JPS62147671A - Terminal structure of flat cable and its joint - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a terminal structure for connecting a metal terminal piece to a flat cable made of a polyester sheet having low heat resistance, and a method for connecting the same.

[Prior art]

In recent years, electronic components used in electronic devices have become thinner and smaller, and an important issue in making electronic components thinner and smaller is the reduction of electronic components (printed circuit boards) and Efforts have been made to reduce the thickness of cables that connect terminals, and so-called flat cables have been developed. FIG. 2 is a diagram showing the flat cable, in which FIG. 2(a) is a plan view and FIG. 2(b) is a partially sectional view on line A in FIG. 2(a). Flat cable 20 as shown
A wiring pattern 22 made of a conductive material such as metal is provided on a polyester resin film 21, and an insulating coating made of a synthetic resin material is provided thereon except for the portions to which terminals are connected. When using the flap 1 and cable to read directly between printed circuit board terminals, for example,
Since polyester resin has low heat resistance, it is not easy to solder the ends of the wiring pattern directly, so it is necessary to attach the connector to the terminal part of the printed circuit board in advance.
The flat cable is connected by press-fitting it into the connector or by holding it in place.

FIG. 3 is a partially perspective view showing the connector attached to the end of the flat cable 20. As shown in the figure, the ends of the flat cable 20 are clamped or press-fitted into a connector 26 provided with a plurality of terminals 25 to electrically connect the ends 22a of the wiring pattern 22 and the terminals 25. After attaching the connector 26 to the end of the flat cable 20 as described above, connect the terminal 25 to the printer 1.
- Electrical connections are made between printed circuit boards or between printed circuit boards and other electronic components by directly soldering them to the terminals of circuit boards or inserting them into connectors of electronic components.

[Problem that the invention seeks to solve]

However, the method of connecting the connector 26 by attaching it to the end of the flat cable 20 as described above is difficult because the size of the connector 26 is large.
There is a drawback that the purpose of using 0 to make the cable thinner is diminished, and it becomes an obstacle to miniaturization of electronic equipment, and the connector 26 is also expensive, which increases the cost of the electronic equipment.

To solve this problem, as shown in FIG. 4, a copper foil formed on a highly heat-resistant polyimide film 31 is etched to form a wiring pattern 32 and a terminal pattern 33 at its end, and the terminal pattern An insulating coating 34 is placed on the polyimide film 31 except for the portion where 33 is located.
There is a flat cable 30 that has been subjected to.

Polyimide resin material has extremely high heat resistance compared to polyester resin, so the flat cable 30 with the above structure
Although it is possible to directly solder the terminal pattern to the terminal portion of a printed circuit board or the like, polyimide resin film has the disadvantage that it is several times more expensive than polyester film. Further, since the soldering surface of the flat cable 30 is limited to the surface on which the terminal pattern 33 is completely formed, the degree of freedom in soldering is limited when the flat cable 30 is soldered to the terminal portion of a printed circuit board. , there was a drawback that the routing for wiring the flat cable 30 was also limited.

Therefore, a method of directly soldering a metal terminal piece 24 to the end 22a of the wiring pattern 22 of the flat cable 20 based on the polyester film 21 shown in FIG. 2 may be considered, but since polyester film has low heat resistance, There are the following problems.

The polyester film used in the polyester film-based flat cable 20 is mostly a biaxially stretched polyester film, and this film has a low glass transition point Tg of about 70°C due to its physical properties. If a temperature exceeding Tg is applied, the film will shrink.

On the other hand, the metal (copper foil) is soldered with 6:4 solder (Sh:Pb=6:4
), the liquidus temperature of 6:4 solder is 190°C, and in general when soldering, the appropriate temperature is about 50°C above the liquidus temperature, and at least 30'C is necessary.

Therefore, as shown in FIG.
Wiring pattern 2 of flat cable 20 based on
When soldering a metal terminal piece to the end 22a of 2, it can be done relatively easily by using low melting point solder, but low melting point solder is expensive and the mechanical strength of soldering is also lower than that of the normal 6. =4 It has the disadvantage of being weaker than solder. When attempting to solder using ordinary 6=4 solder, a minimum heating temperature of about 220° C. is required to properly perform soldering as described above. However, as mentioned above, polyester film has low heat resistance, so if soldering is performed without fixing the base polyester film 21, the wiring pattern 22 made of metal foil such as copper will not shrink when exposed to temperatures of 200-odd degrees. ,
The flat cable 20 may be deformed like waves,
There is also the problem of softening.

The present invention has been made in view of the above-mentioned points, and is a flat cable in which a metal terminal piece is soldered to the end of the wiring pattern of a flat cable using a polyester film (which has low heat resistance as a paste film material). The purpose of this invention is to provide a terminal structure and its connection method.

[Means for solving problems]

In order to solve the above problems, the present invention provides a flat cable in which a wiring pattern of copper foil is formed on a polyester film, and a polyester insulation coating is applied to the portion of the polyester film other than the connecting portion of the terminal piece. At the same time, the end of the flat cable is placed and fixed on a base made of a material with poor thermal conductivity, and a metal paste is applied onto the cream solder on the wiring pattern. The terminal structure of the flat cable was constructed by placing a terminal piece made of material and applying local heating, such as by blowing hot air locally, to melt the cream solder and instantly connect the wiring pattern and the terminal piece.

[Effect]

The terminal strip is connected to the end of the wiring pattern on the polyester sheet with solder as described above, but since the polyester sheet is placed and fixed on a base made of a material with poor thermal conductivity, the joint between the terminal strip and the wiring pattern is Even if the solder is heated locally, the cream solder will melt before the heat is transmitted to other parts of the polyester sheet, so the terminal piece can be read directly onto the end of the wiring pattern without damaging other parts of the polyester sheet. becomes possible.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a flat cable equipped with a terminal structure according to the present invention, in which (a) is a plan view, and (b) is an enlarged sectional view of a portion above AB in (a). . In addition, Fig. 5 is a plan view showing the flat cable, Fig. 6 (a), (b)
) is a diagram showing a plate body provided with a terminal piece.

The flat cable 10 has a structure in which - the copper foil of a polyester sheet 1 whose surface is coated with copper foil is etched to form a plurality of wiring patterns 2, and an insulating coating 4 is applied to the portions excluding the terminal portions. It is something. Also, terminal piece 3
The terminal has a shape in which a plurality of terminal pieces 3 and a plate body 9 are integrally formed by punching one side of a long and thin metal plate.

End portion 2a of the wiring pattern 2 of the flat cable 10
To solder terminal piece 3 to
Cream solder 7 is applied to the end portion 2a by screen printing or the like. The end of the flat cable 10 with the cream solder 7 applied to the end 2a of the wiring pattern 2 is placed on a base 5 made of a material with poor thermal conductivity such as Bakelite, as shown in FIG. . A vacuum hole 5a is provided on the top surface of the base 5.
, 5b are bored, a vibrator 11 is connected to the vacuum holes 5a, 5b, and a vacuum pump 1 is connected to the vibrator 11.
2 are connected. When the vacuum pump 12 is driven, the flat cable 1o is suctioned into the vacuum holes 5a and 5b and securely fixed on the base 5. Next, the terminal piece 3 is placed on the cream solder 7 applied to the end portion 2a of the wiring pattern 2, and only the area where the wiring pattern 2 and the terminal piece 3 overlap is locally heated. This local heating is approximately 220'C~2
The process is carried out at a temperature of 30°C for 3 to 5 seconds. At this time, the polyester film 1 also momentarily exceeds 200'c and tries to deform, but the polyester film 1 is firmly placed in a vacuum on the top surface of the base 5. Since it is fixed by suction, this deformation is prevented. In addition, if a material (for example, Bakelite) with a thermal conductivity of 0.5Kca 17m, h"c or less is used as the material for the base 5, the base 5 will not absorb the heat from the polyester film 1 of the flat cable 1o. On the other hand, if a material with a thermal conductivity of 10 Kcal/m, h'c or more is used as the material for the base 5, the thermal conductivity is too good and the wiring pattern 2 will absorb heat from the polyester film 1. The temperature also does not rise instantaneously, making instantaneous soldering impossible.Furthermore, if the temperature is heated to the point where soldering becomes possible, the temperature of the entire base 5 will rise to nearly 200 degrees Celsius, so the flat cable 10
becomes deformed. As a local heating means, for example, 20
It is preferable to use a method in which hot air with a temperature exceeding 0°C is locally blown onto the terminal piece 3.

After soldering the terminal piece 3 to the end 2a of the wiring pattern 2 as described above, the plate 9 is removed by cutting along the B-B line in FIGS. 6(a) and (b), and then the flat cable is 1
A reinforcing plate 8 made of a resin material is bonded to the end portion including the exposed portion of the terminal piece 3 of 0 for reinforcement, and the flat cable 10 is completed.

In the flat cable 10 having the terminal structure as described above, since the terminal piece 3 protrudes from the end of the cable, the terminal piece 3 can be directly soldered to the terminal part of a printed circuit board. Furthermore, if the terminal pattern 33 is provided only on one side of the flat cable 30 as shown in FIG. 4, the soldering surface is limited to one side of the flat cable, and the degree of freedom in soldering is limited. In addition, while the cable routing for wiring is limited, in the terminal structure of the above embodiment, the terminal piece 3 protrudes from the end of the cape, so soldering is not limited to one side of the cable, but can be done on both the front and back sides. Since it is possible to perform soldering on both sides, the degree of freedom in soldering increases, and at the same time, the degree of freedom in routing cables for wiring also increases.

[Effects of the Invention] As explained above, according to the flat cable terminal connection method of the present invention, the terminal piece can be reliably connected to the end of the wiring pattern even if a polyester film with low heat resistance is used for the flat cable body. You can get excellent results. In addition, the flat cable with the terminal structure obtained by this terminal connection method uses an inexpensive polyester film with low heat resistance as the base film, and the terminal piece protrudes from the end of the cape, making it difficult to solder and wire. It has the excellent effect of providing flexibility in routing and being extremely inexpensive.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a flat cable equipped with a terminal structure according to the present invention; FIG. 1(a) is a plan view, FIG. Figure 2 shows a flat cable using a polyester film as the base film, where (a) is a plan view and (b) is a plan view of the same figure (a).
Figure 3 is a perspective view showing an example of the use of a full-throttle cable using polyester film with low heat resistance as the base film, Figure 4 shows a polyimide film with high heat resistance as the base film. FIG. 5 is a plan view showing the flat cable according to the present invention, FIG. 6 is a plan view showing the shape of the terminal piece according to the present invention, and FIG. 7 is a plan view showing the shape of the terminal piece according to the present invention. It is a figure showing the outline of the terminal connection method of the flat cable concerned. In the figure, 1... Polyester sheet, 2... Wiring pattern, 3... Terminal piece, 4... Insulating coating, 5
...Base, 7...Cream solder, 8...
Insulation sheet, 10...Flat cable.

Claims (2)

[Claims] (1) A flat cable has a metal foil wiring pattern on a polyester film, and a synthetic resin insulating coating is applied to the polyester film except for the connecting portion of the terminal piece.The ends of the wiring pattern are covered with metal. A terminal structure for a flat cable, characterized in that a terminal piece consisting of the above protrudes from the end of the flat cable and is connected by soldering. (2) Wiring pattern of the connection part of the terminal piece of a flat cable made by applying a metal foil wiring pattern on a polyester film, and applying an insulating coating of synthetic resin to the part of the polyester film other than the connection part of the terminal piece. A cream solder is applied on the top, and the flat cable is placed on a base made of a material with poor thermal conductivity, and a terminal piece made of a metal material is placed on the cream solder on the wiring pattern, and by local heating. A method for connecting terminals of a flat cable, characterized in that the cream solder is melted to connect the wiring pattern and the terminal piece.