JP2873758B2 - Mounting method and mounting structure of film carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a structure for mounting a film carrier by soldering an outer lead of the film carrier to a conductor pattern formed on a wiring board by a thermocompression bonding method.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a mounting structure when connecting outer leads of a film carrier to a wiring board.
In the mounting structure of FIG. 3, the vicinity of the soldered portion of the outer lead 1 is bent stepwise at portions A and E, and the thermocompression bonding tool is lowered from directly above the conductor pattern 2 to wire the portion beyond the bent portion B. It is connected to the conductor pattern 2 of the substrate 5 by soldering. At this time, in order to prevent the solder 3 from rising to the bent portion A, both ends of the conductor pattern 2 are covered with the solder resist 4, and the bent portions A and E are positioned on the solder resist 4. That is, by using the solder resist 4 as an obstacle, the solder 3 melted at the time of heating is prevented from rising to the bent portion A of the lead, and the mechanical stress is concentrated on the boundary portion B with the flexible insulating film 6. , Trying to prevent it from being easily damaged. Also, as an obstacle to prevent solder from rising,
It is also known to arrange a dry film 8 and the like as shown in FIG. Heretofore, the thermocompression bonding tool has been made to descend from directly above the conductor pattern.

[0003]

By the way, in the above-mentioned conventional example, various conditions at the time of soldering, that is, the amount of solder,
Due to slight differences and variations in conditions such as heating temperature, heating time and pressure, as shown in FIG. 5, the molten solder 3 climbs over obstacles such as the solder resist 4 and rises to the lead bent portion A, It was not possible to completely prevent the strength against mechanical stress from being significantly reduced.

[0004] The present invention eliminates the drawbacks of the above-mentioned conventional example, and is used for soldering the outer leads of a film carrier.
It is an object of the present invention to provide a method and a structure for preventing solder from rising to a bent portion of a lead.

[0005]

In order to achieve the above object, according to the present invention, as illustrated in FIG.
In the method in which the outer leads 1 of the film carrier bent in a stepwise manner and the conductor patterns 2 formed on the wiring board 5 are connected by soldering by a thermocompression bonding method, both ends of the conductor patterns 2 are covered with a solder resist 4. Then, the portion to which the outer lead is attached is placed on the conductor pattern 2 and the bent portions A and E of the outer lead 1 are
The outer lead bent portions A and E are soldered by the thermocompression bonding tool 7 from the vertical line of the end of the solder resist on the side facing the outer lead bent portions A and E.

[0006]

According to the above construction, the outer lead 1 is sandwiched between the thermocompression bonding tool 7 and the solder resist 4,
The molten solder 3 can flow to the side where the outer lead bent portions A and E do not face each other, and it is possible to prevent the solder 3 from rising to the outer lead bent portion A.
Further, the thermocompression bonding tools 7 for the outer leads are arranged in parallel.
If the tip C side is taken longer than the descending portion as the allowance for the flow of the solder 3, the flow of the solder 3 between the adjacent terminals can be prevented, and the short circuit between the adjacent terminals can be prevented.

[0007]

1 is a sectional view showing a mounting method and a mounting structure of a film carrier according to an embodiment of the present invention.

In FIG. 1, an outer lead 1 of a film carrier is previously bent stepwise at portions A and E. Further, both ends of the conductor pattern 2 formed on the wiring board 5 are covered with the solder resist 4 in advance.

In order to connect the film carrier to the wiring board, first, the outer lead bent portions A and E of the film carrier bent in a stepwise manner are connected to one side 4 of a solder resist covering the conductor pattern 2 on the wiring board 5. It is arranged at a position opposite to. At this time, the outer lead 1
Between the bent portion E and the solder resist end D, a clearance is required for the thermocompression bonding tool 7 having a width of 2 mm, for example, to be lowered. After the outer lead 1 and the conductor pattern 2 on the wiring board 5 are arranged as described above, a part of the thermocompression bonding tool 7 is placed on the vertical line of the solder resist end D on the side opposite to the outer lead bent portion A. Thermocompression bonding is performed in such a positional relationship. At this time, the thermocompression bonding tool 7
The outer lead 1 is sandwiched between the outer lead 1 and the solder resist 4, and the molten solder 3 can flow to the side where the outer lead bent portion A does not face as shown in FIG. Further, at this time, as a margin for the solder 3 to flow out from the descending portion of the thermocompression bonding tool 7 to the tip C side, the outer lead 1 is extended, for example, by 2 to 3 mm to prevent the solder from flowing between adjacent leads. Can be.

[0010]

As described above, the outer leads of the film carrier are arranged at positions facing the solder resist covering the conductor pattern on the wiring board, and the end of the solder resist on the side where the bent portion of the outer leads is opposed. By performing thermocompression bonding in such a positional relationship that a part of the thermocompression tool is applied to the portion, it is possible to prevent the molten solder from rising to the bent portion of the lead. As a result, a mounting structure capable of absorbing mechanical stress at the bent portion of the outer lead could be provided.

At this time, by extending the lead as a margin for the solder to flow out from the lower part of the thermocompression bonding tool, it is possible to prevent the solder from flowing between the adjacent leads and to prevent a short circuit between the adjacent electrodes. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a mounting method and a mounting structure according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a state after soldering by the method of FIG. 1;

FIG. 3 is a cross-sectional view showing a conventional mounting structure.

FIG. 4 is a cross-sectional view showing another conventional mounting structure.

FIG. 5 is a cross-sectional view showing a defect of a conventional mounting structure.

[Explanation of symbols]

1: outer lead, 2: conductor pattern, 3: solder,
4: Solder resist, 5: Wiring board, 6: Flexible insulating film, 7: Thermo-compression tool, 8: Dry film,
A, E: bent portion, B: boundary portion, C: lead end, D: solder resist end.

Claims (3)

(57) [Claims] 1. A method of mounting a film carrier, wherein outer leads of a film carrier bent stepwise and a conductor pattern formed on a wiring board are connected by soldering by a thermocompression bonding method. Covered portion of the outer lead is placed on the conductor pattern, the bent portion of the outer lead is placed on the solder resist, and a thermocompression bonding tool is placed on the end of the solder resist on the side where the lead bent portion is located. A method of mounting a film carrier, wherein the outer lead is pressed down from above a vertical line onto a conductor pattern and a solder resist and soldered to the conductor pattern. 2. The mounting method according to claim 1, wherein the outer lead of the film carrier is extended from the descending portion of the thermocompression bonding tool toward the tip as a margin for flowing out the molten solder. 3. A mounting structure of a film carrier in which outer leads of a film carrier bent stepwise and a conductor pattern formed on a wiring board are connected by soldering by a thermocompression bonding method. Covered with a solder resist, the bent portion of the outer lead is located on one of the solder resists, and the tip extends from the lead bent portion of the outer lead to the other solder resist as a margin for the flow of molten solder. A mounting structure of a film carrier, characterized in that: