JPH0243811B2 - RIIDOFUREEMUYODOGOKINOYOBISONOSEIZOHO - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a copper alloy for lead frame materials and a method for producing the same. [Prior Art] Semiconductor technology has been making rapid progress with a focus on higher integration, and along with this, the performance requirements for lead frame materials used in integrated circuits have become even more stringent. Typical lead frame materials conventionally used include 42 alloy and Kovar. Copper containing iron and copper containing Sn have also been proposed. JP-A-54-104597 discloses Zr-containing copper,
Further, in Japanese Patent Application Laid-Open No. 57-70244, copper containing Ag is proposed. [Problems to be Solved by the Invention] 42 alloy, Kovar, etc., do not have sufficient electrical conductivity and thermal conductivity, and iron-containing copper, Sn-containing copper, etc. do not have sufficient strength. For Zr-containing copper, if heat treatment is performed to sufficiently precipitate the Cu-Zr compound, the softening temperature and conductivity will be relatively high.
A short heat treatment results in a lower softening temperature and lower electrical conductivity. Furthermore, Ag-containing copper also has a low softening temperature and a decrease in strength due to heat. When a chip is mounted on a lead frame or encapsulated, it typically undergoes a heating process, and it is undesirable to reduce conductivity or reduce strength or hardness during such a process. The purpose of the present invention is to solve these problems with conventional materials, and to provide a copper alloy for lead frame materials that has high strength and conductivity, has a softening temperature of 400°C or higher, and has good workability. This is the purpose. [Means for solving the problem] The copper alloy for lead frame material of the present invention has a weight %
In, Zr; 0.04-0.5%, Ag; 0.05-4.0%,
The remainder consists of Cu and unavoidable impurities. And in weight%, Zr; 0.04-0.5%, Ag;
A slab consisting of 0.05~4.0% Cu and unavoidable impurities is hot rolled, then cold rolled to the desired thickness with intermediate annealing in between, and after final cold rolling, it is heated at 450℃~150℃. The present invention provides a method for producing a copper alloy for lead frame material, which comprises annealing at a temperature within a range. The background to this invention is that Zr-containing copper
The present inventors have discovered that when Ag is added, Ag provides an effect of promoting the precipitation of Zr that has been dissolved in copper. In general, copper alloys have better electrical conductivity as the amount of solute elements is smaller, although there are differences depending on the type of solute element. Zr is an element with a small solid solubility limit in Cu. For example, the solid solubility of r in Cu is 950℃
0.124wt.% at 850℃, 0.068wt.% at 700℃
It is said to be 0.020wt.%, and if appropriate conditions are selected, the intermetallic compound of Cu and Zr can be finely dispersed in the matrix. This fine precipitation and dispersion of intermetallic compounds makes it possible to achieve high strength and high heat resistance while maintaining high electrical conductivity. However, this requires solution treatment and aging treatment. On the other hand, although Ag is an element that can be alloyed in copper as a solid solution, the rate of decrease in electrical conductivity is relatively small. The present inventors made this Ag
When we tried adding Zr to the Cu-Zr system, we found that the precipitation of Zr was promoted. Therefore, it has been found that a copper alloy for lead frame materials with good electrical conductivity, strength, workability, hardness, and excellent heat resistance properties can be easily produced without requiring special solution treatment and aging treatment. As shown in Comparative Example No. 7 below, if the amount of Zr added is less than 0.04 wt.%, the effect of improving strength is not sufficient. On the other hand, if the content exceeds 0.5 wt.%, the strength will improve, but the electrical conductivity will decrease and the workability will also decrease. For this reason, the amount of Zr added is preferably in the range of 0.04 to 0.5 wt.%. The amount of Ag added is 0.05 wt.% or more, since at least 0.05 wt.% is required to obtain the effect of promoting Zr precipitation as described above. However, 4.0wt.
It has been found that processability deteriorates when the content exceeds 4.0 wt.%. In this way, Zr; 0.04~0.5% in copper
The copper alloy for lead frame materials of the present invention containing 0.05 to 4.0% Ag can effectively achieve the above-mentioned objectives, but the alloy of the present invention containing Ag in a composite manner requires the manufacturing process. In the case of a Cu-Zr binary system, it is advantageous in that it can exhibit sufficient physical properties without the need for solution treatment and aging treatment, which are required to fully exhibit its properties. In other words, it is sufficient to produce a cold-rolled sheet with the target thickness by hot rolling and cold rolling under normal conditions, and then low-temperature annealing is performed with the main purpose of removing residual stress caused by cold rolling. By doing this, elongation can be significantly restored. This annealing treatment after final rolling is performed on Zr and Ag.
Although it varies depending on the amount of addition, generally 450℃
The following may be carried out at a temperature of 400°C or lower depending on the case. However, recovery of elongation is not sufficient at temperatures below 150°C. It has been found that carrying out this low temperature final annealing treatment also improves electrical conductivity. Regarding the preferred manufacturing method, Zr; 0.04~
A copper alloy ingot containing 0.5% and 0.05 to 4.0% Ag is produced, hot rolled, cooled with a water shower to prevent surface oxidation, and then cold rolled.
In this cold rolling, it is preferable to reduce the plate thickness to a desired plate thickness by performing several cold rollings with intermediate annealing in between. This intermediate annealing may be performed at a temperature slightly higher than the softening temperature; if it is performed at too high a temperature, surface oxidation will be promoted and the furnace material will deteriorate, which is not economical. The obtained final cold-rolled material can be annealed at a temperature of 450°C or lower and 150°C or higher to remove local stress and recover elongation. At the same time, the conductivity also improves. When considering productivity, it is desirable that this final annealing be performed at 400°C for approximately 30 minutes. [Example] Oxygen-free copper was melted using a high frequency furnace, and then
Ag and Cu-Zr master alloy were added in the amounts shown in Table 1, and after maintaining the mixture at approximately 1200°C, it was cast into a graphite mold under reduced pressure to form an ingot of 40 mm x 40 mm x 150 mm. After cutting the surface of this ingot, it is heated to 900℃.
It was hot rolled to a thickness of 10 mm and immediately cooled with a water shower. After removing the oxide scale on the surface of this hot-rolled sheet, it was cold-rolled (primary) to a thickness of 5 mm. Then, after annealing at 600℃ for 30 minutes, pickling was carried out.
It was cold rolled (secondary) to a thickness of 2 mm. next,
After annealing at 450°C for 30 minutes and pickling, it was cold rolled (tertiary) to a thickness of 0.5 mm. A sample was cut out from the obtained cold-rolled thin sheet,
Electrical conductivity, strength, elongation at break, hardness and softening temperature were measured. The tensile test was conducted according to JIS-Z2241.
The conductivity was measured in accordance with JIS-H0505. The softening temperature was expressed as the heating temperature at which the hardness of the as-cold rolled sheet reached 80%. However, the heating time is
It is 30 minutes. The results are also listed in Table 1. In addition, for the above-mentioned as-cold-rolled sample, 400°C
Annealing was performed for 30 minutes. The electrical conductivity, strength, elongation at break, and hardness of these annealed materials were measured, and the results are also shown in Table 1. In addition, for the as-cold-rolled material mentioned above,
Annealing was performed for 30 minutes. The electrical conductivity of these annealed materials,
The strength, elongation at break, and hardness were measured, and the results were also the first.
Shown in the table.

【table】

[Function and effect]

The following can be seen from the results in Table 1. for example,
No. 3 has higher strength and better conductivity than No. 8, which does not contain Ag. This is because, as mentioned in the main text, Ag improves strength and Ag
It has been shown that the release of Zr is promoted and the conductivity is improved. However, in No. 7, in which the amount of Ag is less than the amount prescribed in the present invention, the hardness is inferior to that in No. 6. Further, No. 9, which does not contain Zr, shows remarkable softening. It can be seen that all of the alloys of the present invention containing Zr and Ag have improved electrical conductivity and greatly recovered elongation by annealing at 400°C for 30 minutes.

Claims (1)

[Claims] 1% by weight, Zr; 0.04-0.5%, Ag;
A copper alloy for lead frame materials consisting of 0.05-4.0%, the balance being Cu and unavoidable impurities. 2 In weight%, Zr; 0.04-0.5%, Ag;
A slab consisting of 0.05 to 4.0% Cu and unavoidable impurities is hot rolled, then cold rolled to the desired thickness with intermediate annealing, and after final cold rolling, it is heated at 450℃ to 150℃. A method for producing copper alloys for lead frame materials, comprising annealing at temperatures within a range.