JP2009194271A - Wiring board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a through wiring board which is excellent for mass production and is low-cost, and has an increased flexibility in arranging a wiring board on which LED devices and optical components are to be mounted. <P>SOLUTION: A conductor pattern is arranged on both opposed faces of insulating substrate. On a wiring board, part of these conductor patterns is electrically conductive by means of a conductor arranged on a through-hole penetrating the insulating substrate. The through-hole of the insulating substrate includes a first through-hole having an inner wall surface exhibiting a small change in relative angle against a substrate side of the insulating substrate, and a second through-hole which has an inner surface with a parabolic cross-section on a surface side and on an opposite side of the insulating substrate, and penetrates the substrate. The average width of the cross-section of the first through-hole is smaller than the minimum width of the second through-hole. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a wiring board in which wiring patterns provided on both surfaces of an insulating substrate are connected by through wiring provided in a metal via hole.

  Conventionally, in a wiring board having a structure (for example, a through wiring structure) in which wirings provided on both surfaces of the board are electrically connected by via holes (through holes), a method of directly processing the board to form a through hole is as follows. There are two main methods.

  One is a method of filling a via hole formed by using a microblasting method or a sandblasting method on a wiring board and forming a through wiring part by heating and connecting the upper and lower surfaces of the wiring board.

  In this method, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-363212 (Patent Document 1), through holes are formed by sandblasting from both sides of a glass substrate, and wiring is formed in the through holes by a conductive paste. is doing. In addition, there is also described an example in which the through-holes are formed eccentrically on both sides of the insulating substrate so that the conductive paste does not fall out after heating.

  The other is a method in which the inside of the via hole formed in the wiring board is completely filled with a metal paste or a metal plating method. This method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-347726 (Patent Document 2).

  Plating metal is embedded in a via hole having a diameter of 70 to 130 μm provided by laser processing on an insulating resin plate having a thickness of 0.2 mm to 0.8 mm.

  In addition, as a method for forming a straight nozzle, there is JP 2000-302488 A (Patent Document 3). In this method, after forming micropores in a glass substrate by laser processing or ultrasonic processing, substrate polishing is performed in a state in which the resin material or hot melt material is filled, and then one of the peripheral edges of the opening is microblasted. A taper is formed in the opening by etching.

JP 2004-363212 A JP 2003-347726 A JP 2000-302488 A

  In recent years, high-density arrangement and high-density mounting are required for wiring boards including LED boards. As an application of the wiring board, there is a high output LED (Light Emitting Diode) board which has been attracting attention in recent years. This LED substrate uses a ceramic material as the substrate material because it is necessary to thermally enhance the cooling effect in response to the heat radiation of the LED. It aims at high output lighting equipment and car headlights using a plurality of LEDs arranged at high density on the LED substrate.

  A method of connecting the upper and lower surfaces of the wiring board by using a microblasting method or a sandblasting method for forming a through hole or a via hole in such a wiring board can be employed.

  When micro-blasting or sand blasting is used, the entire board can be processed at a time, so it is excellent in mass productivity. However, when mounting bumps and electronic parts on a board with high-density mounting, the arrangement pitch for forming through holes Therefore, it is inevitably difficult to apply to a narrow pitch arrangement.

  The structure in which through holes or via holes are formed in the substrate by laser processing and the inside of the through holes is embedded by plating is considered to be capable of high-density arrangement of LEDs, but in laser processing, the processing speed for forming individual through holes is Although it is fast, there is a possibility that hundreds of through-holes may be formed in the substrate, and the total processing time increases. Therefore, it is considered that there is a problem in mass productivity.

  Furthermore, when the insulating resin plate is applied to the material of the substrate, the thermal conductivity of the substrate is small, and when applied to the LED substrate, a thermal cooling effect cannot be expected.

  An object of the present invention is to provide a wiring board on which various elements can be mounted with high density in a free arrangement using through wiring.

  In order to solve the above-described problems, the wiring board of the present invention is provided with conductor patterns on opposite surfaces of an insulating substrate, and a part of these conductor patterns is provided by a conductor provided in a through-hole penetrating the insulating substrate. In the electrically conductive wiring board, the through hole of the insulating substrate is opposite to the first through hole in which the wall surface of the inner wall has a small relative angle change with respect to the substrate surface of the insulating substrate, and the surface of the insulating substrate. And a second through-hole penetrating with a parabolic inner wall surface, and an average width in a cross-section of the first through-hole is equal to or less than a minimum width of the second through-hole. .

  The second through hole may be provided such that the center of the opening on one surface of the insulating substrate and the center of the opening on the other surface are shifted from the substrate surface.

  As a material of the insulating substrate, any material of glass mainly containing alumina, silicon carbide, aluminum nitride, or silicon dioxide may be used.

  According to the present invention, it is easy to embed a metal material, and it is possible to provide a wiring board that is inexpensive and excellent in mass productivity.

  Figure 2 shows the problem of embedding through-holes by applying electrolytic plating after forming two types of through-holes in a different substrate using laser processing and microblasting on a substrate made of a ceramic material. 12 will be described.

  FIG. 12A shows a cross-sectional view after a through hole is formed using laser processing and microblast processing. The through hole 9b formed by laser processing has an entrance side dimension 16b on which a laser beam is incident of about 150 μm, The outlet side dimension 16c is about 100 μm.

  Generally, in the through processing of a ceramic material, when a cross section of the through hole is seen, a substrate having a thickness of 0.2 mm or less can be processed substantially vertically. However, when the substrate thickness is larger than that, the cross section of the through hole becomes oblique.

  On the other hand, the dimension 16a on the through hole entrance side by microblasting is 350 μm at the minimum, and the gap at the center is about 200 μm.

  Next, FIG. 12B shows a state in which a metal film is formed by electrolytic plating in a through hole provided by laser processing as shown in FIG. A mask resist 15 is formed on the surface of the substrate 1.

  When electrolytic plating is stopped in a state in which the through hole 9b provided by laser processing in the substrate 1 is embedded with the plating film 6b, the through hole 9a formed by microblasting is insufficient in the growth of the plating film 6a. The hole is not blocked at the center. This is because the plating growth rate is constant, and the microblast hole has a large gap at the center, so that the metal cannot sufficiently fill the through hole 9a.

  When electrolytic plating is added until the metal is embedded in the hole, the plated metal greatly protrudes from the surface of the through hole 9b formed by laser processing. Therefore, in grinding or polishing the surface of the substrate after completion of electrolytic plating, the metal part that protrudes greatly forms an uneven part on the entire substrate, and the uneven part exists on both sides of the substrate, so that a reference surface can be obtained. It becomes difficult and grinding or polishing becomes difficult, resulting in poor productivity.

  As described above, when through holes having different diameters are arranged on the same substrate, first, it is difficult to embed a metal in the through hole. Second, it takes time to process the substrate.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a wiring board according to an embodiment of the present invention. Various wiring patterns 8 are provided on the front side and the back side of the substrate 1. The wiring pattern 8 provided on both surfaces of the substrate 1 is electrically connected to the front and back surfaces of the substrate by the through wiring portion 11 in which a metal material is embedded in the through hole 9 provided through the substrate 1.

  The substrate 1 is provided with through holes 9b having a narrow pitch arranged by laser processing, which are first through holes. Moreover, the through-hole 9a which is a hole provided in both surfaces of the board | substrate by the microblast process which is a 2nd through-hole is provided.

  The first through hole, which is the through hole 9b, is a hole formed by irradiating a high energy ray from one substrate surface and penetrating the insulating substrate, for example, as in a laser processing method.

  The 2nd through-hole which is the through-hole 9a is provided so that the center axis | shaft of a hole may differ in front and back. For example, it is a hole in which a large number of fine particles are applied to the masked substrate surface at a high speed from the front and back surfaces of the insulating substrate, as in the microblasting method.

  In the substrate 1, the minimum width of the through hole 9 a provided by using the microblasting method from the front and rear surfaces is equal to or less than the average size width of the through hole 9 b provided by laser processing. . Details will be described later.

  The wiring pattern 8 is provided with, for example, titanium, chromium, or any alloy as a base film, on which a wiring is provided with gold, and further on which a wiring pattern of copper, nickel, or gold is provided. This is a so-called multilayer wiring in which wiring patterns are stacked in layers.

  The base film is provided to improve the adhesion between the substrate material and the gold wiring. In the case where thermal addition is applied in a later process, a platinum layer may be sandwiched between the base film and gold. The wiring materials are not limited to those listed here, and other metal materials may be combined as long as they provide the same action.

  The above-described method for manufacturing the substrate 1 includes the first through-hole formed from one surface of the substrate 1 by laser processing and the second through-hole formed from both surfaces of the substrate 1 by microblasting. The metal film of the plating wiring is formed from both sides of the substrate. On the metal film, titanium or chromium is used as a base film, and nickel and gold films are formed thereon.

  Thereafter, electrolytic copper plating is performed to embed copper in the through hole. At this time, even if there is a difference in the cross-sectional shape of the through-hole due to a difference in processing method, the minimum cross-sectional width of the through-hole 9a that is the second through-hole is equal to or less than the average cross-sectional width of the through-hole 9b that is the first through-hole. If so, there is no time difference in the growth of the copper film in both cross sections, and copper can be buried in both cross sections in substantially the same time.

  If there is excess copper grown from the surface of the substrate 1 when the growth of the copper plating film proceeds and the plating is stopped, the excess copper is removed by grinding or polishing.

  In this way, the surface of the substrate 1 is smoothed and the wiring pattern 8 is formed on the substrate 1. In this case, a resist is provided in a portion where the plating film is not required, and the resist is peeled off after plating.

  According to the above, when through holes with different diameters are arranged on the same substrate, when the metal is embedded in the through holes by plating, there is almost no difference in the growth rate of the embedded metal, and the size of the cross section Even if conductive processing is performed on the through-holes having different diameters by plating, the processing time does not have to be set in accordance with the through-hole having a large cross section, so that the time required for substrate processing is shortened.

  FIG. 2 shows another embodiment of the present invention processed by the same manufacturing method as described above. In the structure of FIG. 2, the inside of the through hole is entirely filled with metal. The difference from the substrate shown in FIG. 1 is that a thick substrate having a thickness of 600 μm is prepared first, and the surface of the substrate is ground after the metal is completely embedded in the through-hole using, for example, the plating method described in FIG. It is processed to a thickness of 300 μm by processing or polishing. Then, by forming the wiring pattern 8 on the surface of the substrate 1, a substrate structure in which all the through holes 9 are embedded can be realized.

  As a substrate material used in this embodiment, a material such as glass mainly containing alumina, silicon carbide, aluminum nitride, or silicon dioxide may be used. This is preferably applied from the viewpoint of excellent long-term reliability and excellent heat resistance as a substrate material. In this embodiment, the substrate material is not limited to the materials described above, and other ceramic materials may be applied. In addition, although the said glass has mentioned the thing which has silicon dioxide as a main component, the material in which sodium oxide, magnesium oxide, calcium oxide, boron oxide, phosphorus oxide, etc. are mixed as a subsidiary component is preferable.

  Next, a method for forming a microblast hole provided in the substrate 1 in the embodiment of the present invention will be described. FIG. 3 shows a cross-sectional view before embedding a metal material (through wiring portion 11) in the through hole 9a provided by the microblast processing method in FIG.

  As shown in FIG. 3, an upper hole 2 and a lower hole 3 are formed in the substrate 1 by a microblasting method. The upper hole 2 and the lower hole 3 are connected to each other at a substantially central portion of the substrate 1. Note that the formation of the upper hole 2 and the lower hole 3 in the substrate 1 is performed individually from both sides of the substrate. Since each hole is provided from each surface of the substrate 1 at the same processing speed, the upper hole 2 and the lower hole 3 are connected (penetrated) near the center in the thickness direction of the substrate 1.

  The center axis 2a of the upper hole 2 and the center axis 3a of the lower hole 3 are provided so as to be shifted. With such a configuration, the penetrating portion 5 between the upper hole 2 and the lower hole 3 can have a smaller penetrating portion 5 as compared with the case where the central axes are the same. Although this is strictly different, since the cross section of the hole provided by microblasting is parabolic, the inner wall surface of the hole is a curved surface that gradually changes its inclination from the bottom to the opening on the surface of the substrate 1. . Since the inclination of the curved surface changes from the bottom of the hole, each hole can penetrate more than the opening opening on the surface of the substrate 1 near the center in the thickness direction of the substrate 1 where the upper hole 2 and the lower hole 3 intersect. The opening is narrower.

  Note that the microblasting method is a method in which fine particles are sprayed at a high speed, and the shape of the hole formed varies depending on the hardness of the substrate material. For example, when silicon carbide is used as the substrate material, the angle between the bottom surface of the substrate and the through hole is about 70 °. When aluminum nitride is used as the substrate material, the angle between the bottom surface of the substrate and the through hole is about 55 °.

  As described above, the shape of the through hole differs depending on the material of the substrate. This is because the microblasting method is processing while physically cutting the material. Since the particles sprayed at high speed are discharged to the periphery, that is, the upper side of the hole while scraping the material, the curvature of the hole differs depending on the material of the substrate. More specifically, the inclination varies between the bottom surface portion and the side surface portion of the hole. That is, the closer to the substrate surface, the closer the inclination angle of the hole is to be vertical.

  As a processing method for simply forming holes in the substrate 1, a microblast processing method may be used. This is because the entire surface of the substrate can be processed at once by providing a mask on the substrate 1. Therefore, it can be said that the microblast processing method is excellent in mass productivity.

  Moreover, the electroplating method is good for embedding the metal material in the through hole formed by penetrating the substrate 1. This is because the metal material can be stably embedded.

  As the mask material, a resist that can be used for microblasting is used. By applying such a resist, fine patterning can be performed and the position of the hole can be formed with an accuracy of ± 1 μm.

  When holes are processed from both sides of the substrate, the shape change of the penetrating portion where the upper hole and the lower hole are in contact with each other will be described with reference to FIG. A plan view is shown in the upper part of FIG. 4 and a sectional view is shown in the lower part.

  4A shows a case where the center axis of the hole provided in the substrate is the same on the front and back surfaces, and FIG. 4B shows that the center position of the hole on the front and back surfaces provided on the substrate is the distance 4a (the upper hole radius 4 (c) shows a case where the center positions of the holes on the front and back surfaces provided on the substrate are shifted by a distance 4b (length corresponding to the upper hole radius).

  When the center axis of the hole is the same on the front and back surfaces, when processing is performed from both sides of the substrate 1, a substantially circular penetrating portion 5 is formed at the center of the substrate. Next, when the pilot hole is shifted as shown in (b), the penetrating portion has a shape close to an ellipse as shown in 5a, and the area is formed smaller than that of the penetrating portion 5. Further, when shifted as shown in (c), it is formed in an elongated oval shape like the penetrating portion 5b, and the area of the penetrating portion and the width of the penetrating portion are reduced.

  This is because by changing the central axis of the lower hole with respect to the upper hole, the position where the penetrating portion comes into contact with the upper hole changes. For example, when the central axes are the same, the hole penetrates with the curvature of the bottom surface of the hole, but the penetrating portion moves in the direction of the side surface of the upper hole by shifting the position of the pilot hole.

  Next, how the metal material is embedded according to the difference in size of the through portion provided near the center of the substrate when the through hole is embedded by the electrolytic plating method will be described.

  FIG. 5 shows an example of embedding in which the center axis of the upper hole and the lower hole shown in FIG. 4A is the same, and FIG. 6C shows the case where the center axis of the upper hole and the lower hole shown in FIG. An example of embedding is shown. Both figures are assumed to have been subjected to electrolytic plating for the same time.

  FIG. 5 shows a cross-sectional view in which a plated metal film 6 is grown by electrolytic plating on a substrate 1 in which an upper hole 2 and a lower hole 3 are formed with the same central axis.

  As shown in FIG. 5A, a plated wiring (not shown) is formed along the shape of the through hole. When a voltage is applied by immersing in the plating solution in this state, the plating film grows along the shape of the through hole as shown in FIGS. 5 (b) and 5 (c).

  When the plating film continues to grow, as shown in FIG. 5 (d), the portions with the shortest distance (minimum width of the through holes) intersect and grow in the direction of filling the holes from there as a base point. FIG. 5 (e) is a diagram after polishing the metal plating material provided on the front and back surfaces of the substrate 1, and a space 7 is formed in the central portion of the upper hole 2 and the lower hole.

  FIG. 6 shows a cross-sectional view in which a plated metal film 6 is grown by electrolytic plating on the substrate 1 formed by shifting the central axis of the lower hole 3 with respect to the central axis of the upper hole 2.

  As shown in FIG. 6A, a plated wiring (not shown) is formed along the shape of the through hole. When a voltage is applied by immersing in the plating solution in this state, a plating film grows along the shape of the through hole as shown in FIG. 6B.

  When the plating film continues to grow, as shown in FIGS. 6C and 6D, the portions with the shortest distance (minimum width of the through-hole) intersect and grow in the direction of filling the hole with that as a base point.

  FIG. 6E is a view after the metal plating material provided on the front and back surfaces of the substrate 1 is polished. The upper hole 2 and the lower hole 3 are completely filled with the metal material.

  Compared with FIG. 5, it can be seen that, in the electroplating process for the same time, the method in which the relative positions of the upper hole and the lower hole are shifted is quickly filled in the hole. That is, in the growth of the plated film of the through hole provided from both surfaces of the substrate by microblasting, the hole is sealed by the growth of the through hole in the radial direction, and then grows in the height direction. For this reason, the narrower the penetration portion formed in the central portion of the substrate, the shorter the time for embedding.

  In addition, when a metal material is embedded in a hole formed in the substrate, a resist mask is formed on the surface of the substrate and a metal film is formed only on a necessary portion. As a result, it is not necessary to form a film on unnecessary portions, and polishing in subsequent steps is facilitated.

  Next, a method of simultaneously embedding a laser processing hole and a microblast processing hole formed in the same substrate by decentering from both surfaces of the substrate by electrolytic plating will be described with reference to FIG.

  A state in which the substrate 1 is formed with a through hole 11b formed by laser processing and a through hole 11a formed by microblast processing is embedded by electrolytic copper plating. The average dimension width 5b in the cross section of the through hole 11b and the minimum dimension width 5a of the opening provided at the center of the through hole are formed to be substantially equal.

  Since the copper metal to be embedded is substantially equal at the center of the through hole, the plating time for sealing is equal.

Incidentally, the experimental conditions at this time, the plating solution: using MICROFAB Cu500 of Electroplating Engineers of Japan Ltd., Temperature: 25 ° C., a current density of 3A / dm ^2.

  In the present invention, the through holes 5b formed in the substrate have an average size width because the shape of the through holes differs as described above depending on the thickness of the substrate to be processed. When the plate thickness is thin, almost vertical holes are formed. On the other hand, when the plate thickness is increased, the through hole differs between the inlet side and the outlet side, but when the plate thickness is about 500 μm, the value is 50 μm or less. The through hole can be defined by an average dimension width.

  On the other hand, the width at the central opening of the microblast hole formed from both sides of the substrate is preferably equal to or smaller than the average dimension width of the through holes formed by laser processing. This is because the through-hole provided by microblasting is larger than the through-hole provided by laser processing as compared with the volume to be embedded.

  The position where the opening is formed in the substrate is preferably a half thickness portion of the substrate. This is because when the metal material is embedded, the speed of embedding to the front and back surfaces of the substrate is almost the same. However, the upper hole and the lower hole do not necessarily have to penetrate through the half thickness portion of the substrate. For example, as shown to Fig.8 (a), the opening part of the 2nd through-hole by a microblast process is not restricted only to a center part. If the opening (opening) part which penetrates is small, the position of the opening part opened to the board | substrate 1 surface is not ask | required.

  As shown in FIG. 8B, the present invention is applied to the same substrate by grinding or polishing the surface side of FIG. 8A even if the upper hole and the lower hole of the substrate are not displaced. It is possible to form through holes provided by laser processing and through holes provided by microblasting.

  Even if the cross-sectional shape of the through hole formed in the substrate is different, if the size of the opening partly constricted is the same, the plated metal protruding from the surface of the substrate has the same height and is ground or polished in the manufacturing process. Processing becomes easy.

  FIG. 9 shows another embodiment of the present invention. A wiring pattern may be formed at the same time as embedding with plating metal in the substrate 1 in which the through hole provided by laser processing and the through hole provided by microblasting are formed. In this system, a thick film through wiring 10a by microblasting and a thick film through wiring 10b by laser processing can be formed, and a thick film wiring by electrolytic plating can be formed on the substrate surface. A surface wiring thickness of about 80 μm could be formed on both sides of the substrate. Even if a space is formed on the substrate, the substrate can be applied to an application capable of preventing liquid leakage such as solder or LED sealing material.

  Further, in the structure in which a space is provided in the hole, even when a thermal load such as gold-tin solder is generated due to the formation of the space, the linear expansion coefficient is larger than that of a ceramic material having a small linear expansion coefficient. Although the embedded metal tends to expand greatly, there is an advantage that thermal stress is dispersed by the presence of the space. As a result, the stress applied to the wiring is also reduced, so that the thermal stress at the boundary between the buried metal portion and the wiring portion on the substrate surface is reduced.

  When holes are formed on both sides of the substrate using microblasting, a mask is formed on both sides of the substrate and patterning is performed. In that case, first, an alignment mark and a pattern are formed using one surface of the substrate as a reference surface, and the position of the hole on the opposite surface is determined according to the pattern on the alignment mark. Since the exposure apparatus applied to this uses an apparatus that combines from both sides, the alignment accuracy is in the range of several μm, and the good one is in the range of ± 1 μm.

  Generally, the arrangement pitch for arranging the holes in the microblasting method cannot be arranged narrowly because it has a slope in the hole cross section. The arrangement pitch varies depending on the thickness of the substrate, but when the hole diameter is about 350 μm, the arrangement pitch is about 500 μm. On the other hand, since it is possible to process vertical holes in laser processing, it is possible to arrange holes with a narrow pitch, and the arrangement pitch is about 100 to 150 μm.

  In each embodiment of the present invention, the laser processing holes can be arranged at a narrow pitch by shifting the position of the microblast holes. Conventionally, it is possible to realize a substrate with a hole arrangement that cannot be realized only with microblasted holes. Thereby, a low-cost substrate can be provided without reducing productivity.

  The pattern formed on the front surface and the back surface of the substrate using microblasting is not limited to a circle, and a square, a polygon, an ellipse, or the like may be applied. Further, the size of the hole in the patterning may be changed depending on the thickness of the substrate, and the center axis of the hole on the opposite surface is shifted with respect to one hole or has an angle with the bottom of the hole inner surface, that is, the substrate. If the contact is made at a portion other than the portion that is not, it is possible to form a small through hole as compared with the case where the central axes are the same.

  An example in which elements are mounted on a wiring board formed by using the above method is shown in FIGS.

  As shown in FIG. 10, the substrate 1 has a plurality of through-holes 9a formed by microblasting and a plurality of through-holes 9b formed by a laser processing method. Wiring is formed.

  Each through wiring is formed with a multilayer wiring 8a provided on the surface portion of the substrate, and a photodiode 12 and a laser diode 13 are mounted on the multilayer wiring 8a via a solder material or a bump.

  In FIG. 11, the LED element 14 is mounted on the substrate 1, and the wiring 8a on the front surface of the substrate and the wiring 8b on the back surface of the substrate are electrically connected to each other on the front and back surfaces of the substrate through the through holes 9a and 9b. Although not shown, the reflector substrate and the sealing material are formed in contact with the substrate 1.

  The resistance value in the through wiring of the wiring board provided as described above was measured and found to be 0.05Ω or less. Further, in the reliability test, in the thermal cycle test in which the holding at −40 ° C. for 30 minutes and the holding at 85 ° C. for 30 minutes is performed for 1000 cycles, the increase in resistance value is 0.004Ω or less and the reliability is excellent. .

  By forming a single wiring board using a laser processing method and a microblasting method from the front and back surfaces of the substrate as in this embodiment, the through holes can be arranged in a narrow pitch by laser processing, and the microblasting It is possible to provide a substrate excellent in mass productivity by processing.

  The embedding process is performed in electrolytic copper plating by setting the minimum width formed in the through hole formed by using the microblasting method from the front and back surfaces of the substrate to the average size width in the laser processing method, which is equal to or less than the same size. In this case, since the plating speed for embedding the holes is equal, the through portions of the holes are embedded almost simultaneously. Therefore, the plating metal that protrudes from the substrate surface does not grow greatly, and the polishing work in the subsequent process can be easily performed.

  The metal embedded in the through hole in this example is embedded by using an electrolytic copper plating method, so that the resistance value of the front and back surfaces of the substrate has a low resistance value, and there is no difference even when compared with the bulk copper material. can get.

  Electrolytic plating is preferable as a method for filling the through hole. When applied as a thermal cooling substrate, it is preferable to embed all the through holes with a metal material. However, for the purpose of preventing leakage of solder, sealing material, etc., a part of the through holes may be embedded with a metal material. It ’s fine.

The penetration wiring sectional view in one example of the present invention. The penetration wiring sectional drawing regarding the other Example of this invention. Sectional drawing of the through-hole in position shift. The detailed view of the through-hole in position shift. The figure explaining the conventional through-hole plating process. The figure explaining the through-hole plating process in one Example of this invention. The detailed sectional view for explaining one example of the present invention. Sectional drawing regarding the other Example of this invention. The penetration wiring sectional view concerning other examples of the present invention. The perspective view regarding one Example of this invention. The perspective view regarding the Example which mounts the LED element of this invention. Sectional drawing regarding a conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Upper hole 3 Lower hole 4 Position shift length 5 Through portion 6 Plating metal film 7 Space 8 Wiring pattern 9 Through hole 10 Thick film through wiring 11 Through wiring portion 12 Photo diode 13 Laser diode 14 LED element 15 Resist 16 Dimensions width

Claims (4)

  Conductor patterns are provided on both opposing surfaces of the insulating substrate, and a part of these conductor patterns is electrically connected by a conductor provided in a through-hole penetrating the insulating substrate. The hole has a first through hole in which the wall surface of the inner wall has little change in relative angle with respect to the substrate surface of the insulating substrate, and an inner wall surface having a parabolic cross section on the surface opposite to the surface of the insulating substrate. And a second through hole penetrating, wherein an average width in a cross section of the first through hole is equal to or less than a minimum width of the second through hole.   2. The wiring board according to claim 1, wherein the second through hole has an opening center of one surface of the insulating substrate and an opening center of the other surface being shifted from the substrate surface. Wiring board to be used.   2. The wiring substrate according to claim 1, wherein the insulating substrate is a ceramic or glass substrate mainly containing any one of alumina, silicon carbide, aluminum nitride, and silicon dioxide.   The wiring board according to claim 1, wherein the conductor provided in the through hole is embedded by an electrolytic copper plating method.

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