JPH0459751B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flexible printed circuit board terminal formed by etching an aluminum foil formed on a thermoplastic synthetic resin film such as a polyester film to form a pattern. It's about structure.

[Prior art]

In recent years, electronic components used in electronic devices have become smaller and thinner, and flexible printed circuit boards are extremely useful in terms of effective use of space as electronic components become smaller and thinner. This is why it is widely used. That is, flexible printed circuit boards are often used as components of membrane switches, flat cables, and the like.

The above-mentioned flexible printed circuit board is one in which a conductor pattern is formed on a so-called insulating film, and commonly used flexible printed circuit boards include the following. In other words, a substrate made by pasting copper foil on a thermoplastic synthetic resin film such as a polyimide film, which is subjected to an etching process to form a conductive pattern, and a substrate made by applying a conductive pattern to a thermoplastic synthetic resin film such as polyester. A conductive pattern is formed by etching the attached substrate, or a conductive pattern is formed by screen printing a conductive paste such as silver paste on a polyester insulating film.

[Problem to be solved by the invention]

Among the above-mentioned flexible printed circuit boards, since a polyimide film with high heat resistance is used, it has the advantage of being soldered, but has the disadvantage of being very expensive. Therefore, a film using an inexpensive thermoplastic synthetic resin film such as the above-mentioned polyester film is used.

However, for example, when copper foil is pasted on a polyester film and then etched to form a conductive pattern, it is possible to solder with low-temperature solder because the polyester film has poor heat resistance. teeth,
There is a problem that the workability is poor compared to normal soldering work.

In addition, if aluminum foil is attached to a thermoplastic synthetic resin film such as polyester film and then etched to form a conductive pattern, it is possible to solder it using a special solder for aluminum, but it is possible to solder it using a special solder for aluminum. There is a problem that soldering is not possible.

In addition, manufacturing costs are low for those in which a conductive pattern is formed by screen printing a conductive paste such as silver paste on a thermoplastic synthetic resin film such as a polyester film, but since the pattern is formed by printing the conductive paste, this pattern has a large electrical resistance, which limits its range of use and makes it impossible to solder.

The present invention has been made in view of the above-mentioned points, and it is possible to flow a large current through a conductive pattern, that is, it has a large current capacity, has high electrical connection reliability and mechanical connection strength, and is extremely inexpensive and flexible. The purpose of the present invention is to provide a terminal structure for a printed circuit board.

[Means to solve the problem]

In order to eliminate the above-mentioned problems, the present invention configures the terminal structure of a flexible printed circuit board as follows.

An aluminum foil is formed on a thermoplastic synthetic resin film such as a polyester film by adhering it with an adhesive or by vacuum deposition, and the aluminum foil is etched to form a pattern of a predetermined shape, and then the thermoplastic synthetic resin is A conductive paste layer made by kneading nickel powder with polyester resin is formed on the terminal pattern of a flexible printed circuit board, which is made by applying a synthetic resin insulating coating to a predetermined portion of the film, excluding the terminal portions, and then coats the conductive paste layer on the conductive paste layer. A metal terminal piece is placed so as to protrude to the outside by a predetermined distance from the terminal part, and a terminal fixing film made of a thermoplastic synthetic resin of the same quality as the thermoplastic synthetic resin film is placed on the terminal part from above the metal terminal piece. Then, the terminal fixing film is locally thermally welded to a predetermined portion of the flexible printed circuit board other than the portion where the metal terminal piece is located, and the conductive paste layer is heated to bond the metal terminal piece to the pattern.

In addition, conductive paste is 20% to 70% by weight, similar to polyester resin which is 80% to 30% by weight.
Manufactured by kneading with nickel powder.

[Effect]

By configuring the terminal structure of the flexible printed circuit board as described above, the conductive paste for adhering the metal terminal piece to the terminal part of the pattern made of aluminum foil is a conductive paste made by kneading polyester resin nickel powder. The contact resistance between the aluminum foil and the metal terminal piece becomes extremely small. Further, since no soldering is required, there is no problem in using an inexpensive thermoplastic synthetic resin film such as polyester film, which is low in heat resistance, as the substrate base material.

Furthermore, since aluminum foil, which has good conductivity and is inexpensive, is used as the material for the conductive pattern, the terminal structure of the flexible printed circuit board has a large current capacity and is inexpensive.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. 1 is a diagram showing the terminal structure of a flexible printed circuit board according to the present invention, and Fig. 1a is a partial plan view;
Figure b is an enlarged cross-sectional view taken along line A-A in figure a, figure c is an enlarged cross-sectional view taken along line B-B in figure a, and figure d is an enlarged view of part D in figure c. be. Also, the second
3 is a plan view showing a metal terminal piece, and FIG. 4 is a plan view showing a terminal fixing film.

The manufacturing of the flexible printed circuit board 11 is carried out in the second
As shown in Figure a, aluminum foil 13 and polyester film 12 are prepared. Next, the aluminum foil 13 and the polyester film 12 are
Glue as shown. Next, the aluminum foil 13 is etched to form a conductive pattern 13a.

As for the method of the above-mentioned etching treatment, since aluminum is a metal that dissolves in both acids and alkalis, a solvent-removable etching resist HR is applied to the shape of the conductive pattern 13a to be formed on the aluminum foil 13, as shown in FIG. The portion where the etching resist HR is not applied is removed by dissolving it with an acid or alkali to form a conductive pattern 13a, and finally the etching resist HR is removed with an organic solvent to expose the conductive pattern 13a. Note that the aluminum foil 13 may be formed on the polyester film 12 by vacuum deposition or the like.

The terminal structure of the flexible printed circuit board according to the present invention is as shown in FIGS. A conductive paste layer 16 is formed by kneading powder, and a metal terminal piece 17 is placed thereon.
From above, a terminal fixing film 1 made of the same polyester film as the polyester film 12.
8 is placed, and a predetermined portion of the terminal portion 14 other than the portion where the metal terminal piece 17 is located is attached to the terminal fixing film 18 of the polyester film 12 at the welded portion 19.
are formed and welded, and the metal terminal piece 17 is sandwiched between the polyester film 12 and the terminal fixing film 18. Thereafter, the conductive paste layer 16 is heated and hardened, and the metal terminal piece 17 and the conductive pattern 13 of the terminal portion 14 are connected.

Hereinafter, a method for manufacturing the terminal structure of the flexible printed circuit board will be described in detail. Metal terminal piece 17
As shown in FIG. 3, a plurality of metal terminal pieces 17 are integrally formed with a base material 20 by sheet metal processing of an aluminum plate. The surface of this metal terminal piece 17 is solder plated to improve soldering workability.
In this case, aluminum and solder are connected, but since aluminum is incompatible with lead, low-lead solder with less than 10% lead in the solder is used. Further, a plurality of convex portions 17a are formed on both side edges of the metal terminal piece 17. Incidentally, the protrusions 17a in the above example may be formed on one side by forming a plurality of protrusions on both side edges of the metal terminal piece 17, and the number of protrusions need not be plural but may be one.

As shown in FIG. 4, the terminal fixing film 18 is the same polyester film as the polyester film 12, and its width _l1 is approximately equal to the width _l3 of the flexible printed circuit board 11, and its length _l2 is the same as that of the flexible printed circuit board. The length dimension _l4 of the terminal portion 14 of No. 11 is slightly larger than that of the terminal portion 14 of No. 11. In addition,
The dimensions of the terminal fixing film 18 are not limited to the above dimensions; for example, the width dimension _l1 may be made larger than the above, and after welding the polyester film 12 and the terminal fixing film 18, the portion protruding from the terminal portion 14 is cut off. May be removed.

The conductive paste is made by kneading polyester resin nickel powder. Normal conductive paste is made by properly kneading metal flakes and spheres, but in this embodiment, electrical continuity between the metal terminal piece 17 and the conductive paste 13a in the thickness direction In order to measure this, good metal contact is required, and stable conduction can be obtained by using spherical nickel powder as the metal powder. Furthermore, if the particle size is too small, many conductive paths will be formed in the film thickness direction, so a particle size of about several μm is preferable. In addition, if the content of nickel powder is too low, electrical conductivity will become unstable, and if it is too high, the mechanical adhesion will be weak due to the lack of polyester resin.Furthermore, the polyester resin in the conductive paste will seal the adhesive part and allow various types of circulating humidity to be used. If the amount of polyester resin in the conductive paste is small, the sealing effect of the fixed portion will be reduced, making it unsuitable as a conductive paste.

In this example, the content of nickel powder was 50% by weight.
%, but it was confirmed that it can be used at 20% to 70%.

Terminal section 1 of the flexible printed circuit board 11
The conductive paste is printed on the conductive pattern 13a of No. 4 to form a conductive paste layer 16, and the conductive paste layer 16 is heated and dried.

Next, as shown in FIG. 6, the polyester film 12 on which the conductive paste layer 16 is formed on the conductive pattern 13a of the terminal portion 14 is placed on a metal stand 21, and the base plate is placed on the conductive pattern 13a. material 2
A metal terminal piece 17 integrally formed with the metal terminal piece 0 is placed thereon, and a terminal fixing film 18 is further placed thereon. In this state, the horn 22 for emitting ultrasonic waves is placed on the terminal fixing film 18. Here, as shown in the figure, the tip of the horn 22 is formed with a convex portion 22a so as to touch the terminal fixing film 18 other than the portion where the metal terminal piece 17 of the terminal portion 14 is located. The metal terminal piece 17 is brought into contact with the terminal fixing film 18 other than the part where it is located, and the horn 22 emits ultrasonic waves, and the convex part 22a
The polyester film 12 and the terminal fixing film 18 in the area where is located are locally melted by ultrasonic heating. Here, since the polyester film 12 and the terminal fixing film 18 are made of the same material,
Both are welded together. As a result, as shown in FIG. 1a, a welded part 19 is formed at a predetermined position other than the part where the metal terminal piece 17 of the terminal part 14 is located, and
The terminal fixing film 18 in which the concave portion of the horn 22 is located is also heated, and the metal terminal piece 17 is firmly sandwiched between the insulating film 12 and the terminal fixing film 18 by the contraction force caused by the cooling. At this time, convex portions 17 formed on both edges of the metal terminal piece 17
Since a is engaged with the welded portion 19, the metal terminal piece 17 is prevented from being easily attached or detached even if the metal terminal piece 17 is pulled. Furthermore, when this polyester film 12 and the terminal fixing film 18 are welded by ultrasonic heating, the ultrasonic vibrations are transmitted to the nickel powder of the conductive paste layer 16 of the terminal portion 14 and break through the thin oxide film on the surface. The conductivity becomes even better.

As described above, the terminal fixing film 18 is welded to the terminal portion 14 of the insulating film 12, and the metal terminal piece 17 is welded.
As shown in FIG. 7, the fixed conductive paste layer 16 is placed on a stand 23, and the heating iron 24 is brought into contact with it to heat the conductive paste layer 16, so that the conductive paste layer 16 hardens and forms a metal terminal. Piece 17 is fixed to conductive pattern 13a. As a result, the metal terminal piece 17 and the conductive pattern 13a are electrically and mechanically connected, and since adjacent terminals are separated by the already welded insulating film 12 and terminal fixing film 18, the metal terminal Piece 17
and 17 are not short-circuited by the conductive adhesive.

Finally, the metal terminal piece 17 is cut along the line EE in FIG. 3, and the base material 20 is removed. As a result, the metal terminal pieces 17 are separated individually, and the terminal structure of the flexible printed circuit board according to the present invention is completed, in which the tips of the metal terminal pieces 17 protrude outward by a predetermined distance from the terminal portions 14 of the insulating film 12.

Further, the convex portion 1 formed on the edge of the metal terminal piece 17
Although the convex portion 7a engages with the welded portion 19 and has the effect of increasing the tensile strength, the convex portion 17a is not necessarily necessary and may be omitted if the tensile strength is sacrificed to some extent.

FIG. 8 is a diagram showing the measurement results of the contact resistance between aluminum foil and metal terminal piece of the conductive paste made by kneading nickel powder into the polyester resin used in the above example and another conductive paste. As is clear from the figure, the initial contact resistance value when using a conductive paste made by kneading nickel powder into polyester resin is higher than that when using copper powder or silver powder as metal powder or when using solder. becomes smaller. Especially polyester film 12 and terminal fixing film 1
If ultrasonic welding is carried out locally between 8 and 8, the ultrasonic vibrations are transmitted to the nickel powder of the conductive paste and break through the thin oxide film on its surface, resulting in even better conductivity. (see section). Also,
When accelerated tests are conducted in an environment with a temperature of 60°C and a relative humidity of 90-95%, it can be seen that the contact resistance value of products kneaded with nickel powder is smaller than those kneaded with other metal powders. .

In the above embodiment, the polyester film 12 was used as the substrate film of the flexible printed circuit board 11, but the substrate film is not limited to this, and any thermoplastic synthetic resin film may be used. Further, the terminal fixing film 18 is not limited to a polyester film, but may be any thermoplastic synthetic resin film having the same quality as the substrate.

〔Effect of the invention〕

As explained above, according to the present invention, the following excellent effects can be obtained.

The conductive paste used to bond the metal terminal pieces to the terminals of the aluminum foil pattern uses a conductive paste made by mixing nickel powder with polyester resin, so the contact resistance between the aluminum foil and the metal terminal pieces is extremely low. Become.

In addition, although it is very difficult to solder directly to the aluminum foil conductor, since the metal terminal piece is already attached to the flexible printed circuit board, it is easy to solder through the metal terminal piece, and the board base is easy to solder. Thermoplastic synthetic resin film such as polyester film, which is inexpensive and has low heat resistance, can be used as the material, and aluminum foil, which has good conductivity and is extremely cheap, can be used as the material for the conductive pattern, so it has a large current capacity and is inexpensive. This results in an extremely inexpensive terminal structure for flexible printed circuit boards.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the terminal structure of a flexible printed circuit board according to the present invention, and Fig. 1a is a partial plan view;
Figure b is an enlarged cross-sectional view taken along line A-A in figure a, figure c is an enlarged cross-sectional view taken along line B-B in figure a, figure d is an enlarged view of part D in figure c, Fig. 2 is a diagram for explaining the method for manufacturing a flexible printed circuit board, Fig. 3 is a plan view showing a metal terminal piece, Fig. 4 is a plan view showing a terminal fixing film, and Fig. 5 is a plan view showing the formation of a conductive pattern. Figures 6 and 7 are diagrams showing the process, and Figures 6 and 7 are diagrams for explaining the manufacturing method of the terminal structure of a flexible printed circuit board. Figure 8 is a diagram showing a conductive paste made by kneading nickel powder into polyester resin and other conductive pastes. FIG. 3 is a diagram showing the measurement results of contact resistance between aluminum foil and metal terminal piece. In the figure, 11...Flexible printed circuit board, 12
... Polyester film, 13... Aluminum foil, 14... Terminal portion, 15... Insulating coating, 16... Conductive paste layer, 17... Metal terminal piece, 18... Terminal fixing film, 19... Welding part.

[Claims]

1. In a housing having a terminal accommodating portion for accommodating a connecting terminal, a first locking protrusion is formed at the bottom of the terminal accommodating portion of the housing body to prevent the connecting terminal from coming off later, and a tip end of the bottom portion is formed. is provided with a locking piece that has elasticity toward the inside and locks the front end of the connection terminal, and a base portion is attached to the housing body on the ceiling of the terminal storage portion, and the connection terminal is attached to the intermediate portion. A movable piece is provided with a second locking protrusion and a free end for preventing the terminal from coming off later, and after the connecting terminal is stored, the second locking protrusion of the movable piece locks the connecting terminal. A connector housing characterized in that a fixing member that moves and fixes the movable piece so as to fit into the housing body is inserted into the housing body.