JPH0617336Y2 - Bonding tools - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention is designed such that a large number of lead wires such as integrated circuits are temporarily heated to a large number of connecting parts such as a printed wiring board which is pre-coated with solder by plating or the like. It concerns a bonding tool for soldering to.

(Background of the Invention) A bonding tool for soldering a large number of leads such as an integrated circuit at a time is known. This bonding tool has a long pressing surface that is heated by resistance heating with an electric current, and evenly presses this pressing surface onto a number of soldering parts to simultaneously solder, and the pressing surface should be as wide as possible. It is desirable to maintain a uniform temperature throughout. However, the side that forms the pressing surface (pressing side)
Since both ends of the pressing surface are connected to the power supply terminals, the heat of the pressing surface escapes to these power supply terminals, the temperature near the center of the pressing surface becomes high and the temperature becomes low near both ends, and the temperature nonuniformity becomes strong. For this reason, the length within a certain allowable temperature range (soaking length) becomes short, and there arises a problem that the soldering state of each portion to be soldered at one time becomes uneven.

Therefore, in order to increase the soaking length, a tool as shown in FIGS. 3 and 4 has been conventionally proposed (see Japanese Utility Model Laid-Open No. 57-53638).

In FIGS. 3 and 4, the side (pressing side) 2 forming the pressing surface 1 is shown.
Both ends of are connected to the pair of power supply terminals 4 (4a, 4b) by the pair of connecting sides 3 (3a, 3b), and the conductive plate material is formed in a substantially rectangular frame shape. Here, the upper surface of the pressing side 2, that is, the vicinity of the center of the surface on the opposite side of the pressing surface 1 is raised upward, and the raised portion 5 enhances the heat dissipation in the vicinity of the center to increase the soaking length.

That is, these are intended to make the temperature distribution as a whole uniform by cooling both ends of the pressing side by heat transfer to the power supply terminal 4 and cooling the vicinity of the center by heat radiation.

In FIG. 5, the horizontal axis x indicates the position of the pressing side in the lengthwise direction, and the vertical axis y indicates the temperature t. Δt shows the allowable temperature range, curve A shows the characteristic without the ridge 5, and curve B shows the characteristic with the ridge 5 as shown in FIGS. As described above, according to the tool shown in FIGS. 3 and 4, the soaking length a is narrow in the conventional characteristic A, but can be expanded like the soaking length b by providing the raised portion 5. .

However, in these conventional ones, in order to increase the soaking length, it is necessary to increase the size of the raised portion 5 to increase the amount of heat radiation and also the amount of current to increase the amount of heat generation. As a result, the heat capacity of the whole is increased and the response of heating / cooling is deteriorated. Further, since the amount of heat transferred to the power supply terminal 4 in the vicinity of both ends of the pressing side 2 does not decrease, the temperature drop in the vicinity of these both ends becomes large, and there is a limit to the expansion of the soaking length. Further, in the case where the raised portion 5 is provided, a bending force is generated due to a temperature change of the pressing side 2, the pressing surface 1 is bent, and it becomes impossible to solder a large number of soldering portions with uniform pressure, or power feeding is performed. There is also a problem that thermal or mechanical stress is repeatedly applied to the terminals 4 and the connecting sides 3 and the strength is likely to decrease due to fatigue.

(Purpose of the Invention) The present invention has been made in view of such circumstances, and has good responsiveness of heating / cooling, a soaking length can be greatly increased, and the pressing surface does not bend due to temperature change. It is an object of the present invention to provide a bonding tool in which the strength of each part is less likely to decrease due to fatigue.

According to the present invention, according to the present invention, a conductive plate material is formed into a substantially rectangular frame shape, and one side of the frame is cut out at the center to form a pair of power supply terminals, and the power supply terminals are opposed to each other. In a bonding tool in which the side to be pressed is a pressing side that presses the material to be bonded, two sides that connect both ends of the pressing side and each of the power supply terminals are formed in a curved shape bent inside the rectangle, This is achieved by a bonding tool characterized in that the cross-sectional area of the pressing side is at least approximately constant.

(Embodiment) FIG. 1 is a front view showing an embodiment of the present invention, and FIG. 2 is a right side view thereof. Reference numeral 10 denotes a tool formed by processing a conductive plate material, for example, a metal material such as molybdenum, tungsten or stainless into a substantially rectangular frame shape by wire cutting. The frame-shaped one side (upper side) is notched in the center, and the pair of power supply terminals 12 (12a, 1a, 1
2b) is formed. The lower side facing these power supply terminals 12 is a pressing side 14 having a rectangular cross section with a constant cross-sectional area,
The lower surface of the pressing side 14 serves as a pressing surface 16 for pressing a material to be bonded, for example, many lead wires of an integrated circuit. A pair of sides (connecting sides) 18 (18a, 18b) that connect both ends of the pressing side 14 and the power supply terminal 12 are formed in a rectangular shape, that is, a curved shape that is bent to the upper side of the pressing side 14, and are substantially horizontal. It has a V-shape that has been laid down. This direct connection side 1
The cross section of 8 has substantially the same shape and the same area as the pressing side 14.

Reference numeral 20 is a thermocouple for detecting the temperature near the center of the pressing side 14.

Therefore, when current is supplied to the power supply terminals 12a and 12b by the pulse current heating method, the pressing side 16 and the connecting side 18 generate heat. When the thermocouple 20 detects a constant temperature, the current conduction rate changes, the average current decreases, and the temperature is kept constant. While the temperature is kept constant as described above, the pressing surface 16 is pressed against the material to be bonded (not shown) to perform bonding, and then the current is cut off. Then, since the tool 10 has a small heat capacity, the temperature thereof is rapidly lowered, and if the tool 10 is raised and separated from the material to be bonded, the bonding operation is completed.

Since the connecting side 18 is bent above the right and left ends of the pressing side 14, the heat generated by the connecting side 18 is applied to the pressing side 1.
4 will be heated near the left and right ends. Therefore, the temperature near the left and right ends of the pressing side 16 rises, and the temperature drop due to the heat escaping from this vicinity to the power supply terminal 12 is compensated. As a result, the temperature in the vicinity of both ends of the pressing side 14 rises, eventually resulting in a temperature distribution like the characteristic C shown in FIG. 5, and the soaking length c becomes longer. Further, since the pressing side 14 does not have the raised portion 5 unlike the conventional one shown in FIGS. 3 and 4, the heat capacity becomes small and the temperature can be raised and lowered quickly. Further, since the pressing side 14 has an equal cross-sectional area, no bending occurs due to the temperature change, the flatness of the pressing surface 16 is improved, and a large number of bonding portions can be pressed uniformly to achieve uniform soldering. At this time, since the portion of the connecting side 18 acts as a kind of spring, the impact applied to the pressing surface can be absorbed here, and the stress due to thermal deformation can also be absorbed here. Therefore, the thermal and mechanical stress applied to the tool 10 is reduced, and the tool 10 is less likely to be damaged by fatigue.

(Effects of the Invention) As described above, the present invention bends the connecting side connecting the power supply terminal and the pressing side to the inside of the frame shape, that is, above the pressing side,
Since the pressing side has a substantially uniform cross section, the left and right ends of the pressing side can be heated by the heat generation of the connecting side. Therefore, the temperature drop caused by the heat escaping from the left and right ends of the pressing side to the power supply terminal can be compensated by the heating by the connecting side, and the soaking length of the pressing side can be greatly expanded. Further, since the pressing side does not have a raised portion or the like, the heat capacity thereof is small, rapid heating / cooling is possible, and the working speed can be increased. Also, since the cross section of the pressing side is constant, it is possible to press many bonding parts uniformly without curving due to temperature change.
Uniform soldering is possible. Furthermore, since the connecting edge has a kind of spring action, it can absorb the thermal deformation of each part and the mechanical impact during bonding, etc., and prevent the tool from being damaged by fatigue due to thermal and mechanical stress. .

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a right side view thereof, FIGS. 3 and 4 are perspective views of a conventional tool, and FIG. 5 is a temperature distribution diagram of a pressing surface. 10 ... Tool, 12 ... Power supply terminal, 14 ... Pressing side, 16 ... Pressing surface, 18 ... Connecting side.

Claims (1)

[Scope of utility model registration request] 1. A conductive plate material is formed into a substantially rectangular frame shape, and one side of this frame is cut out at the center to form a pair of power supply terminals, while the sides facing these power supply terminals are pressed against a material to be bonded. In the bonding tool having a pressing side, two connecting sides connecting both ends of the pressing side and each of the power supply terminals are formed in a curved shape bent inside the rectangle, and at least a cross-sectional area of the pressing side is formed. Bonding tool characterized in that