JPH11261207A - Printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed board to which good soldering can be performed by making the filling up of a through hole which is connected to a solder pad or its vicinity and is hard to be filled up with a solder resist with the solder resist easier or preventing the flowing-in of molten solder in the through hole. SOLUTION: For the through hole 51 of a printed board having the through hole 51 at such a prescribed distance or shorter from a pad 50 for soldering surface mounting parts that molten solder on the pad 50 can flow in the through hole 51 at the time of performing reflow soldering, the hole 51 is filled up or a flowing-in blocking measure is taken to prevent the molten solder from flowing in the hole 51 or flowing to the rear surface of the printed board through the through hole 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a through hole connected to a solder pad of a surface mount component on a printed circuit board. In particular, the present invention relates to a printed circuit board that seals a through hole that is connected to or in the vicinity of a solder pad where solder resist processing cannot be performed.

[0002]

2. Description of the Related Art In a printed circuit board used in a high frequency region extending over a microwave band, it is important to dispose a through hole (including a via hole) and a solder pad of a mounted component. In particular, GN
It is necessary to connect the bypass capacitor connected to the D layer and the ground terminal of the IC lead to the through hole with a wiring pattern that generates as little L component (coil component) as possible.

FIG. 2A shows an example of a connection arrangement between a soldering pad 50 of an IC and through holes 51a to 51d, and FIG. 2B shows an example of a connection arrangement between a chip component (a capacitor or the like) and a through hole 51b. It is assumed that the boundary of the printable solder resist adjacent to these is in the state shown in the drawing. The through hole 51a is connected to the solder pad 50 by a relatively long wiring pattern, and the through hole 51b is
The through hole 51c is formed in a region of 0, and is connected to and connected to the soldering pad 50, and the through hole 51d is connected to the soldering pad 50 by a short wiring pattern.

FIG. 2C is an example of a side sectional view showing a case where there is a through hole 51b in the area of the soldering pad 50, printing and applying cream solder, and completing the soldering process by a reflow soldering method. In this case, since it is in the soldering pad 50, the solder resist printing cannot be naturally performed. For this reason, looking at the through hole 51b in FIG. 2C, the cream solder is printed and applied on the soldering pad 50, and despite the proper reflow soldering processing,
There is a problem that the molten solder flows into the through hole 51b and flows out to the back surface. As a result, the soldering pad 50 and the electrode of the mounted component are not soldered favorably, resulting in poor soldering or reduced reliability. A similar solder outflow may also occur in the through hole 51c shown in FIG. 2A where the solder resist is not printed.

[0005]

As described above, FIG.
A through hole 51 without solder resist printing shown in FIG.
In the case of b to 51d, there is a possibility that a problem that molten solder flows into the through hole 51b may occur even though the reflow soldering process is properly performed. For this reason, good soldering treatment cannot be expected, and there is a practical difficulty from the viewpoint of improving the quality of soldering. Therefore, the problem to be solved by the present invention is that a soldering pad that is connected to or in the immediate vicinity of the soldering pad and that is capable of performing solder filling difficult through hole filling processing or solder inflow inhibition processing can perform good soldering. It is to realize a simple printed circuit board.

[0006]

First, an embodiment of the invention for solving the above-mentioned problem is that the molten solder at the soldering pad 50 of the surface mounting component formed on the printed circuit board is formed during the reflow soldering process. In a printed circuit board having a through hole (for example, through holes 51b to 51d) within a predetermined distance that may flow into a through hole (including a via hole), the through hole flows into the through hole or from the through hole to the back surface of the printed circuit board. A printed circuit board characterized in that a filling process or a solder inflow inhibiting process is performed on the through hole so as not to flow. According to the above invention, a printed circuit board that can be connected to or in the immediate vicinity of the soldering pad and that can perform a filling process for a through-hole that is difficult to be solder-resisted or a process for inhibiting solder inflow, thereby enabling good reflow soldering is realized. it can.

FIG. 4 shows a solution according to the present invention. Second, in order to solve the above problem, in the configuration of the present invention, at the time of reflow soldering processing, the molten solder at the soldering pad 50 site of the surface mount component formed on the printed circuit board flows into the through hole. In a printed circuit board having through holes 51b to 51d provided within a predetermined distance that may come, a target through hole 51d from the back side of the surface of the soldering pad 50 of the surface mount component.
There is a printed circuit board in which a photosensitive agent 60, which easily penetrates into the through-hole inner wall by screen printing, is printed on a predetermined portion, the photosensitive agent 60 of the printed printed board is exposed, and the photosensitive agent is exposed and solidified.

FIG. 1 shows a solution according to the present invention. Third, in order to solve the above problem, in the configuration of the present invention, at the time of the reflow soldering process, the molten solder at the soldering pad 50 site of the surface mount component formed on the printed circuit board flows into the through hole. In a printed circuit board having through holes 51b to 51d provided within a predetermined distance that may come, a desired through hole 51b is formed from the back side of the surface of the solder pad 50 of the surface mount component.
To 51d, the photosensitive agent 60 is infiltrated so as not to be exposed on the surface of the soldering pad 50, and exposed from the surface of the soldering pad 50 of the infiltrated printed circuit board to expose the photosensitive agent 65a in the through holes 51b to 51d. There is a printed circuit board obtained by subjecting the through holes 51b to 51d to filling (sealing) by exposing and coagulating the through holes 51b to 51d by washing and removing the photosensitive agent 62 on the back side of the printed and coagulated board.

Further, in a printed circuit board on which surface mount components are mounted from both sides of the printed circuit board, after filling the through holes 51b to 51d on one of the board surfaces or processing for inhibiting the inflow of solder, the other board surface is treated. The above printed circuit board is characterized in that through holes 51b to 51d are filled or solder inflow is inhibited. Further, the through holes 51b to 51d for filling or inhibiting the inflow of solder include at least the through holes 51b in the pad region of the soldering pad 50 of the surface mount component, or the solder resist adjacent to the soldering pad 50 within a predetermined distance. Surhole 5 not done
The printed circuit board described above is characterized in that a filling process or a solder inflow inhibiting process is performed on 1c and 51d.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings together with embodiments.

FIG. 1 is a process diagram showing one embodiment of the formation of a printed circuit board according to the present invention. 1A, a printed circuit board is immersed in a container containing a photosensitive agent 60 with the soldering pad 50 side of the surface mount component facing upward. At this time, the photosensitive agent 6
Depending on the viscosity of the photosensitive agent 60, the photosensitive agent 60 is
Gently penetrate into the inside for a sufficient time to fill, for example, a few minutes. However, care should be taken so that the photosensitive agent 65a does not flow to the upper surface of the soldering pad 50 when the predetermined time is completed. In addition, the viscosity of the photosensitive agent 60 used is appropriate for the exposure time described below.

FIG. 1B shows that a photosensitive agent 60 is introduced into the through hole 51.
After the printed circuit board filled with is removed and the lower surface of the board is wiped out, a photosensitive light source (for example, ultraviolet light or the like) corresponding to the photosensitive agent 60 is irradiated from the upper side of the soldering pad 50 from the vertical direction for a predetermined time to form the inside of the through hole 51. Is exposed. During this exposure time, the photosensitive agent 65b filled into the through-hole has an appropriate viscosity without dripping. On the other hand, the photosensitive agent 62 adhering to the back surface is not exposed because it is shielded by the substrate itself. As a result,
Only the photosensitive agent 65b in the through hole 51 is gelled and solidified.

FIG. 1C is completed by washing and removing the unnecessary photosensitive agent 62 adhered to the back surface of the printed circuit board after the exposure. As a result, the target hole of the through hole 51 is filled (filled and sealed) with the solidified body 65c.

In the above description, all the through holes 51 on the entire surface of the printed circuit board are filled and sealed. At this time, the photosensitive agent 65b in the through holes 51 is appropriately solidified so as not to project to the rear side. It is possible to form. When formed in this way, in a printed circuit board having soldering pads 50 on both sides of the printed circuit board, the desired through holes 51 on both sides can be filled and sealed at one time.

Even if cream solder is printed and applied using the printed circuit board subjected to the above-described filling process and the reflow soldering process is performed, there is a great advantage that the problem that the molten solder flows into the through hole 51 as in the related art can be solved. Will be obtained.

The configuration of the present invention is not limited to the above embodiment. For example, if desired, as shown in FIG. 3, an exposure mask 7 for preventing exposure of a through hole in an area other than the target through hole 51 site.
0 may be arranged and inserted between the light source and the substrate for exposure. This can be applied, for example, when there is a through hole in which a component lead needs to be inserted. Also, using the above-described exposure mask method, solder pads 5 are formed on both sides of the printed circuit board.
The through holes 51 having 0 may be individually filled and sealed.

In the above description, the method of directly immersing the printed circuit board in the photosensitive agent 60 has been described. However, a process of printing the photosensitive agent 60 on a print target portion using a general screen printing method may be employed. In the case of this processing method, the inside of the through hole 51 is not filled. However, as shown in the enlarged view of the printing result in FIG. 4, the printing condition is such that the photosensitive agent to be printed penetrates to some extent into the conductor wall in the through hole to form a film. By doing so, it is possible to prevent a large amount of molten solder from flowing into the through hole 51, so that it is sufficiently practical. In this case, there is an advantage that the processing can be performed in a short time, and an advantage that only the target through hole 51 can be subjected to the inflow prevention processing. Alternatively, there is obtained an advantage that the temperature condition and the like at which stable processing can be performed at the time of reflow soldering can be greatly reduced. In addition, depending on the printing pattern shape of the screen printing, all the photosensitive agents 60 from the screen printed surface side
May be exposed to eliminate the step of washing and removing the photosensitive agent.

In the above description, the reflow soldering method is mainly used. However, in the case of the flow soldering method, if the through hole 51 is likely to flow from the through hole 51 to the back surface of the printed circuit board, the filling is similarly performed. The soldering may be applied to a printed circuit board that has been subjected to the processing or the solder inflow inhibition processing.

[0019]

According to the present invention, the following effects can be obtained from the above description. As described above, according to the present invention, it is often used in a high frequency region extending to a microwave band, and is required to be connected to the through hole 51 in the shortest time. By using a printed circuit board having a filling hole or a means for inhibiting the inflow of the solder, the through hole 51 where the solder resist to be formed cannot be formed can solve the problem of the inflow of the molten solder into the through hole 51 during the reflow soldering process. As a result, a great advantage that good soldering of the mounted component can be realized is obtained. In addition, there is obtained an advantage that the temperature condition and the like at which stable processing can be performed at the time of reflow soldering can be greatly reduced. Therefore, the technical effect of the present invention is great,
Industrial economic effects are also great.

[Brief description of the drawings]

FIG. 1 is a process chart showing one embodiment of a printed circuit board formation of the present invention.

FIG. 2 is an explanation of the arrangement of soldering pads and through holes,
It is explanatory drawing which the conventional molten solder flows out to a back surface.

FIG. 3 is another embodiment of the printed circuit board formation of the present invention.

FIG. 4 is another embodiment of forming a printed circuit board according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 50 soldering pad 51, 51 a to 51 d through hole 60, 62, 65 a, 65 b photosensitizer 65 c solidified body 70 exposure mask

Claims (5)

[Claims] 1. A printed circuit board having a through hole in which a molten solder at a solder pad portion of a surface mount component formed on the printed circuit board flows within a predetermined distance during a reflow soldering process.
A printed board, wherein a filling process or a solder inflow inhibiting process is performed on the through hole so as not to flow into the through hole or flow from the through hole to the back surface of the printed circuit board. 2. A printed circuit board having a through hole having a molten solder at a solder pad portion of a surface mount component formed on the printed circuit board within a predetermined distance flowing into the through hole during a reflow soldering process, A photosensitive agent is printed in a predetermined manner by screen printing from the back side of the soldering pad surface of the surface mount component to the through hole portion, the photosensitive agent on the printed printed board is exposed, and the photosensitive agent is exposed and solidified. And printed circuit board. 3. A printed circuit board having a through hole in which a molten solder at a solder pad portion of a surface mount component formed on the printed circuit board flows within the through hole during a reflow soldering process. A photosensitive agent is permeated into the through hole from the back side of the soldering pad surface of the surface mount component so as not to be exposed on the soldering pad surface, and is exposed from the soldering pad surface side of the permeated printed circuit board. A printed circuit board, wherein the through hole is solidified by exposing and solidifying a photosensitive agent in the through hole. 4. In a printed circuit board on which surface mount components are mounted from both sides of the printed circuit board, after filling a desired through hole on one substrate surface or a process for inhibiting solder inflow, a desired through hole on the other substrate surface is provided. 4. The printed circuit board according to claim 1, wherein a filling process or a process for inhibiting solder inflow is performed. 5. The through hole for filling or inhibiting solder inflow is a through hole at least in a pad region of a soldering pad of a surface mount component or a solder resist adjacent within a predetermined distance from the soldering pad. 4. The printed circuit board according to claim 1, wherein a filling process or a process for inhibiting the inflow of solder is performed on the through holes that do not exist.