JPH07169898A - Junction of lead and substrate - Google Patents

Abstract

PURPOSE:To realize junction of a lead with a higher junction strength by heating the leas which is enhanced in thermal conductivity in the junction direction on the occasion of thermally pressure-bonding the tip of the lead to a semiconductor mounting substrate. CONSTITUTION:A lead 2 which is enhanced in thermal conductivity in the junction direction is heated for thermally pressure-bonding the end portion of the lead 2 to a semiconductor device mounting substrate 1. For instance, a thinner- walled area 17 is formed at the end portion of the lead 2 by eliminating the opposite surface (upper surface) of the junction surface of the lead 2 by the half-etching method, etc. Thereby, a distance from the tip of a heating tool 14 to the junction surface becomes short enhancing thermal conductivity. Accordingly, heat is conducted at a higher rate to the junction surface from the heating tool 14. Moreover, a thermal capacity of the tip of the lead 2 becomes small, resulting in a quick temperature rise. Therefore, tin and gold used for plating the lead 2 and circuit quickly form an eutectic alloy of Au-Sn, followed by formation of a fillet 12 having good wettability to realize higher junction strength of the lead 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining leads and substrates in a resin-sealed semiconductor device.

[0002]

2. Description of the Related Art A lead has been conventionally bonded to a semiconductor mounting substrate by thermocompression bonding, as disclosed in, for example, Japanese Patent Laid-Open No. 52-147067. That is, for example, a circuit 1 made of copper or the like is formed on the surface of a semiconductor mounting substrate 1 made of a laminated plate of modified polyimide resin or the like.
As shown in FIG. 5A, the tip end of the lead 2 used as an outer lead is overlaid on the circuit 13. In this state, titanium or molybdenum is used as shown in FIG. 5B. The upper surface of the lead 2 is pressed and heated by the heating tool 14 formed. Here, the surface of the circuit 13 is plated with nickel and gold, and the tips of the leads 2 are plated with tin. Then, when the tip end of the lead 2 is overlapped with the circuit 13 and heat-pressed as described above, the tin and gold plated on the surface of the lead 2 and the circuit 13 are melted into an Au-Sn eutectic alloy, and the Au and Sn are melted. The -Sn eutectic alloy serves as a bonding layer to bond the lead 2 to the circuit 13.

As described above, the lead 2 can be joined to the circuit 13 by using tin and gold plated on the surface of the lead 2 and the circuit 13 as a brazing material. At this time, the molten Au is melted.
-The Sn eutectic alloy protrudes from the joint surface of the lead 2 or the circuit 13 to form the fillets 12 attached to the surface of the circuit 13 and the side surface of the lead 2, respectively, so that the joint strength of the lead 2 to the semiconductor mounting substrate 1 is increased. Can get higher.

[0004]

The fillet 12 is formed by the molten eutectic alloy wetting the surface of the circuit 13 and the side surface of the lead 2, respectively. When the eutectic alloy has good wettability, the fillet 12 shown in FIG. The fillet 12 can be brought into close contact with the circuit 13 and the lead 2 as shown in FIG. However, if the heat transfer from the heating tool 14 to the joint is slow, Sn oxidizes before the Au—Sn eutectic is formed, and the wettability of the Au—Sn eutectic alloy deteriorates. When the wettability of the eutectic alloy is poor as described above, the fillet 12 cannot be brought into close contact with the circuit 13 and the lead 2 as shown in FIG. 6B, and high joint strength cannot be obtained.

Conventionally, no attempt has been made to improve the wettability of the eutectic alloy, and the current situation is that high joint strength cannot be obtained. The present invention has been made in view of the above points, and an object thereof is to bond leads with high bonding strength.

[0006]

According to the method for connecting a lead and a substrate according to the present invention, when the tip of the lead 2 is bonded to the semiconductor mounting substrate 1 by thermocompression bonding, the thermal conductivity in the bonding direction of the lead 2 is obtained. It is characterized by increasing the temperature and heating. In the present invention, the thermal conductivity in the joining direction of the lead 2 can be enhanced by forming the tip portion of the lead 2 thin in the joining direction.

Further, in the present invention, the groove 3 is provided in the joint surface of the lead 2 to enhance the thermal conductivity in the joint direction of the lead 2. Further, in the present invention, by forming the concave step portion 4 on the joint surface of the lead 2, it is possible to enhance the thermal conductivity in the joint direction of the lead 2. Further, in the present invention, the width of the tip portion of the lead 2 is reduced to form the narrow portion 5, so that the thermal conductivity in the joining direction of the lead 2 can be enhanced.

Further, in the present invention, in the lead 2 in which the width of the tip end portion is narrowed to form the narrow width portion 5 as described above, the base portion of the narrow width portion 5 is widened to form the wide width portion 6. Preferably. Further, in the present invention, when the plurality of leads 2 having the wide portions 6 formed as described above are bonded to the semiconductor mounting substrate 1, the adjacent wide portions 6 of the wide portions 6 are displaced in the longitudinal direction of the leads 2. It is preferable to arrange each lead 2.

Further, in the present invention, by forming the slit 7 on the side surface of the tip of the lead 2, the lead 2
The thermal conductivity in the joining direction can be increased. Further, in the present invention, by forming the tapered notches 8 at both ends of the bonding surface of the lead 2, it is possible to enhance the thermal conductivity of the lead 2 in the bonding direction.

Further, in the present invention, by covering the outer surface of the tip portion of the lead 2 with the good thermal conductor 9, it is possible to enhance the thermal conductivity in the joining direction of the lead 2.

[0011]

When the tip of the lead 2 is joined to the semiconductor mounting substrate 1 by thermocompression bonding, the heat from the heating tool 14 is conducted by increasing the heat conductivity in the joining direction of the lead 2 for heating. It is possible to quickly transmit to the bonding surface through the lead 2 having improved wettability, and to form a eutectic before the brazing material metal is oxidized to form a fillet with a eutectic metal having good wettability.

[0012]

EXAMPLES The present invention will be described in detail below with reference to examples. The semiconductor mounting substrate 1 is made of a laminated plate of modified polyimide resin or the like. The semiconductor chip mounting portion is formed in the central portion and the circumference of the surface of the semiconductor mounting substrate 1 surrounds the semiconductor chip mounting portion. A large number of circuits 13 are formed of copper foil or the like at the ends as shown in FIGS. The surface of the circuit 13 is nickel-plated and the surface thereof is further gold-plated.

On the other hand, the lead 2 is formed of, for example, a 42 alloy as an outer lead by a lead frame or the like, and at least the joint surface of the tip portion thereof is plated with tin. The lead 2 is connected to the semiconductor mounting substrate 1
When thermocompression-bonding to the circuit 13 of FIG. 5, the tip portion of the lead 2 is overlaid on the circuit 13 and the above-described FIG.
As shown in (b), the upper surface of the lead 2 is pressed and heated by the heating tool 14 formed of titanium, molybdenum, or the like. For example, the heating temperature (the temperature of the contact portion of the tool 14) is set to 350 ° C., the energization time (temperature holding time) to the tool 14 is set to 2 seconds, and the pressure applied to each lead 2 is set to 150 gf to perform thermocompression bonding. You can When the tip end of the lead 2 is overlapped with the circuit 13 and thermocompression bonded in this way,
As described above, the tin and gold plated on the surfaces of the leads 2 and the circuit 13 are melted into an Au-Sn eutectic alloy, and the Au-Sn eutectic alloy serves as a bonding layer to form the circuit 13.
The lead 2 can be joined to. Thus, the tin and gold plated on the surfaces of the leads 2 and the circuit 13 are bonded as the brazing material, but the brazing material is not limited to the tin or gold.

By thus joining the lead 2 to the semiconductor mounting substrate 1, the semiconductor chip 15 mounted on the semiconductor mounting substrate 1 as shown in FIG. 4 is electrically connected to the lead 2 via the wire 16 and the circuit 3. The connected semiconductor device A can be manufactured, and the product can be finished by resin-sealing it. FIG. 1 shows an embodiment of the present invention, in which the surface (upper surface) opposite to the bonding surface of the lead 2 is removed by half etching or the like to form a thin portion 17 at the tip of the lead 2. I am doing it. The means for forming the thin portion 17 is not limited to half-etching, and is arbitrary, and its size and shape are not particularly limited. And FIG. 1 (a)
As shown in FIG.
By stacking on 3 and thermocompression bonding with a heating tool 14, tin and gold plated on the leads 2 and the circuit 13 are Au-S.
The n-eutectic alloy melts and the Au-Sn eutectic alloy allows the leads 2 to be joined to the circuit 13 as shown in FIG. 1B.

In the thermocompression bonding as described above, since the tip portion of the lead 2 is thin in the joining direction due to the thin portion 17, the distance from the tip of the heating tool 14 to the joining surface becomes short. The thermal conductivity becomes high, and the heat conduction from the heating tool 14 to the bonding interface becomes fast. Moreover, by making the thickness thinner, the heat capacity of the tip portion of the lead 2 becomes smaller and the temperature rises faster. As described above, even if the lead 2 is made of a material having a low thermal conductivity such as 42 alloy, the thin portion 17 allows the heat from the heating tool 14 to be conducted quickly and the temperature rises quickly. The Au-Sn eutectic crystal can be quickly formed before the oxide is oxidized, and the wettability of the Au-Sn eutectic alloy can be improved. Therefore, the fillet 12 as shown in FIG. 6A has good wettability with respect to the surface of the circuit 13 and the side surface of the lead 2.
And the fillet 12 is closely attached to the circuit 13 and the lead 2 to form the lead 2 with respect to the semiconductor mounting substrate 1.
It is possible to obtain a high bonding strength.

When the thin portion 17 is formed on the lead 2 and joined to the semiconductor mounting substrate 1, the lead portion 2 is joined with the base portion of the thin portion 17 extending outward from the edge of the semiconductor mounting substrate 1 as shown in FIG. As a result, the thickness of the edge portion (indicated by the arrow) where the bending stress is concentrated on the lead 2 becomes thin, and there is a possibility that the portion easily bends and breaks. For this reason, as shown in FIG.
It is preferable to join the leads 2 so that the base of the above is inside the edge of the semiconductor mounting substrate 1.

FIG. 7 shows an embodiment in which the groove 3 is provided in the joint surface of the lead 2, and in the embodiment of FIG. 7 (a), the joint surface at the tip of the lead 2 is formed in the width direction. A plurality of grooves 3 are provided in parallel. The tip of the lead 2 is placed on the circuit 13 of the semiconductor mounting substrate 1 so that the heating tool 1
By heating and pressure bonding at 4, the lead 2 and the circuit 13
The tin and gold plated to form the Au-Sn eutectic alloy melts, and the lead 2 can be joined to the circuit 13 by the Au-Sn eutectic alloy. When thermocompression bonding is performed in this way, the heat capacity of the tip portion of the lead 2 is reduced due to the formation of the groove 3, and the heat from the heating tool 14 is quickly transmitted to increase the temperature rise. Therefore, the Au—Sn eutectic crystal can be quickly formed before tin is oxidized, and the wettability of the Au—Sn eutectic alloy can be improved, and the wettability of the surface of the circuit 13 and the side surface of the lead 2 can be improved. By forming a good fillet 12 as shown in FIG. 6A, the bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be increased. Further, by forming the groove 3 in the joint surface of the lead 2, the fillet 12 is also formed in the groove 3, so that the joint area by the fillet 12 is increased and the joint strength can be further improved. Is.

In the embodiment shown in FIG. 7B, the groove 3 is provided in the vicinity of the bonding surface of the tip of the lead 2 facing the edge of the semiconductor mounting substrate 1. Even in this case, the tip 2 of the lead 2 has a small heat capacity due to the formation of the groove 3 and the heat from the heating tool 14 is quickly transmitted to increase the temperature rapidly, so that the Au is quickly added before the tin is oxidized. A fillet 12 as shown in FIG. 6A, in which the -Sn eutectic can be formed to improve the wettability of the Au-Sn eutectic alloy and the wettability with respect to the surface of the circuit 13 and the side surface of the lead 2, can be improved. Is formed, the bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be increased. Further, as shown in FIG. 7B, a large fillet 12 is formed in the groove 3 at the edge portion of the semiconductor mounting substrate 1,
The peel strength of the lead 2 bonded to the semiconductor mounting substrate 1 can be increased.

In the embodiment shown in FIG. 7C, an inverted V-shaped groove 3 is provided in the vicinity of the bonding surface of the tip of the lead 2 facing the edge of the semiconductor mounting substrate 1. In this structure, a laser device is used, and the fillet 12 can be stably formed in the groove 3 by irradiating the groove 3 with laser light and heating. Since the groove 3 has an inverted V shape, the laser light is multiply reflected as shown by an arrow, and the fillet 12 can be formed by efficiently raising the temperature. Thus, since the fillet 12 having a large area is formed in the groove 3 at the edge portion of the semiconductor mounting substrate 1, the peel strength of the lead 2 bonded to the semiconductor mounting substrate 1 can be increased.

FIG. 8 shows an example in which the recessed step portion 4 is provided on the joint surface of the lead 2 so that the lower surface of the recessed step portion 4 is formed on the semiconductor mounting substrate 1 as shown in FIG. 8A. By contacting the surface of the circuit 13 and the step surface 4a of the recessed step portion 4 with the side end surface of the semiconductor mounting substrate 1 and heating and pressure bonding with the heating tool 14, the lead 2 and the tin and gold of the circuit 13 are separated. Au
It becomes a -Sn eutectic alloy and melts, and the lead 2 can be bonded to the circuit 13 by this Au-Sn eutectic alloy. When thermocompression bonding is performed in this manner, the tip end of the lead 2 has a thin thickness in the joining direction due to the concave step portion 4, so that the thermal conductivity is high and the heat is quickly transferred from the heating tool 14 to the joining interface. Moreover, since the thickness is thin, the heat capacity of the tip portion of the lead 2 becomes small, and the temperature rises quickly. Therefore, it is necessary to quickly increase the Au before tin is oxidized.
A fillet 12 as shown in FIG. 6A, which is capable of forming a --Sn eutectic and has good wettability of the Au--Sn eutectic alloy and good wettability with respect to the surface of the circuit 13 and the side surface of the lead 2. The bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be obtained by forming the same.

In the embodiment shown in FIG. 8B, the semiconductor mounting board 1 is used.
A concave step portion 18 is also provided on the edge portion of the lead 2 and the base of the concave step portion 4 of the lead 2 is fitted into the concave step portion 18 so that the lead 2 is bonded to the semiconductor mounting substrate 1 by thermocompression bonding. is there. In the embodiment of FIG. 8A, when a force as indicated by an arrow is applied to the lead 2 at the edge portion of the semiconductor mounting substrate 1, a shearing force acts on the thin portion of the base of the recessed step portion 4, Although it is weak against shearing force,
In the case of (b), the shearing force acts on the thick portion of the lead 2 and becomes stronger against the shearing force.

In the embodiment shown in FIG. 9, the width of the tip portion of the lead 2 is narrowed to form the narrow portion 5. Lead 2
Any means for narrowing the width of the tip end portion of the device can be used, and its size and shape are not particularly limited. Then, the tip end of the lead 2 is overlapped with the circuit 13 of the semiconductor mounting substrate 1 and thermocompression-bonded by the heating tool 14, whereby the tin and gold plated on the lead 2 and the circuit 13 become an Au—Sn eutectic alloy and melt. , With this Au-Sn eutectic alloy, circuit 13
The lead 2 can be joined to. In the thermocompression bonding as described above, the heat capacity is reduced by forming the narrow end portion 5 of the lead 2 to reduce the heat capacity.
The heat from the heat is quickly transmitted and the temperature rises faster. Therefore, the Au—Sn eutectic crystal can be quickly formed before tin is oxidized, and the wettability of the Au—Sn eutectic alloy can be improved, and the wettability of the surface of the circuit 13 and the side surface of the lead 2 can be improved. By forming a good fillet 12 as shown in FIG. 6A, the bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be increased.

In forming the narrow portion 5 by narrowing the width of the tip portion of the lead 2 as described above, in the embodiment of FIG. 10, the wide portion wider than the width of the lead 2 is formed at the base of the narrow portion 5. 6
Is provided. The means for providing the wide portion 6 is arbitrary, and its size and shape are not particularly limited. In this embodiment, the wide portion 6 is brought into contact with the surface of the circuit 13 at the edge portion of the semiconductor mounting substrate 1,
The tip of the lead 2 is placed on the surface of the circuit 13, and the lead 2 is joined by thermocompression bonding with a heating tool 14. In this structure, the joining strength of the lead 2 can be increased as described above by forming the leading end portion of the lead 2 into the narrow portion 5, but the base portion of the narrow portion 5 becomes the wide portion 6. Since the semiconductor mounting substrate 1 is connected to the circuit 13 with the lead 2,
The bonding area is increased, and the peel strength of the lead 2 bonded to the semiconductor mounting substrate 1 can be improved.

When a plurality of leads 2 formed by providing the wide portion 6 as described above are bonded to the semiconductor mounting substrate 1,
As shown in FIG. 1 (b), the wide portions 6 of the leads 2 adjacent to each other are close to each other, and there is a risk of short-circuiting between the leads 2. Therefore, in this case, as shown in FIG. 11A, the wide portions 6 of the adjacent leads 2 are arranged in a staggered manner so that the wide portions 6 are displaced in the longitudinal direction of the leads 2, and the wide portions of the adjacent leads 2 are arranged. 6 are not close to each other to prevent a short circuit between the leads 2.

FIG. 12 shows an example in which the slit 7 is formed on the side surface of the tip of the lead 2.
In the embodiment (a), the slits 7 are formed by notching both sides of the lead 2 in the V shape in the vicinity of the edge portion of the semiconductor mounting substrate 1. The means for forming the slit is arbitrary, and its size and shape are not particularly limited. Then, the tip end of the lead 2 is overlapped with the circuit 13 of the semiconductor mounting substrate 1 and thermocompression-bonded by the heating tool 14, whereby the tin and gold plated on the lead 2 and the circuit 13 become an Au—Sn eutectic alloy and melt. The lead 2 can be joined to the circuit 13 by this Au—Sn eutectic alloy. In thermocompression bonding like this,
Since the slit 7 is provided on the side surface of the tip of the lead 2 to reduce the heat capacity, the slit 7 can reduce the escape of heat through the lead 2, and the heat from the heating tool 14 can be quickly transferred to the joint surface. The temperature rises faster. Therefore, the Au—Sn eutectic crystal can be quickly formed before tin is oxidized, and the wettability of the Au—Sn eutectic alloy can be improved, and the wettability of the surface of the circuit 13 and the side surface of the lead 2 can be improved. By forming a good fillet 12 as shown in FIG. 6A, the bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be increased. In addition, a fillet 12 having a large area is formed in the slits 7 provided on both side surfaces of the lead 2 in the vicinity of the edge portion of the semiconductor mounting substrate 1, so that the lead 2 bonded to the semiconductor mounting substrate 1 is formed. The peel strength can be increased.

In the embodiment shown in FIG. 12B, a large number of slits 7 are formed on both side surfaces of the tip of the lead 2. Also in this embodiment, the provision of the slit 7 reduces the heat capacity of the tip portion of the lead 2,
Further, the slit 7 can reduce the escape of heat through the lead 2, the heat from the heating tool 14 is quickly transmitted to the joint surface, and the temperature rises quickly, so that the Au-Sn can be rapidly cooled before the tin is oxidized. A eutectic crystal can be formed to improve the wettability of the Au—Sn eutectic alloy, and the wettability of the surface of the circuit 13 and the side surface of the lead 2 is excellent.
By forming the fillet 12 as described above, the bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be increased. Further, since the fillets 12 are formed in the multiple slits 7, respectively, the total area of the fillets 12 is increased, and the peel strength of the leads 2 bonded to the semiconductor mounting substrate 1 can be increased.

In the embodiment shown in FIG. 13, tapered notches 8 are formed at both ends of the joint surface of the tip of the lead 2. The means for forming the tapered notch portion 8 is arbitrary, and its size and shape are not particularly limited. Then, the tip end of the lead 2 is placed on the circuit 13 of the semiconductor mounting substrate 1 and is thermocompression bonded by the heating tool 14, so that the tin and gold plated on the lead 2 and the circuit 13 are Au-.
The Sn eutectic alloy is melted and melted, and the lead 2 can be joined to the circuit 13 by this Au—Sn eutectic alloy.
When the thermocompression bonding is performed as described above, the heat capacity of the tip portion of the lead 2 is reduced by providing the tapered notch portion 8, and the heat from the heating tool 14 is quickly transferred to the joint surface to accelerate the temperature rise. Therefore, the Au—Sn eutectic crystal can be quickly formed before tin is oxidized, and the wettability of the Au—Sn eutectic alloy can be improved, and the wettability of the surface of the circuit 13 and the side surface of the lead 2 can be improved. By forming a good fillet 12 as shown in FIG. 6A, the bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be increased. Further, since the tapered notch portions 8 provided at both ends of the joint surface of the lead 2 have inclined side surfaces, the fillet 12 is formed.
Since the wetting angle with and becomes easier, and the area of the fillet 12 becomes larger, the bonding strength of the lead 2 can be further increased. Further, if the tapered notch 8 is provided even near the edge of the semiconductor mounting substrate 1, the fillet 2 is formed in the tapered notch 8 so as to reach the vicinity of the edge of the semiconductor mounting substrate 1.
Can be formed, and the peel strength of the lead 2 joined to the semiconductor mounting substrate 1 can be increased.

In the embodiment shown in FIG. 14, the outer surface of the tip of the lead 2 is coated with a good thermal conductor 9. Good conductor 9
As the material, for example, copper can be used, and the good thermal conductor 9 can be formed by applying copper plating to a part or the whole of the outer surface of the lead 2 on four sides. Of course, the good thermal conductor 9 is not limited to copper, and the coating method is not limited to plating and may be arbitrary. In the embodiment of FIG. 14A, tin plating 19 is applied only to the joint surface of the lead 2 on the outer surface of the good thermal conductor 9.

In this structure, the tip of the lead 2 is placed on the circuit 13 of the semiconductor mounting substrate 1 and is thermocompression-bonded by the heating tool 14, so that the tin and gold plated on the lead 2 and the circuit 13 are Au--Sn. It becomes a eutectic alloy and melts, and the lead 2 can be bonded to the circuit 13 by this Au—Sn eutectic alloy. In this heat-press bonding, since the outer surface of the lead 2 is covered with the good thermal conductor 9, the heat of the heating tool 14 brought into contact with the upper surface of the lead 2 passes through the good thermal conductor 9 and the lower surface of the lead 2. It is rapidly transmitted to the joint surface of, and the temperature rise at the joint interface becomes faster. Therefore, the Au-Sn eutectic crystal is rapidly formed before tin is oxidized.
The wettability of the u-Sn eutectic alloy can be improved, and the wettability with respect to the surface of the circuit 13 and the side surface of the lead 2 is excellent. It is possible to obtain a high bonding strength of the lead 2 with respect to.

In the embodiment shown in FIGS. 14A and 14B, the lead 2 is used.
Although the tin plating 19 is applied only to the joint surface of FIG.
4B, tin plating 19 may be applied to the lower surface and both side surfaces of the lead 2 except for the upper surface which is the contact surface of the heating tool 14. If tin plating 19 is applied to the upper surface of the lead 2 which is the contact surface of the heating tool 14, tin oxide will adhere to the heating tool 14. Therefore, avoid applying the tin plating 19 to the upper surface of the lead 2. Good to do.

[0031]

As described above, according to the present invention, when the tip portions of the leads are bonded to the semiconductor mounting substrate by thermocompression bonding,
Since the heat is increased by increasing the thermal conductivity in the joining direction of the leads, the heat from the heating tool can be quickly transferred to the joining surface through the leads with improved thermal conductivity, and the brazing metal is oxidized. It is possible to form a eutectic before and form a fillet with a eutectic metal having good wettability.
The leads can be joined with high joining strength.

Further, in the present invention, since the thickness of the tip of the lead in the joining direction is formed thin, the thermal conductivity in the joining direction of the lead can be enhanced, and the eutectic metal having good wettability can be used. A fillet can be formed. Further, in the present invention, since the groove is provided in the joining surface of the lead, it is possible to enhance the thermal conductivity in the joining direction of the lead, and the fillet is made of a eutectic metal having good wettability. It can be formed.

Further, according to the present invention, since the recessed step portion is provided on the bonding surface of the lead, the heat conductivity in the bonding direction of the lead can be enhanced and the eutectic metal having good wettability can be obtained. A fillet can be formed with.
Further, in the present invention, since the width of the tip end portion of the lead is narrowed to form the narrow width portion, it is possible to enhance the thermal conductivity in the joining direction of the lead and the wettability is good. It is possible to form a fillet with a eutectic metal.

Further, in the present invention, when forming the narrow portion by narrowing the width of the tip portion of the lead as described above, the width of the base portion of the narrow portion is widened to form the wide portion. Therefore, the lead bonding area can be increased in the wide portion, and the peel strength of the lead bonded to the semiconductor mounting substrate can be improved. Further, in the present invention, when a plurality of leads having the wide portions formed as described above are bonded to the semiconductor mounting substrate, the adjacent leads are arranged such that the wide portions are displaced in the longitudinal direction of the leads. Therefore, it is possible to prevent the wide portions of the adjacent leads from coming close to each other, and it is possible to prevent a short circuit from occurring between the leads.

Further, in the present invention, since the slit is formed on the side surface of the tip portion of the lead, it is possible to enhance the thermal conductivity in the joining direction of the lead, and the eutectic having good wettability. The metal can form the fillet. Further, in the present invention, since the tapered notches are formed at both ends of the bonding surface of the lead, it is possible to enhance the thermal conductivity in the bonding direction of the lead and to improve the wettability. A crystal metal can form a fillet.

Furthermore, in the present invention, the outer surface of the tip of the lead is coated with a good thermal conductor, so that the thermal conductivity in the joining direction of the lead can be increased and the wettability is good. A crystal metal can form a fillet.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention (a),
(B) is a side view, respectively.

FIG. 2 is a side view of another aspect of the above embodiment.

FIG. 3 shows a semiconductor mounting substrate and leads,
(A) is a side view and (b) is a partial plan view.

FIG. 4 is a side view of a semiconductor device.

FIG. 5 shows a step of connecting leads by a heating tool, and (a) and (b) are side views, respectively.

FIG. 6 is a cross-sectional view showing a state of a fillet at a joint portion of a lead, in which (a) and (b) are enlarged views, respectively.

FIG. 7 shows another embodiment of the present invention, (a)
Each of (c) is a partial side view.

FIG. 8 shows still another embodiment of the present invention,
(A) and (b) are some side views, respectively.

FIG. 9 is a plan view of a part of still another embodiment of the present invention.

FIG. 10 is a partial plan view of still another embodiment of the present invention.

FIG. 11 shows still another embodiment of the present invention, in which (a) and (b) are partial plan views respectively.

FIG. 12 shows still another embodiment of the present invention, and (a) and (b) are partial plan views respectively.

FIG. 13 shows still another embodiment of the present invention, (a) is a partial front view and (b) is a partial side view.

FIG. 14 shows still another embodiment of the present invention, (a) is a partial front sectional view, (b) is a partial side view, and (c) is a partial view of another embodiment. It is a front sectional view.

[Explanation of symbols] 1 semiconductor mounting substrate 2 lead 3 groove 4 concave step portion 5 narrow portion 6 wide portion 7 slit 8 tapered notch portion 9 good thermal conductor

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[Procedure amendment]

[Submission date] April 18, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 6

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

The fillet 12 is formed by the molten eutectic alloy wetting the surface of the circuit 13 and the side surface of the lead 2, respectively. When the eutectic alloy has good wettability, the fillet 12 shown in FIG. The fillet 12 can be brought into close contact with the circuit 13 and the lead 2 as shown in FIG. However, if the heat transfer from the heating tool 14 to the joint is slow, Sn oxidizes before the Au—Sn eutectic is formed, and the Au—Sn eutectic hardly occurs, resulting in poor wettability . In such a case, the wettability is good as shown in FIG. 6 (b).
The fillet 12 is not formed , and high joint strength cannot be obtained.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

According to the method for connecting a lead and a substrate according to the present invention, when the tip portion of the lead 2 is joined to the semiconductor mounting substrate 1 by thermocompression bonding, the joining surface of the lead 2 is joined.
It is characterized by increasing the thermal conductivity in the direction and heating. In the present invention, the lead 2 is joined by forming the tip 2 of the lead 2 thin in the joining direction.
The thermal conductivity can be increased in the surface direction .

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Further, according to the present invention, in the lead 2 in which the width of the tip portion is narrowed to form the narrow portion 5 as described above, the width of the lead 2 near the edge portion of the semiconductor mounting substrate 1 is increased. It is preferable to form the wide portion 6. Further, in the present invention, when the plurality of leads 2 having the wide portions 6 formed as described above are bonded to the semiconductor mounting substrate 1, the adjacent wide portions 6 of the wide portions 6 are displaced in the longitudinal direction of the leads 2. It is preferable to arrange each lead 2.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

Further, in the present invention, by forming the slit 7 on the side surface of the tip of the lead 2, the lead 2
It is possible to increase the thermal conductivity in the joint surface direction . Further, in the present invention, by forming the tapered notches 8 at both ends of the joint surface of the lead 2, it is possible to enhance the thermal conductivity in the joint surface direction of the lead 2.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Further, in the present invention, by covering the outer surface of the tip portion of the lead 2 with the good thermal conductor 9 , the thermal conductivity can be enhanced in the joint surface direction of the lead 2.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

When the tips of the leads 2 are bonded to the semiconductor mounting substrate 1 by thermocompression bonding, the heat from the heating tool 14 is transferred by increasing the thermal conductivity in the bonding surface direction of the leads 2 and heating. It is possible to quickly transmit to the bonding surface through the lead 2 having improved wettability, and to form a eutectic before the brazing material metal is oxidized to form a fillet with a eutectic metal having good wettability.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

In forming the narrow portion 5 by narrowing the width of the tip portion of the lead 2 as described above, in the embodiment of FIG. 10, the width of the lead 2 is closer to the edge portion of the semiconductor mounting substrate 1 than the width of the lead 2. A wide wide portion 6 is provided. Wide part 6
The means for providing is optional, and its size and shape are not particularly limited. In this embodiment, the tip end of the lead 2 is placed on the surface of the circuit 13 so that the wide portion 6 is brought into contact with the surface of the circuit 13 at the edge portion of the semiconductor mounting substrate 1, and is heated and pressure-bonded by the heating tool 14. By doing so, the lead 2 is joined. In this structure, the joining strength of the lead 2 can be increased as described above by forming the leading end portion of the lead 2 into the narrow portion 5, but the base portion of the narrow portion 5 becomes the wide portion 6. Since the lead 2 is joined to the circuit 13 by the circuit 13, the joining area of the lead 2 is large at the edge portion of the semiconductor mounting substrate 1, and the peel strength of the lead 2 joined to the semiconductor mounting substrate 1 can be improved. is there.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

In the embodiment shown in FIG. 12B, a large number of slits 7 are formed on both side surfaces of the tip of the lead 2. Also in this embodiment, the provision of the slit 7 reduces the heat capacity of the tip portion of the lead 2,
Further, the slit 7 can reduce the escape of heat through the lead 2, the heat from the heating tool 14 is quickly transmitted to the joint surface, and the temperature rises quickly, so that the Au-Sn can be rapidly cooled before the tin is oxidized. A eutectic crystal can be formed to improve the wettability of the Au—Sn eutectic alloy, and the wettability of the surface of the circuit 13 and the side surface of the lead 2 is excellent.
By forming the fillet 12 as described above, the bonding strength of the lead 2 to the semiconductor mounting substrate 1 can be increased. Further, since the fillet 12 is formed in each of the large number of slits 7, the total area of the fillet 12 becomes large, and the contact of the lead 2 bonded to the semiconductor mounting substrate 1 becomes large.
The total strength can be increased.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

[0031]

As described above, according to the present invention, when the tip portions of the leads are bonded to the semiconductor mounting substrate by thermocompression bonding,
Since the heat conductivity is increased in the direction of the joint surface of the lead for heating, the heat from the heating tool can be quickly transferred to the joint surface through the lead with improved thermal conductivity, and the brazing metal is oxidized. It is possible to form a eutectic before and form a fillet with a eutectic metal having good wettability.
The leads can be joined with high joining strength.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

Further, according to the present invention, since the thickness of the tip portion of the lead in the joining direction is formed thin, the joining of the leads is performed.
The fillet can be formed of a eutectic metal having good wettability, which can increase the thermal conductivity in the surface direction . Further, in the present invention, since the groove is provided as a recess on the bonding surface of the lead, it is possible to enhance the thermal conductivity in the bonding surface direction of the lead, and the fillet is formed of a eutectic metal having good wettability. It can be formed.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

Further, according to the present invention, since the recessed step portion is provided in the joining surface of the lead, it is possible to enhance the heat conductivity in the joining surface direction of the lead, and the eutectic metal having good wettability. A fillet can be formed with.
Further, in the present invention, since the width of the tip end portion of the lead is narrowed to form the narrow width portion, it is possible to enhance the thermal conductivity in the bonding surface direction of the lead. The fillet can be formed of a eutectic metal having good wettability.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

Further, in the present invention, in forming the narrow portion by narrowing the width of the tip portion of the lead as described above, the lead width near the edge portion of the semiconductor mounting substrate is widened to form the wide portion. Since it is formed, the bonding area of the lead can be increased in the wide portion, and the peel strength of the lead bonded to the semiconductor mounting substrate can be improved. Further, in the present invention, when a plurality of leads having the wide portions formed as described above are bonded to the semiconductor mounting substrate, the adjacent leads are arranged such that the wide portions are displaced in the longitudinal direction of the leads. Because I chose
It is possible to prevent the wide portions of adjacent leads from coming close to each other, and to prevent a short circuit from occurring between the leads.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Further, according to the present invention, since the slit is formed on the side surface of the tip portion of the lead, it is possible to enhance the thermal conductivity in the direction of the joint surface of the lead, and the eutectic having good wettability. The metal can form the fillet. Further, in the present invention, since the tapered notches are formed at both ends of the bonding surface of the lead, it is possible to enhance the thermal conductivity in the bonding surface direction of the lead, and to improve the wettability. A crystal metal can form a fillet.

[Procedure Amendment 16]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Further, in the present invention, the outer surface of the tip of the lead is coated with a good thermal conductor, so that the thermal conductivity can be enhanced in the direction of the joint surface of the lead, and the good wettability can be obtained. A crystal metal can form a fillet.

[Procedure Amendment 17]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

Claims (10)

[Claims] 1. A method for joining a lead and a substrate, which comprises heating the tip of a lead to a semiconductor mounting substrate by thermocompression bonding to enhance the thermal conductivity in the joining direction of the lead. 2. The method for joining a lead and a substrate according to claim 1, wherein the thickness of the tip of the lead in the joining direction is formed thin. 3. The method for joining a lead and a substrate according to claim 1, wherein a groove is provided in the joining surface of the lead. 4. The method for joining a lead and a substrate according to claim 1, wherein a concave step portion is provided on the joining surface of the lead. 5. The method for joining a lead and a substrate according to claim 1, wherein the width of the tip of the lead is narrowed to form a narrow portion. 6. The lead and the substrate according to claim 5, wherein the width of the base portion of the narrow portion is widened to form the wide portion in the lead having the narrowed width at the tip portion to form the narrow portion. How to join. 7. When joining a plurality of leads having the wide portion of claim 6 to a semiconductor mounting substrate, adjacent leads are arranged such that the wide portions are displaced in the longitudinal direction of the lead. And the method of joining the lead and substrate. 8. The method for joining a lead and a substrate according to claim 1, wherein a slit is formed on the side surface of the tip of the lead. 9. The method for joining a lead and a substrate according to claim 1, wherein tapered notches are formed at both ends of the joining surface of the lead. 10. The method for joining a lead and a substrate according to claim 1, wherein the outer surface of the tip portion of the lead is coated with a good thermal conductor.