JPS6365748B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing a pin grit array IC lead wire. A pin grit array IC is a rectangular ceramic substrate with 2.54 mm pitch metallized electrodes and the top of a headered wire rod, which are brazed together using silver solder under heating at 800 to 900 degrees Celsius. It is a highly integrated, highly reliable semi-package IC. [Prior art] Conventionally, Fe-Co-Ni alloy (ASTM standard F-15 alloy) or Fe-42Ni alloy (ASTM standard F-30 alloy) has been used as pin wire material for bottle grit array IC leads. has been done. However, the electrical conductivity of this F15 alloy or F-30 alloy is as low as 3% IACS, so it is easy to generate Joule heat when used as an IC lead wire, and the heat generated inside the IC element is not sufficiently dissipated. In particular, it has been pointed out that as the density of recent IC elements increases, the amount of heat generated inside the IC element increases, resulting in poor dissipation.
There is a need for a material with superior heat dissipation properties to replace F-15 and F-30. [Problems to be Solved by the Invention] The present invention solves the problem by improving the electrical conductivity and thermal conductivity of F-15 or F-30 alloy, which has been used as the conventional pin grit array IC lead wire material as described above. This was done in consideration of the
A method for manufacturing a pin/grit array IC lead wire material that has excellent strength, repeated bendability, electrical conductivity, thermal conductivity, solderability, and resistance to peeling under solder heating even after silver brazing at temperatures of It provides: [Means for Solving the Problems] The method for manufacturing pin grit array IC lead wire according to the present invention is characterized by: 1.0 to 5.0 wt% Ni, 0.2 to 1.0 wt% Co, Si0 A copper alloy ingot containing .2 to 1.5 wt%, Zn 0.05 to 5.0 wt%, and Cr 0.002 to 0.5 wt%, with the remainder being Cu and unavoidable impurities, is hot extruded and then cold wire drawn. ,
During this cold wire drawing process, intermediate annealing is performed at least once at a temperature of 550 to 800°C. The method for manufacturing the pin grit array IC lead wire according to the present invention will be described in detail below. First, the pin grit array according to the present invention
The components and component ratios of the copper alloy used in the method for manufacturing an IC lead wire will be explained. Ni, Co, and Si are elements that improve strength.
In particular, Ni, alone or partially substituted with Co, forms an intermetallic compound with Si, thereby contributing to improved strength. Ni content is less than 1.0wt%, Si content is 0.2wt%
If the Co content is less than 1.0wt%, sufficient strength cannot be obtained even if the Co content exceeds 1.0wt%.
As the Si content increases, sufficient strength and conductivity can be obtained even after brazing at temperatures of 800 to 900°C, but when the Ni content exceeds 5.0 wt%, this effect becomes saturated. , when the Si content exceeds 1.5wt%, hot workability deteriorates. Then,
Ni content is 1.0~5.0wt%, Si content is 0.2~1.5wt
%. Like Ni, Co is an element that contributes to improving strength, and is particularly effective in suppressing the growth of crystal grains during brazing at temperatures of 800 to 900°C.
After brazing at a temperature of , the grain size is 50 μm.
If it becomes larger than , the number of repeated bending will decrease,
After the lead material is plated, surface roughness and reduction in fatigue strength tend to occur.If the content is less than 0.2wt%, this effect will be small, and if the content exceeds 1.0wt%, it will still be effective. is expensive, and the improvement in effectiveness is small considering the cost. Therefore, the Co content is set to 0.2 to 1.0 wt%. Zn is an essential element for improving the thermal peeling resistance of the tin plating or tin alloy plating layer applied to the surface of the lead material, and if the content is less than 0.05wt%, this effect will be small. If the content exceeds 5.0wt%, solderability will deteriorate. By the way, Zn
The content is 0.05-5.0wt%. Cr is an element that strengthens the grain boundaries of the ingot and improves hot workability.If the content is less than 0.002wt%, this effect will be small, and if the content exceeds 0.5%, the molten metal will oxidize. , castability deteriorates. Therefore, the Cr content is set to 0.002 to 0.5 wt%. In addition to the above ingredients, Ag, Al, In,
Containing up to 0.2wt% of one or more of Fe, Mn, and Sn, and up to 0.1wt% of one or more of B, Be, Mg, Ti, Zr, and P is required for silver brazing. The above content is acceptable because it can be maintained without causing problems such as properties, strength, flexibility, conductivity, solderability, peeling resistance of solder under 150℃ heating, and number of repeated bending of lead materials. be done. Next, the pin grit array according to the present invention
The manufacturing conditions of the method for manufacturing IC lead wire will be explained. In other words, wire rods for pin grit array IC leads can be manufactured by hot extrusion of a copper alloy ingot having the above-mentioned composition and composition ratio, and then cold wire drawing. , at least once during this cold wire drawing process.
The reason why intermediate annealing is performed at a temperature of 800 to 900 °C is to prevent the generation of twin crystal structures perpendicular to the wire drawing direction after silver brazing at a temperature of 800 to 900 °C. , a pin grit array IC manufactured using only cold wire drawing.
After silver brazing at a temperature of 800 to 900°C, lead wires often develop a twin structure, and the diameter of 50μ
The following uniform best-crystalline structure cannot be obtained, and in particular, the stiffness properties are deteriorated. However, if the intermediate annealing temperature is less than 550℃, recrystallization and softening will be insufficient, resulting in poor workability in the subsequent cold wire drawing process, and if the temperature exceeds 800℃, the heat treatment cost will increase, resulting in high However, the improvement in the above-mentioned characteristics is small. Then,
The intermediate annealing temperature is 550 to 800°C. This intermediate annealing time is preferably 5 seconds to 180 minutes. Furthermore, a pin grit array according to the present invention
The lead wire manufactured by the IC lead wire manufacturing method only needs to be cooled to a level that does not break the ceramic base after silver brazing, and after this silver brazing, the lead wire is kept at a temperature of 400 to 550°C for 5 to 30 minutes. Hardness and electrical conductivity can be improved by performing heat treatment. As described above, the reason why the lead wire manufactured by the method for manufacturing pin grit array IC lead wire according to the present invention has high hardness and high conductivity even after hard brazing is due to cooling after brazing. When passing through a temperature range of 400-550℃ during the process,
(Ni ₁ xCox) ₂ Si is precipitated to improve the purity of the matrix,
This is because it strengthens it. [Example] Next, a pin grit array according to the present invention
An example of a method for manufacturing an IC lead wire will be described. Example A copper alloy having the components and proportions shown in Table 1 was melted in the air in a Kryptor furnace under charcoal coating, and cast into a tilting cast iron cylindrical book mold to produce an ingot with a diameter of 70 mm and a length of 180 mm. was created. The outer circumferential surface of this ingot was milled 2.5 mm each, hot extruded at a temperature of 850°C, and made into a wire rod with a diameter of 10 mm.
After heating to a temperature of 700°C for 30 minutes, it was rapidly cooled in water. moreover,
After removing the oxide scale with sulfuric acid, cold wire drawing was repeated at a one-pass processing rate of approximately 20% to obtain a wire rod with a diameter of 5.7 mm, which was then shaved to a diameter of 0.25 mm.
It was made of a 5.2mm wire rod. Next, the wire rod manufactured in this way was
Repeated cold drawing with a pass processing rate of approximately 20% to a diameter of 2 mm.
A wire with a diameter of 0.46 mm was produced by vacuum annealing at a temperature of 600° C. for 120 minutes, and then repeating cold wire drawing at a processing rate of about 20% per pass. Also, for comparison, 1 without any intermediate annealing.
By repeating cold wire drawing with a pass processing rate of approximately 20%, the diameter
A 0.46mm wire rod was manufactured. In this way, wire rods manufactured by the method for manufacturing wire rods for pin grit array IC leads according to the present invention (method of the present invention) and wire rods manufactured by the comparative method are attached to electrodes formed by metallizing ceramic. Setting the conditions for joining with JIS standard BAg-8 silver solder, heating at 850℃ for 5 minutes, cooling to room temperature at a rate of about 14℃/min, and heating to 500℃.
After aging for 15 minutes at a temperature of The relationship between bending moment and displacement angle is shown in FIG. 1, and it can be seen that the wire produced by the method of the present invention has a better bending moment than the wire produced by the comparative method.
Further, the micrograph of the metallographic structure of the wire obtained by the method of the present invention shown in FIG. 2a shows fine crystal grains, but the micrograph of the metallographic structure of the wire obtained by the comparative method shows that the crystal grains are coarse. It can be seen from Table 2 that the wire produced by the method of the present invention is superior to the wire produced by the comparative method.

【table】

[Table] 2: Wire rod manufactured by the comparative method.
≪Test method≫ (1) Electrical conductivity: Using a double bridge,
Measured based on JISH0505. The calculation method was based on the average cross-sectional area method. (2) Hardness: Using a micro-Bitzkers hardness tester, the load
Measured at 100g. (3) Stiffness strength: Using a test piece of 0.46mmφ x 60mml, stress was applied at a bending radius of 40mm, and the moment when the displacement angle was 15° was determined. (4) Repeated bendability of the lead: A load of 450 g is suspended at the end of the test piece, and the test piece is bent in one direction at 90 degrees back and forth, and the number of times it takes to break is counted as one round trip. Average value of 5 test pieces. I asked for (5) Peeling resistance of solder after heating: Using a weakly activated flux, a test piece was soldered in a Sn60-Pb40 solder bath at a temperature of 230°C, and the test piece was soldered at a temperature of 150°C.
After holding it for 500 hours, it was bent 90 degrees and the solder adhesion was investigated. The wire rod manufactured by the method for manufacturing a pin grit array IC lead wire rod according to the present invention has been described above, but in more detail, as shown in FIG. By performing at least one intermediate annealing, the lead wire has significantly superior stiffness strength after silver brazing at 850℃ for 5 minutes, compared to wire rods manufactured by a comparative method without intermediate annealing. This shows that it is difficult to deform due to external stress. In addition, it is a micrograph of the metal structure of the wire rod manufactured by the method of the present invention shown in FIG. Figure 2b is a micrograph of the metal structure of the wire manufactured by the comparative method,
A twin structure is generated perpendicular to the wire drawing direction, resulting in a mixed grain structure. Furthermore, from Table 2, it is clear that the wire manufactured by the method for manufacturing a pin grit array IC wire according to the present invention has excellent properties overall. [Effects of the Invention] As explained above, since the method for manufacturing a pin grit array IC lead wire according to the present invention has the above configuration, the manufactured wire can be used as a pin grit array IC lead pin. (1) Improved thermal conductivity and electrical conductivity can simplify the design and improve the performance of the package regarding heat dissipation. (2) Since it has a stiffness strength higher than that of F-30 alloy, the reliability of the package is improved. (3) Silver solder gets wet easily, reducing the amount of silver solder used. In the future, it will be possible to use it in pin grit array IC packages where the number of pins will increase to more than 100 due to increased packaging density and integration, and it will be used in the electronics industry. The contribution of

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between bending moment and displacement angle, and FIG. 2 is a diagram showing the metals of wire rods manufactured by the method for manufacturing wire rods for pin grit array IC leads according to the present invention and wire rods manufactured by a comparative method. This is a microscopic photograph of the tissue.

Claims (1)

[Claims] 1 Contains 1.0 to 5.0 wt% Ni, 0.2 to 1.0 wt% Co, 0.2 to 1.5 wt% Si, 0.05 to 5.0 wt% Zn, and 0.002 to 0.5 wt% Cr, After hot extrusion of a copper alloy ingot consisting of residual Cu and unavoidable impurities, cold wire drawing is performed.
A method for producing a pin grit array IC lead wire, which comprises performing at least one intermediate annealing at a temperature of 550 to 800° C. during the cold wire drawing process.