JPH0744204B2 - Heater for thermocompression bonding - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocompression bonding heater used for thermocompression bonding of an electronic circuit connecting terminal such as an integrated circuit to a connecting terminal such as a flexible printed wiring board via an anisotropic conductive film. Is.

[0002]

2. Description of the Related Art With the miniaturization of electronic equipment, there is a great demand for high-density mounting, and recently, a connection terminal interval with an external circuit is required to be 0.2 to 0.5 mm. Therefore, anisotropic conductive films have come to be used for such terminal connection.

This anisotropic conductive film is composed of a polymer film in which conductive particles are evenly dispersed in an adhesive, and the film is sandwiched between connection terminals to be thermocompression-bonded so that electrical anisotropy is achieved. Is to have. That is, it has conductivity only in the thickness direction of the film and has insulation properties in the plane direction of the film. Therefore, on a large number of connection terminals arranged side by side on the surface of the electronic circuit board with a slight interval, external connection terminals such as a flexible printed wiring board having the same intervals are superposed with the anisotropic conductive film interposed therebetween. If it is heated with a thermocompression bonding heater from above the overlapping portion of the connection terminals of
Connection terminals can be connected while ensuring insulation between adjacent terminals.

In order to obtain stable electric characteristics and adhesive strength by thermocompression bonding using this film, it is necessary that a uniform pressure is applied to the connection surface and the entire connection surface is heated to a uniform temperature. is necessary. Further, if the heater is released while the connection surface is still heated, the adhesive does not solidify and the adhesive surface separates. Therefore, it is necessary to continue pressing until the adhesive solidifies.

In view of this, the applicant proposed in Japanese Utility Model Application Laid-Open No. 64-2474 an instantaneous heating system in which a heater is provided with a cooling air introduction passage to perform rapid cooling while pressing the heater.

FIG. 7 is a front view showing the previously proposed heater assembly, and FIG. 8 is a perspective view of the heater. In FIG. 7, reference numeral 10 is a lifting shaft, which is lifted and lowered by an air cylinder or the like (not shown). 12 is an insulator block fixed to the lower end of the lifting shaft 10, and 14 is an insulator block 12
Is a cooling plate having a rectangular shape in a plan view, which is fixed to a lower end surface of the. The cooling plate 14 is entirely made of an insulating material, and a cooling air passage 16 is formed inside the cooling plate 14.

A pair of power supply blocks 18 (18a, 1a) are provided on the lower surface of the cooling plate 16 with a gap along the longitudinal direction.
8b) is fixed. These power supply blocks 18a,
A thermocompression bonding heater 20 is attached to the opposing surface of 18b.

The heater 20, as shown in FIG.
2 and the pair of side plate portions 24 (24a, 24b) form a substantially U-shaped cross section. These side plate portions 24a and 24b are
The power feeding block 18 is sandwiched between the facing surfaces of the power feeding blocks 18a and 18b, and the long bolts 26 (26a and 26b) are used to feed the power feeding block 18
It is firmly fixed so that it adheres to. In FIG. 8, 28 is a bolt hole into which the long bolt 26 is screwed. As a result, the side plate 2
4 is in close contact with the power supply block 18 over the entire length in the longitudinal direction.

Power supply plates 30 (30a, 30b) having the same length as the entire length of the power supply block 18 are fixed to the outer end surfaces of these power supply blocks 18, that is, the end surfaces parallel to the longitudinal direction, with bolts 32 (32a, 32b). ing. These power supply plates 30 have a wider flexible electrode strip 34 (34).
a, 34b) to the electrode 36 (36a, 36b).

For example, a flexible printed wiring board 44 having a corresponding terminal pattern formed by sandwiching an anisotropic conductive film 42 on a substrate 40 having a large number of comb-teeth-shaped terminals.
Pile up. Then, the pressing portion 22 of the heater 20 is pressed against this overlapping portion to energize the heater 20.

A power supply circuit (not shown) applies a DC voltage controlled by a phase control method between the electrodes 36a and 36b. Therefore, an electric current flows from one side plate portion 24 to the other side plate portion 24 across the pressing portion 22 in a direction orthogonal to the longitudinal direction thereof. This current causes the heater 20 to generate heat. The heater 2 is heated for a predetermined time, and when the heater 20 reaches a predetermined temperature, the current is cut off, and the cooling air is sent to the cooling air passage 16 to send the heater 2
Quench 0. Then, after the film 42 is sufficiently solidified, the assembly is raised to separate the heater 20 from the wiring board 44.

[0012]

However, it has been clarified that the non-uniformity of the temperature distribution on the pressing surface of the heater becomes relatively large in the previously proposed one. That is, the temperature near both ends of the pressing surface in the longitudinal direction becomes lower than that near the center. For this reason, there is a problem that the reliability of adhesion is lowered.

[0013]

According to the present invention, such a problem is caused by the pressing portion and a pair of side plate portions sandwiching the pressing portion having a substantially U-shaped cross section in a plane orthogonal to the longitudinal direction. However, in the thermocompression-bonding heater head that energizes from one of the side plate parts to the other of the side plate parts through the pressing part, both ends of the pressing part in the longitudinal direction are set back from both end faces of the side plate part. This is solved by a thermocompression bonding heater.

[0014]

1 is a side view of an embodiment of the present invention, and FIG. 2 is a front view thereof. The heater 20 of this embodiment has a pressing portion 22A.
The side plates 24A, 24A have a substantially U-shaped cross section in a plane orthogonal to the longitudinal direction thereof. Slopes 24a facing both ends of the pressing portion 22A are formed at both ends of the side plate portion 24A. As a result, the entire length of the side plate portion 24A is the power supply block 1
The pressing portion 22A has a shorter overall length than the side plate portion 24A, and both ends of the pressing portion 22A recede from both end faces of the side plate portion 24A.

FIG. 3 is a side view of another embodiment. In the heater 20B of this embodiment, the side plate portion 24B is provided at both ends in the longitudinal direction with stepwise cutouts in the longitudinal plane of the pressing portion 22B and the plane orthogonal thereto.

FIGS. 4, 5 and 6 are graphs showing the effects of the present invention by experimental data. FIG. 4 shows the temperature distribution immediately after energization when the temperature of the pressing portion 22 of the heater 20 is set to 200 ° C., 300 ° C. and 375 ° C. As shown in FIG. 1, the temperature is detected by the thermocouples 30 (see FIG. 7) attached at seven positions in order from one end of the pressing portion 22 as shown in FIG.

Similarly, FIG. 5 shows the temperature distribution after 10 seconds of heating. 4 and 5, when the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 3 are used,
It can be seen that the temperature fluctuation range depending on the place is significantly smaller than that of the conventional one shown in FIG.

FIG. 6 is a diagram showing a time change of temperature at different places when the temperature is set to 200.degree. Here, CH1 to CH7 are measured thermocouple mounting positions shown in FIGS. From FIG. 6, according to the conventional heater, the temperatures of CH1 and CH7 near the end of the pressing portion 22 are always extremely low, whereas according to the first and second embodiments, the temperature is uniform throughout.

The present invention is not limited to the embodiment shown in FIGS. 1 and 3, but the longitudinal ends of the pressing portion are retracted from the power supply block mounting portion of the side plate portion so that the vicinity of both ends of the pressing portion can be reduced. If the current density is increased, the desired effect can be obtained.

[0020]

As described above, according to the present invention, since both ends of the pressing portion in the longitudinal direction are made to recede from the power supply block mounting portion of the side plate portion, the current density near the both ends of the pressing portion is increased and the temperature near the both ends is increased. Can be raised to make the temperature distribution of the pressing portion uniform. As a result, the reliability of adhesion of the connection terminals can be improved (claim 1). Here, the end face in the longitudinal direction of the side plate portion may be a slope inclined toward both ends of the pressing portion (claim 2). Also, instead of this slope,
This may be formed stepwise (claim 3).

[Brief description of drawings]

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

[Figure 2] Similarly, a front view

FIG. 3 is a side view showing a second embodiment of the present invention.

[Figure 4] Temperature distribution measurement diagram

[Figure 5] Temperature distribution measurement diagram

[Figure 6] Temperature change measurement diagram

FIG. 7 is a front view of a heater assembly.

FIG. 8 is a perspective view of a conventional heater.

[Explanation of symbols]

 20A, 20B Heater 22A, 22B Pressing part 24A, 24B Side plate part 24a Slope

Claims (3)

[Claims] 1. A pressing portion and a pair of side plate portions sandwiching the pressing portion form a substantially U-shaped cross section in a plane orthogonal to the longitudinal direction, and one of the side plate portions passes through the pressing portion and the other of the side plates is formed. A thermocompression-bonding heater head for energizing a side plate part, wherein both ends of the pressing part in the longitudinal direction are set back with respect to both end faces of the side plate part. 2. The heater for thermocompression bonding according to claim 1, wherein both ends of the side plate portion in the longitudinal direction are formed in a slope shape facing both ends of the pressing portion. 3. The heater for thermocompression bonding according to claim 1, wherein both ends of the side plate portion in the longitudinal direction are notched in a step shape in a plane in the longitudinal direction of the pressing portion and a plane orthogonal to the plane.