JPS5950222B2 - Lead material for semiconductors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides transistors and I
The present invention relates to lead materials for semiconductors such as C.

Conventionally, in general, semiconductors such as ICs are manufactured by (a) first forming a lead material made of a Cu alloy strip with a plating layer of Ni, Sn, Ag, or their alloys formed on the surface by press punching; , mold a lead frame that conforms to the shape of the semiconductor to be manufactured, and (b) then sequentially plate semiconductor elements such as high purity Si or Ge at predetermined locations on the lead frame at a temperature of about 300 to 450°C. (c) applying connections for collector and emitter across the semiconductor element and the lead frame; (d) subsequently bonding the semiconductor element, the connections, and the semiconductor element of the lead frame; Manufactured by the main steps (a) to (e) above, in which the mounting portion is coated with resin, and (e) the interconnected parts of the lead frame are finally cut out to form a semiconductor having lead material. ing.

Therefore, the lead material used as a semiconductor lead material has good plating properties and press punching properties, heat softening resistance that does not cause thermal distortion and thermal softening when semiconductor elements are thermocompression bonded at about 300 to 450°C, and It will be required to have properties such as good heat dissipation and conductivity, and repeated bending resistance that will not cause damage when transporting semiconductors or incorporating them into electrical equipment.

However, the Cu alloy, which is currently in practical use as a lead material for semiconductors and has a composition consisting of Sn: 0.01 to 0.20% by weight, Cu, and the remainder of unavoidable pure matter, has poor plating properties and pressability. Although it has excellent punching properties, heat dissipation properties, repeated bending resistance, and electrical conductivity,
Since it softens at a temperature of 80°C, thermal softening and thermal strain are prevented during thermocompression bonding of semiconductor elements in the temperature range of approximately 300 to 450°C in the above step (b), especially during thermocompression bonding at the high temperature side of the temperature range. Therefore, the current situation is that it is subject to extremely severe restrictions in its manufacture and cannot exhibit satisfactory performance in its use.

Therefore, from the above-mentioned viewpoint, the inventors of the present invention have developed the above-mentioned Sn: 0.0, which is conventionally used as a lead material for semiconductors.
Focusing on the Cu content of 1 to 0.20% by weight, we conducted research to improve the heat softening resistance without impairing the properties of this conventional lead material.
When Zn: 0.20 to 1.0% is contained, the excellent plating properties, press punching properties, heat dissipation properties, and repeated bending resistance of the conventional Sn-containing lead materials are not impaired in any way. While maintaining the high electrical conductivity of 90% or more required for lead materials, there is no thermal distortion or thermal softening even when high temperatures in the temperature range of 300 to 450°C are applied during thermoelectrodeposition of semiconductor elements. They found that it is possible to obtain reed material that is completely free of generation.

Therefore, the present invention was made based on the above knowledge, and the present invention is based on the above-mentioned knowledge, and a semiconductor lead material having Sn: 0.0% by weight.
01-0.20%, Zn: 0.20-1.0%, Cu and unavoidable lower purity. The feature is that the composition consists of the following.

In the semiconductor lead material of the present invention, the Zn content is limited to 0.20 to 1.0% because if the Zn content is less than 0.20%, the desired improvement effect on heat softening resistance will not be achieved. This is based on the reason that if the content exceeds 1.0%, it becomes impossible to secure the electrical conductivity of 90% (IACS%) or more required for semiconductor lead materials.

Next, the semiconductor lead material of the present invention will be explained with reference to Examples.

Slabs each having the component composition shown in the attached table and having dimensions of 1500 mm in length x 380 mm in width x 160 mm in thickness were prepared, each of the slabs was hot rolled to a thickness of 12 mm, and one side of the slab was Face milling is performed on both sides by .5 mm, then cold rolling, intermediate annealing, and pickling are repeated, and finally cold rolling is performed at a processing rate of 15% to give a final plate thickness of 0.4 mm. Inventive alloy thin plates 1 to 9 and comparative alloy thin plates 1 to 6, which can be used as lead materials for semiconductor manufacturing, were manufactured, respectively.

Note that all of Comparative Alloy Thin Sheets 1 to 6 have Zn contents outside the range of the present invention.

The electrical conductivity and softening temperature of the invention alloys 1 to 9 and comparative alloys 1 to 6 thus obtained were measured, and the measurement results are shown in the attached table.

Regarding the softening temperature, the above alloy thin plate was heated and held at various temperatures for 1 hour, and the Vickers hardness of the alloy thin plate after heating was measured at each heating temperature. The heating temperature was defined as the softening temperature.

As is clear from the results shown in the attached table, Comparative alloy thin sheets 1, 3, and 3 whose Zn content was lower than the range of the present invention
Although No. 5 exhibits extremely high conductivity, its softening temperature is relatively low, so it completely prevents the occurrence of thermal distortion and thermal softening, especially when high temperatures must be applied during thermocompression bonding of semiconductor elements. It cannot be avoided.

Comparative alloys 2, 4, and 6, whose Zn content is higher than the range of the present invention, exhibit extremely high softening temperatures, but have a conductivity of 90% or more, which is required for semiconductor lead materials. I haven't. On the other hand, the thin alloy sheets 1 to 9 of the present invention, in which the Zn content is within the range of the present invention, all maintain a conductivity of 90% or more, which is required for semiconductor lead materials, and are significantly improved. It shows the softening temperature. As mentioned above, the semiconductor lead material of the present invention is
Compared to the above-mentioned conventional lead materials for semiconductors, it has superior heat softening resistance while maintaining high electrical conductivity.

Claims (1)

[Claims] 1. A lead material for a semiconductor having a composition consisting of 1 Sn: 0.01 to 0.20%, Cu and lower purity: the remainder, Zn: 0.
A lead material for a semiconductor, characterized in that it has improved heat softening resistance while maintaining high electrical conductivity by containing 20 to 1.0% (or more by weight).