JPH11162539A - Connecting structure of conductor and substrate and connecting method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting structure and a connecting method suitable for mutually connecting a base board to an extra fine gauge smaller than AWG No.40. SOLUTION: A conductor 22 of an individual electric wire is placed on the connecting pad of a substrate 10. Next, a layer of an adhesive 30 is formed on it. Then, an insulating sheet 40 endurable to thermocompression bonding is placed on it. The adhesive 30 is also fluidized by heating/pressurizing it by a thermocompression bonding head from above the insulating sheet 40. The conductor 22 and the substrate 10 are interconnected by sandwiching the conductor 22 between the insulating sheet 40 and the substrate 10 by adhesive strength of the adhesive 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection structure between an electric wire and a circuit board or an electric terminal (hereinafter, collectively referred to as a board) and a connection method therefor, and in particular, an AWG (U.S.A. And a connection structure and a connection method suitable for interconnecting substrates.

[0002]

2. Description of the Related Art Numerous techniques such as soldering, crimping, pressure welding, resistance welding, laser welding, and ultrasonic welding have been widely used as techniques for connecting electric wires and substrates. Have been. Of these, mechanical connection techniques such as crimping and crimping are used for wires smaller than AWG No. 32, for example, in the case of crimping, the connection state is not mechanically stable, and in the case of crimping, a slot for receiving the fine wire is formed. It is no longer possible to apply because of problems such as the inability to do so or the lack of strength of the fine wire when pressed into the slot. In addition, soldering can be applied to the connection of wires with a wide range of wire diameters, from relatively thick wires to thin wires.However, since soldering is basically performed manually, the amount of solder supplied and the heating time Further, it is difficult to control the heating temperature, and the connection quality depends not only on the skill of the operator but also on the labor saving. Furthermore, resistance welding, laser welding, ultrasonic bonding, etc. are suitable for connection of thin electric wires, but the equipment is expensive and not suitable for connection in the field of medical equipment and measuring instruments, which mainly produce small quantities of many kinds. There is a problem that is.

[0003] Also, although it is not the connection between the ultrafine wire and the substrate,
In order to interconnect a flat cable and a printed circuit board, a connection structure (method) in which a conductive adhesive sheet or a non-conductive adhesive is interposed therebetween and thermocompression bonding is performed from the flat cable side has also been proposed (Japanese Unexamined Patent Application, First Publication No. H11-163873). Showa 51-21192
And JP-A-59-203378). Since these connection structures can be connected only by thermocompression bonding, there is an advantage that the connection workability is good. However, the former is
Since a special conductive adhesive is used, there is a problem that the connection becomes expensive. Although the latter has an advantage in terms of cost, the exposed surfaces of both the flat cable conductors and the connection pads of the printed circuit board are flat, so that the adhesive interposed between the conductors is completely removed during the thermocompression bonding process. There is a possibility that interconnection cannot be secured because it cannot be excluded.

[0004] In view of the above problems, the present invention can handle very fine wires, does not depend on the skill of workers, can save labor, can be realized with relatively simple equipment, and has high reliability. An object of the present invention is to provide a low-cost conductor and substrate connection structure and connection method.

[0005]

According to a first aspect of the present invention, there is provided a connection structure between a conductor and a substrate, wherein the substrate and the substrate are disposed on the substrate.
A conductor formed of a core wire having a substantially circular cross section, an insulating sheet disposed on the conductor, and a non-conductive adhesive interposed between the substrate and the insulating sheet; The conductor is sandwiched between the insulating sheet and the substrate to interconnect the conductor and the substrate.

According to a second aspect of the present invention, there is provided a method for connecting a conductor and a substrate, wherein a step of forming an adhesive layer on the substrate, a step of arranging a conductor having a core having a substantially circular cross section on the adhesive layer, Disposing an insulating sheet on the agent layer; and thermally interconnecting the insulating sheet to sandwich the conductor between the insulating sheet and the substrate to interconnect the conductor and the substrate. It is characterized by becoming.

According to a third aspect of the present invention, there is provided a method of connecting a conductor and a substrate, wherein a step of arranging a conductor having a core having a substantially circular cross section on the substrate and a step of forming an adhesive layer on the substrate on which the conductor is arranged. Arranging an insulating sheet on the adhesive layer, and thermally compressing the insulating sheet to sandwich the conductor between the insulating sheet and the substrate to interconnect the conductor and the substrate. And a method for connecting a conductor and a substrate.

According to a fourth aspect of the present invention, there is provided a method for connecting a conductor and a substrate, wherein a conductor comprising a core having a substantially circular cross section is disposed on the substrate, and an adhesive layer and an insulating sheet are provided on the substrate on which the conductor is disposed. A step of arranging the integrated sheet made of the adhesive layer and the conductor so as to face each other, and pressing the insulating sheet by thermocompression to sandwich the conductor between the insulating sheet and the substrate; Interconnecting the substrates.

A method of connecting a conductor and a substrate according to a fifth aspect of the present invention is a method of connecting a conductor having a core wire having a substantially circular cross section to the adhesive layer of an integrated sheet comprising an adhesive layer and an insulating sheet; A step of arranging the integrated sheet on the substrate so that the layer and the substrate face each other, and pressing the insulating sheet by thermocompression to sandwich the conductor between the insulating sheet and the substrate; Interconnecting the substrates.

[0010]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan view showing one embodiment of a connection structure between an electric wire and a circuit board according to the present invention.
Note that a part of the pressure-bonded sheet is removed. FIG.
FIG. 2 is a right side view of the connection structure in FIG. 1. FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4 shows FIG.
FIG.

1 to 3, a connection structure according to the present invention is a printed circuit board (hereinafter simply referred to as a board) 1.
0, a plurality of individual electric wires 20, an adhesive 30, and a pressure bonding sheet 40. The electric wire 20 is, for example, an AWG 42
It is an extra-fine wire like a wire. At the end of the electric wire 20, the coating is peeled off, and the conductor 22 is exposed. Conductor 2
2 may be a single wire composed of a single core wire having a substantially circular cross section or a stranded wire composed of a plurality of core wires having a substantially circular cross section. Conductor 22
Are mounted on conductive connection pads 12 formed on a substrate 10. The adhesive 30 is a generally used thermocompression adhesive such as an epoxy resin, and may be either a thermoplastic adhesive or a thermosetting adhesive. The thickness of the adhesive 30 is preferably equal to or larger than the diameter of the conductor 22 to be connected. If the thickness of the adhesive 30 is smaller than the diameter of the conductor 22, a gap in which the adhesive 30 is not filled occurs between the substrate 10 and the pressure-bonded sheet 40, and the substrate 10 and the pressure-bonded sheet 40 may not be bonded to each other. It is. The pressure-bonding sheet 40 is preferably made of a polyimide resin or polyethylene terephthalate (PET) resin, but may be made of another material as long as it is an insulating material that can withstand the heat and mechanical load during thermocompression bonding.

In FIG. 4, the substrate 10 and the pressure-bonding sheet 4
0 are mutually pulled by the adhesive force of the adhesive 30. As a result, the conductor 22 of the electric wire 20 is
As a result, the connection pad 12 on the substrate 10 is pressed, so that a stable electrical connection between the conductor 22 and the connection pad 12 can be obtained. Since the connection portion (contact portion) between the conductor 22 and the connection pad 12 is shielded from the outside air by the adhesive 30, it is hard to corrode. Therefore, a stable connection can be obtained for a long period of time.

Next, the connection process of the connection structure of the present invention will be described. 5A and 5B show a first step of the connection, wherein FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view taken along line Vb-Vb of FIG. FIG. 6 is a view similar to FIG. 5, illustrating a second step of the connection. FIG. 7 is a view similar to FIG. 5, showing a third step of connection. FIG. 8 is a cross-sectional view similar to FIG. 7B, illustrating the fourth step of connection.

Referring to FIG. 5, first, a layer of an adhesive 30 is formed on the connection pads 12 of the substrate 10. The layer of the adhesive 30 may be formed by placing the sheet-like adhesive 30 on the substrate 10 by hand or the like, or may be formed by a method such as screen printing or thermal transfer.

Next, as shown in FIG.
The conductor 22 of the individual electric wire 20 is placed on the bonding pad 1 using a comb-shaped jig (not shown) or a temporary fixing tape or the like.
Place it in a state where it is aligned with 2. In order to prevent the positions of the conductor 22 and the bonding pad 12 from shifting,
The adhesive 30 desirably has tackiness.

Subsequently, as shown in FIG.
The pressure-bonding sheet 40 is placed thereon. The crimp sheet 40
As described above, any material may be used as long as it is an insulating material having predetermined heat resistance and mechanical strength.

Finally, as shown in FIG.
0, the substrate 10 on which the conductor 22 of the electric wire 20 and the crimping sheet 40 are laminated is placed on a crimping table 54 of a thermocompression bonding machine, and heat and pressure are applied to the crimping sheet 40 by a crimping head 52.
By heating and pressing, the adhesive 30 is fluidized and the substrate 1
0, the space between the conductor 22 and the crimping sheet 40 is filled,
Is pressed against the connection pad 12 by the pressure bonding sheet 40. At the time of thermocompression bonding, the adhesive 30 existing between the conductor 22 and the connection pad 12 is removed by being washed away,
Electrical conduction between the conductor 22 and the connection pad 12 is ensured.

The thermocompression bonding operation differs slightly depending on the type of the adhesive 30 used. When the adhesive 30 is thermosetting, the pressure bonding head 52 is separated from the pressure bonding sheet 40 after the adhesive 30 is sufficiently hardened. On the other hand, when the adhesive 30 is thermoplastic, after the temperature of the pressure bonding head 52 becomes sufficiently lower than the melting point of the adhesive 30, the pressure bonding head 52 is
Separate from zero. In this case, the thermocompression bonding machine is preferably of a pulse heat type.

[0019]

【Example】

Board connection pad: gold plating and solder plating (0.3 to 0.6 mm pitch) Electric wire: AWG No. 42 stranded wire (copper-tin alloy conductor with silver plating: manufactured by Junkosha) Adhesive: thermosetting epoxy adhesive Sheet (10mm ×
2 mm, thickness 0.1 mm) Pressure bonding sheet: Polyimide resin sheet (10 mm x 3 mm)
Thickness: 0.1mm) Conditions for thermocompression bonding: temperature 180 ° C, pressure 20kgf (1
For a sample of the connection structure formed under the condition of 30 seconds or more,
A thermal shock test was performed at 0 ° C to 100 ° C for 100 cycles.

As a result, the contact resistance after the test was 5.19 to 7.62 mΩ for the gold-plated connection pad, and 4.65 to 6.67 for the solder-plated connection pad.
mΩ, and the connection characteristics were extremely stable.

The following factors can be considered as reasons why the connection structure of the present invention was subjected to the thermal shock test to obtain the above-mentioned favorable results. That is, since the thickness of the adhesive becomes smaller as the diameter of the conductor becomes smaller, the difference between the amount of thermal expansion / contraction of the conductor and the amount of thermal expansion / contraction of the adhesive becomes extremely small. It is considered stable.

The connection technique of the present invention has the following advantages.

1) Since the substrate, the adhesive, the conductor, and the pressure-bonded sheet are merely overlapped and thermocompression-bonded under predetermined conditions, there is little variation in connection quality. In addition, since collective connection is possible, labor saving can be achieved. Furthermore, since the heating temperature is lower than that of soldering, there is an advantage that the strength is less deteriorated due to oxidation of the conductor and the like. Also, if an appropriate alignment jig is used, a connection at a narrow pitch, such as a 0.3 mm pitch, which is difficult by soldering, is also possible.

2) Since the connection equipment can be obtained only with a relatively inexpensive thermocompression bonding machine, there is an advantage that the initial investment cost can be reduced.

3) Generally, the conductor of the individual electric wire has a substantially circular cross section of the core wire, so that the adhesive interposed between the conductor and the connection pad of the substrate is effectively eliminated during the thermocompression bonding step. You. For this reason, there is an advantage that interconnection between the conductor and the connection pad can be secured.

4) Since the insulator around the conductor and the pressure-bonded sheet are separate bodies, the insulator around the conductor is not limited to a relatively hard resin such as polyimide or PET as in FPC. Since there is a degree of freedom in selection, there is an advantage that sufficient flexibility of the electric wire including the conductor can be ensured.

Although the preferred embodiment of the present invention has been described above, the present invention should not be limited to the above-described embodiment, and various modifications or changes can be made as necessary. For example, in the above-described connection method, the conductor placement step was performed after the adhesive layer formation step. However, these steps are reversed. First, the conductor is placed on the substrate, and then the adhesive layer is formed thereon. May be. In this case, since there is no adhesive, which is an insulator, between the conductor and the substrate, there is an advantage that the reliability of the connection between the conductor and the substrate is increased. In the above-described embodiment, the adhesive 30 and the pressure-bonded sheet 40 are separate bodies, but an integrated sheet may be used. In this case, the conductor is aligned on the connection pad of the substrate by the above-described jig or tape, and a sheet in which the adhesive and the pressure-bonded sheet are integrated (hereinafter, referred to as an integrated sheet) is disposed thereon, or
The conductor may be directly transferred onto the adhesive layer of the integrated sheet at a relatively low temperature, and the integrated body of the conductor, the adhesive and the pressure-bonded sheet may be disposed on the substrate. In the former case, it is not necessary to separately manage the adhesive sheet and the pressure-bonded sheet, and the number of steps at the connection site can be reduced by one compared with the above-described embodiment. In the latter case, there is an advantage in that the conductor is less likely to be displaced during the operation, in addition to advantages in management and process. Furthermore, what is connected to the conductor may be an electric terminal instead of the circuit board. The conductor is not limited to the conductor of the individual electric wire, and may be a conductor of a ribbon cable or a flat cable as long as the cross section of the core wire constituting the conductor is substantially circular.

[0028]

According to the connection structure of the conductor and the substrate according to the first aspect, the conductor consisting of the core wire having a substantially circular cross section is sandwiched between the insulating sheet and the substrate by the adhesive force of the adhesive, and the conductor and the substrate are mutually connected. Since the connection is made, it is suitable for connection of extra fine wires, and has an effect of obtaining a highly reliable and low-cost connection structure.

According to the method for connecting a conductor and a substrate according to the second aspect, a step of forming an adhesive layer on the substrate, a step of arranging a conductor having a substantially circular core wire on the adhesive layer, and a step of arranging the insulating sheet Since the process and the thermocompression bonding process are performed, there is an effect that the conductor and the substrate can be interconnected at a low cost with high reliability without depending on the skill of the operator. Furthermore, while being able to cope with the narrow pitch connection of extra fine conductors,
When the adhesive has tackiness, a member such as a tape for temporarily fixing the conductive wire can be unnecessary.

According to the method for connecting a conductor and a substrate according to claim 3, a step of arranging the conductor on the substrate, a step of forming an adhesive layer,
Since the process includes the insulating sheet arranging step and the thermocompression bonding step, there is an advantage that the conductor and the substrate can be interconnected at a low cost with high reliability without depending on the skill of the operator.

According to the method for connecting a conductor and a substrate according to a fourth aspect of the present invention, the method includes a conductor arranging step on the substrate, an integral sheet arranging step including an adhesive layer and an insulating sheet, and a thermocompression bonding step. The conductor and the substrate can be interconnected with high reliability and at low cost without depending on the skill level, and the use of the integrated sheet makes it easy to manage the parts and realize further labor saving.

According to the method for connecting a conductor and a substrate according to a fifth aspect of the present invention, the method includes a step of arranging the conductor on the adhesive layer of the integrated sheet, a step of arranging the integrated sheet on the substrate, and a thermocompression bonding step. The conductor and the substrate can be interconnected with high reliability and at low cost without depending on the degree, and the use of the integral sheet makes it easy to manage the parts and realize further labor saving. Furthermore, there is very little possibility that the conductor will shift during the operation.

[Brief description of the drawings]

FIG. 1 is a plan view showing a connection structure of the present invention.

FIG. 2 is a right side view of the connection structure of FIG. 1;

FIG. 3 is a sectional view taken along line III-III in FIG. 1;

FIG. 4 is an enlarged view of a portion A in FIG. 3;

5A and 5B show a first step of the connection method of the present invention, wherein FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view taken along line Vb-Vb of FIG.

6A and 6B show a second step of the connection method of the present invention, wherein FIG. 6A is a plan view, and FIG. 6B is a cross-sectional view taken along the line VIb-VIb of FIG.

7A and 7B show a third step of the connection method of the present invention, wherein FIG. 7A is a plan view, and FIG. 7B is a cross-sectional view taken along line VIIb-VIIb of FIG.

8 shows a fourth step of the connection method of the present invention, and FIG.
It is sectional drawing similar to (b). However, the thermocompression bonding machine is not sectioned.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 12 Connection pad 20 Electric wire 22 Conductor 30 Non-conductive adhesive 40 Insulating sheet

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaki Uchida 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa KSP C Building 8F Inside Amp Technology Japan Co., Ltd. (72) Inventor Susumu Nagao Kawasaki, Kanagawa Prefecture 8-2-1 KSP C Building, 3-2-1 Sakado, Takatsu-ku, Kyushu, Japan Inside the Amplifier Technology Japan K.K. (72) Inventor Koichi Iino 8-2-1 KSP C Building, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa Prefecture Technology Japan Co., Ltd.

Claims (5)

[Claims] 1. A substrate, a conductor comprising a core wire having a substantially circular cross section disposed on the substrate, an insulating sheet disposed on the conductor, and the substrate and the insulating sheet. A conductor and a substrate, wherein the conductor and the substrate are interconnected by sandwiching the conductor between the insulating sheet and the substrate by an adhesive force of the interposed non-conductive adhesive; Connection structure. 2. A step of forming an adhesive layer on a substrate; a step of arranging a conductor consisting of a core wire having a substantially circular cross section on the adhesive layer; and arranging an insulating sheet on the adhesive layer. Connecting the conductor and the substrate by thermally pressing the insulating sheet and sandwiching the conductor between the insulating sheet and the substrate to interconnect the conductor and the substrate. Method. 3. A step of arranging a conductor composed of a core wire having a substantially circular cross section on a substrate, a step of forming an adhesive layer on the substrate on which the conductor is arranged, and an insulating sheet on the adhesive layer. And a step of interconnecting the conductor and the substrate by thermocompressing the insulating sheet, sandwiching the conductor between the insulating sheet and the substrate, and interconnecting the conductor and the substrate. Board connection method. 4. A step of arranging a conductor consisting of a core wire having a substantially circular cross section on a substrate; and forming an integrated sheet comprising an adhesive layer and an insulating sheet on the substrate on which the conductor is arranged, A step of arranging the conductor so as to face each other, and a step of thermocompressing the insulating sheet to sandwich the conductor between the insulating sheet and the substrate to interconnect the conductor and the substrate. A method for connecting a conductor and a substrate. 5. A step of arranging a conductor consisting of a core wire having a substantially circular cross section on said adhesive layer of an integrated sheet comprising an adhesive layer and an insulating sheet; and said substrate so that said adhesive layer and said substrate face each other. Arranging the integrated sheet thereon, and thermally bonding the insulating sheet to sandwich the conductor between the insulating sheet and the substrate to interconnect the conductor and the substrate. A method for connecting a conductor and a substrate.