WO2018150526A1

WO2018150526A1 - Printed circuit board and production method for printed circuit board

Info

Publication number: WO2018150526A1
Application number: PCT/JP2017/005806
Authority: WO
Inventors: 佳郎西中; 佐々木　俊介
Original assignee: 三菱電機株式会社
Priority date: 2017-02-17
Filing date: 2017-02-17
Publication date: 2018-08-23

Abstract

This production method is for a printed circuit board comprising: a main base board having an elongated connection hole and a plurality of main side electrodes arrayed along the length direction of the periphery of the connection hole; and a standing base board having a connection strip section formed at one edge, and a plurality of standing side electrodes arrayed in the connection strip section along the one edge, the plurality of the main side electrodes being connected respectively to the plurality of the standing side electrodes via soldering portions when the connection strip section is in an inserted state in the connection hole of the main base board. The surface area of at least one of the main side electrodes or the standing side electrodes provided at an end portion on one side in the electrode array direction is formed so as to be larger than the surface area of the main side electrode or the standing side electrode provided at an end portion on the other side in the electrode array direction, and the soldering portions are sequentially formed from the end portion on the one side to the end portion on the other side, in the electrode array direction.

Description

Printed wiring board and printed wiring board manufacturing method

The present invention relates to a printed wiring board configured by combining a main board and a standing board, and a manufacturing method thereof.

Conventionally, as this type of three-dimensional printed wiring board, a connection hole is provided in a main board, a board is inserted perpendicularly to the connection hole, and the electrode at the insertion portion and the electrode around the connection hole are soldered. A substrate in which the size of the substrate is reduced by attaching is known (see, for example,

Patent Documents

1, 2, and 3). However, the amount of solder that joins the electrodes on the standing board and the main board may vary between the electrodes. Depending on the position of the electrodes, the amount of solder decreases, and thermal strain due to temperature cycling in the usage environment Therefore, cracks may occur in the solder joints.

On the other hand, the printed wiring board is increasingly manufactured by a flow soldering method from the viewpoint of improving production efficiency. In this flow soldering method, the lower part of the main board with the standing board assembled is immersed in the surface layer of the molten solder stored in the solder flow tank while moving the lower part of the main board in the horizontal direction by, for example, a conveyor belt. In this case, a series of electrodes that require solder bonding are sequentially brought into contact with the molten solder and soldered.

JP 2004-153178 A JP 2006-237176 A Registered Utility Model No. 3111232

However, when manufacturing a printed wiring board by the above-described flow soldering method, the electrode on which solder joining is to be started in the forefront of the board moving direction is short because the solder immersion time of the board itself is short and the amount of heat received from the molten solder is small. Moreover, the wetness of the molten solder is not sufficient, and the amount of solder joining is reduced. In addition, the surface layer part of the molten solder itself is brought into contact with the moving substrate electrode and is flowed by being pulled to the downstream side in the substrate moving direction while being used for solder bonding. Solder tends to accumulate, and an unbalance in the amount of solder joining occurs between the front and rear portions in the board moving direction. When thermal strain due to temperature cycling is applied to the board under such solder joint condition, stress concentrates on the electrode part at the top of the board where the amount of solder joint is small, and cracks are likely to occur, and reliability deteriorates. There was a problem to say.

The present invention has been made to solve the above-described problems, and obtains a highly reliable printed wiring board by suppressing variations in the amount of solder at the solder joint between the standing board and the main board. With the goal.

In order to achieve the above object, a printed wiring board manufacturing method according to the present invention includes a long connection hole, and a plurality of the connection holes are arranged around the connection hole along the longitudinal direction of the connection hole. A main substrate having a main-side electrode, a connection piece formed on one side, and a plurality of standing-side electrodes arranged on the connection piece along the one side. A printed wiring board comprising: a plurality of the main-side electrodes and a standing substrate in which each of the plurality of standing-side electrodes is connected by a solder portion in a state where one part is inserted into the connection hole of the main substrate The area of the at least one main side electrode or the standing side electrode provided at one end portion in the electrode arrangement direction is provided at the other end portion in the electrode arrangement direction. The area of the main side electrode or the standing side electrode Are also larger, the solder portion is sequentially formed from an end portion of the one side of the electrode arrangement direction toward the end of the other side.

According to the present invention, it is possible to obtain a highly reliable printed wiring board by suppressing variations in the amount of solder at the solder joint between the standing board and the main board.

It is a disassembled perspective view which shows the structural relationship of the main board | substrate and standing board | substrate of a printed wiring board in Embodiment 1 of this invention. It is a bottom view which shows the main board | substrate of the printed wiring board in Embodiment 1 of this invention. It is a side view which shows the standing board of the printed wiring board in Embodiment 1 of this invention. It is a side view which shows the solder joint start state in the printed wiring board in Embodiment 1 of this invention. 2A and 2B are diagrams illustrating a state immediately before completion of soldering in the printed wiring board according to the first embodiment of the present invention, where FIG. 1A is a side view, and FIG. 2B is a partial cross-sectional view taken along line AA ′ in FIG. It is. It is a bottom view which shows the main board | substrate of the general printed wiring board used as the comparison form of this invention. It is a side view which shows the standing board | substrate of the general printed wiring board used as the comparison form of this invention. It is a graph of the experimental result which showed the relationship between the solder joint width and electrode position in the general printed wiring board used as the comparison form of this invention. It is a bottom view which shows the main board | substrate of the printed wiring board in Embodiment 2 of this invention. It is a side view which shows the standing board of the printed wiring board in Embodiment 2 of this invention. It is a bottom view which shows the main board | substrate of the printed wiring board in Embodiment 3 of this invention. It is a side view which shows the standing board of the printed wiring board in Embodiment 3 of this invention. It is a bottom view which shows the main board | substrate of the printed wiring board in Embodiment 4 of this invention. It is a side view which shows the standing board of the printed wiring board in Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is an exploded perspective view showing a configuration relationship between a main board and a standing board of a printed wiring board according to Embodiment 1 of the present invention, and FIG. 2 is a bottom view showing the main board of the printed wiring board according to Embodiment 1 of the present invention. FIG. 3 is a side view showing the standing substrate of the printed wiring board according to Embodiment 1 of the present invention.
In each figure, the three-dimensional printed wiring board according to this embodiment includes a long connection hole 3 and a plurality of main sides arranged around the connection hole 3 along the longitudinal direction of the connection hole 3. A main substrate 1 having electrodes 5A (2) to 5A (n) and 5B (2) to 5B (n), a connection piece 2a formed on one side 21, and a connection portion along one side 21 A plurality of standing-side electrodes 4A (2) to 4A (n) and 4B (2) to 4B (n) arranged on the piece 2a, and the connection piece 2a is connected to the connection hole 3 of the main board 1. Are inserted into the plurality of main side electrodes 5A (2) to 5A (n), 5B (2) to 5B (n) and the plurality of standing side electrodes 4A (2) to 4A (n), 4B (2 ) To 4B (n) are each provided with a standing substrate 2 connected by a joining solder portion 6. The connection 3 is formed in, for example, a rectangular shape in plan view extending vertically through the main substrate 1.

The main side electrodes 5A (1) to 5A (n) and 5B (1) to 5B (n) of the main substrate 1 and the standing side electrodes 4A (1) to 4A (n) and 4B (1) of the standing substrate 2 described above. The electrode widths in the substrate movement direction M of 4B (n) are all W. The board moving direction M is a direction in which the assembly of the main board 1 and the standing board 2 moves relative to the molten solder in the solder flow tank, and the assembly is made by keeping the molten solder stationary. This is a concept that includes both cases where the assembly is moved, the assembly is kept stationary and the molten solder is moved, or the fusion solder and assembly are simultaneously moved in the opposite direction. The substrate moving direction M is a direction along the longitudinal direction of the connection hole 3 or one side 21 of the standing substrate 2. The main-side electrodes 5A (1) to 5A (n) and 5B (1) to 5B (n) of the main substrate 1 are all provided at the same pitch P and adjacent electrodes are provided with the same gap S therebetween. ing. The standing side electrodes 4A (1) to 4A (n) and 4B (1) to 4B (n) of the standing substrate 2 are all provided with the same pitch P and adjacent electrodes with the same gap S therebetween. .

Further, the length of the main-side electrodes 5A (1) and 5B (1) at the forefront position in the substrate movement direction M in the direction orthogonal to the substrate movement direction M is L1. The electrode length in the direction orthogonal to the substrate movement direction M in the main side electrodes 5A (2) to 5A (n) and 5B (2) to 5B (n) up to the last position in the substrate movement direction M is the main side electrode 5A. It is L2 shorter than the electrode length L1 of (1) and 5B (1). The length in the direction orthogonal to the substrate movement direction M in the standing-side electrodes 4A (1) and 4B (1) at the forefront position in the substrate movement direction M is L′ 1. Subsequent electrode lengths in the direction perpendicular to the substrate moving direction M in the standing side electrodes 4A (2) to 4A (n) and 4B (2) to 4B (n) up to the last position in the substrate moving direction M are as follows. (1), L′ 2 shorter than the electrode length L′ 1 of 4B (1).

That is, in this printed wiring board, the area (= L1 × W) of the main-side electrodes 5A (1) and 5B (1) at the foremost position in the board movement direction M of the standing board 2 is upstream of the board movement direction M. It is set to be larger than the area (= L2 × W) of the main side electrodes 5A (2) to 5A (n) and 5B (2) to 5B (n) at the (rear position). Further, the area (= L′ 1 × W) of the standing-side electrodes 4A (1) and 4B (1) at the foremost position in the substrate moving direction M of the standing substrate 2 is also the standing side on the upstream side of the substrate moving direction M. It is set larger than the area (= L′ 1 × W) of the electrodes 4A (2) to 4A (n) and 4B (2) to 4B (n). As a result, the main-side electrodes 5A (1) to 5A (n) and 5B (1) to 5B (n) of the main substrate 1 are connected to the individual rising-side electrodes 4A (1) to 4A (n ), 4B (1) to 4B (n) are arranged so that electrical connection can be made at positions corresponding to each other, and are arranged so as to be soldered to each other in contact or in contact with each other. Yes.

Next, a manufacturing mode of the printed wiring board will be described.
First, the connecting piece 2a of the standing board 2 is inserted into the connecting hole 3 of the main board 1 and assembled. At this time, the connecting piece 2a is in a state of protruding downward from the lower surface 1A of the main board 1. Then, the assembly is transported in a state of being placed on a conveyor (not shown) attached to the solder flow tank, and as shown in FIG. 4, the main side electrode 5 of the main board 1 and the standing side of the standing board 2 The electrode 4 starts to be immersed in the surface layer of the molten solder 10 in the solder flow tank from the foremost side in the board movement direction M. Incidentally, the hot-melted molten solder 10 is heated to about tens of degrees Celsius, and the temperature of the electrode in contact with the solder is about 100 degrees Celsius. Then, while the assembly is immersed in the surface layer of the molten solder 10, the molten solder 10 is moved horizontally along the surface of the molten solder 10 in the connecting direction of each electrode (that is, the substrate moving direction M). Towards the upstream side of the substrate movement direction M (flow direction F), the immersion electrode 4 and the main electrode 5 are repeatedly immersed and detached sequentially and then cooled and solidified to be joined and soldered

parts

6, 6, 6, Are formed and electrical connection and mechanical fixation are made. That is, the joint solder portion 6 sequentially transfers the printed wiring board along the one side 21 while sequentially moving the main side electrodes 5A (1) to 5A from the one end in the electrode arrangement direction toward the other end. (N), 5B (1) to 5B (n) and the standing electrodes 4A (1) to 4A (n) and 4B (1) to 4B (n) are immersed in the molten solder 10. As a result, the main-side electrodes 5A (1) to 5A (n) and 5B (1) to 5B (n) of the main substrate 1 and the standing-side electrodes 4A (1) to 4A (n) and 4B ( 1) to 4B (n) are respectively soldered and electrically connected.

As described above, in the printed wiring board of this embodiment, the main-side electrode 5 (1) at the foremost position in the board movement direction M of the main board 1 in FIG. The main side electrodes 5 (2) to 5 (n) are longer than the electrode length L2, thereby increasing the electrode area. Similarly, in the standing side electrode 4 of the standing substrate 2 shown in FIG. 3, the electrode length L′ 1 at the foremost position in the substrate moving direction M is longer than the upstream electrode length L′ 2 in the substrate moving direction M. The electrode area is increased.
Accordingly, it is possible to increase the solder amount of the joint solder portion 6 in the electrodes 5 (1) and 4 (1) at the foremost position, and the electrodes 5 (1) and 4 (1) at the foremost position and the electrodes at the rear position. With 5 (2) to 5 (n) and 4 (2) to 4 (n), variations in the amount of solder to be joined can be suppressed. That is, since a sufficient amount of solder can be joined with the electrodes 5 (1) and 4 (1) having a large area at the forefront position in the board movement direction M, a highly reliable printed wiring board can be obtained.

Comparative form.
On the other hand, all the electrodes 5 of the conventional main substrate 1 which is a comparative form shown in FIG. 6 have the same area, that is, the electrode length of the electrode 5 (only L1 and L2 are shown in the figure) are all the same length, The electrode width of the electrode 5 (only W1 and W2 are shown in the figure) is also the same width. Similarly, for the electrodes 4 of the conventional standing substrate 2, as shown in FIG. 7, all the electrodes 4 have the same electrode length (only L′ 1 and L′ 2 are shown in the figure), and The electrode width is the same (only W′1 and W′2 are shown in the figure).

Here, when solder joining is performed by the flow soldering method in a state where the conventional standing substrate 2 is inserted into the conventional main substrate 1, the substrate moving direction M in the same manner as described above with reference to FIG. Immersion is started in the molten solder 10 from the standing side electrode 4 at the foremost position, and the main side electrode 5 of the main substrate 1 and the standing side electrode 4 of the standing substrate 2 are soldered to each other. At this time, there is a difference in the immersion time in the molten solder 10 between the standing side electrode 4 and the main side electrode 5 at the foremost position in the substrate moving direction M and the standing side electrode 4 and the main side electrode 5 at the subsequent rear position. There is a difference in the amount of heat received. That is, since the standing side electrode 4 and the main side electrode 5 at the foremost position are in the stage of starting immersion in the molten solder 10, the amount of heat received is small, and the subsequent standing side electrode 4 and the main side electrode 5 at the rear position are the molten solder 10. Since the main substrate 1 and the standing substrate 2 arrive while being immersed in sequence, the amount of heat received increases.

Further, the molten solder 10 starts to be immersed from the front-side standing electrode 4 and main-side electrode 5 and is sequentially adjacent to the upstream side in the substrate movement direction M (flow direction F) and the standing-side electrode 4 and main-side electrode. 5 moves relatively in the flow direction F of the main substrate 1 and the standing substrate 2 while being soldered, so that the solder becomes more likely to accumulate on the electrodes as the

electrodes

4 and 5 are located at the rear position. Therefore, the viewpoint of the difference in the amount of heat received between the main side electrode 5 of the conventional main substrate 1 and the standing side electrode 4 of the conventional standing substrate 2 and the tendency of the molten solder to accumulate due to the moving direction (flow direction F) of the molten solder 10. Therefore, the amount of solder to be joined to the

electrodes

4 and 5 at the rear of the

electrodes

4 and 5 at the back of the

electrodes

4 and 5 at the foremost position in the board movement direction M is increased, resulting in variations in the amount of solder joining.

Next, FIG. 8 shows a combination of the conventional main board 1 and the conventional standing board 2 using a solder flow bath and soldering the joint solder portion 6 for all electrodes as an index indicating the amount of solder after soldering. It is the experimental result measured. In the figure, it can be seen that the width of the solder joint increases as the position becomes rearward in the substrate movement direction (direction of electrode No. 30 in the figure).

Variation in bonding solder amount between the

electrodes

5 and 4 at the foremost position in the board movement direction M and the

electrodes

5 and 4 behind the front position, that is, a product due to a small amount of bonding solder between the

electrodes

5 and 4 at the foremost position The main board 1 and the standing board 2 are configured as printed wiring boards and are used in a product such as an air conditioner outdoor unit. Stress is repeatedly applied to the solder joint 6 due to the difference in thermal expansion coefficient of the standing substrate 2. Furthermore, in the case of a continuous electrode arrangement like the conventional main substrate 1 or the conventional standing substrate 2, the stress of the electrodes at the front end, that is, the

electrodes

5 and 4 at the foremost position in the substrate moving direction M with a small amount of solder joints. Since it becomes large, there is a possibility that the joint solder portion at that position may undergo fatigue failure.

Embodiment 2. FIG.
In the first embodiment described above, the main-side electrodes 5A (1) and 5B (1) and the standing side are used as means for increasing the electrode area of the electrodes 5 (1) and 4 (1) at the foremost position in the substrate movement direction M. The example in which the electrode lengths L1 and L′ 1 of the electrodes 4A (1) and 4B (1) are increased has been described, but the second embodiment for increasing the electrode area as described above will be described next.
9 and 10 show the main board 1 and the standing board 2 in such a case. In the main substrate 1 of FIG. 9, the electrode width W1 of the main-side electrodes 5A (1), 5B (1) at the foremost position in the substrate movement direction M is set to the following main-side electrodes 5A (2) -5A (n), 5B ( 2) to 5B (n) are set larger than the electrode width W2. Further, in the standing substrate 2 of FIG. 10, the electrode width W′1 of the standing-side electrodes 4A (1) and 4B (1) at the foremost position in the substrate moving direction M is equal to the subsequent standing-side electrodes 4A (2) to 4A (n ), 4B (2) to 4B (n) are set to be larger than the electrode width W′2.

By adopting the configuration as described above, the electrode areas of the electrodes 5 (1) and 4 (1) at the foremost position are changed to the following electrodes 5 (2) to 5 (n) and 4 (2) to 4 (n). The electrode area can be made larger. Thereby, similarly to the effect by Embodiment 1 mentioned above, the variation in the amount of solder joined can be suppressed about each electrode. That is, since a sufficient amount of solder can be joined with the electrodes 5 (1) and 4 (1) having a large area in the forefront position in the board movement direction M, a printed wiring board having high reliability can be obtained.

Embodiment 3 FIG.
FIG. 11 is a bottom view showing a main board of a printed wiring board according to Embodiment 3 of the present invention, and FIG. 12 is a side view showing a standing board of the printed wiring board according to Embodiment 3 of the present invention.
Main side electrodes 5A (1) to 5A (n). In 5B (1) to 5B (n), the electrode length at the foremost position in the substrate movement direction M is L1, and the length of the main side electrode 5 adjacent to the upstream side in the substrate movement direction M (flow direction F) is Sequentially L2, L3, L4 (not shown),..., Ln-1 (not shown), Ln. These electrode lengths are set such that L1>L2>L3>...>Ln-1> Ln and gradually become shorter in the upstream direction of the substrate movement direction M (flow direction F). On the other hand, the standing side electrodes 4A (1) to 4A (n). The lengths of 4B (1) to 4B (n) are the same as those of the main substrate 1, and the length of the electrode 4 at the foremost position in the substrate movement direction M is L′ 1, and , L′ 2, L′ 3, L′ 4 (not shown),..., L′ n−1 (not shown), L′ n. These electrode lengths are set such that L′ 1> L′ 2> L′ 3>...> L′ n−1> L′ n and gradually decrease in the flow direction F.

By adopting the above-described configuration, it is possible to suppress variation in the solder amount of the joining solder portion 6 (see FIG. 5) between the main-side electrode 5 of the main board 1 and the rising-side electrode 4 of the standing board 2 over all the electrodes. In addition to the effects of the first embodiment, since a sufficient amount of solder can be joined to the electrodes 5 (1) and 4 (1) at the foremost position in the board movement direction M, a printed wiring board having extremely high reliability can be obtained. Obtainable.

Embodiment 4 FIG.
FIG. 13 is a bottom view showing a main board of a printed wiring board according to Embodiment 4 of the present invention, and FIG. 14 is a side view showing a standing board of the printed wiring board according to Embodiment 4 of the present invention.
Main side electrodes 5A (1) to 5A (n). In 5B (1) to 5B (n), the width of the electrode at the forefront position in the substrate movement direction M is W1, and the width of the adjacent electrodes in the flow direction F is sequentially set to W2, W3, W4 (not shown),. .., Wn-1 (not shown), Wn. These electrode widths are set such that W1>W2>W3>...>Wn-1> Wn and gradually decrease in the flow direction F. On the other hand, the standing side electrodes 4A (1) to 4A (n). Similarly to the main substrate 1, the electrode widths of 4B (1) to 4B (n) are W′1 as the electrode width at the foremost position in the substrate movement direction M, and the electrode widths of the adjacent electrodes in the flow direction F are Sequentially W′2, W′3, W′4 (not shown),..., W′n−1 (not shown), W′n. These electrode widths are set so as to gradually decrease in the flow direction F as W′1>W′2>W′3>...>W′n−1> W′n. .

By adopting the above-described configuration, it is possible to suppress variation in the solder amount of the joining solder portion 6 (see FIG. 5) between the main-side electrode 5 of the main board 1 and the rising-side electrode 4 of the standing board 2 over all the electrodes. In addition to the effects of the second embodiment, since a sufficient amount of solder can be joined to the electrodes 5 (1) and 4 (1) at the foremost position in the board movement direction M, a printed wiring board having extremely high reliability can be obtained. Obtainable.

In the first to fourth embodiments, the individual main side electrodes of the main board and the individual standing side electrodes of the standing board are set to have the same area. However, the present invention is limited to this. Not a thing. For example, in each of the configurations of the first to fourth embodiments, the characteristic configuration of the present invention can be employed for either the main side electrode or the standing side electrode. Even with such a configuration, the effects specific to the present invention can be obtained accordingly.

1 Main substrate, 1A bottom surface, 2 Standing substrate, 2a Connection piece, 3 Connection hole, 4A (1) to 4A (n) Standing side electrode,
4B (1) to 4B (n) Standing side electrode, 5A (1) to 5A (n) Main side electrode, 5B (1) to 5B (n) Main side electrode, 6 Junction solder, 10 Molten solder, F flow Direction, L1, L2, L'1, L'2 electrode length, M substrate moving direction, P pitch, S interval, W, W1, Wn, W'1, W'n electrode width

Claims

A main substrate having a long connection hole and a plurality of main-side electrodes arranged around the connection hole along the longitudinal direction of the connection hole;
A connecting piece formed on one side and a plurality of standing electrodes arranged on the connecting piece along the one side, wherein the connecting piece is the connection hole of the main board. A plurality of the main-side electrodes and a standing substrate in which each of the plurality of standing-side electrodes is connected by a solder part, and a printed wiring board manufacturing method comprising:
The area of the at least one main side electrode or the standing electrode provided at one end in the electrode arrangement direction is equal to the area of the main side electrode or the standing electrode provided at the other end in the electrode arrangement direction. It is formed larger than the area of the side electrode,
The said solder part is a manufacturing method of the printed wiring board formed in order toward the said other edge part from the said one edge part of the said electrode arrangement direction.
The solder portion sequentially conveys the printed wiring board along the one side from the end on the one side to the end on the other side in the electrode arrangement direction, sequentially from the main side electrode and the standing side. The manufacturing method of the printed wiring board of Claim 1 formed by immersing an electrode in molten solder.
The length of the main-side electrode of the main substrate or the standing-side electrode of the standing substrate in the direction orthogonal to the longitudinal direction of the connection hole is more on the one side than the other side in the electrode arrangement direction. The manufacturing method of the printed wiring board of Claim 1 or Claim 2 in which the direction is formed long.
The length along the longitudinal direction of the connection hole of the main side electrode of the main substrate or the standing side electrode of the standing substrate is formed longer on the one side than the other side in the electrode arrangement direction. The manufacturing method of the printed wiring board as described in any one of Claim 1- Claim 3.
The area of the main-side electrode of the main substrate or the area of the standing-side electrode of the standing substrate is formed so as to gradually decrease from the one side in the electrode arrangement direction toward the other side. The manufacturing method of the printed wiring board as described in any one of Claims 1-4.
The individual main-side electrodes of the main board and the individual standing-side electrodes facing the main-side electrode of the standing board are both formed in the same area. The manufacturing method of the printed wiring board as described in any one of Claims.
A main substrate having a long connection hole and a plurality of main-side electrodes arranged around the connection hole along the longitudinal direction of the connection hole;
A connecting piece formed on one side and a plurality of standing electrodes arranged on the connecting piece along the one side, wherein the connecting piece is the connection hole of the main board. A plurality of main-side electrodes and a plurality of standing-side electrodes, each of which is connected by a solder portion,
The area of the at least one main side electrode or the standing electrode provided at one end in the electrode arrangement direction is equal to the area of the main side electrode or the standing electrode provided at the other end in the electrode arrangement direction. A printed wiring board formed larger than the area of the side electrode.