JPH04165695A - Method of soldering flexible board and rigid board, and connection structure - Google Patents

Abstract

PURPOSE:To make it possible to execute a non-contact type soldering using an electric furnace, a laser beam or the like, for example, by a method wherein a flexible board is supported at a position on a rigid board at an angle to the rigid board, a solder is provided on the edge part of the flexible board and a part, which comes into contact to the edge part and is located on the surface of the rigid board, the solder is heated and melted and the boards are connected to each other and are fixed. CONSTITUTION:An edge part 32 of a flexible wiring board 12 is bent at 180 deg., a coverlay 40 of this bent part is removed and a copper foil 38 is made to expose. When the edge part 32 of the board 12 is made to abut on the surface 16 of a rigid wiring board 10, the edge part 32 comes into contact to a conductor part 42 provided on the surface 16 of the board 10. There, a pasty solder 44 is applied on the conductor part 42 of the board 10 and/or the exposed conductor part 38 of the board 12 in advance or after the contact and the solder 44 is remelted, whereby both wiring boards are electrically connected to each other. Thereby, a non-contact system soldering method can be executed and the danger to damage the boards and the conductor parts is avoided.

Description

[Detailed Description of the Invention] [Summary] When connecting a rigid board and a flexible board by soldering, the flexible board is placed against the rigid board with the edge of the flexible board in contact with the surface of the rigid board. By holding the flexible board in an upwardly tilted position, it is possible to perform soldering with both sides in close contact due to the elasticity of the flexible board itself, making it possible to improve solder quality and use non-contact soldering.

[Industrial application field]

The present invention relates to a method for mutually soldering a rigid board and a flexible board, and a connection structure for implementing this method.

[Conventional technology]

There are two types of substrates on which electronic components are mounted and electrical connections are made: those that are rigid and unflexible, and those that are thinner and more flexible. For example, in the case of printed wiring boards, the former so-called rigid wiring board is made using a laminate consisting of a laminate of sheets made of a base material such as paper or glass cloth impregnated with a resin material such as phenol. Provides hardness that does not bend.

On the other hand, the latter so-called flexible wiring board is generally 1
It is made of copper-clad film, which is made by bonding copper foil to two thin plastic films using an adhesive.The highly flexible and thin layer allows products to be made smaller and lighter, and is now widely used. ing.

Flexible wiring boards are used for printed wiring boards, cables,
And/or since it has a function as a connector, higher functionality is promoted by interconnecting the rigid wiring board and the flexible wiring board. Conventionally, such connections were made using contact soldering to prevent the two connection parts (conductor parts) from coming into close contact with each other due to the undulations and warping caused by the flexibility of the flexible wiring board. . Contact soldering is soldering in which a soldering iron, heat block, etc. is brought into direct contact with the connection part, and the connection part of the flexible wiring board is pressed against the rigid wiring board with the heat block etc. while soldering. was melted by heating.

[Problem to be solved by the invention]

In the case of contact soldering, for example, when using a soldering iron, the heat conduction efficiency may deteriorate due to solder scum or flux adhering to the iron tip, and as a result, heating may be concentrated in one place for a long time. This may cause damage to the conductor (copper foil) and board. Also, as a part to apply the iron,
It is necessary to prevent the copper foil from being damaged by providing leads to connect to the copper foil at the edges of the flexible wiring board.

The same applies when using a heat block, but complicated equipment is required for raising and lowering the heat block, cooling it, etc.

In view of the above-mentioned matters, the present invention, when connecting a rigid board and a flexible board, ensures that the connecting parts of each board are brought into close contact with each other without pressing with a soldering tool, for example, by using an electric furnace or a laser beam, etc. The object of the present invention is to provide a soldering method that allows non-contact soldering, and to provide a connection structure for implementing this method.

[Means to solve the problem]

The soldering method according to the present invention is a tanu soldering method for connecting a rigid substrate having a conductor portion on its surface to a flexible substrate having an end of the conductor disposed at the edge. The flexible substrate is supported in a predetermined posture, the edge of the flexible substrate is placed on the surface of the rigid substrate, and the flexible substrate is flexed near the edge while the edge is in contact with the surface. The substrates are supported at an angle upward relative to the rigid substrate, and solder is provided at the contact portion between the edge and the surface, and the solder is heated and melted to connect and fix each of the substrates to each other. This is how it was done.

Further, the connection structure according to the present invention for carrying out the above method includes a rigid substrate having a conductor portion on the surface, a flexible substrate having an end of the conductor arranged at the edge, and supporting the rigid substrate. a pedestal having a first support surface and a second support surface supporting the flexible substrate at an upward angle with respect to the first support surface, the base having a second support surface supporting the flexible substrate; When secured to the second support surface, an edge of the flexible substrate contacts a surface of the rigid substrate secured to the first support surface, and the flexible substrate is near the edge. The lower surface is bent convexly.

[For production]

The flexible substrate is fixed at an inclined position with respect to the rigid substrate, the edge of the flexible substrate is brought into contact with the surface of the rigid substrate, and the bottom surface near the edge of the flexible substrate is made convex. When bent, the elastic force of the flexible substrate itself forces the edges against the surface of the rigid substrate.

As a result, the conductor portions of the respective substrates are brought into close contact with each other. By performing soldering in this state, reliable connections between each board can be obtained.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a connection structure between a rigid substrate (hereinafter referred to as a rigid wiring board) 10 and a flexible substrate (hereinafter referred to as a flexible wiring board) 12 according to an embodiment of the present invention. 14 is each wiring board 1
This is a pedestal that fixes 0 and 12 in a predetermined posture. The rigid wiring board 10 is made of a double-sided copper-clad laminate with copper foil on the front side 16 and the back side 18, and uses paper or glass cloth as the base material and is impregnated with resin, so it has a hardness that does not bend easily. Be prepared. As will be described later, the flexible wiring board 12 is made by adhering copper foil, for example, with an adhesive, to a flexible and thin base film, and then applying a coverlay (insulating film), which is a thin layer and has excellent flexibility. Note that the rigid wiring board 10 can be variously modified, such as a multilayer ceramic laminate, a metal-based laminate, etc., in addition to the copper-clad laminate described above.

The pedestal 14 includes one floor surface 20, three side walls 22 extending perpendicularly to the floor surface 20, and one side wall 26 extending with an inclined surface 24. The floor surface 20 is rectangular, has a similarly rectangular opening 28 in the center (see FIG. 2), and acts as a first support surface for supporting the rigid wiring board 10.

The side walls 22 and 26 surround the floor surface 20 and
Extends above and below 0. As a result, recesses surrounded by side walls are formed above and below the floor surface 20. The sloped surface 24 of the sidewall 26 extends upwardly from the floor 20 at an obtuse angle and terminates near the top of the sidewall 26. Moreover, the inclined surface 24 is
It acts as a second support surface that supports the flexible wiring board 12, and includes a mounting hole (not shown) for fixing.

Below is a rigid wiring board 10 and a flexible wiring board 1
The soldering procedure with 2 will be explained.

The floor surface 20 of the pedestal 14 has an opening 2 as shown in FIG.
The rigid wiring board 10 is fixed with an adhesive or the like so as to cover the wiring board 8 . At this time, the opening 28 allows components to be mounted on the back surface 18 of the rigid wiring board 10, which has copper foil on both sides. The flexible wiring board 12 is fixed to the inclined surface 24 of the side wall 26 of the pedestal 14 with screws 30. In addition to this fixation 6, the flexible wiring board 12 is provided with a reinforcing plate 34 extending laterally in proximity to the edge 32. Then, the screws 30 pass through the holes provided at both ends of the reinforcing plate 34, and the inclined surface 2
The flexible wiring board 12 is fixed by screwing into the mounting hole 4. When each wiring board is fixed to the pedestal 14 in this manner, the edge 132 of the flexible wiring board 12 comes into contact with the surface 16 of the rigid wiring board 10. The flexible wiring board 12 is inclined parallel to the inclined surface 24 of the pedestal 14 at a portion of the reinforcing plate 34 near the edge 32 with respect to the rigid wiring board 10, and the edge 32 is in contact with the rigid wiring board 10. At this time, the lower surface of the portion below the reinforcing plate 34 is curved convexly as shown in the figure. At this time, due to the elastic force of the flexible wiring board 12 itself, the edge 3
2 is pressed against the rigid wiring board 10.

The angle of inclination of the inclined surface 24 and the length of the flexible wiring board 12 extending below the reinforcing plate 34 are set so that the above elastic force, that is, the pressing force is sufficiently obtained.

As shown in FIG. 3, the flexible wiring board 12 includes a base film 36 made of polyimide or polyester.
It has a laminated structure of a conductor portion 38 made of copper foil and a coverlay 40 made of the same material as the base film 36. In this embodiment, the edge 32 of the flexible wiring board 12 is
is bent by 180° as shown in FIG. 3, and the coverlay 40 at this bent portion is removed to expose the copper foil 38. When the edge 32 of the flexible wiring board 12 is brought into contact with the surface 16 of the rigid wiring board 10 as described above, the edge 32 comes into contact with the conductor portion 42 provided on the surface 16 of the rigid wiring board 10. Therefore, after contacting the conductor part 42 of the rigid wiring board 10 and/or the exposed conductor part 38 of the flexible wiring board 12, paste solder 4 is applied.
4 and remelting the solder 44 to electrically connect both wiring boards.

In this embodiment, the soldering process described above is performed by a non-contact method using laser light.

At this time, due to the aforementioned elastic force, the flexible wiring board 1
Since the edge 32 of the rigid wiring board 10 and the surface 16 of the rigid wiring board 10 are in close contact with each other, there is no need to press it with a soldering iron or the like. Therefore, reliable soldering can be achieved by heating and melting the paste-like solder 44 applied to the connecting portion of each conductor using a laser beam, and then cooling it.

In addition, instead of using laser light, so-called reflow soldering, in which solder is melted in an electric furnace, can also be used. According to reflow soldering, a group of electronic components (not shown) mounted on the rigid wiring board 10 can also be soldered in the same process.

In addition, after soldering the boards together and the electronic components and each board in this way, by filling the recesses above and below the pedestal 14 with a resin material such as silicone, it is possible to create an integrated electronic device with excellent heat resistance. can also be formed.

〔Effect of the invention〕

The present invention fixes the flexible substrate in an upwardly angled position with respect to the rigid substrate by curving the flexible substrate near the edge while the edge of the flexible substrate is in contact with the surface of the rigid substrate. However, since the contact portions are soldered, each board is brought into close contact with each other due to the elastic force of the flexible board itself, and there is no need for a device to press the edge of the flexible board. Therefore, a non-contact soldering method can be implemented, and the risk of damaging the board and conductor parts is avoided. Additionally, non-contact soldering allows electronic components to be mounted on the board to be soldered at the same time, making it possible to reduce the number of man-hours.

[Brief Description of the Drawings] Figure 1 is a perspective view of the board connection structure according to the present invention, Figure 2 is a sectional view taken along line ■-H in Figure 1, and Figure 3 is the soldering shown in Figure 2. FIG. 10... Rigid board, 12... Flexible board, 14... Pedestal, 16... Surface,
20... Floor surface, 24... Inclined surface, 32
...Edge, 38, 42...Conductor part,
44...Solder. Perspective view of board connection structure Fig. 1 Cross-sectional view taken along the line ■-■ Fig. 2 Fig. 4 Enlarged view of the soldering part

Claims (2)

[Claims] 1. A soldering method for connecting a rigid substrate having a conductor on its surface and a flexible substrate having a conductor end disposed at the edge, the rigid substrate being supported in a predetermined posture, Place the edge of the flexible substrate on the surface of a rigid substrate, and flex the flexible substrate near the edge and upward relative to the rigid substrate, with the edge in contact with the surface. A soldering method in which the substrates are supported at an angled position, solder is provided at the contact portion between the edge and the surface, and the solder is heated and melted to connect and fix each of the substrates to each other. 2. a rigid substrate having a conductor portion on its surface; a flexible substrate having an end of the conductor disposed at the edge; a first support surface supporting the rigid substrate; and an upper surface with respect to the first support surface. a pedestal having a second support surface that supports the flexible substrate at an angle, and when the flexible substrate is fixed to the second support surface, the A rigid substrate and a flexible substrate, the edge of which is in contact with the surface of the rigid substrate placed on the first support surface, and the flexible substrate has a lower surface bent convexly near the edge. Connection structure with the board.