JPH0441632A - High strength and high conductivity copper alloy for electronic equipment and its manufacture - Google Patents

Abstract

PURPOSE:To reduce the anisotropy of strength, electrical conductivity, heat resistance or the like in a high strength and high conductivity copper alloy by preparing a copper alloy contg. specified ratios of Cr and Sn. CONSTITUTION:An alloy ingot contg., by weight, >0.25 to l.0% Cr, >0.5 to <l.0% Sn, or contg., as auxiliary components, total 0.01 to 2.0% of one or more kinds selected from the group constituted of Be, Co, Fe, Hf, In and Zr and the balance Cu with inevitable impurities is subjected to hot and cold rolling into a sheet material, is thereafter heated at 900 to l000 deg.C for l to 120min, is cooled to <=400 deg.C at >=1 deg.C/sec cooling rate, is furthermore subjected to cold rolling of <96% and is subjected to aging treatment. In this way, the high strength and high conductivity copper alloy suitable as the Quad type lead material for a semiconductor integrated circuit (IC) and the spring material for terminals, connectors, relays, switches or the like can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to high-strength, high-conductivity copper for electronic equipment suitable for lead frame materials and terminals of semiconductor integrated circuits (XC), conductive spring materials for connectors, relays, switches, etc. It concerns alloys and their manufacturing methods.

[Prior art and problems] Kovar (F e-29N i -16Co), which has a low coefficient of thermal expansion and has good adhesion and adhesion to elements and ceramics, has been used as a lead material for semiconductor devices.
High nickel alloys such as Fe-42Ni have been preferred. However, in recent years, with the increase in the degree of integration of semiconductor circuits, there has been an increase in the number of semiconductor circuits with high power consumption, resins are often used as sealing materials, and improvements have been made to the bonding between elements and lead frames. As a result, copper-based alloys with good heat dissipation properties have come to be used as lead materials.

Generally, lead materials for semiconductor devices are required to have the following properties.

(1) Leads must exhibit excellent thermal and electrical conductivity, as they are required to act as an electrical signal transmission unit and also have the function of discharging heat generated during the unpacking process and during use of the circuit to the outside. .

(2) Since the adhesion between the lead and the mold is important from the viewpoint of protecting the semiconductor element, the thermal expansion coefficients of the lead material and the mold material should be similar.

(3) It must have good heat resistance since various heating processes are involved during packaging.

(4) Most leads are manufactured by punching or bending lead material, so the workability of these is good.

(5) Since the surface of the lead is plated with precious metals, the plating adhesion to these precious metals must be good.

(6) exposed outside the sealing material after packaging;
Many items are soldered to the so-called outer lead part, so good soldering shows good soldering properties.

(7) Good corrosion resistance from the standpoint of equipment reliability and lifespan.

(8) With the transition from DIP type to Quad type,
Lead materials are required to have low anisotropy in their properties.

(9) Himeji is inexpensive.

Alloys conventionally used have advantages and disadvantages with respect to these various required characteristics, and no one has been found that satisfies these requirements.

In addition, as spring materials for terminals, connectors, relays, switches, etc., inexpensive brass, nickel silver, which has excellent spring properties and corrosion resistance, or phosphor bronze, which has excellent spring properties, have been used. However, brass has poor strength and spring characteristics, nickel silver, which has excellent strength and spring characteristics, contains a large amount of Ni, and phosphor bronze contains a large amount of Sn, so it is difficult to use raw materials and manufacture. It was an expensive alloy due to processing constraints such as poor hot workability. Furthermore, when used for electrical equipment, etc., it has a drawback of low electrical conductivity. Therefore, the emergence of an inexpensive alloy with good electrical conductivity and excellent spring properties has been awaited.

[Means for Solving the Problems] In view of the above points, the present invention has developed, as a result of various studies, a high-strength, high-conductivity copper alloy for electronic devices that satisfies the above-mentioned characteristics, and a method for manufacturing the same.

That is, the present invention has a Cr content of more than 0.25 νt% and 1.0
Wt% or less, S n more than 0.5νt% and 1.0νt%
or further contains Be as a subcomponent.

One or more selected from the group consisting of CosFe-, HfSInsZr in a total amount of 0.
This is a high-strength, high-conductivity copper alloy for electronic devices, characterized in that it contains 01 to 2.0 νt%, and the balance consists of Cu and unavoidable impurities.

The present invention also provides that after hot and cold rolling the ingot of the above alloy into a plate material,
A high-strength product for electronic devices characterized by heating for ~120 minutes, cooling the plate material to 400°C or less at a cooling rate of 1°C/sec or more, further cold rolling to less than 96%, and then aging treatment. This is a method of manufacturing conductive copper alloy.

[Detailed description of the invention] Next, the reasons for limiting the alloy components constituting the present invention will be explained.

Cr is added to improve strength and heat resistance, and the content is set to more than 0.25wt% and 1.0wt% or less because the above effects cannot be expected if it is less than 0.25vt%. On the contrary, 1. ．． This is because if it exceeds 0w1%, the electrical conductivity, plating adhesion, and solderability will significantly deteriorate.

Sn is added to improve strength and spring characteristics, and the reason why the content is more than 0.5 wt% and less than 1.0 wt% is because if it is less than 0.5 wt%, the above-mentioned effects cannot be expected. On the other hand, if the content exceeds 1.0 wt%, a significant decrease in conductivity occurs.

Furthermore, the total amount of one or more selected from the group consisting of Be5Co, Fe%Hf, In, and Zr is 0.01~
The reason for adding 2.0 νt% is that it can be expected to have the effect of improving the strength without significantly reducing the conductivity, but if the total amount is less than 0.01 wt%, the above-mentioned effect cannot be expected.
On the other hand, if it exceeds 2.0 νt%, significant deterioration in conductivity and workability will occur.

The alloy of the present invention is produced by hot and cold rolling an alloy ingot having the above composition range into a sheet material, then heating it at a temperature of 900 to 1000°C for 1 to 120 minutes, and cooling the sheet material at a rate of 1°C/sec or more. It is produced by cooling to 400° C. or less at a speed, further cold rolling to less than 96%, and then aging treatment.

In this manufacturing process, after hot and cold rolling, the
Heating at a temperature of 1000°C for 1 to 120 minutes and then cooling the plate material to 400°C or less at a cooling rate of 1°C/sec or more is to keep the added Cr in a solid solution state and reduce the carbon content.
This is to suppress the generation of coarse precipitates due to cooling of r. That is, this heat treatment is generally called solution treatment. Even if the heating temperature is less than 9 [10° C. or the heating time is less than 1 minute, the above-mentioned effects cannot be expected and the target properties (strength, heat resistance) cannot be obtained. Also, the heating temperature is 10
If the temperature exceeds 00°C, there is a risk that a liquid phase will appear in some parts, and if the heating time exceeds 120 minutes, the recrystallized grains will become coarser and the strength, heat resistance, and bending workability will deteriorate, which is not preferable. If the cooling rate is less than 1° C./sec, coarse Cr precipitates will be generated, resulting in a decrease in strength and heat resistance, which is not preferable. It is preferable to cool at a cooling rate of 3° C./sec or more. In addition, the reason why the degree of work before aging is set to less than 96% is that it is possible to reduce the anisotropy of the properties of the lead material, and when the degree of work before aging is 96% or more (with respect to the rolling direction) This is undesirable because the difference in strength between the orthogonal and parallel samples becomes large, and the bending workability of the orthogonal samples becomes worse than that of the parallel samples.

[Example] Next, the present invention will be specifically explained using examples.

Ingots having various compositions of the present invention alloy and comparative alloy shown in Table 1 were melted using electrolytic copper or oxygen-free copper as a raw material in a high frequency melting furnace in air, an inert atmosphere, or a reducing atmosphere. After performing the face side of these ingots, 850
It was hot rolled at ℃ to a thickness of 8 cm, and after the surface side, solution treatment was performed to a thickness of 7 cm. Thereafter, for the purpose of controlling the degree of work before aging, it was cold rolled to a thickness of 1, 2, 0, 6, and 0.27 mm, respectively. During cold rolling, aging treatment was performed, and further cold rolling was performed to a plate thickness of 0.25 mm. and,
Finally, strain relief annealing was added to produce a high-strength conductive copper alloy for electronic devices. Table 2 shows the manufacturing conditions after solution treatment.

As evaluation items for lead materials and spring materials, strength and elongation were measured by a tensile test, bendability was measured by a 90" repeated bending test, and the number of bends until breakage was measured, with a round trip being one time. Conductivity (heat dissipation) The solderability was determined by the electrical conductivity (%IAC8).The solderability was measured by immersing the solder in a solder bath (60% tin, 40% lead) at 230 ± 5°C for 5 seconds using the vertical dipping method. Evaluation was made by visual observation.

Plating adhesion was evaluated by applying Ag plating to a thickness of 3 μm on a sample, heating it at 450° C. for 5 minutes, and visually observing the presence or absence of blisters occurring on the surface. Heat resistance was expressed as the annealing temperature at which the hardness was 80% of the hardness before annealing when annealed for 5 minutes.

The spring properties were evaluated by measuring the spring limit value (Kb). These results are shown in Table 3.

Table 1 Table 2 Table 3 The present invention alloy and comparative alloy will be explained below.

Inventive alloys Nos. 1 to 5 are based on the basic component system of the present invention, and Nos. 6 to 10 are alloys in which subcomponents are added to the basic component system. Since both use the manufacturing method of the present invention, they have excellent properties such as strength, conductivity, and heat resistance, and have small anisotropy in properties - H.

Comparative alloys No. and 11.12 are C' and S, respectively.
The amount of n added was insufficient, and in No. 13.14, the amount of Cr and Sn added was 1.0 νt% or more, and further,
All alloys were manufactured under conditions different from those of the manufacturing method of the present invention. That is, No. 11 has a solution treatment temperature of 850°C, No. 12.13 has a solution treatment heating time of 0.5 minutes and 180 minutes, respectively, and No. 14 has a cold rolling process before aging. The degree was set to 96% or higher. Therefore, No. 11.12 is inferior in strength, spring characteristics, and heat resistance compared to the invention alloy, and No. 13 is inferior in conductivity, bending workability, solderability, and plating adhesion. ,or,
In addition to poor conductivity, No. 14 had large anisotropy in characteristics.

[Effects of the Invention] As detailed above, the alloy of the present invention has excellent properties such as strength, conductivity, and bending workability by applying the manufacturing method of the present invention, and has excellent anisotropy in strength, bending workability, etc. becomes smaller. therefore,
The alloy of the present invention is suitable for quad-type lead materials and terminals of semiconductor integrated circuits (IC), spring materials for connectors, relays, switches, etc.

Claims (3)

[Claims] (1) Cr more than 0.25wt% and 1.0wt% or less, S
Contains more than n0.5wt% and less than 1.0wt%, the remainder C
A high-strength, high-conductivity copper alloy for electronic devices, characterized by comprising u and inevitable impurities. (2) More than 0.25 wt% Cr and less than 1.0 wt%, S
n more than 0.5 wt% and less than 1.0 wt%, and one or more selected from the group consisting of Be, Co, Fe, Hf, In, and Zr as subcomponents in a total amount of 0.01 to 2.
A high-strength, high-conductivity copper alloy for electronic devices, characterized in that it contains 0 wt% of Cu, and the balance consists of Cu and unavoidable impurities. (3) An ingot of the alloy described in claim (1) or (2) is hot- and cold-rolled into a plate material, and then heated at a temperature of 900 to 1000°C for 1 to 120 minutes. death,
A high-strength, high-conductivity copper alloy for electronic devices, characterized in that a sheet material is cooled to 400°C or less at a cooling rate of 1°C/sec or more, further cold-rolled to less than 96%, and then subjected to aging treatment. Manufacturing method.