WO2001031982A1

WO2001031982A1 - Filling printing method for hole-plugging printing for printed wiring board and plate for the same

Info

Publication number: WO2001031982A1
Application number: PCT/JP2000/007405
Authority: WO
Inventors: Hironobu Akada
Original assignee: Ibiden Co., Ltd.
Priority date: 1999-10-26
Filing date: 2000-10-23
Publication date: 2001-05-03
Also published as: JP4334705B2; JP2001127405A

Abstract

PURPOSE: To provide a hole-plugging printing method for a printed wiring board capable of satisfactorily filling a blind hole with a filling agent with no air bubble inside the hole, and a plate for the method. MEANS: A window (11) of a metallic plate (10) is defined in a position shifted from a via hole (81) in a board (82) to the downstream side in the direction (F) of the movement of a squeegee (93). A recess (12) that is continuous with the window (11) is defined on the upstream side of the window (11). When the filling agent (90) is squeezed by the squeegee (93), the filling agent (90) first flows through the window (11) into a portion of the via hole (81) the downstream side in the direction of the movement of the squeegee (93), and spreads out toward the upstream side. As a consequence, air is not confined in the via hole (81), and the via hole (81) is filled satisfactorily with the filling agent (90).

Description

Description Print-filling method for printed wiring board and plate therefor

Technical field

The present invention relates to printing for filling non-through holes, which is one of the processes in the manufacture of printed wiring boards. More particularly, the present invention relates to a printing method for filling holes in a printed wiring board and a printing plate for the method, in which non-through holes can be filled with a filler without leaving air bubbles inside.

Background art

In printed wiring boards, non-through holes for conduction between conductor layers are formed everywhere. It is desirable that this non-through hole be filled and flattened for convenience of upper layer lamination. Therefore, non-through holes on the surface of the substrate are generally filled by a printing method using a plate. Conventionally, as shown in Fig. 14, a window 101 about twice the size of the non-through hole 91 is formed in the plate 102, and the non-through hole 91 is The substrate 92 and the plate 102 were overlapped so as to be located at the center, and in this state, the filler 90 was poured into the non-through hole 91 through the window 101 by the squeegee 93.

However, the conventional technique described above has a problem that air bubbles 103 are likely to remain inside the non-through holes 91 as shown in FIG. This is considered to be due to the fact that the filler 90 covers almost the entire surface of the non-through hole 91 at once during printing. In other words, the air inside the non-through hole 91 loses its escape space, and the air bubbles 103 remain.

The present invention has been made to solve the above-mentioned problems of the conventional technology. That is, an object of the present invention is to provide a method for filling a printed wiring board with holes, which can fill non-through holes with a filler without leaving air bubbles inside, and a plate therefor. .

Disclosure of the invention

In a method for filling a hole in a printed wiring board according to the present invention, which has been made to solve this problem, A plate having a window corresponding to the non-through hole of the substrate is placed on the substrate, and the filler is placed thereon. The filler is poured into the non-through hole through the window by sweeping the plate with a squeegee. Thus, the filler is supplied to the non-through holes formed in the surface of the substrate. Here, the upstream end position of the window in the squeegee moving direction is within the area of the non-through hole, and the downstream end position of the window in the squeegee moving direction is located downstream of the downstream end position of the non-through hole in the squeegee moving direction. Printing is performed. In this method, the filler that has been extruded by the squeegee and passed through the window of the plate first lands on the downstream side in the squeegee moving direction even in the non-through hole of the substrate. Then, it flows on the bottom surface of the non-through hole in the direction opposite to the squeegee movement direction and spreads throughout the inside of the non-through hole. For this reason, the air that had been inside the non-through hole escapes without losing the escape. Therefore, the filler can be filled well without leaving any air bubbles inside the non-through holes. After that, through post-processes such as hardening of the filler and polishing of the excess, a printed wiring board with flat non-through holes is manufactured.

In the hole-filling printing method for a printed wiring board according to the present invention, it is preferable that a recessed portion is provided on the back surface of the plate at the upstream end of the window in the squeegee moving direction. In other words, a window corresponding to the non-through hole on the surface of the printed wiring board is opened, and a recess with a continuous recess at one end of the window is used on one side, and the recess comes upstream in the squeegee moving direction. They are arranged and printed in this way. In other words, the eaves protrude from the upstream side in the squeegee moving direction above the non-through holes during printing, and the tip of the eaves is in the area of the non-through holes.

In this way, there is a space by the recess above the non-through hole on the upstream side in the squeegee moving direction. For this reason, an escape route for air from inside the non-through holes during printing is secured. Therefore, the residual air bubbles inside the non-through holes are more reliably prevented.

In the hole filling printing method for a printed wiring board according to the present invention, it is preferable that a ventilation hole communicating between the front and back of the plate is formed in the recess portion of the plate. In other words, printing is performed using a plate that has ventilation holes in the recessed part so that the front and back sides communicate. In this way, the air pushed out of the non-through holes during printing can escape to the outside through the ventilation holes. As a result, pressure does not accumulate in the space inside the recess, and the residual air bubbles inside the non-through hole are more reliably prevented.

In the filling printing method for a printed wiring board according to the present invention, it is also preferable that the recess portion of the plate has a tapered shape that becomes shallower toward the upstream side in the squeegee moving direction. In other words, a plate with a tapered recess that is shallower from the window toward the position is used. In this way, when cleaning the plate after printing, the filler adhering to the inner surface of the recess can be easily removed, which is convenient. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view showing an outline of a substrate having a via hole.

FIG. 2 is a diagram showing an outline of off-contact screen printing.

FIG. 3 is a cross-sectional view showing filling of via holes in the embodiment.

FIG. 4 is a plan view showing the arrangement of via holes and windows.

FIG. 5 is a cross-sectional view showing filling of via holes (first half of inflow) in the embodiment. FIG. 6 is a cross-sectional view showing filling of via holes (end of inflow) in the embodiment. FIG. 7 is a diagram simply showing a post-process after filling the via hole.

FIG. 8 is a cross-sectional view showing an example in which ventilation holes are provided.

FIG. 9 is a cross-sectional view showing a case where the ventilation holes are too large.

FIG. 10 is a cross-sectional view showing an example in which a groove is provided.

FIG. 11 is a plan view showing the arrangement of via holes and windows when grooves are provided.

FIG. 12 is a cross-sectional view showing an example in which the inner surface of the recess is tapered.

FIG. 13 is a plan view showing another example of the arrangement of via holes and windows.

FIG. 14 is a diagram showing filling of via holes by conventional printing.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, as one process in the manufacture of a printed wiring board, a via hole 81, which is a non-through hole of the substrate 82 shown in FIG. 1, is filled with a filling resin.

The substrate 82 will be described briefly. The structure 82 is formed by laminating a conductor layer and an insulating layer. That is, the conductor layer 84 is formed on the insulation layer 83, the insulation layer 85 is formed thereon, and the conductor layer 86 is further formed thereon. The conductor layer 84, the insulation layer 85, and the conductor layer 86 are appropriately patterned. In particular, at the via hole 81, the insulating layer 85 and the conductor layer 86 have been removed. In the via hole 81, the conductive layer 84 and the conductive layer 86 are electrically connected by the plating layer 87. The size of the via hole 81 is about 100 to 200 μπι. The depth depends on the thickness of the insulating layer 85 and is about 40 to 70 πι.

In this embodiment, a metal plate 10 and a squeegee 93 are used as schematically shown in FIG. Filling the via hole 81 by filling the via hole 81 of the substrate 82 with a filling resin as a filler by off-contact screen printing. The metal plate 10 has a flat plate shape as a whole, and a window is opened at a position corresponding to the via hole 81 on the substrate 82. Then, a metal plate 10 is placed slightly above the substrate 82, a filler 90 is placed thereon, and the metal plate 10 is filled in the direction of arrow F while pressing the metal plate 10 against the substrate 82 with a squeegee 93. Sweep agent 90. As a result, the filler 90 flows into the via hole 81 through the window provided in the metal plate 10. As shown in the enlarged view of the main part in Fig. 3, the window 11 of the metal plate 10 is slightly offset from the via hole 81 on the downstream side of the arrow F (moving direction of the squeegee 93). I have. That is, the upstream end 11 A of the window 11 is located on the right side in FIG. 3 of the upstream end 81 A of the via hole 81. Similarly, the downstream end 11 B of the window 11 is located closer to the right in FIG. 3 than the downstream end 81 B of the via hole 81. However, the upstream end 11 A of the window 11 is located to the left of the downstream end 81 B of the via hole 81 in FIG. Therefore, the upper part of the via hole 81 is neither completely closed by the metal plate 10 nor completely opened by the window 11. Approximately half of the downstream side (rightward in FIG. 3) of arrow F is opened by window 11.

A recess 12 is provided at a position upstream of the window 11 and on the back side of the metal plate 10 (the surface in contact with the substrate 82). The recess 12 is provided continuously with the window 11. The upstream end 12 A of the recess 12 is located to the left in FIG. 3 of the upstream end 81 A of the via hole 81. Therefore, there is always a space for the window 11 or the recess 12 above the via hole 81. In Fig. 3, the distance from the upstream end 12A of the recess 12 to the downstream end 11B of the window 11 is approximately the same as the distance from the upstream end 81A of the via hole 81 to the downstream end 11B. It is twice. Compared to the conventional structure shown in Fig. 14, the structure of the window 11 and the recess 12 can be regarded as having an eaves from the upper half in the thickness direction of the upstream end of the window. Can also.

When the via hole 81 and the window 11 in Fig. 3 are viewed from above, the arrangement is as shown in Fig. 4. The metal plate 10 having such a structure of the window 11 and the recessed portion 12 is manufactured by forming the window 11 and then etching the recessed portion 12 from the back side to reduce the thickness. You. Alternatively, it can be manufactured by laminating a thin plate with holes of the same shape as that of window 11 and a thin plate with holes of the same shape as window 11 and recess 12.

When the squeegee 93 is moved in the direction of arrow F in the state shown in FIG. 3, the filler 90 that has reached the window 11 first passes through the window 11 as shown in FIG. Part from right in figure Flows into. Then, it flows on the bottom of the via hole 81 in the direction opposite to the arrow F and spreads throughout the via hole 81 (Fig. 6). Thus, instead of covering the entirety of the via hole 81 at once with the filler 90, the force first penetrates partially and spreads over the entirety.

For this reason, the air in the via hole 81 escapes to the outside naturally without being confined. In particular, the filler 90 first flows downstream in the direction of movement of the squeegee 93, and spreads upstream. For this reason, in the latter half of filling (Fig. 6), the pressing of the metal plate 10 by the squeegee 93 has already been released at the recess 12 and upstream thereof. This also contributes to the smooth escape of air. Therefore, no air bubbles remain in the via hole 81, and the via hole 81 is satisfactorily filled with the filler 90. If the movement of the squeegee 93 is reversed in Figs. 3, 5, and 6, the escape of the air from the via hole 81 will be hindered by the pressing of the squeegee 93 in the latter half of filling. .

Thus, when the via hole 81 is filled with the filler 90, the substrate 82 is taken out, and as shown in FIG. 7, the filler 90 is hardened and the protruding portion is polished. As a result, a substrate 82 having the via hole 81 flattened is obtained. The substrate 82 is then further subjected to post-processing such as build-up of the upper layer. The metal plate 10 is used to fill the via holes 81 of the substrate 82 again after cleaning and removing the attached filler 90.

In the present embodiment, various modifications can be made to the recess 12 in the metal plate 10.

First, as shown in Fig. 8, near the upstream end 12A of the recess 12 is provided a ventilation hole 13 that communicates the space above the metal plate 10 with the space inside the recess 12. Deformation. In this way, the air in the recess 12 can escape above the metal plate 10 through the ventilation holes 13 in the latter half of the filling. Therefore, the pressure in the recess 12 does not increase due to the air escaping from the via hole 81. Therefore, the via hole 81 can be more favorably filled with the filler 90. However, if the diameter of the vent hole 13 is too large, the filler 90 drops from the vent hole 13 into the recess 12 and further into the via hole 81 in the first half of filling (Fig. 9). Would. In this case, the diameter of the vent hole 13 must not be too large, since the significance as the present invention is lost. On the other hand, if it is too small, it is not preferable because the airflow resistance is large and it is useless. An appropriate diameter depends on the viscosity of the filler 90, but is generally about 10 to 20 µm.

Second, as shown in FIGS. 10 and 11, a methanol plate further upstream of the recess 12 is provided. A modification is to provide a groove 14 that is continuous with the recess 12 on the back surface of the groove 10. In this way. In the latter half of filling, the air in the recess 12 can escape to the outside through the groove 14. For this reason, as in the case where the ventilation hole 13 is provided, the pressure in the recess 12 is prevented from rising. It is particularly preferable that the groove 14 has a length reaching the front of the pattern of the conductor layer 86. However, there is some effect even if it is not so long. This is because after the squeegee 93 passes, the pressing is released and a slight gap is generated between the metal plate 10 and the substrate 82. The grooves 14 are different from the air holes 13 and do not cause any adverse effects in the first half of filling even if the diameter is too large. Also, both the groove 14 and the ventilation hole 13 in FIG. 8 may be provided.

Third, as shown in Fig. 12, there is a modification that makes the inner surface 12E of the recessed portion tapered. This has the advantage that the filler adhering to the inside of the recess can be easily and cleanly removed when cleaning the metal plate 10 after the filling operation is completed. Of course, the ventilation holes 13 in FIG. 8 and the grooves 14 in FIG. 10 may be provided, and the inner surface 12 E of the recess may be tapered.

As described above in detail, according to the present embodiment, the window 11 is provided so as to be shifted downstream of the via hole 81 in the moving direction of the squeegee 93, and the window 11 is provided upstream of the window 11. A recessed part 12 continuous with 11 is provided. Therefore, the filler 90 first flows into the via hole 81 on the downstream side in the moving direction of the squeegee 93, and then spreads toward the upstream side. As a result, no air is trapped in the via hole 81, and the via hole 81 is favorably filled with the filler 90. Thus, a hole filling printing method for the substrate 82 that can fill the via hole 81 with the filler 90 without leaving air bubbles therein, and a metal plate 10 for that purpose have been realized.

The present embodiment is merely an example, and does not limit the present invention in any way. Therefore, naturally, the present invention can be variously improved and modified without departing from the gist thereof. For example, the arrangement viewed from above the via holes and windows may be replaced by the arrangement shown in Fig. 4 instead of the arrangement shown in Fig. 4. However, since the squeegee may run diagonally, the arrangement shown in Fig. 4 is better in that case. The material of plate 10 is not limited to metal, but may be other materials.

Industrial applicability

As is apparent from the above description, according to the present invention, a method for filling a printed wiring board with holes, which can fill non-through holes with a filler without leaving air bubbles inside, and a plate therefor. Is provided

Claims

The scope of the claims

1. A method of filling a printed wiring board for supplying a filler to a non-through hole formed on the surface of a substrate,

A plate having a window corresponding to the non-through hole is placed on the substrate, a filler is placed on the plate, and the plate is swept with a squeegee to flow the filler through the window into the non-through hole. Including

An upstream end position of the window in the squeegee moving direction is within a region of the non-through hole;

A hole filling printing method for a printed wiring board, wherein the downstream end position of the window in the squeegee moving direction is downstream of the downstream end position of the non-through hole in the squeegee moving direction.

2. In the method for filling a hole in a printed wiring board according to claim 1,

A hole filling printing method for a printed wiring board, characterized in that a continuous recess is provided on the back surface of the plate at the upstream end of the window in the squeegee moving direction.

3. In the method for filling a hole in a printed wiring board according to claim 2,

A hole filling printing method for a printed wiring board, wherein a ventilation hole communicating between the front and back of the plate is formed in the recess portion.

4. In the method for filling a hole in a printed wiring board according to claim 2,

The recessed portion has a tapered shape that becomes shallower toward the upstream side in the squeegee moving direction.

5. The whole is flat,

Windows corresponding to the non-through holes on the surface of the printed wiring board are opened,

A recess for printing a hole in a printed wiring board, wherein a recessed portion continuous to one end of the window is formed on one surface.

In the plate for fill-in printing of the printed wiring board described in claim 5,

A plate for filling a hole in a printed wiring board, wherein the recess portion has a ventilation hole communicating between the front and back of the plate.

The recess portion is formed in a tapered shape in a position farther from the window, the shallower as the position is, and a printing plate for filling holes in a printed wiring board.