JP2755087B2 - Removable jig - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detachable jig,
The conductive heating part that heats the conductive part of the electric circuit board is vertically supported by the lead heating part, and the lead is heated first, and then the lead is heated. Is what you do.

[0002]

2. Description of the Related Art Conventionally, surface-mount type semiconductor integrated circuit packages such as SOP, MSP and QFP are mounted on a printed circuit board. Prior to this mounting, a thick film solder plating is applied to the external leads of the package. A thermocompression-bonding jig having a shape suitable for a package is used for joining the external lead and the copper foil on the printed board. As shown in FIG. 6, in this thermocompression bonding jig 20, the pressing surface 20A with the external lead 21 of the package, that is, the lower surface of the thermocompression bonding jig 20 is formed in a plane. This pressing surface 2
0A is for heating while pressing the external leads 21 of the package against the copper foil 24. When this heating is performed, the temperature of the external lead 21 increases. Therefore, the heat 25 propagates from the solder 22 plated around the external lead 21 to the copper foil 24 on the printed circuit board 23 in that order, and the external lead 21 and the copper foil 24 are soldered. .

[0003]

However, such a thermocompression bonding jig 20 has the following disadvantages. That is, the molten solder 22 is in a semi-liquid state including a liquid or a solid. The solder 22 has a property of gathering at a higher temperature. For this reason, the solder 22 concentrates near the tip 21A of the external lead 21. That is, as shown in FIG. 7, the result is that the solder 22 does not spread to the desired surface 24A of the copper foil 24. Therefore, there is an excessive solder 22 near the external lead 21, which causes a bridge (adjacent leads are connected by solder and short-circuit) or a phenomenon that the solder 22 sucks (wicking) occurs. was there.
Furthermore, the pressing surface 21 of the external lead 21 against the copper foil 24
B, the solder 22 is easily removed and the external leads 2
1 and the copper foil 24 were reduced in bonding strength.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a conductive heating portion for heating a conductive portion of an electric circuit board, and the conductive heating portion is supported by a lead heating portion so as to be movable up and down. It is an object of the present invention to provide a detachable jig capable of giving appropriate quality to bonding with a lead.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a detachable jig for joining or detaching a lead of a circuit element component to or from a conductive portion of an electric circuit board via a heating bonding material. And a lead heating unit that heats the lead. The conductive heating unit is a detachable jig that is vertically movably supported by the lead heating unit via an elastic member.

[0006]

With the attachment / detachment jig according to the present invention, the leads of the circuit element component are joined to the conductive portion of the electric circuit board via the heating joining material. In addition, the attachment / detachment jig detaches a lead of a circuit element component mounted on a conductive portion of an electric circuit board via a heating bonding material. In this attachment / detachment jig, a conductive heating section for heating the conductive section of the electric circuit board and a lead heating section for heating the leads of the circuit element parts are provided, and the lead heating section is capable of vertically moving the conductive heating section. I support it. When the attachment / detachment jig joins the lead of the circuit element component to the conductive portion of the electric circuit board via the heating bonding material, the conductive portion of the electric circuit board is first heated, and then the heating bonding material and the circuit element component are heated. Heat the reed. As a result, the molten heat bonding material easily spreads from the conductive portion of the electric circuit board to the leads of the circuit element components.
Therefore, the heat bonding material does not concentrate on the leads of the circuit element component. Therefore, occurrence of a bridge can be prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A circuit device component attaching / detaching jig according to an embodiment of the present invention will be described below with reference to FIGS. FIG.
Is a thermocompression bonding jig 1 as a detachable jig for circuit element parts.
6 is a longitudinal sectional view schematically showing a state in which the external lead 11 of the QFP 10 is thermocompression-bonded. FIG. 2 shows a thermocompression jig 1
6 is a perspective view showing a state before the external lead 11 of the QFP 10 is joined. FIG. 3 is a plan view showing the copper pad 13 after soldering. FIG. 4 is a cross-sectional view showing a main part of the thermocompression bonding jig before thermocompression bonding. FIG. 5 is a cross-sectional view illustrating a state of the thermocompression bonding jig 16 during thermocompression bonding.

As shown in FIG. 2, the thermocompression bonding jig 16 is a square metal frame, and has a mounting portion 2 mounted on a soldering iron and an external lead 1 of the QFP 10.
It is composed of a heating unit 3 for heating 1 and the like. The external lead 11 is made of an iron-nickel alloy or a copper alloy.
The heating unit 3 has a thermocouple 4 for detecting its temperature.
Is buried. The width of the heating section 3 is 1.8 mm. In addition, a step is formed on the lower surface of the heating unit 3. The stepped lower surface of the heating section 3 has a lead heating surface 5 for warming the external lead 11, and a pad heating surface 6 projecting downward from the lead heating surface 5 and heating the copper pad 13. ing.

More specifically, as shown in FIG. 4, the thermocompression bonding jig 16 includes a lead heating section 17 for heating the external leads 11 of the QFP 10 and a pad heating section 18 for heating the copper pad 13. have. The pad heating section 18 is provided to be vertically movable with respect to the lead heating section 17. A spring 19 is interposed between the pad heating section 18 and the lead heating section 17.
Specifically, a hole 18 </ b> A is formed in the upper surface of the pad heating unit 18, and one end of a spring 19 is locked on the bottom surface of the hole 18. The other end of the spring 19 is locked to the lower surface of the lead heating unit 17 (the surface facing the upper surface of the pad heating unit 18). The thermocompression jig 16 may be integrated with the soldering iron.

Before the QFP 10 is mounted on the printed circuit board 14, a thick film solder 12 is plated on the tip of the external lead 11 of the QFP 10. More specifically, the thickness of the external lead 11 is 0.125 mm, and the tip of the external lead 11 is plated with a solder 12 having a thickness of 0.025 mm. That is, the tip of the external lead 11 is 0.175 m
m thick. On the other hand, on the printed circuit board 14,
A rectangular copper pad 13 is formed at a predetermined position for an electric circuit.

Next, a method of mounting the QFP 10 on the printed circuit board 14 using the thermocompression bonding jig 16 will be described. First, as shown in FIG. 2, the QFP 10 is temporarily fixed to a predetermined position on the printed circuit board 14 with an adhesive. That is, the external leads 11 of the QFP 10 are mounted on the copper pads 13. Next, the thermocompression bonding jig 16 attached to the soldering iron is arranged at a predetermined position above the QFP 10. At this time, in the thermocompression bonding jig 16, as shown in FIG. 4, a step having a height T is formed between the lead heating section 17 and the pad heating section 18. The step T is T >> t + 2H, and is, for example, 0.3 mm, which is longer than 0.175 mm which is the thickness (t + 2H) of the tip of the solder-plated external lead 11.

In this state, the thermocompression bonding jig 16 is lowered with respect to the printed board 14. Then, first, the lower surface of the pad heating unit 18 contacts the upper surface of the copper pad 13. And
When the switch of the soldering iron is turned on, the tip of the soldering iron generates heat, and the heat is transmitted to the thermocompression bonding jig 16. This heat is
It propagates to the copper pad 13 via the pad heating surface 6.
As a result, the thermocompression bonding jig 16 starts heating only the copper pad 13.

The temperature is detected by the thermocouple 4,
When the temperature reaches a predetermined temperature, the thermocompression bonding jig 16 is further lowered. At this time, the pad heating unit 18 keeps pressing the copper pad 13. Then, as shown in FIGS. 1 and 5, the lower surface of the lead heating unit 17 contacts the upper surface of the pad heating unit 18. At this time, the step T ′ between the lead heating unit 17 and the pad heating unit 18 is t + 2H> T ′> t (the thickness of the lead itself).
, For example, down to 0.15 mm. As a result,
The external lead 11 is also heated, and the solder 12 plated on the tip of the external lead 11 is melted. This molten solder 1
2 enters the gap between the pad heating surface 6 and the copper pad 13 from the tip of the external lead 11 as shown in FIG. The tip fillet 15 is easily formed. As a result, the solder 12 has a shape with the most stable surface energy. Therefore, the solder 12 does not concentrate only on the external leads 11. In addition, the occurrence of bridges can be prevented. Therefore, bonding failure due to soldering is eliminated.

A predetermined clearance (conductor) is provided between the pad heating surface 6 of the thermocompression bonding jig 16 and the upper surface of the copper pad 13 and between the lead heating surface 5 and the upper surface of the external lead 11, respectively. Distance between the support and the support). Therefore, the flow of the molten solder 12 is promoted by the capillary phenomenon. Solder dispersion to each part becomes active. That is, as shown in FIG. 3, the solder 12 is dispersed on the copper pad 13 to the left side in the figure.

Further, as shown in FIG. 1, a solder 1 is provided between the external lead 11 and the copper pad 13 having different linear expansion coefficients.
2 easily enters. Further, the residual stress of the external lead 11 is reduced by the clearance. Therefore, the QFP 10 is connected to the printed circuit board 1 using the thermocompression bonding jig 16.
4, when soldering, it is possible to perform soldering of appropriate quality. That is, the bonding strength between the external lead 11 and the copper pad 13 is improved. Therefore, stress hardly remains on the external leads 11. In addition, since the copper pad 13 is heated before the external lead 11, compared to the case of simultaneous heating,
The solder 12 easily flows to the left side in the drawing of the copper pad 13 shown in FIG.

The thermocompression bonding jig according to the present invention can be used for removing a circuit element component mounted on a printed circuit board. Further, this thermocompression bonding jig is also applicable to constant heating and instantaneous heating. The circuit element component is not limited to the semiconductor package of the surface mounting type and the semiconductor package of the tape carrier type, but may be any circuit element component having leads. In addition, the thermocompression jig
The package may be configured to heat four sides simultaneously, two sides simultaneously, or only one side. Alternatively, a thermocompression jig configured so that each side of the package can be joined by an arbitrary combination may be used.

[0017]

According to the present invention, a conductive heating portion for heating a conductive portion of an electric circuit board is provided, and the conductive portion is heated first.
Then, the leads are heated, so that appropriate quality can be applied to the joining between the conductive portion and the leads of the circuit element component.

[Brief description of the drawings]

FIG. 1 shows a thermocompression bonding jig according to an embodiment of the present invention;
FIG. 6 is a longitudinal sectional view showing a state in which the external lead is heated.

FIG. 2 is a perspective view showing a state before a thermocompression bonding jig according to an embodiment of the present invention joins external leads.

FIG. 3 is a plan view showing a copper pad after soldering by a thermocompression bonding jig according to one embodiment of the present invention.

FIG. 4 shows a thermocompression bonding jig according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view schematically showing a state before bonding external leads.

FIG. 5 is a cross-sectional view schematically showing a state where the thermocompression bonding jig according to the embodiment of the present invention joins external leads.

FIG. 6 is a longitudinal sectional view showing a state where a thermocompression bonding jig according to a conventional example is heating an external lead of a QFP.

FIG. 7 is a plan view showing a copper foil after soldering according to a conventional example.

[Explanation of symbols]

1 thermocompression jig (detachment jig), 10 QFP (circuit element parts), 11 external leads (circuit element parts leads), 12 solder (heat bonding material), 13 copper pads (conductive part), 14 printed circuit board ( Electric circuit board), 1
6 Lead heating section, 17 conductive heating section, 19 spring (elastic member).

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H05K 3/34 507 H05K 3/34 510

Claims (1)

(57) [Claims] An attachment / detachment jig for joining or detaching a lead of a circuit element component to or from a conductive portion of an electric circuit board via a heating bonding material, wherein the conductive heating portion heats the conductive portion; And a lead heating section for heating the conductive heating section, and the conductive heating section is vertically movably supported by the lead heating section via an elastic member.