JPS61194158A - Production of lead frame material for semiconductor - Google Patents

Abstract

PURPOSE:To obtain a lead frame for a semiconductor having high strength, good repetitive bending characteristic and high heat resistance by subjecting a specifically composed copper alloy casting ingot to controlled cooling after hot rolling then to temper finish rolling after the cycle of cold cooling and annealing followed further by a short period of annealing. CONSTITUTION:The copper alloy contg. 1.0-3.5wt% Ni, 0.2-0.9% Si, 0.02-1.0% Mn, 0.1-5.0% Zn, 0.001-0.01% Mg and further 0.001-0.01>=1 kinds among Cr, Ti and Zr is cast. The casting ingot thereof is hot rolled and is then cooled at >=5 deg.C/sec rate from >=600 deg.C. The hot rolled sheet is subjected to >=30% cold working, then to annealing for 1-10hr at 300-600 deg.C. Such stage is repeated >=2 times. The worked material is then subjected to annealing for a short period of 5-60sec at 300-600 deg.C after temper finish rolling. The material formed in such a manner has the excellent electrical conductivity of >=60% IACS and has the excellent stiffness strength and repetitive bending characteristic.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a method for manufacturing lead frame materials for semiconductors such as ICs and LSIs. The present invention relates to a method for manufacturing lead frame materials for semiconductors that have excellent strength, repeated bendability, and heat resistance.

[Prior Art 1 In general, lead frame materials for semiconductors have been made of Fe, which has a coefficient of linear expansion similar to that of elements and ceramics.
A 42 wt% Ni alloy has been used.

However, in recent years, with improvements in device bonding technology and sealing materials, Cu, which has excellent heat dissipation properties and is relatively inexpensive, has been developed.
- ICs that are being replaced by materials such as Ni-8i alloy, but require high reliability.

As a lead frame material for semiconductors such as LSI, copper-based materials that can satisfy the excellent electrical conductivity and the excellent strength, repeated bendability, and heat resistance of Fe-42wt%Ni alloy have been sufficiently developed. In addition, IC, LSI
In order to improve the efficiency of heat dissipation from the lead frame material itself,
It is difficult to satisfy the high demand for electrical conductivity of 60% lAC3 or more using the conventional manufacturing method of the Cu-Ni-8i alloy.

[Problems to be Solved by the Invention] The present invention has been made in order to solve the numerous problems in the conventional lead frame materials for semiconductors as explained above. The rate is 6
0%lAC3 or more, and has the high strength, good repeated bending property, and high heat resistance that Fe-42wt%Ni alloy has as a lead frame material for semiconductors, and also has corrosion resistance and stress corrosion resistance. We have developed a method for manufacturing lead frame materials for semiconductors that have excellent crackability, solderability, and peeling resistance after heating of plated tin and solder.

[Means for Solving the Problems] The method for manufacturing a semiconductor lead frame material according to the present invention is characterized by: Ni 1.0 to 3.5 wt%, Si 0.2 to 0.9 u+
L%, Mn 0.02-1.0wt%, Zn 0.1-
5.0 wt%, Mg 0.001-0.01 wt%, and further contains 0.001-0.01 wt% of one or more selected from Cr, Ti, and Zr, with the remainder being substantially After hot-rolling a copper alloy ingot consisting of Cu, it is cooled at a rate of 5°C/second or more from a temperature of 600°C or higher, and then cold-worked by 30% or more.
After repeating the process of annealing for 1 to 10 hours at a temperature of 00 to 600°C twice or more, heat-finish rolling is performed, and then annealing for 5 to 60 hours at a temperature of 300 to 600°C is performed.
The purpose is to perform short-time annealing of seconds. The method for manufacturing a semiconductor lead frame material according to the present invention will be described in detail below.

First, the components and component ratios of the copper alloy used in the method for manufacturing a semiconductor lead frame material according to the present invention will be explained.

Ni is an element that imparts the effect of improving strength, and when the content is less than 1.0 wt%, the Si content is 0.2 to 0.9 wt%.
Even if Ni is contained within the range of
The content is 1.0 to 3.5 wt%.

Si is an element that contributes to improving strength, and the content is 0.2
If the Ni content is less than 0.9 wt%, no improvement in strength can be expected even if the Ni content is in the range of 1.0-3.5 wt%, and furthermore, high conductivity cannot be achieved.
If the content exceeds t%, processability and conductivity will decrease, and in addition, soldering properties will also decrease.

Therefore, the Si content is set to 0.2 to 0.9 wt%.

Mn is an element that has a cleaning effect on molten metal and improves hot workability.If the content is less than 0.2wt%, improvement in hot workability cannot be expected, and if the content exceeds 1.0wt%, If it is contained, conductivity and solder wettability are likely to deteriorate. Therefore, the Mn content is set to 0.02 to 1.0 wt%.

Zn is an essential element for improving the peeling resistance of plating tin and solder after heating. If the content is less than 0.1 wt%, this effect will be small, and if the content exceeds 5.0 wt%, Soldering becomes less effective. Therefore, the Zn content is set to 0.1 to 5.0 wt%.

Mg is an essential element that fixes the mixed S in the matrix in the form of a stable compound with Mg and enables hot working, and S is stable when the content is less than 0,001 wt%. The M, S does not form any compound, and S exists as it is or in the form of MnS, and these S or MnS migrate to the grain boundaries during heating during hot rolling or during hot rolling, causing cracks. Moreover, if the content exceeds 0.01 wt%, a eutectic of Cu + M g Cu 2 (melting point 722°C) will occur in the ingot, and if heated to a temperature of 722°C or higher, cracks will occur. However, the molten metal oxidizes and the flowability of the metal deteriorates (I), making the ingot unsound. Therefore, the M8 content is set to 0.001 to 0.01 wt%.

One or more of Cr, Ti, and Zr are contained in order to prevent cracking during hot working, and the content is 0.
If the content is less than 0.001 wt%, cracking during hot working cannot be suppressed, and if the content exceeds 0.01 wt%, the molten metal is likely to oxidize, making it impossible to obtain a sound ingot. Therefore, the content of one or more of Cr, Ti, and Zr is set to 0.001 to 0.01 wt%.

Next, a method for processing a copper alloy in the method for manufacturing a semiconductor lead frame material according to the present invention will be described.

After hot rolling a copper alloy ingot with the ingredients and proportions explained above, it is heated to 5℃ from a temperature of 600℃ or higher.
Cooling at a rate of 1/sec or more is for the purpose of solution treatment, and when cooling from a temperature below 600°C, even if the cooling rate is 5°C/sec or more, it is necessary to cool before starting cooling. Precipitation has already occurred and sufficient solution treatment effect cannot be obtained.
Further, even when cooling from a temperature of 600°C or higher, precipitation occurs during cooling if the cooling rate is less than 5°C/sec, and a sufficient solution treatment effect cannot be obtained. It worsens subsequent cold workability. Therefore, after hot rolling, the copper alloy ingot is cooled from a temperature of 600°C or less at a cooling rate of 5°C/second or more.

Next, after 30% or more cold working, 300~600
Annealing for 1 to 10 hours at a temperature of
This is to precipitate Ni and Si compounds. At temperatures below 300°C, precipitation of Ni and Si compounds is insufficient even if annealing is performed for 1 to 10 hours, and at temperatures above 600°C, precipitation does not occur. Most of Ni and Si remain in solid solution, and in any case, the solid solution of NiB and Si seriously reduces the peeling resistance of plated tin and solder at a temperature of 150°C, so the annealing temperature is set at 300° C. The annealing time must be 600°C, and annealing time of less than 1 hour is insufficient, and even if it exceeds 10 hours, precipitation will not proceed any further and is uneconomical, so the annealing time is set to 1 to 10 hours.

Cold working before annealing has the effect of promoting precipitation due to strain energy introduced by cold working, and a cold working ratio of 30% or more is required to obtain this effect.

The reason why the above-described cold working and annealing steps are performed two or more times is because Ni remains in solid solution and cannot be precipitated in one step.
This is to precipitate , Si as a Ni, Si compound, and the precipitation will normally proceed sufficiently by repeating the process 2 to 3 times.

Furthermore, after performing temper finish rolling, 300 to 600
The reason for performing short-time annealing at a temperature of 300°C for 5 to 60 seconds is to recover the elongation decreased by rolling, reduce residual stress, and equalize the stress.
At temperatures below 600°C, even if annealing is performed for 5 to 60 seconds, this effect is insufficient, and at temperatures above 600°C, the precipitated Ni and Si compounds re-dissolve, resulting in the required conductivity. The annealing temperature needs to be 300 to 600°C, since the properties and peeling resistance of the solder after heating will deteriorate.
Furthermore, if the annealing time is less than 5 seconds, the effects of elongation recovery, residual stress reduction, and stress uniformity will be insufficient, and furthermore, such heat treatment is carried out on a continuous heat treatment line. If the annealing time exceeds 2 seconds, the productivity decreases and becomes uneconomical, so the annealing time is set to 5 to 60 seconds.

[Example 1] An example of the method for manufacturing a semiconductor lead frame material according to the present invention will be described.

Example A copper alloy having the ingredients and proportions shown in Table 1 was melted in the atmosphere under charcoal coating using a Kryptor melting furnace, and then melted in a cast iron book mold to a thickness of 45 mm x width of 80 mm. After casting an ingot with a length of 200 cm, the front and back sides of this ingot were hardened by 2.5 m, and then hot rolled to a thickness of 10 mm at a temperature of 880°C, and then heated to a temperature of 600°C or higher. After cooling with water at a rate of 30°C/sec from a temperature of
The first annealing was performed for 5 hours at a temperature of
After cold rolling to 5 m11, a second annealing was further performed at a temperature of 450° C. for 5 hours. Thereafter, it was cold rolled into a plate having a thickness of 0.2511 Im, and was annealed for a short period of 20 seconds at a temperature of 425° C. using a saltpetre furnace.

The comparative example (conventional material) was hot-rolled to a thickness of 10 mm at a temperature of 880°C, and then rolled to a thickness of 30°C/30°C from a temperature of 600°C or higher.
After water cooling at a cooling rate of seconds, the scale is removed and the thickness is 0.
．． Cold rolled to a thickness of 5 mm, annealed at 500°C for 2 hours, and then cold rolled to a thickness of 0.2 mm.
511 II 11 plate materials were manufactured and 50
Short-time annealing was performed at a temperature of 0° C. for 20 seconds.

The following tests were conducted on the samples produced in this way.

(1) Electrical conductivity was calculated by the average cross-sectional area method using a double bridge.

(2) The tensile test was conducted using JIS13 cut parallel to the rolling direction.
No. test piece All test pieces Hardness was measured using a micro Vickers hardness tester.

These test results are shown in Table 2. Cases based on the manufacturing method of semiconductor lead frames according to the present invention are designated as 1-1 and 2-1 in Table 2, and comparative examples are designated as 1-2 and 2-1 in Table 2. It is shown as 2-2.

As is clear from Table 2, 1-1 and 2-1 of the method for manufacturing a lead frame material for semiconductors according to the present invention have overall excellent performance as a lead frame material for semiconductors, Furthermore, it can be seen that the results are superior to Comparative Examples 1-2 and 2-2, as explained below.

In other words, since 1-1 and 2-1 are subjected to cold working and annealing twice, Ni
, the precipitation of Si compounds is promoted, the electrical conductivity is improved, and other properties are the same.

■Effect of the invention 1 As explained above, since the method for manufacturing a semiconductor lead frame material according to the present invention has the above configuration, it has an excellent electrical conductivity of 60%lAC3 or more, Furthermore, it has the effect that it is possible to manufacture a lead frame material that has high strength, excellent stiffness strength, and repeated bendability, and has high heat resistance.

Procedural amendment (voluntary) November 12, 1985 Patent application No. 033554 2, Title of invention: For semiconductor use - Method for manufacturing Y frame material 3, Relationship with the case by the person making the amendment Address of the patent applicant 1-3-18 Wakihama-cho, Chuo-ku, Kobe Name (1)
19) Kobe Steel Co., Ltd. Representative: Fuyuhiko Maki 4, Agent Address: 901-6, Fujiwazukayo-cho Co-op, 2-2-15 Minamisuna, Koto-ku, Tokyo, Subject of Amendment (1) Details of the invention in the specification Explanation column 7, Contents of correction (1) [Lead frame material itself] in lines 2 and 3 on page 3 of the specification is corrected to "lead frame material."

(2) "Plated tin" on page 3, line 15 of the specification is corrected to "plated tin."

(3) In page 5, line 7 of the specification, "contributes to..." is amended to "gives...".

(4) In page 5, line 20 of the specification, [...plated tin...] is corrected to [...plated tin...].

(5) "...60" from page 7, line 20 to page 8, line 1 of the specification
0℃ or less...'' is corrected to ``600℃ or more...''.

Claims (1)

[Claims] Ni 1.0 to 3.5 wt%, Si 0.2 to 0.9 wt%
, Mn0.02-1.0wt%, Zn0.1-5.0w
t%, Mg0.001-0.01wt%, and further contains 0.001-0.01wt% of one or more selected from Cr, Ti, and Zr, and the remainder is substantially Cu. After hot-rolling a copper alloy ingot consisting of
After repeating the process of annealing for 1 to 10 hours at a temperature of 0 to 600°C twice or more, heat-finish rolling is performed, and then short-time annealing for 5 to 60 seconds at a temperature of 300 to 600°C. A method for manufacturing a lead frame material for semiconductors, characterized by performing the following steps.