JP2024055319A - Manufacturing method of core board and through-hole printing mask - Google Patents

Abstract

[Problem] A technology for uniformly filling a plurality of through holes in a core board with a paste material is disclosed. [Solution] A method for manufacturing a core board 10, in which a product area 13 having a plurality of through holes 15 is surrounded by an outside-product area 14 having no through holes 15, is performed through-hole printing on the core board 10 to manufacture the core board 10 in which the through holes 15 are filled with a filling material 43A, and the through-hole printing mask 30 is provided with a plurality of first through holes 32 formed in a first area 31 overlapping the product area 13 and communicating with the plurality of through holes 15, and a plurality of second through holes 33 formed in a second area 34 overlapping the outside-product area 14. [Selected Figure] Figure 1

Description

This disclosure relates to a method for manufacturing a core substrate and a mask for through-hole printing.

Conventionally known through-hole printing is a technique in which a through-hole printing mask having multiple through holes corresponding to the multiple through holes in the core board is overlaid on the core board, and a paste material placed on the through-hole printing mask is smoothed with a squeegee and filled into the multiple through holes through the multiple through holes (see, for example, Patent Document 1).

JP 2001-298257 A (paragraph [0009], Figures 1-2)

However, when a product area having multiple through holes in a core substrate is surrounded by an outside-product area that does not have through holes, the through holes in the product area that are far from the outside-product area are filled with sufficient paste material, but the through holes close to the outside-product area are not filled with sufficient paste material, and the surface of the hole filling material formed by the paste material solidifying in the through holes may have a concave shape. Therefore, this application discloses a technology for uniformly filling the paste material into multiple through holes in a core substrate having an outside-product area.

The invention of claim 1, which has been made to solve the above problem, is a method for manufacturing a core board in which a product area having a plurality of through holes is surrounded by an outside-product area having no through holes, and the through holes are filled with a filling material by performing through-hole printing on the core board, and the through-hole printing mask is provided with a plurality of first through holes formed in a first area overlapping the product area and communicating with the plurality of through holes, and a plurality of second through holes formed in a second area overlapping the outside-product area.

The through-hole printing mask used in the method for manufacturing a core substrate of claim 1 not only has a plurality of first through holes formed in a first region overlapping the product region of the core substrate, which are connected to a plurality of through holes, but also has a plurality of second through holes formed in a second region overlapping the outside-product region of the core substrate. This makes it possible to equalize the conditions related to the flow of the paste material between positions in the product region far from and near the outside-product region, and to uniformly fill the paste material. This makes it possible to suppress dents in the surface of the hole-filling member.

FIG. 1 is a perspective view of a core substrate, a mask, and a support table according to an embodiment of the present disclosure. Core board enlarged view Close-up of the mask Screen printing process for core board FIG. 13 is a perspective view of a core substrate, a mask, and a support table according to another embodiment of the present disclosure.

Below, an embodiment of the present disclosure will be described with reference to Figures 1 to 4. The core substrate 10 shown in Figure 1 is, for example, a resin layer made of glass cloth impregnated with epoxy resin or the like, with conductive layers laminated on both sides, and has an overall rectangular shape. The core substrate 10 also has insulating layers and conductive layers (not shown) laminated alternately on the front and back of the core substrate 10. That is, build-up layers are laminated on the front and back of the core substrate 10. The multilayer wiring substrate including the core substrate 10 and the build-up layers is then divided into multiple pieces to become the final product, which is then incorporated into a commercially available product.

More specifically, the outer frame-shaped region of the core substrate 10 is a non-product region 14 that will not ultimately become a product and is discarded, for example, and the inside of the non-product region 14 is a product region 13 that will ultimately become a product. In this embodiment, the product region 13 is partitioned, for example, into a number of rectangular small regions 13A, and is ultimately divided into each of these small regions 13A. Each small region 13A of the product region 13 then becomes part of the product (i.e., the multilayer wiring board).

In addition, in the product area 13 of the core substrate 10, circuits are formed in the conductive layers on the front and back by a common method such as a subtractive method. Furthermore, the product area 13 of the core substrate 10 is provided with a plurality of through holes 15 that penetrate from the front to the back, and the circuits in the conductive layers on the front and back of the core substrate 10 and the circuits in the build-up layers on the front and back are connected to each other by hole filling material 43A that is formed to cover the inner surface of the through holes 15. The plurality of through holes 15 are then filled with hole filling material 43A.

In this embodiment, the core substrate 10 and the product area 13 are rectangular, but are not limited to rectangular shapes and may be other polygonal, circular, semicircular, elliptical, or irregular shapes. Additionally, the product area 13 is ultimately divided into multiple parts, but may not be divided. The hole filling material 43A may be an insulating material or a conductive material.

In the core substrate manufacturing method of this embodiment, the core substrate 10 is prepared in an incomplete state in which the through holes 15 are not provided with the hole filling material 43A. Then, in the core substrate manufacturing method of this embodiment, through-hole printing is performed on the prepared core substrate 10 to form the hole filling material 43A, thereby completing the core substrate 10.

The through holes 15 in the prepared core substrate 10 are formed by a drill or the like, and penetrate the core substrate 10 with a constant inner diameter. Three alignment holes 18 are formed in the three corners of the outer product area 14 of the core substrate 10. The outer product area 14 of the core substrate 10 is a flat plate with no holes or irregularities other than the alignment holes 18.

Figure 1 shows the support table 40 of the through-hole printer and the through-hole printing mask 30 (hereinafter simply referred to as "mask 30"). The support table 40 has a flat upper surface on which the core substrate 10 is placed, and on the upper surface, a number of countersunk holes 45 are arranged along each side of the frame-shaped region 40R corresponding to the outside product region 14 of the core substrate 10. Positioning pins 48 stand upright from three corners of the frame-shaped region 40R. The three positioning pins 48 of the support table 40 are passed through the three positioning holes 18 of the core substrate 10, and the core substrate 10 is placed in a positioned state on the support table 40.

The mask 30 is in the form of a rectangular sheet that is approximately the same as the core substrate 10, and has a first region 31 that overlaps with the product region 13 of the core substrate 10, and a frame-shaped second region 34 that overlaps with the non-product region 14 of the core substrate 10. Positioning holes 38 are formed in three corners of the second region 34. Three positioning pins 48 of the support table 40 are passed through the three positioning holes 38 of the mask 30, and the mask 30 is placed in a positioned state on the core substrate 10.

In FIG. 1, for the purpose of explanation, the mask 30 is shown with a boundary line between the first region 31 and the second region 34, but such a boundary line does not have to be shown on the mask 30. The same applies to the boundary line between the product region 13 and the non-product region 14 of the core substrate 10. In addition, the mask 30 is preferably made of a metal such as stainless steel, but may be made of resin.

When manufacturing multiple core boards 10 with different arrangements and numbers of through holes 15, a mask 30 is prepared for each core board 10. As an example, the multiple through holes 15 of the core board 10 shown in FIG. 1 are as follows. That is, in the core board 10, although there is some variation between places where the multiple through holes 15 are densely packed and places where they are sparsely scattered, the multiple through holes 15 are roughly evenly distributed throughout the entire product area 13. Also, as described above, the non-product area 14 of the core board 10 is a flat plate with no holes or irregularities other than the three positioning holes 18. Note that only some of the multiple through holes 15 are shown in FIG. 1.

1, a plurality of first through holes 32 are formed, which have the same arrangement and inner diameter as all the through holes 15 in the product region 13 of the core substrate 10. That is, in the mask 30, a plurality of first through holes 32 are arranged almost evenly throughout the entire first region 31 overlapping the product region 13, similar to the product region 13 of the core substrate 10 (see FIG. 2). In addition, a plurality of second through holes 33 are formed in the second region 34 overlapping the outside product region 14 of the core substrate 10 that does not have through holes 15. The plurality of second through holes 33 are, for example, copies of the plurality of first through holes 32 in a part of the first region 31, and are arranged almost evenly throughout the entire second region 34. That is, in the mask 30, there is no distinction between the first region 31 and the second region 34, and a plurality of through holes, each consisting of a plurality of first through holes 32 and a plurality of second through holes 33, are generally evenly distributed throughout the entire mask 30 (see FIG. 3).

In the core substrate manufacturing method of this embodiment, the support table 40 and mask 30 described above are used to manufacture the core substrate 10 as follows.

(1) An unfinished core substrate 10 is prepared, which has multiple through holes 15, but does not have hole filling material 43A in the through holes 15.

(2) A release sheet 50 cut to a size corresponding to the product area 13 of the core substrate 10 is laid inside the frame-shaped area 40R on the upper surface of the support table 40. The core substrate 10 is then placed on top of the release sheet 50 in a positioned state on the support table 40 as described above, and the mask 30 is then placed on top of the release sheet 50 in a positioned state. (See FIG. 4(A)).

(3) The paste material 43 is placed on the outer edge of one of the four sides of the mask 30. Then, the squeegee 46 is moved so as to climb onto the outer edge of one side of the mask 30 from a position horizontally away from the outer edge of one side of the mask 30, and further, the squeegee 46 is moved to pass over the mask 30 while being pressed against the mask 30. As a result, the paste material 43 is filled through the first through hole 32 of the mask 30 toward the multiple through holes 15. At this time, the first through hole 32 and the second through hole 33 are also filled with the paste material 43 to the thickness of the mask 30 (see FIG. 4B). Note that an epoxy resin is used as the paste material 43, but it may be silver paste, conductive ink, or the like.

(4) The core substrate 10 is removed from the support table 40 with the release sheet 50 attached to its underside. The release sheet 50 is then placed over the entire upper surface of the core substrate 10, and the substrate is heated while sandwiched in the thickness direction by a pressure device. This hardens the paste material 43, forming the hole filling material 43A inside the through-holes 15, and the core substrate 10 is completed.

The mask 30 used in the manufacturing method of the core substrate 10 of this embodiment not only has a plurality of first through holes 32 that communicate with a plurality of through holes 15 formed in a first region 31 that overlaps with the product region 13 of the core substrate 10, but also has a plurality of second through holes 33 in a second region 34 that overlaps with the outside-product region 14 of the core substrate 10. This makes it possible to equalize the conditions related to the flow of the paste material 43 between positions in the product region 13 that are far from and close to the outside-product region 14.

More specifically, in the mask 30 of this embodiment, the multiple second through holes 33 in the second region 34 are made by copying the multiple first through holes 32 in a portion of the first region 31, so that the average hole diameter of the multiple first through holes 32 and the average hole diameter of the multiple second through holes 33 are approximately the same, and the number of multiple first through holes 32 per unit area in the first region 31 and the number of multiple second through holes 33 per unit area in the second region 34 are approximately the same, which results in uniform conditions related to the flow of the paste material 43 and uniform filling of the paste material 43. This makes it possible to suppress depressions on the surface of the hole filling member 43A.

In addition, by providing multiple countersinks 45 in the frame region 40R of the support table 40 where the outside-product region 14 of the core substrate 10 overlaps, the conditions for the flow of the paste material 43 are also made uniform. Specifically, the product region 13 of the core substrate 10 has multiple through holes 15, and is therefore less rigid than the outside-product region 14 which does not have these through holes 15. In other words, due to the difference in rigidity, the product region 13 of the core substrate 10 is more likely to deform downwardly due to the pressing force of the squeegee 46 than the outside-product region 14. In contrast, the frame-shaped region 40R of the support table 40 that supports the non-product region 14 of the core substrate 10 from below has multiple countersunk holes 45, while the region that supports the product region 13 of the core substrate 10 from below does not have multiple countersunk holes 45. Therefore, due to the difference in support by the support table 40, the non-product region 14 of the core substrate 10 is more likely to deform downwardly due to the pressure of the squeegee 46 than the product region 13, and the difference in the amount of downward deformation between the non-product region 14 and the product region 13 is reduced, resulting in uniform conditions related to the flow of the paste material 43.

It is assumed that, because the amount of deformation of the mask 30 and the degree to which the squeegee 46 slides on the mask 30 differ due to differences in the "conditions related to the flow of the paste material 43" described above, a problem occurred in the conventional manufacturing method of the core substrate 10 in that the through-holes 15 located closer to the non-product area 14 of the product area 13 of the core substrate 10 were less likely to be filled sufficiently with the paste material 43 than the through-holes 15 located further away. The technology disclosed herein is expected to uniformize the "conditions related to the flow of the paste material 43," thereby solving the conventional problem.

<Other embodiments>
(1) In the above embodiment, the second through holes 33 are formed over the entire surface of the second region 34, but the second through holes 33 may be formed only in a portion adjacent to the first region 31. Also, a plurality of second through holes 33 may be formed only on the side of the second region 34 that is closer to the first region 31 in the width direction.

(2) In the above embodiment, the multiple second through holes 33 in the second region 34 were copies of some of the multiple first through holes 32 in the first region 31, but multiple second through holes 33 having an arrangement and size completely unrelated to the multiple first through holes 32 in the first region 31 may be formed in the second region 34.

(3) In the core substrate 10 of the above embodiment, there is one product region 13 surrounded by the product outside region 14, but as in the core substrate 10A shown in FIG. 5, there may be multiple product regions 13 surrounded by the product outside region 14, and the mask 30A and the support table 40A may be formed to correspond to such a core substrate 10A. Specifically, the core substrate 10A shown in the figure has, for example, four product regions 13, and the product outside region 14 surrounds the entirety of the four product regions 13 and is provided to separate the product regions 13 from each other, so that each product region 13 is surrounded by the product outside region 14. In contrast, the support table 40A has a countersunk hole 45 formed in the frame-shaped region 40R where the entire product outside region 14 of the core substrate 10A overlaps. In addition, in the mask 30A, a plurality of first through holes 32 are formed in each of the four first mask regions 31Q that overlap the four product regions 13 of the core substrate 10A, and a plurality of second through holes 33 are formed throughout the second mask region 34 that overlaps the entire non-product region 14. Even with this configuration, the same effects as those of the above embodiment are achieved.

Note that although specific examples of the technology included in the scope of the claims are disclosed in this specification and drawings, the technology described in the claims is not limited to these specific examples, but includes various modifications and variations of the specific examples, as well as parts of the specific examples taken separately.

REFERENCE SIGNS LIST 10, 10A Core substrate 13 Product area 14 Non-product area 15 Through hole 30, 30A Through hole printing mask 31 First area 32 First through hole 33 Second through hole 34 Second area 43 Paste material 43A Hole filling member 46 Squeegee

Claims (8)

A method for manufacturing a core substrate, the method comprising the steps of: performing through-hole printing on a core substrate, the product region having a plurality of through-holes being surrounded by an outside-product region having no through-holes, to manufacture a core substrate in which the through-holes are filled with a filling material, the method comprising the steps of:
For through-hole printing masks,
a plurality of first through holes formed in a first region overlapping the product region and communicating with the plurality of through holes;
A plurality of second through holes are formed in a second region overlapping the outside-product region. A method for manufacturing a core substrate according to claim 1,
The average diameter of the plurality of first through holes and the average diameter of the plurality of second through holes are substantially the same. A method for manufacturing a core substrate according to claim 1,
The number of the first through holes per unit area in the first region is approximately the same as the number of the second through holes per unit area in at least the width half of the second region closer to the first region. A method for manufacturing a core substrate according to claim 1,
The second plurality of through holes are copies of the first plurality of through holes in a portion of the first region. A through-hole printing mask for use on a core substrate having a product area having a plurality of through-holes surrounded by a non-product area having no through-holes,
a plurality of first through holes formed in a first region overlapping the product region and communicating with the plurality of through holes;
and a plurality of second through holes formed in a second region overlapping the outside-product region. 6. The through-hole printing mask according to claim 5,
The average diameter of the plurality of first through holes and the average diameter of the plurality of second through holes are substantially the same. 6. The through-hole printing mask according to claim 5,
The number of the first through holes per unit area in the first region is approximately the same as the number of the second through holes per unit area in at least the width half of the second region closer to the first region. 6. The through-hole printing mask according to claim 5,
The second plurality of through holes are copies of the first plurality of through holes in a portion of the first region.

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