JPH08148821A - Soldering method of flexible printed circuit board - Google Patents

Abstract

PURPOSE: To easily prevent generation of unsoldered parts. CONSTITUTION: When a terminal 4 is soldered to a land 3 formed on an FPC 2 whose softening point is lower than or equal to 230 deg.C by using a totally soldering method, the land 3 and an aperture 7 which is larger than the land 3 looked down by the terminal 4 are formed on a heat insulating holder 1 composed of a paper phenol board or the like. The heat insulating holder 1 is made to abut against the solder sticking surface side of the FPC 2 in the manner in which the land 3 and the terminal 4 are positioned in the part of the aperture 7, and an overall soldering method is performed while maintaining the abutting state. Thereby, molten solder passes the inside of the aperture 7 and easily reaches the land 3, and generation of unsoldered parts can be prevented, without working the vertical section of the aperture 7 into a trapezoidal shape as in the conventional case.

Description

Detailed Description of the Invention

[0001]

This invention has a softening point of 230 ° C.
The present invention relates to a method for soldering a flexible printed circuit board, in which terminals are soldered to a land formed on the flexible printed circuit board by a total soldering method.

[0002]

2. Description of the Related Art Polyethylene terephthalate (hereinafter PE
In the case of a flexible printed circuit board (hereinafter referred to as FPC) having a board made of T), the softening point of PET is 220 to 230 ° C, which is almost the same as the melting temperature of normal solder, so normal solder is used. The conventional soldering method such as jet soldering or reflow soldering cannot be applied.

On the other hand, it is conceivable to locally heat and solder by using a low melting point solder of 200 ° C. or lower, but there are problems of cost and safety depending on the kind of material added to lower the melting point of the solder. And so on.

Therefore, conventionally, FP has been used without using a low melting point solder.
As a method of soldering the C land and the terminal, Japanese Patent Laid-Open No.
A soldering method described in Japanese Patent No. 218632 has been proposed. As shown in FIG. 9, the soldering method includes a heat insulating holder 1 made of a paper phenol substrate, a paper epoxy substrate, a glass epoxy substrate, etc., a land 3 of an FPC 2 and a terminal. 4, an opening 5 having the same size as the land 3 is formed, and the heat insulating holder 1 is brought into contact with the solder attachment surface side of the board of the FPC 2 so that the land 3 and the terminal 4 are located in the opening 5. The entire soldering method is performed while maintaining this contact state.

At this time, in order to facilitate the penetration of solder, the contact surface side of the opening 5 is formed to have the same size as the land 3 and the opposite side to be larger than the land 3, and the opening 5 has a vertical cross-sectional shape. It has a shape.

[0006]

However, according to the method described in the above publication, the opening 5 formed in the heat insulating holder 1 has the opening F.
Since it is the same size as the land 3 of the PC 2 and is very small, as shown in FIG.
When the entire soldering is performed by bringing the PC 2 into contact with the molten solder 6 in the solder bath, the surface tension of the molten solder 6 may prevent the solder 6 from reaching the lands 3 and become a non-soldered state.

Further, when a large number of terminals are soldered like terminals of a connector, the number of lands is the same as the number of terminals, and the number of openings corresponding to each land is also large. When many trapezoidal openings are manufactured, the number of manufacturing steps and the manufacturing cost increase.

Therefore, the present invention has been made to solve the above problems, and an object thereof is to easily prevent the occurrence of unsoldered solder.

[0009]

According to the first aspect of the present invention,
When a terminal is soldered to a land formed on a flexible printed circuit board having a softening point of 230 ° C. or less by an entire soldering method, an opening through which the land and the terminal can be seen is formed in a heat insulating holder. In a soldering method for a flexible printed circuit board, the adiabatic holder is brought into contact with the solder-attached surface side of the board so that the land and the terminal are located in a portion, and the whole soldering method is performed by holding this contact state. The opening of the heat insulating holder is larger than the land.

Further, as described in claim 2, the softening point is 2
When soldering a plurality of terminals of a connector to a plurality of lands arrayed and formed on a flexible printed circuit board of 30 ° C. or less by a total soldering method, a land row of each land is attached to a heat insulating holder. An opening that is slightly larger than the smallest enclosed rectangle is formed, and the heat insulating holder is brought into contact with the solder attachment surface side of the board so that the lands and terminals are located in this opening. It is also effective to carry out the entire soldering method while holding

Further, as described in claim 3, when the terminal is soldered to the land formed on the flexible printed circuit board having a softening point of 230 ° C. or less by the whole soldering method, the heat insulating holder is used. An opening through which the land and the terminal are viewed is formed, and the heat insulating holder is brought into contact with the solder-attached surface side of the substrate so that the land and the terminal are located in the opening, and the contact state is held to hold the entire solder. In the method of soldering flexible printed circuit board,
The thickness of the heat insulating holder may be about 1/10 to 7 times the thickness of the flexible printed circuit board.

[0012]

According to the present invention, when the opening of the heat insulating holder is made larger than the land of the flexible printed circuit board, the molten solder does not have to be processed into a trapezoidal vertical sectional shape as in the conventional case. Passes through the opening and easily reaches the land to prevent the generation of unsoldered solder.

When a plurality of terminals of the connector are to be soldered by the whole soldering method, the heat insulating holder may have a minimum rectangular shape surrounding the land row of each land. Also, a slightly larger opening may be formed.

Further, according to a third aspect of the present invention, the thickness of the heat insulating holder is set to be equal to the thickness of the flexible printed circuit board.
Even if it is / 10 times to 7 times, since the distance between the surface of the molten solder and the land is short, the molten solder easily reaches the land through the opening and prevents the generation of unsoldered solder.

[0015]

【Example】

(First Embodiment) FIG. 1 is a sectional view of a first embodiment of the present invention,
FIG. 2 is a rear view.

In these figures, the same reference numerals as those in FIGS. 9 and 10 designate the same or corresponding ones.
Is different from paper phenol board, paper epoxy board,
FP is attached to the heat insulating holder 1 made of glass epoxy substrate or the like.
Opening 7 with a rectangular cross section that is larger than the land 3 of C2
Is formed.

At this time, it is preferable that the size of the opening 7 is about 2 to 3.5 times the area of the land 3.

Therefore, the opening 7 of the heat insulating holder 1 is fitted to the FPC.
By making the land 3 larger than the land 2, the molten solder can easily reach the land 3 through the opening 5 without processing the vertical cross-sectional shape of the opening 7 into a trapezoid as in the conventional case. It is possible to reliably prevent the generation of unsoldered solder.

Furthermore, since the vertical cross-sectional shape of the opening 7 does not have to be processed into a trapezoidal shape as in the conventional case, the heat insulating holder 1
The step of forming the opening 7 can be simplified as compared with the conventional case.

(Second Embodiment) FIG. 3 is a sectional view of a second embodiment of the present invention, FIG. 4 is an exploded perspective view, and FIG. 5 is a rear view.

In this embodiment, as shown in FIGS. 3 to 5, the present invention is applied to the soldering of a plurality of terminals mounted on the connector housing 8, and the heat insulating holder 1 and the respective lands 3 are shown. The opening 9 that is slightly larger than the smallest rectangle that surrounds the land row is formed.

By thus forming the opening 9 which is slightly larger than the smallest rectangle surrounding the land row of each land 3, the plurality of terminals 4 of the connector are reliably soldered to the FPC 2 by the entire soldering method. Therefore, it is not necessary to form an opening for each terminal of the connector as in the conventional case, and only one opening 9 is required to be formed, and the process of forming the opening 9 can be simplified as compared with the conventional case.

(Third Embodiment) FIG. 6 is a sectional view of a third embodiment of the present invention.

In FIG. 6, the same symbols as those in FIG. 9 indicate the same or corresponding ones, and the difference from FIG. 9 is that
Instead of the heat insulating holder 1 having a thickness of 2.6 mm shown in FIG.
A heat insulating holder 1 thinner than this, specifically, a thickness of 35 μm to 2 mm and a thickness of about 1/10 to 7 times that of the FPC 2.
0 is used and the opening 11 having substantially the same size as the land 3 of the FPC 2 is formed in the heat insulating holder 10.

At this time, the thickness of the FPC 2 is usually 300 μm.
As described above, the thickness of the heat insulating holder 1 shown in FIG. 1 is 2.6 mm, while the thickness of the FPC 2 is about 1/10 to 7 times the thickness of the FPC 2. 35
Although the heat insulating holder 10 having a thickness of μm to 2 mm is used,
When the thickness is less than 35 μm, the heat insulating holder 10 causes FP
Since the C2 cannot be supported, the thickness of the heat insulating holder 10 is set to 35 μm or more.

The vertical sectional shape of the opening 11 is not a trapezoidal shape like the opening 5 of FIG. 9, but a rectangular shape.

Therefore, the thickness of the heat insulating holder 10 is set to the FPC.
If it is set to about 1/10 to 7 times that of 2, the distance between the surface of the molten solder and the land 3 becomes short, so that the molten solder has an opening 11
It is possible to easily reach the land 3 through the inside, prevent the occurrence of unsoldered, and the size of the opening 11 may be substantially the same as that of the land 3 and need not be larger than the land 3.

(Fourth Embodiment) FIG. 7 is a sectional view of a fourth embodiment of the present invention.

As shown in FIG. 7, on the contact surface side of the heat insulating holder 1 shown in FIG. 9 with the FPC 2, the size is about the same as that of the land 3 and halfway in the thickness direction of the heat insulating holder 1. 1 to 10 times to 7 times deeper than the thickness of FPC2
Of the FPC2 of the heat insulating holder 1 by forming the opening 13a of
2 times the area of the land 3 to the side opposite to the contact surface side with.
A second opening 13b having a size five times larger than that of the first opening 13a is formed so as to communicate with the first opening 13a.
The opening 13 having a vertical cross-section with a convex shape is formed in the heat insulating holder 1.
Is formed.

As described above, by forming the opening 13 having a vertical cross-section in the heat insulating holder 1, the molten solder easily reaches the land 3 through the opening 13 as in the first embodiment, and the unsoldered It is possible to reliably prevent the occurrence of.

(Fifth Embodiment) FIG. 8 is a sectional view of a fourth embodiment of the present invention.

In this embodiment, as shown in FIG.
When soldering the plurality of terminals 4 mounted on the connector housing 16 as in the embodiment, as shown in FIG.
The heat insulating holder 15 having a thickness of μm to 2 mm and a thickness of about 1/10 to 7 times that of the FPC 2 is used.
5, an opening 17 that is slightly larger than the smallest rectangle that surrounds the land row of each land 3 is formed.

As a result, the molten solder 18 easily reaches the land 3.

Therefore, according to the fifth embodiment, as in the case of the second embodiment, the plurality of terminals 4 of the connector can be reliably soldered to the FPC 2 by the whole soldering method.

It should be noted that the thickness of the heat insulating holder is about 1 of the FPC.
/ 10 times to 7 times, and an opening having an area of 2 to 3.5 times the area of the land may be formed in this heat insulating holder.

Of course, even when the leads of the element are soldered instead of the terminals, the present invention can be implemented in the same manner.

[0037]

As described above, according to the first aspect of the present invention, when the opening of the heat insulating holder is larger than the land of the flexible printed circuit board, the molten solder easily reaches the land through the opening. Since it is possible to prevent the generation of unsoldered and it is not necessary to process the vertical sectional shape of the opening into a trapezoidal shape as in the conventional case, the process of forming the opening of the heat insulating holder is simplified as compared with the conventional case. be able to.

According to a second aspect of the present invention, a plurality of terminals of the connector are entirely soldered by forming one opening in the heat insulating holder that is slightly larger than the smallest rectangle surrounding the land row of each land. It becomes possible to solder each by the attachment method.

Further, according to a third aspect of the present invention, the thickness of the heat insulating holder is set to be less than the thickness of the flexible printed circuit board.
When it is set to / 10 times to 7 times, the distance between the surface of the molten solder and the land is short, so that the molten solder can easily reach the land through the opening and prevent the generation of unsoldered solder.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a rear view of the first embodiment.

FIG. 3 is a sectional view of a second embodiment.

FIG. 4 is a perspective view of a second embodiment.

FIG. 5 is a rear view of the second embodiment.

FIG. 6 is a sectional view of a third embodiment.

FIG. 7 is a sectional view of a fourth embodiment.

FIG. 8 is a sectional view of a fifth embodiment.

FIG. 9 is a sectional view of a conventional example.

FIG. 10 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 1,10,15 Insulation holder 2 FPC (Flexible Printed Circuit Board) 3 Land 4 Terminals 7, 9, 11, 13, 17 Opening

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H05K 1/03 670 A 7511-4E

Claims (6)

[Claims] 1. When a terminal is soldered to a land formed on a flexible printed circuit board having a softening point of 230 ° C. or less by a whole soldering method, an opening through which the land and the terminal can be seen is formed in a heat insulating holder. A flexible printed circuit board which is formed and abuts the heat insulating holder on the solder adhering surface side of the substrate so that the land and the terminal are located in the opening and holds the abutting state to perform the entire soldering method. The soldering method for a flexible printed circuit board, wherein the opening of the heat insulating holder is larger than the land. 2. A heat insulating holder for soldering a plurality of terminals of a connector to a plurality of lands arrayed and formed on a flexible printed circuit board having a softening point of 230 ° C. or less by a total soldering method. An opening that is slightly larger than the smallest rectangle that surrounds the land row of each land is formed in the heat insulating holder so that the land and each terminal are located in the opening. A method for soldering a flexible printed circuit board, characterized in that the whole soldering method is carried out by contacting the above with the contact state. 3. An opening through which the land and the terminal can be seen in the heat insulating holder when the terminal is soldered to the land formed on the flexible printed circuit board having a softening point of 230 ° C. or less by the total soldering method. A flexible printed circuit board which is formed and abuts the heat insulating holder on the solder adhering surface side of the substrate so that the land and the terminal are located in the opening and holds the abutting state to perform the entire soldering method. The method for soldering a flexible printed circuit board according to claim 1, wherein the thickness of the heat insulating holder is about 1/10 to 7 times the thickness of the flexible printed circuit board. 4. The method for soldering a flexible printed circuit board according to claim 1, wherein the heat insulating holder is made of a paper phenol substrate, a paper epoxy substrate or a glass epoxy substrate. 5. The method for soldering a flexible printed circuit board according to claim 1, wherein the thickness of the heat insulating holder is about 1/10 to 7 times the thickness of the flexible printed circuit board. 6. The method for soldering a flexible printed circuit board according to claim 2, wherein the thickness of the heat insulating holder is about 1/10 to 7 times the thickness of the flexible printed circuit board.