JP3821072B2 - Electronic circuit board and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic circuit board on which an electronic component chip is mounted, and more particularly to an electronic circuit board having a wiring pattern formed on at least one surface and side surfaces of a ceramic substrate and a method for manufacturing the same.
[0002]
[Prior art]
As a small electronic circuit board mounted inside an optical device package, there is a mount board on which a semiconductor laser diode (LD) or a semiconductor photodiode (PD) is directly mounted. As this type of mounting substrate, one having a wiring pattern formed on the surface and side surfaces of the substrate is known. A conventional electronic circuit board having a wiring pattern formed on the surface and side surfaces of such a substrate has been manufactured as follows, for example, through a process as shown in FIG. That is, first, as shown in FIG. 8A, a base metal thin film (not shown) was formed on one surface (upper surface) of the ceramic substrate 21 by a vacuum deposition method or the like.
[0003]
Thereafter, the resist was patterned by a photolithography technique so that a predetermined wiring pattern was formed on the underlying metal thin film. Next, the substrate 21 was subjected to metal plating, and a metal plating film was formed on the base metal thin film patterned into a predetermined wiring pattern. Thereafter, the ceramic substrate 21 was cut into strips to form a plurality of strip substrates 22, 22,. Next, the strip substrate 22 was rotated 90 degrees so that the surface of the strip substrate 22 on which the metal plating film was formed was turned sideways, and the strip substrate 22 was arranged as shown in FIG. 8B.
[0004]
Next, after forming a base metal thin film on one surface of the strip substrate 22 (a surface perpendicular to the surface on which the metal plating film was previously formed) by a vacuum deposition method or the like, a predetermined metal film is formed on the base metal thin film. The resist was patterned by photolithography so that the wiring pattern 23 was formed. Thereafter, the strip substrate 22 was subjected to metal plating, and a metal plating film was formed on the base metal thin film patterned into a predetermined wiring pattern. As a result, as shown in FIG. 8C, a strip substrate 22 having a wiring pattern 23 formed on the side surface is obtained.
[0005]
By cutting this into a predetermined size, a circuit substrate (mount substrate) 24 as shown in FIG. 8D having a predetermined wiring pattern formed on the surface and side surfaces is obtained. However, in the manufacturing method as described above, after cutting the ceramic substrate 21 into a plurality of strip substrates 22, it is necessary to pattern the side surfaces of the strip substrate 22 into a predetermined wiring pattern. .
[0006]
For this reason, the manufacturing process is complicated, time-consuming, and a long time is required to produce this type of circuit board. Further, in order to improve the alignment accuracy between the wiring pattern formed on the surface and the wiring pattern formed on the side surface, it is necessary to pattern the strip substrates 22 one by one, which is very troublesome. As a result, this type of circuit board is expensive.
[0007]
In view of this, a manufacturing method that does not require patterning for each strip substrate has been proposed in Japanese Patent Application Laid-Open No. 5-291427. In the method proposed in Japanese Patent Laid-Open No. 5-291427, first, as shown in FIG. 9A, a groove 32 having a predetermined depth is processed by dicing at a predetermined interval on a substrate 31. . Next, as shown in FIG. 9B, a metal deposition film 33 is deposited on the surface and both side surfaces of the substrate 31 in the order of Cr / Pt / Au. Thereafter, a photoresist pattern is formed on the metal vapor-deposited film, and then dry etching is performed on the Cr / Pt / Au by ion milling to form a predetermined wiring pattern.
[0008]
Next, as shown in FIG. 9C, the back surface of the substrate 31 was polished flat to obtain a strip-shaped substrate 34. Next, a strip-shaped substrate 34 separated from the substrate 31 in a strip shape was arranged side by side with a portion having a wiring pattern, and then a photoresist was applied, and the photoresist pattern was formed by overlapping the wiring position previously formed on the surface. Next, Cr / Pt / Au is dry-etched using the photoresist pattern as a mask to form a side wiring pattern, and the photoresist is removed. As a result, the wiring pattern 35 is formed on the side surface of the strip-shaped substrate 34 as shown in FIG. Then, by dicing the strip-shaped substrate 34, a circuit substrate (mount substrate) 36 having a predetermined wiring pattern formed on the surface and side surfaces as shown in FIG. 9E is obtained.
[0009]
[Problems to be solved by the invention]
However, in the manufacturing method proposed in Japanese Patent Laid-Open No. 5-291427, a ceramic substrate is cut into strips to form a plurality of strip substrates, and then a pattern is formed on a side surface of the strip substrate in a predetermined wiring pattern. It is necessary to ning. For this reason, the manufacturing process is complicated, time-consuming, and a long time is required to produce this type of circuit board. Further, in order to improve the alignment accuracy between the wiring pattern formed on the surface and the wiring pattern formed on the side surface, it is necessary to pattern the strip substrates one by one. For this reason, there has been a problem that this type of substrate becomes expensive due to much labor.
[0010]
Accordingly, the present invention has been made to solve the above-described problems, and is an electronic circuit board capable of simultaneously and easily forming a wiring pattern on the surface and side surfaces of the board with little effort and without any effort. The object is to provide a manufacturing method.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a method of manufacturing an electronic circuit board according to the present invention includes a through hole forming step for forming a through hole for forming a side wiring pattern in the thickness direction of a ceramic substrate, and the surface of the ceramic substrate and the through hole. A metal thin film forming process for forming a metal thin film on the peripheral wall of the metal simultaneously, a photolithography process for patterning the metal thin film into a predetermined wiring pattern by photolithography, and metal plating on the metal thin film patterned into the predetermined wiring pattern A metal plating step for forming a film, a metal thin film removal step for removing unnecessary portions of the metal thin film, and a cutting step for cutting along a cutting line crossing the through hole are provided.
[0012]
Thus, after forming the through hole for forming the side surface wiring pattern in the thickness direction of the ceramic substrate, a metal thin film is simultaneously formed on the surface of the substrate and the peripheral wall surface of the through hole, and a predetermined wiring pattern is formed by photolithography. When the metal plating film is formed on the patterned metal thin film, it is possible to simultaneously form the wiring pattern on the surface and the wiring pattern on the side surface. For this reason, it is possible to obtain an electronic circuit board in which wiring patterns are simultaneously formed on the surface and side surfaces of the board with ease and accuracy, with little effort.
[0013]
Here, if the side surface wiring pattern is formed by dipping the photoresist under the through hole, the wiring pattern can be formed on the side surface of the substrate with ease, ease and accuracy. Moreover, when a metal thin film is formed by sputtering, the metal thin film can be formed also on the peripheral wall surface of the through hole.
[0014]
In this case, when cutting as a separate electronic circuit board from a ceramic substrate having a wiring pattern formed on the surface and side surfaces, if a cutting line is set across the through hole, the surface of the wiring pattern formed in the through hole Is located at a position recessed from the peripheral wall surface of the ceramic substrate. Thereby, a concave portion formed by cutting along a cutting line crossing the through hole is provided on at least one side surface of the ceramic substrate, and the side wiring pattern is formed by the metallized layer formed on the peripheral wall surface in the concave portion, The metallized layer formed on the bottom surface of the recess is formed continuously with the metallized layer to be the surface wiring pattern formed on the surface, and at least one wiring in the side surface wiring pattern is made up of the other by the photoresist dip. An electronic circuit board formed shorter than the wiring is obtained. As a result, when an electronic component is soldered to the surface of the metallized layer in the recess, it is possible to prevent the solder from protruding and coming into contact with the adjacent metallized layer.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, an electronic circuit board according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. However, the present invention is not limited to this, and may be appropriately modified and implemented without changing the gist thereof. can do. FIG. 1 is a diagram schematically showing a first step for manufacturing the electronic circuit board of the present invention, FIG. 1 (a) is a front view, and FIG. 1 (b) is a diagram in FIG. It is sectional drawing which expands and shows the AA 'cross section of. FIG. 2 is a view schematically showing a second step for manufacturing the electronic circuit board of the present invention, FIG. 2A is a front view, and FIG. 2B is A in FIG. It is sectional drawing which expands and shows -A 'cross section. FIG. 3 is a diagram schematically showing a third step for manufacturing the electronic circuit board of the present invention, FIG. 3A is a front view, and FIG. 3B is A in FIG. It is sectional drawing which expands and shows -A 'cross section.
[0016]
FIG. 4 is a view schematically showing a fourth step for manufacturing the electronic circuit board of the present invention, FIG. 4 (a) is a front view, and FIG. 4 (b) is an A view in FIG. 4 (a). It is sectional drawing which expands and shows -A 'cross section. FIG. 5 is a view schematically showing a fifth step for manufacturing the electronic circuit board of the present invention, FIG. 5 (a) is a front view, and FIG. 5 (b) is an A view in FIG. 5 (a). It is sectional drawing which expands and shows -A 'cross section. FIG. 6 is a view schematically showing a sixth step for manufacturing the electronic circuit board of the present invention, FIG. 6 (a) is a front view, and FIG. 6 (b) is an A view in FIG. 6 (a). It is sectional drawing which expands and shows -A 'cross section. FIG. 7 is a diagram schematically showing a seventh step for producing the electronic circuit board of the present invention, and FIG. 7A is a front view showing a part of FIG. FIG. 7B is a perspective view showing an electronic circuit board manufactured by cutting along the cutting lines XX and Y ₁ -Y ₁ and Y ₂ -Y ₂ of FIG. 7A.
[0017]
First, a ceramic substrate (for example, 96% Al ₂ O ₃ ) 11 having a large area (for example, having a width and length of 76.2 mm × 76.2 mm and a thickness of 1 mm) was prepared. Thereafter, as shown in FIG. 1 (a), drilling is performed with a laser processing machine (the positioning accuracy is set to be within ± 5 μm) in a predetermined shape and in a predetermined arrangement. did. Thereby, as shown in FIG.1 (b), the several through-hole 12 penetrated in the thickness direction of this ceramic substrate 11 was formed. The through hole 12 is provided for forming a side wiring pattern, and a wiring pattern is formed in a subsequent film forming process to form a side wiring pattern.
[0018]
Next, the ceramic substrate 11 on which the plurality of through holes 12 were formed was placed in a sputtering apparatus. Thereafter, a vacuum pump connected to the inside of the sputtering apparatus was operated to keep the inside of the sputtering apparatus in a vacuum state. Next, argon (Ar) gas was introduced into the sputtering apparatus, and a DC high voltage was applied between the Cr target disposed at a predetermined position in the sputtering apparatus and the ceramic substrate 11. Thereby, the ionized argon collides with the target (Cr), and the repelled target material (Cr) adheres to the surface of the ceramic substrate 11 and the peripheral wall surface of each through hole 12.
[0019]
As a result, a Cr sputtered film (for example, a film thickness of 0.03 μm) is formed on the surface of the ceramic substrate 11 and the peripheral wall surface of each through hole 12. Thereafter, in the same manner as described above, a DC high voltage is applied between the Cu target placed at a predetermined position in the sputtering apparatus and the ceramic substrate 11 to thereby provide a surface of the ceramic substrate 11 on which the Cr sputtered film is formed. A Cu sputtered film (for example, a film thickness of 0.2 μm) was formed on the peripheral wall surface of each through-hole 12. As a result, as shown in FIGS. 2A and 2B, the metal film 13 made of the Cr sputtered film and the Cu sputtered film is formed on the surface of the ceramic substrate 11 and the peripheral wall surface of each through hole 12. Become.
[0020]
Next, a photoresist film is formed on the surface of the ceramic substrate 11 on which the metal film 13 is formed, or a resist film is formed using a dry film, and exposed so as to form a predetermined wiring pattern (note that the positioning accuracy during exposure is ± 5 μm). And then developed. Thereby, as shown in FIGS. 3A and 3B, a resist film 14 on which a predetermined wiring pattern is formed is formed on the surface of the ceramic substrate 11 on which the metal film 13 is formed. On the other hand, the resist was dipped in a photoresist solution so that the back surface of the ceramic substrate 11 was on the lower side. Then, after exposing so that a predetermined wiring pattern might be formed in the surrounding wall surface of each through-hole 12, it developed. As a result, as shown in FIGS. 4A and 4B, a resist film 15 is formed on the lower portion of the peripheral wall surface of the predetermined through-hole 12.
[0021]
Next, this ceramic substrate 11 was placed in a gold plating tank (not shown) and plated with gold. As a result, as shown in FIGS. 5A and 5B, the gold plating film 16 is formed on the metal film 13 on which the resist is not patterned. Next, after removing the resist films 14 and 15 previously formed, the metal film 13 where the resist films 14 and 15 were removed was removed by etching. As a result, as shown in FIGS. 6A and 6B, a metal film (Cr sputtered film and Cu sputtered film) 13 having a predetermined wiring pattern is formed on the surface of the ceramic substrate 11 and the peripheral wall surface of each through hole 12. Then, the gold plating film 16 is formed by being laminated thereon.
[0022]
Next, as shown in FIG. 7A, the ceramic substrate 11 is cut along a cutting line XX to form a strip-like substrate in which electronic circuit boards are arranged in a horizontal row, and then the strip-like substrate is cut into cutting lines. By cutting along Y ₁ -Y ₁ and Y ₂ -Y ₂ , individually separated electronic circuit boards 10 as shown in FIG. 7B are produced. In this case, as shown in FIG. 7A, when the cutting line Y ₂ -Y ₂ is set so as to cross the through hole 12, the surface of the gold plating film 16 that becomes the wiring pattern formed in the through hole 12 is As shown in FIG. 7B, the ceramic substrate 11 is located at a position recessed from the surface of the side wall. As a result, when an electronic component is soldered to the surface of the gold plating film 16, it is possible to prevent the solder from protruding and coming into contact with the adjacent gold plating film 16.
[0023]
【The invention's effect】
As described above, in the present invention, after forming the through hole 12 for forming the side wiring pattern in the thickness direction of the ceramic substrate 11, the metal thin film 13 is formed on the surface of the substrate 11 and the peripheral wall surface of the through hole 12. Form. Thereafter, photoresists 14 and 15 are patterned so as to form a predetermined wiring pattern, and a gold plating film 16 is formed on the patterned metal thin film 13. Thereby, it is possible to simultaneously form the wiring pattern on the front surface and the wiring pattern on the side surface. As a result, it is possible to obtain the electronic circuit board 10 that can form the wiring pattern on the front surface and the side surface of the substrate with ease and accuracy, with little effort.
[0024]
In the above-described embodiment, the example in which the sputtering method is applied as the film forming method for forming the Cr film (Cr sputtered film) and the Cu film (Cu sputtered film) has been described. In addition to the method, other film forming methods such as a vacuum vapor deposition method, a metal organic vapor phase method (MOCVD method), a laser ablation method, and an ion plating method may be applied to form a Cr film or a Cu film. .
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a first step for producing an electronic circuit board of the present invention, FIG. 1 (a) is a front view, and FIG. 1 (b) is a diagram of FIG. 1 (a). It is sectional drawing which expands and shows the AA cross section.
FIG. 2 is a diagram schematically showing a second step for manufacturing the electronic circuit board of the present invention, FIG. 2 (a) is a front view, and FIG. 2 (b) is a diagram of FIG. 2 (a). It is sectional drawing which expands and shows an AA 'cross section.
3 is a diagram schematically showing a third step for manufacturing the electronic circuit board of the present invention, FIG. 3 (a) is a front view, and FIG. 3 (b) is a diagram of FIG. 3 (a). It is sectional drawing which expands and shows an AA 'cross section.
FIGS. 4A and 4B are diagrams schematically showing a fourth step for manufacturing the electronic circuit board of the present invention, FIG. 4A is a front view, and FIG. 4B is a view of FIG. It is sectional drawing which expands and shows an AA 'cross section.
FIGS. 5A and 5B are views schematically showing a fifth step for manufacturing the electronic circuit board of the present invention, FIG. 5A is a front view, and FIG. 5B is a view in FIG. It is sectional drawing which expands and shows an AA 'cross section.
6 is a diagram schematically showing a sixth step for manufacturing the electronic circuit board of the present invention, FIG. 6 (a) is a front view, and FIG. 6 (b) is a diagram of FIG. 6 (a). It is sectional drawing which expands and shows an AA 'cross section.
7 is a view schematically showing a seventh step for manufacturing the electronic circuit board of the present invention, and FIG. 7 (a) is a front view showing an enlarged part of FIG. 6 (a). FIG. 7B is a perspective view showing an electronic circuit board produced by cutting along the cutting lines XX and Y ₁ -Y ₁ and Y ₂ -Y ₂ of FIG. 7A.
FIG. 8 is a diagram schematically showing a process for manufacturing a conventional electronic circuit board.
FIG. 9 is a diagram schematically showing a process for manufacturing another conventional electronic circuit board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electronic circuit board, 11 ... Ceramic substrate, 12 ... Through-hole, 13 ... Metal thin film, 13 ... Sputtered copper film, 14 ... Resist film, 15 ... Resist film, 16 ... Gold plating film

Claims (5)

An electronic circuit board having a wiring pattern formed on at least one surface and side surface of a ceramic substrate,
The at least one side surface of the ceramic substrate is provided with a recess formed by cutting along a cutting line crossing a through hole, and a side wiring pattern is formed by a metallized layer formed on a peripheral wall surface in the recess,
The metallized layer formed on the bottom surface of the recess is formed continuously with the metallized layer that becomes the wiring pattern on the surface formed on the surface,
The electronic circuit board according to claim 1, wherein at least one of the side surface wiring patterns is formed shorter than the other wiring by a photoresist dip .   The electronic circuit board according to claim 1, wherein the metallized layer includes at least a metal thin film and a metal plating film. An electronic circuit board manufacturing method for forming a wiring pattern on at least one surface and side surface of a ceramic substrate,
A through hole forming step of forming a through hole for forming a side surface wiring pattern in the thickness direction of the ceramic substrate;
A metal thin film forming step of simultaneously forming a metal thin film on the surface of the ceramic substrate and the peripheral wall surface of the through hole;
A photolithography process for patterning the metal thin film into a predetermined wiring pattern by photolithography;
A metal plating step of forming a metal plating film on the metal thin film patterned into the predetermined wiring pattern;
A metal thin film removing step of removing unnecessary portions of the metal thin film;
And a cutting step of cutting along a cutting line crossing the through hole .   4. The method of manufacturing an electronic circuit board according to claim 3, wherein the side surface wiring pattern is formed by dipping a photoresist under the through hole.   5. The method of manufacturing an electronic circuit board according to claim 3, wherein the metal thin film is formed by a sputtering method.

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