JP4334705B2 - Method for filling hole in printed wiring board and plate therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to printing for filling non-through holes, which is a process in the manufacture of printed wiring boards. More specifically, the present invention relates to a method of filling a printed wiring board with a filling material, which can satisfactorily fill non-through holes with a filler without leaving bubbles inside, and a plate therefor.
[0002]
[Prior art]
In a printed wiring board, non-through holes for conduction between conductor layers are formed everywhere. This non-through hole is preferably filled and flattened for the convenience of upper layer lamination. In general, therefore, non-through holes on the surface of the substrate are filled by a printing method using a plate. Conventionally, as shown in FIG. 14, a window 101 having a size about twice the size of the non-through hole 91 is formed in the plate 102, and the substrate 92 and the plate are positioned so that the non-through hole 91 is located at the center of the window 101. In this state, the filler 90 was poured into the non-through hole 91 through the window 101 by the squeegee 93.
[0003]
[Problems to be solved by the invention]
However, the conventional technique described above has a problem that the 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 the time of printing. That is, the air inside the non-through hole 91 loses the escape space, and the bubbles 103 remain.
[0004]
The present invention has been made to solve the above-described problems of the prior art. That is, it is an object of the present invention to provide a printed wiring board hole-filling printing method and a plate therefor that can satisfactorily fill non-through holes with a filler without leaving bubbles inside.
[0005]
[Means for Solving the Problems]
In the printed wiring board hole-filling printing method according to the present invention made for the purpose of solving this problem, a plate having a window corresponding to a non-through hole of the substrate is covered on the substrate, and a 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 on the surface of the substrate. Here, the upstream end position of the window in the squeegee movement direction is in the non-through hole region, and the downstream end position of the window in the squeegee movement direction is downstream of the non-through hole in the squeegee movement direction downstream position. Printing is performed.
[0006]
In this method, the filler that has been pushed out by the squeegee and passed through the window of the plate first lands on the downstream side of the non-through hole of the substrate in the squeegee movement direction. Then, it flows on the bottom surface of the non-through hole in the direction opposite to the squeegee moving direction and reaches the entire inside of the non-through hole. For this reason, the air existing inside the non-through hole escapes without losing the escape. Therefore, it can be satisfactorily filled with the filler without leaving bubbles inside the non-through holes. Thereafter, a printed wiring board having a flat non-through hole portion is manufactured through subsequent processes such as hardening of the filler and polishing of the excess.
[0007]
In the printed wiring board hole-filling printing method according to the present invention, it is preferable that a recess portion is provided on the back surface of the plate on the upstream end side in the squeegee movement direction of the window. In other words, a plate is formed in which a window corresponding to a non-through hole on the surface of the printed wiring board is opened, and a recess is formed on one side of the window, and the recess comes upstream in the squeegee movement direction. They are arranged and printed. In other words, the eaves portion protrudes from the upstream side in the squeegee movement direction above the non-through hole during printing, and the tip of the eave portion is within the non-through hole region.
[0008]
If it does in this way, the space by a recess part exists above the part of the non-through-hole upstream in the squeegee movement direction. For this reason, the escape route of the air from the inside of the non-through hole at the time of printing is secured. Therefore, the remaining of bubbles inside the non-through hole can be prevented more reliably.
[0009]
In the printed wiring board hole-filling printing method according to the present invention, it is desirable that a vent hole communicating with the front and back of the plate is formed in the recess portion of the plate. That is, printing is performed using a plate in which vent holes are provided in the recess portion so that the front and back sides communicate with each other. If it does in this way, the air pushed out from the non-through hole at the time of printing can also escape outside from a vent hole. For this reason, pressure does not accumulate in the space in the recess portion, and the remaining of bubbles inside the non-through hole is further reliably prevented.
[0010]
In the method for filling holes in a printed wiring board according to the present invention, it is also desirable that the recess portion of the plate has a tapered shape that becomes shallower toward the upstream side in the squeegee movement direction. In other words, a plate having a tapered recess portion that is shallower from the window is used. This is convenient because the filler adhering to the inner surface of the recess can be easily removed when the plate is cleaned after printing.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. In the present embodiment, as one process in the production of a printed wiring board, the via hole 81 that is a non-through hole of the substrate 82 shown in FIG. 1 is filled with a filling resin.
[0012]
The substrate 82 will be briefly described. The substrate 82 is configured by laminating a conductor layer and an insulating layer. That is, the conductor layer 84 is formed on the insulating layer 83, the insulating layer 85 is formed thereon, and the conductor layer 86 is further formed thereon. The conductor layer 84, the insulating layer 85, and the conductor layer 86 are appropriately patterned. In particular, at the location of the via hole 81, the insulating layer 85 and the conductor layer 86 are removed. Also, at the location of the via hole 81, the conductor layer 84 and the conductor layer 86 are electrically connected by the plating layer 87. The size of the via hole 81 is about 100 to 200 μm. The depth depends on the thickness of the insulating layer 85 and is about 40 to 70 μm.
[0013]
In the present embodiment, as schematically shown in FIG. 2, the via hole 81 is formed by pouring a filling resin as a filler into the via hole 81 of the substrate 82 by off-contact screen printing using the metal plate 10 and the squeegee 93. Fill. The metal plate 10 has a flat plate shape as a whole, and a window is opened at a location corresponding to the via hole 81 in the substrate 82. Then, the metal plate 10 is disposed slightly above the substrate 82, the filler 90 is placed thereon, and the filler 90 is swept in the direction of arrow F while pressing the metal plate 10 against the substrate 82 with the squeegee 93. As a result, the filler 90 is poured into the via hole 81 through the window provided in the metal plate 10.
[0014]
As shown in the enlarged view of the main part in FIG. 3, the window 11 of the metal plate 10 is arranged slightly shifted from the via hole 81 on the downstream side of the arrow F (moving direction of the squeegee 93). That is, the upstream end 11 </ b> A of the window 11 is located on the right side in FIG. 3 with respect to the upstream end 81 </ b> A of the via hole 81. Similarly, the downstream end 11 </ b> B of the window 11 is located on the right side in FIG. 3 with respect to the downstream end 81 </ b> B of the via hole 81. However, the upstream end 11 </ b> A of the window 11 is located to the left in FIG. 3 from the downstream end 81 </ b> B of the via hole 81 and is located substantially in the center of the via hole 81 in FIG. 3. Therefore, the upper portion of the via hole 81 is not completely blocked by the metal plate 10 and is not completely opened by the window 11. About half of the downstream side of arrow F (to the right in FIG. 3) is opened by window 11.
[0015]
A recess 12 is provided at a position on the upstream side of the window 11 and on the back surface (surface in contact with the substrate 82) side of the metal plate 10. The recess portion 12 is provided continuously to the window 11. The upstream end 12 </ b> A of the recess 12 is located on the left side in FIG. 3 with respect to the upstream end 81 </ b> 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 about twice the distance from the upstream end 81A of the via hole 81 to the downstream end 11B. The structure of the window 11 and the recess portion 12 can also be understood as having an eaves portion from the upper half in the thickness direction of the upstream end portion of the window when compared with the conventional structure of FIG.
[0016]
When the via hole 81 and the window 11 in FIG. 3 are viewed from above, the arrangement is as shown in FIG. The metal plate 10 having such a structure of the window 11 and the recess portion 12 is manufactured by forming the window 11 and then reducing the thickness by etching the recess portion 12 from the back side. Or it can manufacture also by bonding together the thin plate which opened the hole of the same shape as the window 11, and the thin plate which opened the hole of the shape which combined the window 11 and the recess part 12. FIG.
[0017]
When the squeegee 93 is moved in the direction of arrow F in the state of FIG. 3, the filler 90 that has reached the window 11 first passes through the window 11 as shown in FIG. Flows into the part. Then, it flows in the direction opposite to the arrow F through the bottom surface of the via hole 81 and reaches the entire via hole 81 (FIG. 6). In this way, the filler 90 does not cover the entire via hole 81 at once, but first partially enters and spreads throughout.
[0018]
For this reason, the air in the via hole 81 naturally escapes without being trapped. In particular, the filler 90 first flows into the downstream side in the moving direction of the squeegee 93 and spreads toward the upstream side. For this reason, in the latter half of the filling (FIG. 6), the pressing of the metal plate 10 by the squeegee 93 is already released in the recess 12 and upstream thereof. This also contributes to the smooth escape of air. Therefore, no 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, air escape from the via hole 81 is hindered due to the pressing of the squeegee 93 in the latter half of filling.
[0019]
Thus, when the via hole 81 is filled with the filler 90, the substrate 82 is taken out, and the filler 90 is cured and the protruding portion is polished as shown in FIG. As a result, the substrate 82 in which the via hole 81 is flattened is obtained. Thereafter, the substrate 82 is further subjected to post-processing such as buildup of an upper layer. Further, the metal plate 10 is used for filling the via hole 81 of the substrate 82 again after cleaning and removing the adhering filler 90.
[0020]
In the present embodiment, various modifications can be made to the recessed portion 12 of the metal plate 10.
[0021]
First, as shown in FIG. 8, there is a modification in which a vent hole 13 is provided in the vicinity of the upstream end 12 </ b> A of the recess portion 12 to communicate the space above the metal plate 10 and the space in the recess portion 12. If it does in this way, the air in the recess part 12 can escape to the upper direction of the metal plate 10 through the vent hole 13 in the latter half of filling. For this reason, the pressure in the recess portion 12 does not increase due to the air escaped from the via hole 81. Therefore, the via hole 81 can be more satisfactorily filled with the filler 90. However, if the diameter of the vent hole 13 is too large, the filler 90 falls from the vent hole 13 and enters the recess portion 12 and further into the via hole 81 in the first half of the filling (FIG. 9). In this case, since the significance as the present invention is lost, the diameter of the vent hole 13 should not be too large. On the other hand, if it is too small, the ventilation resistance is too large to be used, which is not preferable. The appropriate diameter is approximately 10 to 20 μm, though it depends on the viscosity of the filler 90.
[0022]
Secondly, as shown in FIGS. 10 and 11, there is a modification in which a groove 14 continuing to the recess portion 12 is provided on the back surface of the metal plate 10 further upstream of the recess portion 12. If it does in this way, the air in the recess part 12 can escape outside through the groove | channel 14 in the latter half of filling. For this reason, similarly to the case where the vent hole 13 is provided, an increase in pressure in the recess portion 12 is prevented. It is particularly preferable that the groove 14 has a length that reaches 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 pressure is released and a slight gap is generated between the metal plate 10 and the substrate 82. In addition, unlike the vent hole 13, the groove 14 does not cause an adverse effect in the first half of the filling even if the diameter is too large. Further, both the groove 14 and the vent hole 13 of FIG. 8 may be provided.
[0023]
Thirdly, as shown in FIG. 12, the inner surface 12E of the recess is tapered. If it does in this way, when cleaning the metal plate 10 after completion | finish of a filling operation | work, there exists an advantage that the filler adhering to the inside of a recess part can be removed easily beautifully. Of course, the inner surface 12E of the recess portion may be tapered by providing the vent hole 13 of FIG. 8 and the groove 14 of FIG.
[0024]
As described above in detail, according to the present embodiment, the window 11 is provided to be shifted downstream of the via hole 81 in the moving direction of the squeegee 93, and a recess portion that is continuous with the window 11 on the upstream side of the window 11. 12 etc. are 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. For this reason, air is not confined in the via hole 81, and the via hole 81 is satisfactorily filled with the filler 90. Thus, the method for filling and printing the substrate 82 that can satisfactorily fill the via hole 81 with the filler 90 without leaving bubbles inside, and the metal plate 10 therefor are realized.
[0025]
Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the arrangement seen from above the via holes and windows may be arranged as shown in FIG. 13 instead of the arrangement shown in FIG. However, since the squeegee may run diagonally, the arrangement shown in FIG. 4 is better in that case. Further, the material of the plate 10 is not limited to metal and may be other materials.
[0026]
【The invention's effect】
As is apparent from the above description, according to the present invention, there is provided a printed wiring board hole-filling printing method and a plate therefor that can satisfactorily fill non-through holes with a filler without leaving bubbles inside. ing.
[Brief description of the drawings]
FIG. 1 is a cross-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 a via hole 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 via hole filling (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 a via hole.
FIG. 8 is a cross-sectional view showing an example in which vent holes are provided.
FIG. 9 is a cross-sectional view showing a case where a vent hole is 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 illustrating filling of via holes by conventional printing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Metal plate 11 Window 12 Recess part 12E Inner surface 13 of recess part Vent hole 81 Via hole 82 Substrate 90 Filler

Claims (7)

In a method for filling holes in a printed wiring board for supplying a filler to non-through holes formed on the surface of a substrate,
A plate with a window corresponding to the non-through hole is placed on the substrate, and a filler is placed thereon,
Pouring filler through the window into the non-through hole by sweeping over the plate with a squeegee;
The upstream end position of the window in the squeegee movement direction is in the region of the non-through hole,
A printed wiring board hole-filling printing method, wherein the downstream end position of the window in the squeegee movement direction is located downstream of the non-through hole in the squeegee movement direction downstream position. In the printed wiring board hole-filling printing method according to claim 1,
A printed wiring board hole-filling printing method, wherein a recess portion is provided on the back surface of the plate on the upstream end side in the squeegee movement direction of the window. In the printed wiring board hole-filling printing method according to claim 2,
A printed wiring board hole-filling printing method, wherein a vent hole is formed in the recess portion so as to communicate the front and back of the plate. In the printed wiring board hole-filling printing method according to claim 2,
The method of filling a printed wiring board with a hole, wherein the recess has a tapered shape that becomes shallower toward the upstream side in the squeegee movement direction. The whole is flat,
A window corresponding to the non-through hole on the surface of the printed wiring board is opened.
A plate for hole-filling printing of a printed wiring board, wherein a recess portion continuous with one end of the window is formed on one surface. In the plate for hole-filling printing of the printed wiring board according to claim 5,
A plate for hole-filling printing of a printed wiring board, wherein the recess portion is formed with a vent hole communicating the front and back of the plate. In the plate for hole-filling printing of the printed wiring board according to claim 5,
A plate for hole-filling printing of a printed wiring board, wherein the recess portion has a shallower taper as it is farther from the window.

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