CN101062608A - Trace forming method, droplet ejection apparatus, and circuit module - Google Patents

Abstract

The present invention provides a track forming method in which liquid droplets of a track forming material are ejected to a substrate, and the liquid droplets (single) sprayed and landed on the substrate are dried by laser irradiation to form For the trajectory formed by the liquid droplets, polarized light having a P polarized light component of 80% to 100% is used as laser light.

Description

Track forming method, droplet ejection device, and circuit module

technical field

The invention relates to a track forming method, a droplet ejection device and a circuit module.

Background technique

In recent years, a circuit module having a low temperature fired ceramic multilayer substrate (Low Temperature Co-fired Ceramics: LTCC multilayer substrate) made of glass ceramics has been known as a circuit module on which electronic components such as semiconductor elements are mounted. In the LTCC multilayer substrate, the laminated green sheet (green sheet) can be fired at a low temperature below 900°C. Therefore, low-melting-point metals such as silver and gold can be used for the internal wiring, and the resistance of the internal wiring can be reduced.

In the manufacturing process of the LTCC multilayer substrate, a wiring pattern is drawn on each green sheet before lamination with metal paste or metal ink. As this drawing method, Japanese Patent Application Laid-Open No. 2005-57139 proposes a so-called inkjet method in which metallic ink is ejected as minute droplets. Since the inkjet method includes the step of drawing wiring patterns by joining tiny liquid droplets, that is, joining ink dots, it is possible to quickly respond to changes in the design of internal wiring, such as high-density internal wiring or wiring width and wiring. Narrowing of intervals.

However, the size and shape of liquid droplets or ink dots landed on the green sheet change over time depending on the surface state of the green sheet or the surface tension of the liquid droplets. Droplets whose size and shape change determine the size of the entire wiring according to the drying timing. For example, a droplet made of metallic ink with an outer diameter of 30 μm expands to 70 μm in 100 milliseconds after landing on a lyophilic green sheet, and expands to 100 μm in 200 milliseconds. Therefore, if the timing of drying the liquid droplets fluctuates in the range of 100 milliseconds to 200 milliseconds later, the size of the ink dots also fluctuates. That is, the line width of the corresponding track fluctuates in the range of about 70 μm˜100 μm.

Therefore, in this liquid droplet drying method, in order to suppress fluctuations in the dot size, laser drying has been proposed in which the liquid droplets landed on the green sheet are irradiated with laser light. In laser drying, droplets are dried only in the irradiated area of the laser. Therefore, the drying timing of the landed liquid droplets can be controlled with high precision, so that fluctuations in the ink dot size can be suppressed.

However, in a droplet ejection device used in the inkjet method, the gap between the droplet ejection head and the object is usually narrowed to several hundred μm in order to ensure droplet landing accuracy. Therefore, when drying the discharged liquid droplets, that is, the liquid droplets located directly under the liquid droplet discharge head, it is necessary to irradiate the laser light in a direction substantially tangential to the object in the narrow gap between the liquid droplet discharge head and the object. . As a result, the optical cross-section (that is, the beam spot) of the laser beam formed on the object is enlarged, and the laser intensity necessary for drying liquid droplets cannot be ensured. Therefore, there is a possibility that the drying of the liquid droplets will be insufficient, resulting in poor formation of trajectories composed of ink dots.

Contents of the invention

An object of the present invention is to provide a track forming method, a droplet ejection device, and a circuit module that improve droplet drying efficiency and reduce poor formation of tracks formed by ink dots.

In order to achieve the object, one aspect of the present invention provides a track forming method. In this method, droplets of a track-forming material are ejected to a substrate, the droplets (individually) dropped on the substrate are dried by irradiating laser light to form tracks composed of the droplets, Polarized light with a P polarized light component of 80% to 100% is used as laser light.

Another aspect of the present invention provides a droplet discharge device. This droplet discharge device includes: a droplet discharge head that discharges droplets of a track-forming material onto a substrate; and a laser irradiation device that irradiates laser light to the droplets landed on the substrate. The laser light is polarized light with a P polarized light component of 80% to 100%.

In addition, still another aspect of the present invention provides a circuit module including: a substrate; circuit elements formed on the substrate; metal wiring formed by the droplet ejection device, the metal wiring formed on the on the substrate and electrically connected to the circuit elements.

Description of drawings

1 is a perspective view showing a circuit module of the present invention;

FIG. 2 is an explanatory diagram illustrating a method of manufacturing the circuit module of FIG. 1;

3 is a perspective view showing a droplet ejection device;

4 is a perspective view showing a droplet ejection head;

5 is a cross-sectional view of the droplet ejection head on line A-A of FIG. 4;

Fig. 6 is a schematic diagram for explaining a semiconductor laser;

FIG. 7 is an electrical module circuit diagram illustrating the electrical configuration of the droplet ejection device.

Detailed ways

Next, an embodiment embodying the present invention will be described with reference to FIGS. 1 to 7 . First, the circuit module 1 of the present invention will be described.

In this specification, +X, +Y, +Z directions refer to directions indicated by arrows in the drawings, and -X, -Y, -Z directions refer to directions opposite to +X, +Y, +Z directions. The X, Y, and Z directions without a specified sign are synonymous with ±X, Y, and Z.

In FIG. 1 , a circuit module 1 includes: a plate-shaped LTCC multilayer substrate 2 ; and a plurality of semiconductor chips 3 connected by wire bonding or flip chip connection on the upper side of the LTCC multilayer substrate 2 .

The LTCC multilayer substrate 2 includes a plurality of low-temperature-fired ceramic substrates (hereinafter simply referred to as insulating layers 4 ) that are laminated in a sheet shape. Each insulating layer 4 is a sintered body made of a glass-ceramic material and has a thickness of several hundred μm. The glass-ceramic material is, for example, a mixture of a glass component such as borosilicate alkali oxide and a ceramic component such as alumina.

Various circuit elements 5 such as resistive elements, capacitive elements, or winding elements, and a plurality of internal wirings 6 serving as metal wirings electrically connecting the circuit elements 5 are formed between insulating layers 4 . The circuit element 5 and the internal wiring 6 are each a sintered body of metal fine particles such as silver or a silver alloy, and are formed by using the droplet ejection device 10 of the present invention. A hole trace 7 having a stacked hole structure or a thermal hole structure is formed in each insulating layer 4 for electrically connecting the circuit element 5 and the internal wiring 6 between layers. Like the circuit element 5 or the internal wiring 6, the hole track 7 is a sintered body of metal fine particles such as silver or silver alloy.

Next, a method of manufacturing the LTCC multilayer substrate 2 will be described with reference to FIG. 2 .

In FIG. 2 , first, a green sheet 4S is a substrate cut out to form an insulating layer 4 , which is subjected to press processing or laser processing to form through holes 7H. Next, screen printing using a metal paste is performed on the green sheet 4S a plurality of times, and the metal paste is filled in the through holes 7H to form hole traces 7F made of the metal paste. Next, inkjet printing is performed on the upper surface of the green sheet 4S, that is, the track forming surface 4Sa using metallic ink F. As shown in FIG. The metallic ink F is a material in which metal nanoparticles are dispersed in an aqueous solvent to form ink droplets to form tracks, and in this embodiment is an aqueous silver ink.

Specifically, the droplet Fb of metal ink F is ejected to the area of the track forming surface 4Sa where the circuit elements 5 and the internal wiring 6 need to be formed (hereinafter simply referred to as the track forming area), and the liquid droplets Fb falling on the track forming area are The droplets Fb are dried. Then, the discharge operation and the drying operation are repeated to draw corresponding element traces 5F and conductive traces 6F in the trace formation area. The liquid droplets Fb landed on the track formation area are dried by irradiating incident light Le (see FIG. 6 ) to the area where the landed and bonded liquid droplets Fb exist.

After forming element traces 5F, conductive traces 6F, and hole traces 7F on the green sheet 4S, multiple green sheets 4S are laminated together, and the area corresponding to the LTCC multilayer substrate 2 is cut into a laminated body 4B and fired . That is, the green sheet 4S, the element track 5F, the conductive track 6F, and the hole track 7F are laminated together and fired at the same time. An LTCC multilayer substrate 2 having an insulating layer 4, circuit elements 5, internal wiring 6, and hole tracks 7 is thus formed.

Next, the droplet ejection device 10 for drawing the element track 5F and the conductive track 6F will be described with reference to FIG. 3 . FIG. 3 is an overall perspective view showing the droplet ejection device 10 .

In FIG. 3 , a droplet ejection device 10 has a base 11 formed in a rectangular parallelepiped shape. A pair of guide grooves 12 extending in the longitudinal direction (±Y direction) of the base 11 are formed on the upper surface of the base 11 . Above the guide groove 12 there is a stage 13 which moves in the ±Y direction along the guide groove 12 . A mounting portion 14 is formed on the upper surface of the table 13 , and the green sheet 4S is mounted on the mounting portion 14 with the track forming surface 4Sa as the upper side. The mounting unit 14 fixes the green sheet 4S in the mounted state with respect to the table 13 and conveys the green sheet 4S in the ±Y direction. In this embodiment, the +Y direction is defined as the scanning direction.

On both sides of the base 11 in the X direction perpendicular to the scanning direction, guide members 16 formed in a gate shape are provided so as to straddle the base 11 . An ink tank 17 extending in the X direction is arranged above the guide member 16 . The ink tank 17 stores the metallic ink F, and supplies the metallic ink F to the droplet ejection heads 21 arranged below it at a predetermined pressure.

On the −Y direction side of the guide member 16 , a pair of upper and lower guide rails 18 extending in the X direction are formed over substantially the entire width in the X direction. The carriage 20 is mounted on a pair of guide rails 18 and moves in the ±X direction along the guide rails 18 . The discharge head 21 is mounted on the bottom surface 20 a of the carriage 20 . 4 is a perspective view of the discharge head 21 viewed from the lower side (green sheet 4S side), and FIG. 5 is a cross-sectional view of the droplet discharge head along line A-A of FIG. 4 . FIG. 6 is a schematic side view of the carriage 20 .

In FIG. 4 , the ejection head 21 is formed in a rectangular parallelepiped shape extending in the X direction. A nozzle plate 22 is provided on the lower portion of the ejection head 21 (green sheet 4S: upper portion in FIG. 4 ). The nozzle plate 22 is formed in a plate shape extending in the X direction, and has a nozzle forming surface 22a formed on its lower surface (upper surface in FIG. 4 ). The nozzle forming surface 22a is formed substantially parallel to the track forming surface 4Sa of the green sheet 4S. When the green sheet 4S is located directly below the discharge head 21, the distance (platen gap) between the nozzle forming surface 22a and the track forming surface 4Sa is kept at a predetermined distance, which is 300 μm in this embodiment. A plurality of nozzles N extending through the nozzle forming surface 22 a in the normal line direction of the nozzle forming surface 22 a are arranged along the X direction on the nozzle forming surface 22 a.

In FIG. 5 , chambers 23 communicating with the ink tanks 17 are formed above the nozzles N, respectively. The chamber 23 supplies the metallic ink F from the ink tank 17 to the corresponding nozzle N. As shown in FIG. A vibrating plate 24 is attached to the upper side of each chamber 23 . The vibrating plate 24 can vibrate in the vertical direction to expand and contract the volume of the chamber 23 . A plurality of piezoelectric elements PZ corresponding to the nozzles N are arranged above the vibrating plate 24 . Each piezoelectric element PZ vibrates the vibrating plate 24 in the vertical direction, and the metal ink F is ejected from the corresponding nozzle N with a liquid droplet Fb of a predetermined volume (10p1 in this embodiment). The liquid droplet Fb ejected from the nozzle N flies in the −Z direction, and lands on a position facing the nozzle N on the trajectory forming surface 4Sa. While scanning in the scanning direction, the dropped liquid droplet Fb wets and spreads on the track forming surface 4Sa, and joins with the previously landed liquid droplet Fb. When the green sheet 4S is scanned in the scanning direction, the joined liquid droplets Fb form a liquid film FL extending in the scanning direction. The liquid film FL extends over the entire top surface of the green sheet 4S, forming a liquid surface FLa parallel to the track forming surface 4Sa.

In the present embodiment, each landing position P is defined as a position corresponding to each nozzle N in the −Z direction, that is, a landing position of the droplet Fb, among positions on the trajectory forming surface 4Sa. In addition, an end portion in the direction opposite to the scanning direction of the liquid surface FLa, that is, in the −Y direction is defined as an incident position Pe. The distance between the landing position P and the incident position Pe is defined as the standby distance WF.

In FIG. 6 , on the bottom surface 20 a of the carriage 20 , an exit hole H is formed along the scanning direction of the ejection head 21 , that is, the +Y direction, and the exit hole H penetrates into the chamber 20 . The width of the exit hole H in the X direction is substantially the same as the width of the nozzle 21 in the X direction. A semiconductor laser module LDM constituting a laser irradiation device is disposed above the emission hole H in the chamber 20 .

The semiconductor laser module LDM has a semiconductor laser LD and an optical element PS constituting an irradiation optical system. The semiconductor laser LD emits collimated laser light in a band shape extending substantially over the entire width of the exit hole H in the X direction downward. The wavelength of the laser light emitted from the semiconductor laser LD is set within the range of the absorption wavelength of the metallic ink F (808 nm in this embodiment). The optical element PS includes a retardation plate, converts the polarization state of the laser light from the semiconductor laser LD into predetermined linearly polarized light, and emits it downward. In this embodiment, the predetermined linearly polarized light is a P-polarized light component for 100% polarized light.

Inside the exit hole H, a cylindrical lens 25 constituting an irradiation optical system is disposed. The lens 25 has curvature only in the Y direction, and the width of the lens 25 in the X direction is the same as the width of the ejection head 21 in the X direction. When lens 25 receives laser light from semiconductor laser module LDM, it condenses only the component of the laser light in the +Y direction (or -Y direction), and emits it downward as incident light Le.

A mirror stage 26 extending downward from the chamber 20 and a mirror 27 rotatably supported by the mirror stage 26 are disposed below the output hole H. The reflection mirror 27 constitutes an irradiation optical system. The mirror stage 26 rotatably supports the reflection mirror 27 about a rotation axis along the X direction. The reflection mirror 27 is a galvano mirror having a reflection surface 27 m on the side opposite to the cylindrical lens 25 , and the width of the reflection mirror 27 in the X direction is the same as the width of the ejection head 21 in the X direction. The reflection mirror 27 receives the incident light Le from the lens 25 on the reflection surface 27m, and reflects the incident light Le in a direction substantially tangential to the track forming surface 4Sa. In the present embodiment, the angle formed by the normal to the liquid surface FLa (track forming surface 4Sa) and the reflected incident light Le is defined as the incident angle θe, which is set to 88°.

The incident light Le reflected by the mirror 27 is introduced into the gap between the ejection head 21 and the green sheet 4S, and the region corresponding to the beam waist is incident on the incident position Pe on the liquid surface FLa. Part of the incident light Le incident on the incident position Pe passes through the liquid film FL and is absorbed. That is, when the green sheet 4S is scanned in the scanning direction, that is, the +Y direction, part of the incident light Le reflected by the mirror 27 sequentially dries the liquid film FL near the incident position Pe to form layer tracks FP extending in the scanning direction.

On the other hand, a portion of the incident light Le incident on the incident position Pe that has not passed through the liquid film FL is reflected in a direction opposite to the scanning direction as reflected light Lr. In the present embodiment, a plane (YZ plane) defined by the reflected incident light Le and the reflected light Lr corresponding to the incident light Le is defined as the incident plane.

The reflectance of the incident light Le with respect to the liquid film FL varies depending on the polarization state of the incident light Le. Specifically, assuming that the refractive index of air is N1 and the refractive index of the liquid film FL is N2, the reflectance Rp of polarized light (P polarized light) with the direction of the electric field vector E parallel to the incident plane is derived from the following formula The reflectance Rs of polarized light (S polarized light) whose direction of the electric field vector E is perpendicular to the incident plane. When the incident angle θe is arbitrary, the reflectance Rp of P-polarized light is lower than the reflectance Rs of S-polarized light.

$\mathrm{<span\; class="notranslate">\; Rp</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="A20071010089600191.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;e</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="N"\; filenames="A20071010089600161.png,A20071010089600171.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; \}</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="A20071010089600191.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;e</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="N"\; filenames="A20071010089600161.png,A20071010089600171.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; \}</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

$\mathrm{<span\; class="notranslate">\; Rs.</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="N"\; filenames="A20071010089600161.png,A20071010089600171.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;e</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="A20071010089600191.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; \}</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="N"\; filenames="A20071010089600161.png,A20071010089600171.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;e</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="A20071010089600191.png"\; state="\{\{state\}\}">N</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; \}</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Here, φ=sin ^-1 {(N1/N2)cos(π/2-θe)}

For example, if the refractive index of air is 1, the refractive index of liquid film FL is 1.3, and the incident angle θe is 88°, then the reflectance Rp of P-polarized light and the reflectance Rs of S-polarized light are 75.2% and 84.5%, respectively. That is, about 10% more of the P-polarized incident light Le incident on the incident position Pe than the S-polarized incident light Le passes through the liquid film FL and is absorbed.

In the droplet discharge device 10 of the present invention, the optical element PS of the semiconductor laser module LDM converts the laser light emitted from the semiconductor laser LD into P-polarized light, and emits P-polarized incident light Le. Here, in this embodiment, the so-called P-polarized light refers to light whose electric field vector vibrates parallel to the incident plane, that is, linearly polarized light that does not substantially contain other components, that is, the P-polarized light component is 100%. polarized light.

As a result, most of the incident light Le whose polarization state has been converted to P-polarized light passes through the liquid film FL and is absorbed. As a result, the absorptivity of the incident light Le is increased, and because of this, the liquid film FL can be reliably dried to form the layer track FP without insufficient drying. By sequentially laminating the layer traces FP, the conductive traces 6F (see FIG. 2 ) can be formed, and formation defects thereof can be reduced.

Next, the electrical configuration of the droplet ejection device 10 configured as described above will be described with reference to FIG. 7 .

In FIG. 7, the control device 40 includes CPU, ROM, and RAM, and moves the table 13 and the carriage 20 according to various stored data and various control programs, and controls the operation of the semiconductor laser module LDM and each piezoelectric element PZ. .

An input device 41 having operation switches such as a start switch and a stop switch is connected to the control device 40 . Information on the position coordinates of the track forming region (layer track FP) relative to the drawing plane (track forming surface 4Sa) is input from the input device 41 to the control device 40 as drawing information Ia in a predetermined format. The control device 40 receives the drawing information Ia from the input device 41, and generates bitmap data BMD.

The bitmap data BMD is data specifying whether each piezoelectric element PZ is turned on or off according to the value (0 or 1) of each bit. The bitmap data BMD is data specifying whether or not to discharge the liquid droplet Fb to each position on the drawing plane (track forming surface 4Sa) through which the discharge head 21 passes. That is, the bitmap data BMD is used to discharge the liquid droplets Fb to respective corresponding target positions defined by the track formation area.

The control device 40 is connected to the X-axis motor drive circuit 42 and outputs corresponding drive control signals to the X-axis motor drive circuit 42 . The X-axis motor drive circuit 42 rotates the X-axis motor MX that moves the carriage 20 forward or backward in response to a drive control signal from the control device 40 . The X-axis motor drive circuit 42 is connected to the X-axis encoder XE, and receives a detection signal from the X-axis encoder XE. The X-axis motor driving circuit 42 generates a signal related to the moving direction and moving amount of the carriage 20 (each landing position P) relative to the trajectory forming surface 4Sa based on the detection signal from the X-axis encoder XE, and outputs the signal to the control device. 40.

The control device 40 is connected to the Y-axis motor drive circuit 43 and outputs a corresponding drive control signal to the Y-axis motor drive circuit 43 . The Y-axis motor drive circuit 43 responds to a drive control signal from the control device 40 to rotate the Y-axis motor MY of the moving table 13 forward or backward. The Y-axis motor drive circuit 43 is connected to the Y-axis encoder YE, and receives a detection signal from the Y-axis encoder YE. The Y-axis motor drive circuit 43 generates a signal related to the moving direction and moving amount of the table 13 (track forming surface 4Sa) based on the detection signal from the Y-axis encoder YE, and outputs the signal to the control device 40 . The control device 40 calculates the relative position of the landing position P with respect to the trajectory forming surface 4Sa based on the signal from the Y-axis motor drive circuit 43, and outputs the ejection timing signal LP every time the landing position P is at the corresponding target position.

The control device 40 is connected to a semiconductor laser drive circuit 44, and outputs a drawing start signal S1 to the semiconductor laser drive circuit 44 when the drawing operation starts, and outputs a drawing end signal S2 to the semiconductor laser drive circuit 44 when the drawing operation ends. The semiconductor laser drive circuit 44 causes the semiconductor laser module LDM to emit P-polarized incident light Le when the drawing start signal S1 is input, and stops the semiconductor laser module LDM from emitting the incident light Le when the drawing end signal S2 is input. That is, the control device 40 controls the operation of the semiconductor laser module LDM via the semiconductor laser drive circuit 44 during the drawing operation period, and emits P-polarized incident light Le.

The control device 40 is connected to the ejection head drive circuit 45 , and outputs the piezoelectric element drive voltage COM for driving each piezoelectric element PZ and the ejection timing signal LP to the ejection head drive circuit 45 synchronously. In addition, the control device 40 generates a discharge control signal SI synchronized with a predetermined clock signal based on the bitmap data BMD, and transmits the discharge control signal SI to the discharge head drive circuit 45 in serial. The ejection head drive circuit 45 sequentially performs serial/parallel conversion on the ejection control signal SI from the control device 40 corresponding to each piezoelectric element PZ. Whenever the ejection head drive circuit 45 receives the ejection timing signal LP from the control device 40, it locks the serial/parallel converted ejection control signal SI, and drives the piezoelectric element drive voltage COM to the corresponding signal SI respectively. The selected piezoelectric elements PZ are supplied.

Next, a method of drawing the element track 5F and the conductive track 6F using the droplet discharge device 10 will be described.

First, as shown in FIG. 3 , the green sheet 4S is placed on the stage 13 so that the track forming surface 4Sa is located on the upper side. At this time, the stage 13 arranges the green sheet 4S on the opposite side to the scanning direction by the carriage 20 .

From this state, the drawing information Ia is input to the control device 40 from the input device 41, and the control device 40 generates bitmap data BMD based on the drawing information and stores it. Next, when the green sheet 4S is scanned, the control device 40 moves the carriage 20 (discharging head 31 ) to a predetermined position via the X-axis motor drive circuit 42 so that the target position passes the corresponding landing position P. When the carriage 20 is arranged at a fixed position, the control device 40 starts scanning the green sheet 4S via the Y-axis motor drive circuit 43 .

When the green sheet 4S starts to be scanned, the control device 40 outputs a drawing start signal S1 to the semiconductor laser drive circuit 44, and the semiconductor laser module LDM emits P-polarized incident light Le. The incident light Le emitted from the semiconductor laser module LDM is reflected by the mirror 27 in a substantially tangential direction of the green sheet 4S, and enters the track forming surface 4Sa at an incident angle θe.

In addition, when the scanning of the green sheet 4S starts, the control device 40 outputs the ejection control signal SI generated based on the bitmap data BMD to the ejection head drive circuit 45 .

In addition, when the scanning of the green sheet 4S is started, the control device 40 outputs the discharge timing signal LP to the discharge head driving circuit 45 every time the target position is located at the corresponding landing position P. That is, the control device 40 selects the nozzle N for ejecting the liquid droplet Fb according to the ejection control signal SI, and every time the ejection position P corresponding to the selected nozzle N is located at the target position, the nozzle N is directed toward the target position. The position ejects the liquid droplet Fb.

Each ejected liquid droplet Fb lands on a predetermined corresponding target position on the trajectory forming surface 4Sa. When the droplet Fb landed on each target position scans the standby distance WF in the scanning direction, it joins with the previously landed droplet Fb to form a liquid film FL spreading in the track formation region. P-polarized incident light Le is incident on the incident position Pe on the liquid film FL.

Most of the P-polarized light of the incident light Le incident on the incident position Pe passes through the liquid film FL and is absorbed, thereby forming a layer track FP without insufficient drying. Thereafter, by sequentially laminating the layer traces FP, the element traces 5F and the conductive traces 6F can be formed, and poor formation thereof can be reduced.

Effects of the present embodiment configured as described above are described below.

A semiconductor laser module LDM having a semiconductor laser LD and an optical element PS is mounted on the carriage 20 on which the ejection head 21 is mounted. The liquid film FL is formed by joining of the liquid droplets Fb discharged onto the green sheet 4S by the discharge head 21 . The semiconductor laser module LDM injects the incident light Le of P-polarized light onto the liquid surface FLa of the liquid film FL.

As a result, the portion of the incident light Le whose polarization state is converted to P-polarized light reduces the amount of reflection from the liquid surface FLa and increases the amount of transmission into the liquid film FL. As a result, the absorptivity of incident light Le with respect to the liquid film FL can be increased, and the drying efficiency of the liquid film FL can be improved. Therefore, formation defects of the element trace 5F and the conductive trace 6F, that is, the circuit element 5 and the internal wiring 6 can be reduced.

The carriage 20 includes an ejection head 21 , a semiconductor laser module LDM, and a reflection mirror 27 . Thereby, the relative position of the incident light Le with respect to the dropped liquid droplet Fb can be maintained. As a result, the incident light Le of P-polarized light can be incident on the incident position Pe of the liquid surface FLa with high reproducibility. Therefore, the dry state of the element trace 5F and the conductive trace 6F can be stabilized, and formation defects of the circuit element 5 and the internal wiring 6 can be further reduced.

In addition, since the light source of the incident light Le is constituted by the semiconductor laser LD, it is possible to reduce the size and weight of the droplet discharge device 10 .

The reflection mirror 27 reflects the incident light Le from the semiconductor laser module LDM along the substantially tangential direction of the green sheet 4S, and makes it incident on the liquid surface FLa facing the ejection head 21 . Accordingly, it is possible to immediately dry the ejected droplets Fb and the joined droplets Fb. As a result, the degree of freedom in the shape and size of the element track 5F and the conductive track 6F can be expanded.

The optical element PS converts the polarization state of the laser light emitted from the semiconductor laser LD, and emits P-polarized incident light Le. Accordingly, regardless of the polarization state of the laser light from the semiconductor laser LD, the P-polarized laser light is always incident on the liquid surface FLa. As a result, pattern formation defects can be more reliably reduced.

The above-described embodiment can be modified as follows.

The incident light Le of P-polarized light may be configured to be incident on the isolated liquid droplet Fb instead of being incident on the liquid film FL formed by joining the liquid droplets Fb. That is, the present invention is not limited by the shape of the liquid droplet Fb which is the object to be irradiated with laser light, as long as the polarization state of the laser light incident on the liquid droplet Fb is P-polarized light.

The incident light Le of P-polarized light may be made to enter in another direction instead of the incident angle θe along the substantially tangential direction of the green sheet 4S. For example, incident light Le of P-polarized light may be incident at an incident angle θe along a substantially normal direction of the green sheet 4S.

The incident light Le, which is the laser light emitted from the semiconductor laser LD, is not limited to P-polarized light having a polarization component of 100%, but may be polarized light having a polarization component of at least 80% to 100%.

For example, the incident light Le from the semiconductor laser module LDM may be divided corresponding to each nozzle N, and each part of the divided incident light Le of the incident light Le irradiates the corresponding liquid film FL, thereby instead of using a common incident light Le to The liquid film FL is dried. Alternatively, the same number of semiconductor laser modules LDM as the number of nozzles N may be arranged, and the incident light Le from each semiconductor laser module LDM may irradiate the corresponding liquid film FL.

At this time, it is preferable to select whether to irradiate or not to irradiate each incident light Le according to the ejection control signal SI for selecting the nozzle N. That is, it is preferable to emit only the incident light Le corresponding to the nozzle N that ejects the liquid droplet Fb. Accordingly, the incident light Le enters only the region of the liquid film FL, and the utilization efficiency of the incident light Le can be improved.

The incident light Le of the P-polarized light not only dries the liquid droplets Fb or the liquid film FL, but also burns the dried liquid droplets Fb or the liquid film FL. Thereby, by the locally irradiated incident light Le, the firing failure of the element track 5F and the conductive track 6F can be reduced.

Instead of the control device 40 generating the bitmap data BMD based on the drawing information Ia, bitmap data BMD generated in an external device in advance may be transmitted from the input device 41 to the control device 40 .

The reflective mirror 27 may be a prism instead of a galvanic mirror. Alternatively, the reflection mirror 27 may be omitted, and the incident light Le from the cylindrical lens 25 may be directly irradiated onto the liquid droplet Fb.

The droplet ejection head is not limited to the liquid droplet ejection head 21 driven by a piezoelectric element, and may be a discharge head of a resistive heating method or an electrostatic drive method.

All the circuit elements 5 and internal wiring 6 may not be formed by the inkjet method. Only relatively fine circuit elements 5 or internal wiring 6 may be formed by the inkjet method.

The track forming material is not limited to metallic ink, and may be a liquid in which an insulating film material or an organic material is dispersed. That is, the track-forming material may be any material that is dried by receiving a laser beam and forms solid-phase tracks.

The traces are not limited to the element trace 5F and the conductive trace 6F. The traces can also be embodied as various metal wirings included in liquid crystal display devices, organic electroluminescence display devices, field effect display devices (FED, SED, etc.) having planar electron emission elements, and the like. The so-called track includes a plurality of linear accumulations forming a pattern, or points forming an identification code. That is, the trajectory may be a solid-phase trajectory formed of dried liquid droplets.

Claims (10)

1. A trajectory forming method, characterized in that, ejecting droplets of track-forming material onto the substrate, drying the droplets that land on the substrate by irradiating them with laser light to form tracks made up of the droplets, Polarized light with a P polarized light component of 80% to 100% is used as laser light. 2. The track forming method as claimed in claim 1, wherein, The droplets are dried by irradiating the laser light in a direction substantially tangential to the substrate. 3. A droplet ejection device comprising: a droplet ejection head that ejects droplets of track-forming material toward the substrate; a laser irradiation device that irradiates laser light to the droplet landed on the substrate, The laser light is polarized light with a P polarized light component of 80% to 100%. 4. The droplet ejection device according to claim 3, wherein: The laser irradiation device irradiates laser light to the liquid droplets opposed to the liquid droplet ejection heads in a substantially tangential direction to the substrate. 5. The droplet ejection device according to claim 3, wherein, further comprising a carriage that carries the droplet ejection head and relatively scans the droplet ejection head in one direction relative to the substrate, The laser irradiation device includes: a semiconductor laser mounted on the carriage and emitting the laser light; The irradiation optical system is mounted on the carriage and irradiates the liquid droplets with laser light emitted from the semiconductor laser. 6. The droplet ejection device according to claim 5, wherein: The irradiation optical system includes an optical element that converts the polarization state of the laser light emitted from the semiconductor laser into P-polarized light. 7. The droplet ejection device according to any one of claims 3 to 6, wherein: The track forming material is metal ink dispersed with metal particles, The substrate is a low temperature fired ceramic substrate. 8. The droplet ejection device according to claim 3, wherein: The droplet ejection head has a nozzle plate including a plurality of nozzles for ejecting droplets, and the laser irradiation device irradiates laser light to the droplets landed on a substrate. 9. The droplet ejection device according to claim 5, wherein: A hole through which laser light from the semiconductor laser passes and emits is formed on the carriage, and a width of the liquid ejection head in a scanning direction of the droplet ejection head is substantially the same as a width of the ejection hole. 10. A circuit module comprising: Substrate; circuit elements formed on the substrate; metal wiring formed on the substrate and electrically connected to the circuit element, Wherein, the metal wiring is formed by a droplet discharge device, The droplet ejection device includes: a droplet ejection head that ejects droplets of track-forming material toward the substrate; a laser irradiation device that irradiates laser light to the droplet landed on the substrate, The laser light is polarized light with a P polarized light component of 80% to 100%.

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