JP2683903B2 - High strength and high conductivity copper alloy with excellent solder heat resistance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a copper alloy suitable as a lead material for semiconductor devices such as transistors and integrated circuits, and a conductive spring material such as connectors, terminals, relays and switches. The present invention relates to a copper alloy having excellent soldering heat peeling resistance. [Prior Art] Conventionally, as a lead material for semiconductor devices, Kovar (Fe-29Ni-16Co), 42 alloy (Fe-42Ni), which has a low coefficient of thermal expansion, and has good adhesion and sealing properties with elements and ceramics. High nickel alloys such as have been used favorably. However, in recent years, with the increase in the integration of semiconductor circuits, ICs with high power consumption
However, the amount of resin used has increased and the adhesion between the element and the lead frame has also been improved. As a result, the lead material used is a copper-based alloy with good heat dissipation. It's starting to happen. Generally, the following characteristics are required as a lead material for semiconductor devices. (1) Since the lead is required to have the function of discharging the heat generated during the packaging process and during the use of the circuit as well as being an electric signal transmission part, it exhibits excellent heat and electric conductivity. . (2) Since the adhesion between the lead and the mold is important from the viewpoint of protecting the semiconductor element, the thermal expansion coefficient of the lead material and that of the molding material are close to each other. (3) Since various heating processes are added during packaging,
Good heat resistance. (4) Most of the leads are manufactured by punching and bending the lead material, and therefore the workability of these is good. (5) Since the surface of the lead is plated with a noble metal, the adhesion of the lead to these noble metals must be good. (6) Exposed outside the encapsulant after packaging,
Since many are soldered to the so-called outer leads, good solderability is required. (7) Good corrosion resistance from the viewpoint of equipment reliability and life. (8) The price is low. Also, conventional electric equipment springs, measuring instrument springs, switches,
Inexpensive brass, nickel silver having excellent spring characteristics and corrosion resistance, or phosphor bronze having excellent spring characteristics has been used as a spring material used for connectors and the like. [Problems to be Solved by the Invention] Oxygen-free copper, tin-containing copper, phosphor bronze, which has been used conventionally, in response to various required characteristics of the semiconductor device described above,
Both cobalt and 42 alloy have merits and demerits, and not all of these characteristics are satisfied. On the other hand, Cu-Cr-Zr
Since the alloy considerably satisfies the above-mentioned required properties, Cu-Cr-
Improved alloys have been developed in which some additional elements are added to the Zr alloy. However, in recent years, the demand for reliability of semiconductors has become more intense, and the number of surface mounting types compatible with miniaturization has increased, so solder heat release, which has not been a problem in the past, is a very important characteristic item. Came. That is, the lead frame and the printed circuit board are soldered, but the temperature of the lead frame and the soldered portion rises up to about 120 ° C. due to external temperature during use and heat generated by energization. When exposed to such a temperature for a long time, the solder and the lead frame may be peeled off and the semiconductor may not operate. Therefore, when high reliability is required from the viewpoint of life, this solder heat resistant peeling property is the most It is one of the important characteristics. Above all, FPP (FLAT PLAS
TIC PACKAGE) and PLCC (PLASTIC LEADED CHIP CARRIER)
The surface-mounting type typified by No. 1 does not mount on the printed circuit board but makes surface contact, so that the heat resistant peeling property of solder becomes more important. In addition, brass as a spring material is inferior in strength and spring characteristics. In addition, nickel white of phosphorous bronze and nickel bronze with excellent strength and spring characteristics is 18% by weight of nickel and phosphor bronze is 8% by weight of Sn. Because of the inclusion, it was an expensive alloy in view of the raw material and manufacturing, and the hot workability was poor and processing restrictions were added. Further, when it is used for electric equipment, it has a drawback of low electric conductivity. Therefore, the emergence of an inexpensive alloy having excellent conductivity and excellent strength and spring characteristics has been awaited. Even in the field of this conductive spring material, since Cu-Cr-Zr alloy satisfies a considerable demand, an improved alloy in which a small amount of additional element is added to Cu-Cr-Zr alloy has been developed. However, similar to the lead material of semiconductor devices, conductive spring materials are often Sn or solder plated or soldered for reasons such as contact resistance reduction and corrosion resistance improvement. Such solder heat resistance peeling property has become extremely important due to the recent demand for improved reliability. The Cu-Cr-Zr alloys that have been developed up to the present with respect to such strict requirements for solder heat-resistant peelability cannot be satisfied, and the emergence of high-strength and high-conductivity copper alloys with improved solder heat-resistant peelability has emerged. I was waiting. [Means for Solving the Problems] The present invention aims to improve the above-mentioned drawbacks of conventional copper-based alloys and to provide a copper alloy having various properties suitable as lead materials and semiconductor spring materials for semiconductor devices. Is. That is, the present invention, Cr0.1 ~ 1.5 wt%, Zr0.05 ~ 1.0
%, Zn 0.01-3.0% by weight, or even A
l, Be, Co, Fe, Hf, Mo, Mg, Ni, P, Pb, Si, Sn, T
High strength and high conductivity with excellent solder heat resistance peeling, characterized by containing 0.01 to 1.0% by weight in total of one or more selected from the group consisting of e and Ti, and the balance Cu and unavoidable impurities. It is a copper alloy. Next, the reasons for limiting the alloy components constituting the alloy of the present invention will be described. The content of Cr is set to 0.1% by weight or more and 1.5% by weight or less because precipitation hardening due to fine Cr grains can be expected during the aging treatment, and further heat resistance can be improved accordingly. If the Cr content is less than 0.1% by weight, the above-mentioned effects can be expected. Conversely, if it exceeds 1.5% by weight, the plating adhesion,
This is because the solderability and workability are deteriorated and the conductivity is remarkably reduced. The content of Zr is set to 0.05% by weight or more and 1.0% by weight or less in order to promote precipitation hardening and obtain heat resistance accompanying it. If the Zr content is less than 0.05% by weight, the above-mentioned curing cannot be expected, and if it exceeds 1.0% by weight, the plating adhesion, solderability, workability deteriorates and the conductivity decreases remarkably like Cr. Is. The Zn content is set to 0.01 wt% or more and 3.0 wt% or less because the solder heat-resistant peeling property can be significantly improved without significantly decreasing the conductivity by adding Zn, and the Zn content is 0.05% or less.
If it is less than wt%, the above-mentioned effect is small, and conversely the Zn content is
This is because if the amount exceeds 3.0% by weight, the conductivity will remarkably decrease. In addition, Al, Be, Co, Fe, Hf, Mo, Mg, Ni, P, Pb,
The addition of one or more selected from the group consisting of Si, Sn, Te, and Ti can be expected to have the effect of improving strength and heat resistance without greatly reducing the conductivity due to the addition of these. Therefore, if the total content is less than 0.01% by weight,
This is because the above-mentioned effect cannot be expected, and if the content exceeds 1.0% by weight, the conductivity will remarkably decrease. [Examples] Next, examples of the present invention will be specifically described together with comparative examples. Ingots of various composition according to the alloy of the present invention and the comparative alloy shown in Table 1 were obtained by a casting method in the atmosphere, an inert or reducing atmosphere. Next, after surface-polishing these ingots,
It was heated for a period of time and hot-rolled into a 5 mm plate, and immediately after the hot-rolling was finished, the processed material was cooled at a rate of 1 ° C / sec or more. This 5mm thick plate is cold-rolled to a 0.25mm plate and 400 ℃
Then, aging treatment was performed for a predetermined time. As the evaluation items for the lead material and the spring material, strength and elongation are tested for bendability by a tensile test and bendability is repeated 90 °, and one reciprocation is performed once to measure the number of bends until breakage, and heat resistance is softened at a heating time of 5 minutes. Depending on the temperature, the electric conductivity (heat dissipation) was shown by the electric conductivity (% IACS). Solderability is 230 + 5 ° solder bath (tin 60
%, Lead 40%) for 5 seconds, and the state of solder wetness was visually observed and evaluated. The plating adhesion was evaluated by subjecting the sample to Ag plating having a thickness of 3 μm, heating the sample at 450 ° C. for 5 minutes, and visually observing the presence or absence of blisters on the surface. These results are shown in Table 1 together with the comparative alloy. Regarding the solder heat-resistant peeling property which is the point of the present invention,
Apply 5μm solder plating (60% Sn, 40% Pb) to the material,
It was kept in a constant temperature bath at 150 ° C for up to 2000 hours, taken out every 100 hours, bent 90 ° once and reciprocated once, and examined for the presence or absence of peeling of solder. The results are shown in Table 1. It is clear from the description in Table 1 that the alloy of the present invention has remarkably improved heat-resistant peeling property of solder, has improved stability of solder, and has excellent properties as a high-strength and high-conductivity copper alloy. [Advantages of the Invention] The present invention provides excellent electrical and thermal conductivity, heat resistance, and processability as a copper alloy and a conductive spring material for leads of semiconductor devices.
Not only does it have plating adhesion, solderability, corrosion resistance, and spring properties, but it also markedly improves solder heat release.

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References Japanese Patent Laid-Open No. 62-13302 (JP, A)                 JP 62-13303 (JP, A)                 JP-A-61-272339 (JP, A)                 JP-A-59-193233 (JP, A)

Claims (1)

(57) [Claims] Cr0.1-1.5% by weight, Zr0.05-1.0% by weight, Zn0.01-
A high-strength and high-conductivity copper alloy with excellent solder heat-resistant peeling characteristics, which is characterized by containing 3.0% by weight and the balance Cu and unavoidable impurities. 2. Cr0.1-1.5% by weight, Zr0.05-1.0% by weight, Zn0.01-
3.0 wt% and Al, Be, Co, Fe, Hf, Mo, Mg, Ni, P, P
Excellent in solder heat-resistant peeling, characterized in that the total amount of one or more selected from the group consisting of b, Si, Sn, Te and Ti is 0.01 to 1.0 wt% and the balance is Cu and unavoidable impurities. High strength and high conductivity copper alloy.