JP4190555B2 - Multi-piece wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a multi-cavity wiring board having a large number of wiring boards made of ceramic and a method for manufacturing the same.

A ceramic wiring board having a square shape in plan view may be chamfered at each corner because the vicinity of each corner may be chipped or cracked. For this reason, in the multi-cavity wiring board for taking a large number of wiring boards chamfered for each corner, through holes are formed in the vicinity of the corners of a large number of wiring boards adjacent vertically and horizontally.
In forming such through holes, slits and through holes (through holes) are provided in the green sheet before firing, a non-slit portion having a predetermined length is provided between the slits and the through holes, and a plurality of wiring board portions are provided. For multi-cavity picking, with a radius of 0.1 to 2.0 mm in the acute angle part of through-holes that are formed in each crossing point of adjacent slits in a square shape, a substantially isosceles triangle, and a right-angled triangle. A method for manufacturing a ceramic substrate has been proposed (see, for example, Patent Document 1).

JP-A-6-91628 (Pages 1-5, FIGS. 1-3)

However, in the form in which the wiring board portion is disposed adjacent to the vertical and horizontal sides of the green sheet as in the ceramic substrate of Patent Document 1, when the cutting is performed along the slit, the radius of the acute angle portion of the through hole is reduced. For each corner of the individual wiring board, a sharp protruding portion that is sharp in plan view remains along the thickness direction. For this reason, there existed a possibility of producing a chip | tip and a crack in the said acute angle protrusion part.
In addition, when the radius that is attached to the acute angle portion of the through hole (through hole) provided in the green sheet is as small as 0.13 mm as in the past, shrinkage stress concentrates on the acute angle portion in the drying process of the green sheet. There was a risk of cracks occurring in the subsequent transport process.

  The present invention solves the problems described in the background art, and can reliably provide a wiring board that is resistant to chipping and cracking without having a sharp corner portion for each corner of the wiring board obtained by separating into individual wiring boards. It is an object of the present invention to provide a multi-piece wiring board and a manufacturing method thereof.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-mentioned problem, the present invention arranges a large number of wiring boards apart from each other, attaches a radius of a predetermined range to the acute angle portion of the through hole for chamfering the corner of each wiring board, It is conceived that such an acute angle portion is arranged on the outer ear portion of the wiring board.
That is, multiple patterning wiring board of the present invention (claim 1), it caused a plan view a rectangular, and a plurality of wiring boards from ceramic ing, positioned around such a plurality of wiring boards, that Do ceramic A through-hole having a substantially triangular shape in a plan view including an ear portion and a straight hypotenuse chamfering each corner of each wiring board and having an acute-angled portion with a radius of 0.2 to 0.5 mm; The acute angle portion is formed in the ear portion.

According to this, each corner of each of the plurality of wiring boards surrounded by the ears and spaced apart from each other is formed with a through-hole having a substantially triangular shape in a plan view including the oblique side of the straight line that obliquely intersects the corner. The acute angle portion of the through hole is rounded with a radius of 0.2 to 0.5 mm and is formed at the ear. For this reason, in the stage of the green sheet, the shrinkage stress generated during drying does not concentrate on the acute angle portion, cracks due to the shrinkage stress are not generated, and when separated into individual wiring boards, they are pointed near the corner. Since no sharp-angled protrusions remain, it is possible to provide a wiring board that is less prone to chipping or cracking.
In addition, if the radius of the radius applied to the acute angle portion is less than 0.2 mm, there is a risk of causing cracks due to shrinkage stress during drying in the green sheet stage. If the radius of the radius exceeds 5.0 mm, the ear Since the area of the through-hole occupying the part becomes excessive and the efficiency at the time of taking a large number decreases, it is within the above range. A desirable radius of the radius is in the range of 0.2 to 0.35 mm.

In other words, the wiring board and the ear portion are composed of a laminate of a plurality of ceramic layers, and a wiring layer is formed between the ceramic layers of each wiring board. Can be. In this case, even when a conductive paste for forming a wiring layer is printed for each ceramic layer, a situation in which cracks resulting from the shrinkage stress at the time of drying accompanying the printing occur in the acute angle portion of the through hole is suppressed. It becomes possible.
The multi-piece wiring board is made of, for example, a high-temperature fired ceramic such as alumina, or a low-temperature fired ceramic such as glass-ceramic.
The through-hole has an isosceles right-angled triangle, an isosceles right-angled triangle, a right angle in addition to a substantially isosceles right-angled triangle in plan view having a hypotenuse obliquely intersecting each corner of the wiring board and a pair of acutely angled portions symmetrically located on both sides thereof. A plan view having an obtuse angle larger than the portion and a pair of acute angle portions substantially forms a triangle is also included.
Further, the wiring board includes four through holes located in each corner, a virtual cutting planned surface passing between them, and a slit passing through at least one of the surface layer side and the back surface side. It is partitioned.
In addition, the wiring board includes a pad connected to an electronic component to be mounted on the front surface, an external electrode for establishing electrical connection with the motherboard on the back surface, and an internal wiring layer and via conductor connecting between them. have.

On the other hand, the manufacturing method for a multi-cavity wiring board according to the present invention (Claim 2) is a hypotenuse for chamfering each corner of each of a plurality of wiring board regions having a rectangular plan view , which are separated from each other vertically and horizontally in a green sheet . And printing a conductive paste on at least one of the front and back surfaces of each wiring board region in the green sheet in which a plurality of such through-holes are formed And a step of drying the green sheet on which the conductive paste is printed, and the through hole formed in the punching step includes a hypotenuse that chamfers each corner of each wiring board region, and both sides thereof. and a pair of acute angle portions located, and Earl radius 0.2~0.5mm is attached to each such pair of sharp edges, such a pair of acute angles Min is formed in the ear portion adjacent to the wiring substrate region, and wherein the.

  According to this, in the vicinity of each corner for each wiring board region of the plurality of green sheets, a through-hole having a substantially triangular shape in a plan view including a hypotenuse of a straight line intersecting the corner is formed, and the acute angle portion of the through-hole is A radius of 0.2 to 0.5 mm is attached, and the radius is formed at the ear. For this reason, in the process of drying the green sheet on which the conductive paste for forming the wiring layer is printed, it is possible to reliably suppress the occurrence of cracks due to the shrinkage stress during drying for each acute angle portion of the through hole. . In addition, when the multi-piece wiring board fired after laminating such green sheets is separated into individual wiring boards, there are no sharp protrusions near each corner. It becomes possible to provide efficiently.

  In other words, after the drying step, there are a step of pressing and laminating a plurality of green sheets that have undergone the punching, printing, and drying steps, and a step of firing the obtained green sheet laminate. A method for manufacturing a multi-piece wiring board can also be included in the present invention. In this case, it is possible to reliably and efficiently provide a wiring board that is less likely to cause chipping or cracking.

In the following, the best mode for carrying out the present invention will be described.
1 is a plan view showing a multi-piece wiring board K1 of the present invention, FIG. 2 is a partially enlarged view of a one-dot chain line portion Y in FIG. 1, and FIG. 3 is an arrow view of line XX in FIG. FIG.
As shown in FIG. 1, the multi-piece wiring board K <b> 1 has a rectangular shape as a whole in plan view, and the four (several) pieces that are rectangular (rectangular) in plan view and are spaced apart from each other vertically and horizontally. The wiring board 1 includes a frame-shaped ear 16 positioned around the wiring board 1, and a plurality of through holes 14 formed in the vicinity of each corner of the wiring board 1. Each wiring board 1 is partitioned from the surrounding ears 16 by four through-holes 14 located for each corner and slits s that pass only through the surface passing between them.

As shown in FIG. 2, the through-hole 14 includes a hypotenuse 11 having a straight line when chamfering each corner of the wiring board 1 at 45 degrees, a pair of acute angle portions 12 symmetrically positioned on both sides thereof, and a right angle portion 13. And a plan view having substantially isosceles right triangles (substantially triangles), and each acute angle portion 12 is provided with a radius r of 0.2 to 0.5 mm. The acute angle portion 12 is formed in the ear portion 16 adjacent to the wiring board 1. For this reason, as shown in FIG. 2, the slit s that partitions between each wiring board 1 and the ear portion 16 intersects the through hole 14 so that the acute angle portion 12 is located in the ear portion 16.
As shown in FIG. 3, the multi-cavity wiring board K <b> 1 is obtained by integrally laminating ceramic layers s <b> 1 to s <b> 6. The wiring board K1 penetrates between the front surface 2 and the rear surface 3 along the thickness direction. The slit s is formed only in the uppermost ceramic s1. Further, the front surface 2 and the back surface 3 are commonly used for the multi-cavity wiring board K1, the individual wiring board 1, and the ear portion 16.

  As shown in FIGS. 1 and 3, each wiring board 1 includes ceramic layers s <b> 1 to s <b> 6 having a front surface 2 and a back surface 3, wiring layers 4 to 8 having a predetermined pattern formed therebetween, and a front surface 2. And a plurality of external electrodes 10 formed on the back surface 3. When the ceramic layers s1 to s6 are high-temperature fired ceramics such as alumina, the wiring layers 4 to 8, the pads 9, and the external electrodes 10 are made of W or Mo and are made of glass-alumina or the like. In this case, it is made of Cu. The pad 9 is connected to an electronic component such as an IC chip to be mounted on the surface 2, and the external electrode 10 is used later to establish conduction with a not-shown server board on which the wiring board 1 is mounted. The

FIG. 4 is a perspective view showing the wiring board 1 obtained by cutting and separating the multi-piece wiring board K1 using a cutter (not shown) along the slits s. As shown in FIG. 4, the separated individual wiring boards 1 are formed with chamfered surfaces 11 in which the oblique sides 11 of the through holes 14 remain as they are at the corners between the four side surfaces. The chamfered surface 11 and each side surface adjacent to each other form an obtuse angle in a plan view, and no sharp acute angle protrusion is formed in the vicinity of each corner. For this reason, the wiring board 1 composed of the ceramic layers s1 to s6 is less likely to be chipped or cracked. Further, as will be described later, the through holes 14 are printed on the green sheets because the sharp corners 12 are rounded with a radius r0.2 to 0.5 mm at the green sheet stage where the ceramic layers s1 to s6 are formed. The layers are laminated and fired without causing cracks during drying after the process.
Therefore, according to the multi-cavity wiring board K1, it is possible to efficiently and surely provide a plurality of wiring boards 1 that have no sharp protrusions in the vicinity of each corner and are resistant to chipping and cracking simultaneously.

The multi-piece wiring board K was manufactured as follows.
Alumina powder, vanida resin, solvent, and plasticizer were blended in advance, and green sheets g1 to g6 having a thickness of about 200 μm were prepared by a doctor blade method.
As shown in FIG. 5, the green sheet g1 has a punch (not shown) and a receiving hole that follows the cross section of the punch in each of the vicinity of the corners of the four vertical and horizontal wiring board regions 1a surrounded by a virtual one-dot chain line. by the die, the hypotenuse 11 plan view of straight line chamfer each corner to 45 degrees, a pair of sharp edges 12 and substantially perpendicular two like-edge triangle of the through hole 14a is a plan view including a positioned symmetrically on both sides (Punching process). The through-hole 14a includes a hypotenuse 11 having a straight line when chamfering each corner of each wiring board region 1a at 45 degrees, a pair of acute angle portions 12 symmetrically positioned on both sides thereof, and a right angle portion 13. Each acute angle portion 12 is provided with a radius r of 0.2 to 0.5 mm. This punching process was similarly performed for the other green sheets g2 to g6.
Each wiring board region 1a has a size of about 40 × about 50 mm in plan view, and a square frame-shaped ear portion 16a surrounds the periphery.

Next, a plurality of via holes (not shown) were punched at predetermined positions in the respective wiring board regions 1a in the green sheets g1 to g6 from which the through holes 14a were punched for each corner vicinity of the wiring board region 1a.
Next, as shown in FIG. 6, a via conductor v was formed by filling a plurality of via holes in each wiring board region 1 a of the green sheets g1 to g6 with a conductive paste containing W powder.
Further, as shown in FIG. 6, the conductive paste 4 to 10 similar to the above is printed in a predetermined pattern on at least one of the front surface (2) and the back surface (3) of the green sheets g1 to g6. Layers 4-8, pad 9, and external electrode 10 were formed by printing (printing process). The wiring layers 4 to 8, the pad 9, and the external electrode 10 were formed inside the front surface 2, the back surface 3, or the green sheets g2 to g6 for each wiring board region 1a.

Subsequently, the green sheets g1 to g6 on which the via conductors v, the wiring layers 4 to 8, the pads 9, or the external electrodes 10 were formed were dried at about 100 ° C. for about 30 seconds (drying process). With such drying, shrinkage stress is generated in the green sheets g1 to g6. However, the acute angle portion 12 of each through-hole 14a is rounded with a radius r of 0.2 to 0.5 mm, and the shrinkage stress is less likely to concentrate in the vicinity of each acute angle portion 12, so that the green sheets g1 to g6 Cracks did not occur.
Next, the green sheets g1 to g6 were laminated and pressure-bonded in the thickness direction so that the through holes 14a communicated with each other and the wiring board regions 1a were stacked (lamination process). As a result, as shown in FIG. 7, the green sheets g1 to g6 are integrally laminated, and the four wiring boards 1 vertically and horizontally, a plurality of through holes 14 penetrating the vicinity of each corner, and surrounding ears The green sheet laminated body gs provided with 16 was obtained.

Next, as shown in FIG. 7, slits s that partition each wiring board region 1 a and ear portion 16 are formed in the acute angle portion 12 of each through-hole 14 with respect to the uppermost green sheet g1 in the green sheet laminate gs. Is formed by inserting a cutter (not shown) so that the is located at the ear 16.
And the green sheet laminated body gs in which the slit s was formed was heated and baked to the predetermined temperature range (baking process).
As a result, the multi-cavity wiring board K1 shown in FIGS. 1 to 3 was obtained. Further, by cutting the multi-piece wiring board K1 along the slit s and separating the ears 16, the four wiring boards 1 shown in FIG. 4 could be obtained.

  According to the manufacturing method of the multi-cavity wiring board K1 described above, since the radius R of 0.2 to 0.5 mm is given to the acute angle portion 12 of each through hole 14a, the conductive layers 4 to 8 and the like are electrically conductive. In the step of drying the green sheets g1 to g6 on which the conductive pastes 4 to 10 are printed, it is possible to reliably prevent the occurrence of cracks due to the shrinkage stress during the drying. Moreover, when the multi-piece wiring board K1 obtained by laminating and firing the green sheets g1 to g6 is cut and separated into individual wiring boards 1, there are no sharp protrusions in the vicinity of each corner. The wiring board 1 that is resistant to chipping and cracking can be provided efficiently.

Now, specific examples of the present invention will be described.
A predetermined amount of alumina powder, vanida resin, solvent, and plasticizer were blended, and a plurality of 100 mm × 100 mm × 180 μm green sheets were produced by the doctor blade method. For each corner of the wiring board region 1a of 40 mm × 50 mm set in advance in the center of each green sheet, a hypotenuse 11 having a length of 7 mm intersecting the corner at 45 degrees is continuous to both ends thereof. A through hole 14a having a pair of acute angle portions 12 with a radius r shown in FIG.
Next, a conductive paste containing W powder having the same solid pattern and a thickness of 20 μm was printed on the front and back surfaces of each green sheet.

Next, each green sheet on which the conductive paste was printed was inserted into a continuous drying furnace (not shown) and dried at 100 ° C. for 30 seconds.
The punching, printing, and drying steps described above were performed on 10 (one set) green sheets for each radius r of the acute angle portion 12 in the through hole 14a. After the drying, the presence or absence of cracks was observed for each set of radii r of the acute angle portion 12.
Of the 10 sheets, “Yes” is given to a group having a crack near the acute angle portion 12 of the through-hole 14a, and “No” is given to a group having no cracks in all 10 sheets. It is shown in Table 1.

According to Table 1, in the green sheet of the comparative example in which the radius r of the acute angle portion 12 was 0.08 to 0.17 mm, at least one crack was generated for each set of the radius r. On the other hand, in the green sheet of the example in which the radius r of the acute angle portion 12 was 0.20 to 0.35 mm, cracks did not occur in all the groups having the radius r.
As a result, in each green sheet of the comparative example, since the radius r of the acute angle portion 12 of the through hole 14a was small, less than 0.20 mm, the shrinkage stress generated during the drying was concentrated on the acute angle portion 12 and cracks were generated in the vicinity thereof. Is estimated to have occurred. On the other hand, in each green sheet of the example, the radius r of the acute angle portion 12 of the through-hole 14a was relatively large as 0.20 to 0.35 mm, so that the shrinkage stress generated during drying was less likely to concentrate on the acute angle portion 12. Therefore, it is presumed that no crack was generated in the vicinity thereof.
The effect of the present invention in which the radius r of the acute angle portion 12 of the through-hole 14a punched into the green sheet is 0.2 mm or more is supported by the above example.

FIG. 8 is a plan view showing a multi-piece wiring board K2 of a different form, and FIG. 9 is a partially enlarged view of a one-dot chain line portion Z in FIG.
The multi-piece wiring board K2, like the multi-piece wiring board K1, is rectangular (rectangular) in plan view, and four (plural) wiring boards 1 that are spaced apart from each other vertically and horizontally, and these A frame-shaped ear portion 16 positioned around the periphery and a plurality of through holes 14 formed in the vicinity of each corner of each wiring board 1 are provided. Each wiring board 1 is partitioned from the surrounding ears 16 by four through-holes 14 positioned for each corner and a virtual cutting plane c that passes only between the surface layers passing between them.
As shown in FIG. 9, the through-hole 14 includes a hypotenuse 11 having a straight line when chamfering each corner of the wiring board 1 at 45 degrees, a pair of acute angle portions 12 symmetrically positioned on both sides thereof, and a right angle portion. 13 has a substantially isosceles right triangle (substantially triangular), and each acute angle portion 12 has a radius r of 0.2 to 0.5 mm. The acute angle portion 12 is formed in the ear portion 16 adjacent to the wiring board 1. Therefore, as shown in FIG. 8, the planned cutting surface c that divides between each wiring board 1 and the ear portion 16 intersects the through hole 14 so that the acute angle portion 12 is located at the ear portion 16. Yes.

The planned cutting plane c is set along the thickness direction at the same position in the plane direction with respect to a plurality of the same ceramic (g1 to g6) layers forming the multi-piece wiring board K2.
The multi-cavity wiring board K2 can be manufactured through the steps of the manufacturing method of the multi-cavity wiring board K1 except for the formation of the slit s.
Even with the multi-piece wiring board K2 as described above, it is possible to efficiently and surely provide a plurality of wiring boards 1 that are resistant to chipping and cracking at the same time without sharp sharp protrusions in the vicinity of each corner. .

The present invention is not limited to the embodiments and examples described above.
The green sheet forming the multi-piece wiring board is not limited to alumina, but may be made of a ceramic such as mullite or aluminum nitride, or a glass-ceramic which is a kind of low-temperature fired ceramic.
In addition, the multi-piece wiring board and the plurality of wiring boards arranged on the wiring board may have a form of a square (rectangle) in plan view.
Furthermore, the through holes formed in the vicinity of each corner of the plurality of wiring boards disposed on the multi-piece wiring board are located on both sides of the corners obliquely intersecting with the corners and have a radius of 0.2 to 0. If the planar view including an acute angle portion with a radius of 5 mm exhibits a substantially triangular shape, a substantially non-equal-sided right triangle or a substantially triangular shape having an obtuse angle portion in addition to a pair of acute angle portions It may be.
Further, the slits that divide the plurality of wiring boards and the ears may be formed on the back side of the multi-piece wiring board, or may be formed on both the front side and the back side.
Further, the planned cutting surface that divides the plurality of wiring boards and the ears may be set to a ceramic layer in which the slit is not formed.
In addition, the plurality of wiring boards may have a form in which the uppermost layer or a ceramic layer on the surface side adjacent thereto has a cavity opened on the surface, and the pad is formed on the bottom surface of the cavity.

The top view which shows one form of the multi-piece wiring board of this invention. The elements on larger scale of the dashed-dotted line part Y in FIG. FIG. 2 is a vertical sectional view taken along line XX in FIG. 1. The perspective view of the wiring board obtained by cutting and dividing | segmenting the said multi-piece wiring board. Schematic which shows one manufacturing process of the said multi-cavity wiring board. Schematic which shows the manufacturing process following FIG. Schematic which shows the manufacturing process following FIG. The top view which shows the multi-cavity wiring board of a different form. The elements on larger scale of the dashed-dotted line part Z in FIG.

Explanation of symbols

1 ……………… Wiring board 1a ……………… Wiring board area 2 ……………… Front side 3 ……………… Back side 4-10 ………… Wiring layer / conductive paste 11 ………… …… Slant side 12 …………… Acute angle part 14, 14a… Through hole r ……………… Radius K1, K2 …… Multiple wiring board g1 to g6 …… Green sheet

Claims (2)

Plan view caused a rectangular, and a plurality of wiring boards ing ceramic,
Positioned around the plurality of wiring boards, and the ears ing ceramic,
A plane view including a straight hypotenuse chamfering each corner of each wiring board, with a radius of 0.2 to 0.5 mm in an acute angle portion, and a substantially triangular through hole,
The acute angle part is formed in the ear part,
A multi-piece wiring board characterized by that. The green sheet includes a hypotenuse that chamfers each corner of each of a plurality of rectangular wiring board regions that are spaced apart from each other in the vertical and horizontal directions, and the green sheet has a step of punching through holes that are substantially triangular in plan view. ,
A step of printing a conductive paste on at least one of the front and back surfaces of each wiring board region in the green sheet in which the plurality of through holes are formed;
Drying the green sheet on which the conductive paste is printed, and
The through hole formed in the punching step includes a hypotenuse that chamfers each corner for each wiring board region, and a pair of acute angle portions located on both sides thereof , and a radius of 0.2 to 0 for each pair of such acute angle portions. .5 mm radius is attached, and the pair of acute angle portions are formed in the ears adjacent to the wiring board region.
A method of manufacturing a multi-cavity wiring board characterized by the above.

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