JPS63183143A - Cu alloyed lead frame material for semiconductor device - Google Patents

Abstract

PURPOSE:To produce the titled lead frame material having high strength and having the excellent thermal exfoliation resistance to a solder by preparing a Cu alloy contg. specific ratios of Ni, Sn, Si, Zn and Ca. CONSTITUTION:The Cu alloy contg., by weight, 1-4% Ni, 1-3% Sn, 0.15-0.8% Si, 0.1-1% Zn, 0.002-0.04% Ca and the balance consisting of Cu with inevitable impurities is prepared. Said Cu alloy has high strength of about >=60kg/mm<2> tensile strength, has the excellent thermal exfoliation resistance to solder and is suitable for the Cu alloyed lead frame material for semiconductor device.

Description

[Detailed Description of the Invention] [Industrial Field] This invention relates to a Cu alloy lead frame material for semiconductor devices that has high strength and excellent solder heat peeling properties. [Technology] Conventionally, for example, 1 military song % and % below C indicate military song %), C
A Cu alloy having a typical composition of u-2%Sn-0,2%Ni-0,05%P is IC-? LS1. Further VL
It is used as a lead frame material for semiconductor devices such as SI.

[Problem that the invention seeks to solve]

However, in recent years, the high performance (hi and high integration f) of semiconductor devices has increased.
With the increasing demand for lead frames, the lead frame materials that make up these materials are also required to have high strength. Abrasion resistance of punching dies, thermal and electrical conductivity, and plating properties.

Although soldering has excellent properties, it may not be possible to meet these requirements due to lack of strength.
However, there is a problem in terms of reliability because the heat resistance and peelability of the solder are not satisfactory.

[Means for solving problems]

Therefore, the inventors of the present invention, etc., from the above-mentioned viewpoint.

The result of research aimed at developing lead frame materials for semiconductor devices that have high strength and excellent heat-removability of solder.

Ni: 1-4%, Sn: 1-3%.

Si: 0.15-0.8%, Zn: 0.1-1
%.

Ca: 0.002-0.04%.

The Cu alloy, which has a composition containing Cu and the rest consisting of Cu and unavoidable impurities, has a high tensile strength of 60 K, /- or more, has excellent heat peeling resistance of solder, and is also suitable for lead frames. Repeated bending properties required for the material, punching die wear resistance, IP4 and electrical conductivity, plating properties,
They discovered that soldering also has excellent properties.

This invention has been made based on the above knowledge, and the component composition is limited as described above and the reason will be explained below.

fal Ni N1E component has the effect of improving strength and repeated bending properties, but if the acid content is less than 1%, the desired effect cannot be obtained, while if the acid content exceeds 4%, hot Since the processability deteriorates, the acid content was determined to be 1 to 4%.

(b) Although the 5n Sn component also has the effect of improving strength and repeated bending properties in the same way as Ni5!2, if the acid content is less than 1%, the desired effect of improving the properties cannot be obtained.

On the other hand, if the acid content exceeds 3%, hot workability similarly decreases, so the content I was set at 1 to 3%.

tel 5i The Si component mainly has the effect of forming an arsenic compound of Ni2Si to improve strength, but if the acid content is 0.1
If the acid content is less than 5%, the desired high strength cannot be ensured, while if the acid content exceeds 0.8%, free Si will be formed, impairing the heat-resistant peelability of the solder. Therefore, the acid content was determined to be 0.15 to 0.8%.

fd) Zn The Zn component has the effect of further improving the heat-resistant peelability of the solder, but if its content is less than 0.1%, the desired excellent heat-resistant peelability of the solder cannot be ensured,
On the other hand, if the acid content exceeds 1%, the soldering properties will deteriorate.

The acid content was determined to be 0.1 to 1%.

fel Ca For the Ca component, press punching (also called stamping)
It has the effect of suppressing the wear of the punching die used when forming lead frame material from a single strip material (effect of improving the wear resistance of the punching die), but its content is less than 0.002%. However, if the acid content exceeds 0.04%, cold ductility will be impaired.
0.04% [Actual example] Next, a practical example of the Cu alloy lead frame material of the present invention will be explained in detail.

Using an ordinary low-frequency groove melting furnace, alloy baths having the compositions shown in Table 1 were prepared in an atmospheric atmosphere under charcoal coating, and cast to a thickness of 160 mm by semi-continuous casting.
An ingot with dimensions of width: 450 + + + m x length: 2400 is cast into an ingot, and this ingot is hot rolled at a temperature of 850°C to form a hot rolling mill with a thickness of 10 mm, and after hot rolling. Immediately, the hot-rolled plate was cooled with water and subjected to scale removal, and then the hot-rolled plate was cold-rolled to a thickness of 0.5 mm, and the plate was kept at a temperature of 500°C for 2 hours. Annealed and rolled under the following conditions, then cold rolled again to a thickness of 0.25ff.
I +++, and finally the temperature = 50 using a continuous annealing furnace.
By annealing at 0°C for 20 seconds.

Inventive Cu alloy lead frame materials (hereinafter referred to as the present invention lead materials) 1 to 12 and Comparative Cu alloy lead frame materials C (hereinafter referred to as comparative lead materials) 1 to 6 were manufactured, respectively.

In addition, comparative lead materials 1 to 6 are all materials in which one of the constituent acids (those marked with * in Table 1) is outside the scope of this invention. Next, the resulting lead materials 1 to 12 of the present invention, comparative lead materials 1 to 6, and commercially available Cu alloy split lead frame materials (hereinafter referred to as conventional lead materials) were subjected to tensile tests and thermal peeling tests of solder. , a repeated bending test, and a punching die wear test were conducted to evaluate the strength, heat peeling resistance of solder, repeated bending property, and punching die wear resistance, respectively.

In addition, the tensile test was conducted using JI35 samples taken parallel to the rolling direction.
The tensile strength and elongation were measured using a No. 1 test piece.

In addition, in the thermal peeling test of solder, a test piece with dimensions of thickness: 0.25+n x width: 1511I11 x length 260 was treated with agin flux,
%5n-40%PB solder bath to adhere the solder to the surface, and in this state, in the atmosphere, at a temperature of:
The test piece was heated at 150'C+2 and held for 1000 hours, and after heating, the test piece was closely bent 180° and then bent back 180° again, and the presence or absence of solder peeling at the 180° bent portion was observed.

The repeated bending test was performed using a thickness of 0.25 m x @:
A test piece with a size of 0.5 F (226.8 F) was placed horizontally and attached to one end with the skin in the center.
One cycle is the process of bending 90 degrees with a weight of 1 ounce (oz) and returning it to the horizontal position.
The number of bending cycles until breakage was measured for each test piece, and the average value of the 10 test pieces was determined based on the measurement results.

Furthermore, the punching die wear test was conducted using commercially available Co as the die.
A 16-lead lead frame was press punched using a WC-based cemented carbide having a composition of: 16%, WC: and the remainder. The number of times of stamping until this occurred was measured. These results are shown in Table 1.

〔Effect of the invention〕

Table 1 (Results shown: 1 Lead materials of the present invention 1 to 1
2 has excellent repeated bending properties and punching die wear resistance that are equal to or better than conventional lead materials, and also have superior strength and heat peeling resistance of solder compared to conventional lead materials. Furthermore, although it is not shown in Table 1, both of them have the minimum required 3% lAC as lead frame material for semiconductor devices.
3-process shows even higher conductivity of 15%lAC3 or higher,
It had excellent thermal and electrical conductivity.

On the other hand, as can be seen in Comparative Lead Materials 1 to 4 (2), if the content of any one of the constituent components falls outside the scope of the present invention, at least one of the above characteristics is inferior. As is clear from the above, the Cu alloy lead frame material of the present invention has high strength and excellent solder heat peeling resistance, and also has the repeated bendability and durability required for lead frames. It has excellent properties such as punching die abrasion resistance, thermal and electrical conductivity, plating properties, and soldering properties, so it greatly contributes to higher performance and higher integration of semiconductor devices. can be.

It is highly reliable and provides excellent performance over a long period of time.

Claims (1)

[Claims] Ni: 1-4%, Sn: 1-3%, Si: 0.15-0.8%, Zn: 0.1-1%, Ca
:0.002 to 0.04%, and the remainder is Cu and unavoidable impurities (weight%). High strength and excellent heat-resistant peeling properties of solder. A lead frame material made of a Cu alloy for semiconductor devices.