem in reliability in actual use.

  SAW filters are often used in small communication devices typified by mobile phones. Recently, functional modules on which electronic components including SAW filters are mounted in advance are created and mounted on the motherboard of the device. Assembling method is used.

  A functional module is an assembly of components formed so as to exhibit specific functions by mounting electronic components at high density on a small circuit board, and is sealed with resin except for external electrode portions. It is common. As the resin sealing method, the transfer mold method is most often used. In the resin molding process, a high temperature of 150 ° C. or higher and a high pressure of several MPa or higher are applied to the electronic component.

  The mounting structure disclosed in Patent Document 1 is a circuit board in which the lid of the space portion is called a printed board. In the circuit board, the surface of the fiber reinforced resin sheet is coated with a copper foil, and the circuit board does not have sufficient rigidity and strength against an external force at a high temperature.

  In the above transfer molding process, when high temperature and high pressure are applied, the circuit board forming the cover of the space part is easily deformed, the space is crushed, and the characteristics of the SAW filter are changed.

  In addition, in order to obtain a circuit board that can withstand high temperature and high pressure, it is necessary to increase the thickness, which increases the overall thickness of the package.

In order to solve the above-mentioned problems, as an electronic component package structure of the present invention, a substrate on which an element having a functional region and an electrode is formed on the surface, and a resin layer disposed with a space on the functional region of the substrate And an electronic component package comprising a metal layer covering the space and an insulating resin layer provided at a position corresponding to the resin layer of the metal layer, wherein the elastic modulus of the resin layer is that of the insulating resin layer. An electronic component package structure characterized by being larger than the elastic modulus is used.
Further, a passage which is connected to the functional area to the resin layer, an external electrode connected to the passage, using electronic component package structure provided in the metal layer.
Also, an electronic component package structure in which the elastic modulus of the resin layer is 2.5 times or more the elastic modulus of the insulating resin layer is used.
Further, an electronic component package structure in which the substrate is a semiconductor single crystal is used.
In addition, an electronic component package structure in which the space has a hollow sealing structure is used.
Further, an electronic component package structure in which the functional area is a surface acoustic wave filter, an acceleration sensor, or an angular acceleration sensor is used.
The conductive circuit pattern uses the above circuit board made of electrolytic copper or phosphor bronze.

  The electronic component package structure of the present invention is a structure in which a resin layer having a space and a metal layer are laminated, and a lid that covers the functional area is formed by the metal layer, so that it has high rigidity, such as a transfer mold. Even when exposed to high temperature and high pressure, there is little deformation of the space part and high reliability can be obtained. Further, even a sufficiently thin structure can withstand high temperature and high pressure, so the thickness of the whole package can be reduced. Has the effect of being able to.

(Embodiment)
Hereinafter, an electronic component package according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a SAW filter package in the embodiment.

  A resin layer 4 having a space 5 is formed on the surface of a single crystal substrate 1 on which an IDT portion 2 (Interdigital Transducer) and an electrode 3 are formed, and a metal layer made of, for example, copper is formed on the surface of the resin layer 4. 6 are stacked.

  The connection from the electrode 3 to the external electrode 7 is performed by filling the connection hole 8 provided in the resin layer 4 with a metal such as copper.

  The external electrode 7 is made of the same metal as the metal layer 6 that forms the lid of the space 5, and is separated from other electrodes and lid portions by the insulating resin layer 9.

  The use of copper for the metal layer 6 forming the electrode and the hollow cover facilitates the plating film formation, allows filling the bottomed hole and plating the cover part simultaneously, and has a low electric resistance and electric power. This is because the mechanical characteristics are good. However, if the same metal layer 6 can be formed, it is not limited to copper.

  When this package is used by being mounted on a circuit board with solder or the like, the external electrode 7 is thermally deformed due to thermal expansion or the like of the insulating resin layer 9. This thermal deformation is transmitted to the single crystal substrate 1 through the connection hole 8 and the electrode 3.

  By making the average value of the elastic modulus of the resin layer 4 larger than the average value of the elastic modulus of the insulating resin layer 9, the thermal deformation generated in the external electrode 7 can be suppressed as much as possible, and the connection hole caused thereby 8 deformation can be suppressed as much as possible, and the influence on the single crystal substrate 1 can be suppressed as much as possible, and the problem that the characteristics are remarkably changed or the single crystal substrate is cracked as much as possible can be prevented as much as possible. A package having the characteristics can be obtained. The elastic modulus is Young's modulus, and the average value of elastic modulus is (Young's modulus at 25 ° C. + Young's modulus at 260 ° C.) / 2. same as below.

  Furthermore, since the structure can be made sufficiently thin, the apparent thermal expansion in the thickness direction of the insulating resin layer 9 is reduced, and the thermal deformation of the external electrode 7 can be reduced.

  Further, since the volume occupied by the insulating resin layer 9 is reduced by forming the metal layer 6, the thermal deformation of the external electrode 7 can be further reduced.

(Examples and Comparative Examples)
The present invention will be described based on examples and comparative examples.

  An electronic component package comprising a single crystal substrate 1 (material: lithium tantalate, thickness: 250 μm), a resin layer 4 (material: polyimide, thickness: 10 μm), and an insulating resin layer 9 (material: epoxy resin, thickness: 30 μm) is used. Then, after reflowing at 260 ° C., the tensile stress generated in the single crystal substrate 1 was obtained by calculation by linear structure analysis (using FEM). The in-plane dimension of the package is 850 × 650 μm.

  The results are shown in (Table 1).

  From this (Table 1), in Comparative Examples 1-3, since the elastic modulus of the insulating resin layer 9 is large, the thermal deformation generated in the external electrode 7 cannot be suppressed, and the tensile stress generated in the single crystal substrate 1. Becomes larger.

  Further, since the elastic modulus of the resin layer 4 is small, the deformation of the connection hole 8 caused by the deformation of the external electrode 7 cannot be suppressed, and the tensile stress generated in the single crystal substrate 1 becomes large.

  Therefore, as in Example 1, when the elastic modulus of the resin layer 4 is 3925 MPa and the elastic modulus of the insulating resin layer 9 is 1464 MPa, thermal deformation generated in the external electrode 7 can be suppressed, and the external electrode 7 Since the deformation of the connection hole 8 caused by the thermal deformation of the single crystal substrate 1 can be suppressed, the tensile stress generated in the single crystal substrate 1 can be reduced, and as a result, no crack is generated.

  Examples 2 and 3 are the same as Example 1. However, it can be seen that the difference in elastic modulus between the resin layer 4 and the insulating resin layer 9 needs to be 2.5 times or more.

  Next, a manufacturing method for realizing such a package structure will be described.

  FIG. 2 is a cross-sectional view of the SAW filter package for explaining the process.

  As shown in FIG. 2A, a photosensitive resin layer 4 is formed with a uniform thickness on the surface of a single crystal substrate 1 on which a plurality of IDT portions 2 and electrodes 3 are formed. Since the thickness of the resin layer corresponds to the height of the space portion, the thickness is determined in consideration of the package height after completion and the required pressure resistance.

  This figure shows a single crystal substrate in which two sets of IDT portions and electrodes are formed.

  Next, as shown in FIG. 2B, using the photosensitivity of the resin layer 4, the space 5 and the connection hole 8 are formed on the electrode 3 on the IDT portion 2.

  Next, as illustrated in FIG. 2C, the film material 10 is bonded to the entire surface of the resin layer 4.

  In this embodiment, a copper foil having a thickness of 3 μm is used as the film material. After laminating a thin sheet-like thermosetting adhesive on the adhesive surface of the copper foil, it can be easily bonded by pressure laminating on the resin layer 4 and heating. Moreover, when an uncured epoxy resin is used for the resin layer 4, the copper foil can be bonded without using another adhesive by curing the resin layer 4 in a state where the copper foil 10 is pressed against the resin layer 4. .

  Next, as shown in FIG. 2D, the copper foil 10 is etched by a photolithography method to form an opening 11 on the connection hole 8 and a pattern 12 for electrical isolation from other electrodes.

  At this time, since the copper foil 10 is sufficiently thin with a thickness of 3 μm, the pattern 12 can be very fine.

  Next, as shown in FIG. 3A, a patterned resin layer 13 is provided.

  The resin layer 13 serves as a boundary for dividing the plated copper layer, and is provided so that at least the opening 11 on the connection hole and the copper foil 10 on the space 5 are exposed.

  The thickness of the resin layer 13 is set to a value equal to or larger than the copper thickness required on the space 5.

  The copper thickness required on the space 5 is a value determined from the pressure resistance required for the completed electronic component package.

  Next, as shown in FIG. 3B, a metal thin film 14 to be a plating electrode in the next step is formed. In this example, a total of 300 nm of a titanium film and a copper film was formed by sputtering.

  The metal thin film 14 needs to be formed inside the connection hole 8 and also on the surface of the electrode 3.

  Next, as shown in FIG. 3C, a copper layer 15 is formed by plating on the entire surface using the metal thin film 14 formed in the previous step as a plating electrode. As the copper layer thickness at this time, it is necessary that at least the inside of the connection hole 8 is filled, and a copper layer having a final thickness or more is formed on the space 5.

  Next, as shown in FIG. 3D, the surface of the plated copper layer 15 is cut, the copper deposited on the resin layer 13 is removed, and cutting is performed until the resin layer 13 is exposed.

  As a result, the plated copper layer formed on the entire surface is divided into a plurality of portions by the resin layer 13. The resin layer 13 is pattern-designed so that the divided portions correspond to the plurality of external connection electrodes 16 and the lid 17 on the space 5.

  Further, the copper layer 17 corresponding to the lid on the space 5 can also serve as an external connection electrode.

  Thus, the plated copper layer 15 can be divided into fine patterns while having a sufficient thickness for protecting the space 5 from external pressure.

  Next, as shown in FIG. 3E, the package is completed by dicing and dividing into individual pieces.

  In this embodiment, a surface acoustic wave filter (SAW) element is used. However, the present invention is not limited to this, and other objects such as an acceleration sensor element and an angular velocity sensor element have a functional structure on the surface. Therefore, the device can be applied to a package in which the element surface is kept in a hollow state.

  As described above, the electronic component package structure of the present invention can be applied to a package in which the element surface is maintained in a hollow state, and is small and highly reliable.

  In addition, the method for manufacturing an electronic component package according to the present invention can form a metal layer 6 having a sufficient thickness that can withstand external pressure and divide the metal layer 6 into fine portions to form electrodes. A highly reliable and small electronic component package is provided.

Sectional drawing of the electronic component package in embodiment of this invention The figure which shows the manufacturing method of the electronic component package in the embodiment The figure which shows the manufacturing method of the electronic component package in the embodiment Cross section of conventional package Cross section of conventional package

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single crystal substrate 2 IDT part 3 Electrode 4 Resin layer 5 Space 6 Metal layer (lid part)
7 External electrode 8 Connection hole 9 Insulating resin layer

Claims (6)

A substrate on which an element having a functional region and an electrode is formed on the surface;
A resin layer disposed with a space on the functional area of the substrate;
A metal layer covering the space;
An electronic component package comprising an insulating resin layer provided at a position corresponding to the resin layer of the metal layer,
The electronic component package structure, wherein the elastic modulus of the resin layer is larger than the elastic modulus of the insulating resin layer. A passage connected to the functional region in the resin layer;
The electronic component package structure according to claim 1, wherein an external electrode connected to the passage is provided on the metal layer. The elastic modulus of the resin layer, the electronic component package structure according to claim 1 or 2 wherein at least 2.5 times the elastic modulus of the insulating resin layer. 4. The electronic component package structure according to claim 1, wherein the substrate is a semiconductor single crystal. 5. The electronic component package structure according to claim 1, wherein the space has a hollow sealing structure. Electronic parts packaging structure of the functional area surface acoustic wave filter, the acceleration sensor over, claims 1 an angular accelerometer 5, wherein.

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