JP3391492B2 - High-strength, high-conductivity copper alloy for lead materials of semiconductor equipment and conductive spring materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead material for a semiconductor device such as a transistor or an integrated circuit (IC) or a conductive spring material for a connector, a terminal, a relay or a switch. The present invention relates to a copper alloy having excellent punching workability and bending workability in addition to strength and conductivity.

[0002]

2. Description of the Related Art Conventionally, as a lead material for semiconductor equipment, Kovar (trade name: Fe-29wt) having a low coefficient of thermal expansion, and good adhesion and sealing properties to elements and ceramics has been used. % Ni-1
High nickel alloys such as "6 wt% Co alloy") or "42 alloy" have been favorably used. However, in recent years, ICs with high power consumption have been increasingly used with the improvement in the degree of integration of semiconductor circuits. For some reasons, such as the fact that the resin has been widely used as a sealing material, and that the adhesion between the element and the lead frame has been improved, the lead material of the semiconductor device has been improved. The tendency to use a copper-based alloy having good heat dissipation properties has become conspicuous.

[0003] Regardless of the type of material, the following characteristics are generally required for the lead material of such a semiconductor device. a) The lead is the electrical signal transmission part and the package
It must have the function of releasing heat generated during the zig process and the use of the circuit to the outside, so it has excellent thermal and electrical conductivity. B) From the viewpoint of semiconductor device protection, “lead and mold The thermal expansion coefficient is close to that of the mold material, and c) various heating steps are added during packaging.
Good heat resistance. D) Most of the leads are made by punching and bending lead materials. ) Since the lead is plated with precious metal on the surface,
Good adhesion to plating with these noble metals; f) good after soldering, often soldered to the so-called "outer lead" exposed outside the encapsulant G) good corrosion resistance from the viewpoint of equipment reliability and life, and h) low price.

[0004] However, with respect to these various required characteristics, conventionally used oxygen-free copper, copper containing tin, phosphor bronze, Kovar (trade name) and 42 alloy all have advantages and disadvantages. Was not always satisfactory. In particular, taking into account the fact that as the number of pins increases and the lead becomes smaller, the shape becomes more complicated and the pins become narrower, and materials are required to have better punching and bending properties. However, it was difficult to say that the above-mentioned conventional materials had sufficient performance in these respects.

On the other hand, spring materials used for electrical equipment, measuring instruments, switches or connectors, which are also required to have excellent electrical conductivity, corrosion resistance, strength, punchability, bending workability, etc., are conventionally known. Therefore, copper alloys such as "brass", which is relatively inexpensive, "phosphor bronze", which has excellent spring properties, and "white steel", which has excellent corrosion resistance in addition to spring properties, have been used.

However, when examining the above-mentioned copper alloy as a spring material for the above-mentioned equipment which is further improved in performance, brass is not sufficiently satisfactory in strength and spring characteristics, and is also excellent in strength and spring characteristics. Even with white and phosphor bronze, stricter punching and bending processes have been applied as the parts have become lighter and shorter, so complaints about the workability of conventional materials have been pointed out. It has become.
Therefore, the appearance of an alloy exhibiting improved punching workability and bending workability and having excellent spring characteristics has been awaited.

Accordingly, an object of the present invention is to make use of the excellent electrical and thermal conductivity of a copper-based material, and at the same time, to have a strength that can be sufficiently satisfied as a lead material or a conductive spring material for semiconductor equipment. The aim was to realize a copper alloy which also had spring properties, corrosion resistance, punching workability and bending workability.

[0008]

Means for Solving the Problems Therefore, the present inventors have conducted intensive studies in order to achieve the above-mentioned object, and found that "Cu-Ni-Si based alloys having excellent strength, spring characteristics, and conductivity, etc." After adjusting the components, add an appropriate amount of Ti, Zr, Hf or Th
Incorporation of manganese significantly improves the punching and bending properties, which were not sufficient, without having a particularly adverse effect on the characteristics required as a lead material or a conductive spring material for semiconductor devices. " The new facts became clear, and furthermore, the finding that "adjustment of the crystal grain size of a copper alloy having such a composition to a specific fine region further improves the punching workability and bending workability" could be obtained. .

[0009] The present invention has been completed based on the above findings matters, the "copper alloy, Ni: 0.5% or more and less than 4% (hereinafter% represents the component ratio is the mass%) , Si: 0.1
% Or more and less than 1%, at least one of Ti, Zr, Hf or Th:
Contains 0.0005% or more and less than 0.05% in total amount, and if necessary, one or more of P, Zn, Fe, Cr, B, Be, Co, Mg, Sn, Al or Mn: 0.01% or more and less than 1% in total amount balance with including a is a component composition consisting of Cu and unavoidable impurities when
Together, By in addition to adjusting the average crystal grain size less than 25 [mu] m, Re semiconductor devices - as de material, or
Even and excellent electrical and thermal conductivity sufficiently satisfactory as a conductive spring material and, strong time, spring characteristics, conductivity, and has punching workability, a major feature in that allowed combines the bending workability " .

Next, in the present invention, the component composition of the copper alloy,
The reason why the average crystal grain size is limited as described above will be described together with its operation. Ni content Ni is a main component that has the effect of forming an intermetallic compound with Si when the alloy is aged, thereby improving both strength and electrical conductivity. Effect is not obtained, while Ni
Since the workability will be reduced if
The Ni content was determined to be "0.5% or more and less than 4%".

[0011] Si content Si has the effect of improving the strength of the alloy in cooperation with Ni without adversely affecting the conductivity.
If it is less than 0.1%, the desired effect cannot be obtained by the above-mentioned action,
On the other hand, when the Si content is 1% or more, the conductivity is significantly reduced. Therefore, the Si content is determined to be "0.1% or more and less than 1%".

Ti, Zr, Hf or Th amount The group IVa elements of Ti, Zr, Hf, and Th have the same effect of improving the punching workability and bending workability by adding a small amount thereof. More than one kind of addition is made. The mechanism by which the above-mentioned elements exert these effects is currently under study. However, when the content of one or more of Ti, Zr, Hf, and Th is less than 0.0005% in total, the above-mentioned effects are exhibited. The desired effect is not obtained, while its content is 0.
When the content exceeds 05%, the punching workability and bending workability are adversely deteriorated, and the conductivity is also reduced. Therefore, the total content of these elements is defined as "0.0005% or more and less than 0.05%".

[0013] P, Zn, Fe, Cr, B, Be, Co, Mg, Sn, Al or Mn amount P, Zn, Fe, Cr, B, Be, Co, Mg, Sn, Al and Mn include:
Since there is an equal action to further improve the strength and heat resistance of the copper alloy, one or two or more kinds are added as necessary. However, if the content is less than 0.01% in total, the desired effect of the above-mentioned action cannot be obtained, while if the total content is 1% or more, the conductivity is significantly reduced.
The content of these elements was determined as "0.01% or more and less than 1%" in total.

Crystal grain size In the copper alloy according to the present invention, coarsening of the crystal grains has a considerable adverse effect on punching workability and bending workability. In particular, when the average crystal grain size is 25 μm or more, the deterioration of punching workability and bending workability becomes remarkable. Therefore, in order to ensure good punching workability and bending workability, it is preferable to adjust the average crystal grain size so as not to be 25 μm or more.

As described above, the copper alloy according to the present invention has excellent strength, spring properties, electrical conductivity, heat resistance, etc., and also exhibits good punching workability and bending workability, as well as solderability. And excellent plating adhesion,
Hereinafter, the present invention will be described more specifically with reference to examples.

[0016]

EXAMPLES Copper alloys of various component compositions shown in Tables 1 and 2 were melted in a high-frequency melting furnace using electrolytic copper as a raw material, and the thickness was 3 mm.
Cast into 0 mm ingot. The melting and casting were performed in the atmosphere.

[0017]

[Table 1]

[0018]

[Table 2]

Next, 3 mm per one side of this ingot
The surface defects are mechanically removed by surface polishing, and 800 to 9
After a solution treatment at a temperature of 00 ° C. for 5 to 10 minutes, water quenching was performed. The crystal grain size after the solution treatment was 25
It was adjusted to less than μm. Subsequently, after finish cold rolling to a thickness of 0.3 mm, aging treatment is performed at a temperature of 400 to 500 ° C. for 1 to 7 hours under the condition that the maximum strength is obtained, and an average of each sheet material thus obtained is obtained. Investigate the crystal grain size,
Various characteristics were evaluated.

The evaluation of "strength" and "elongation" was carried out by a tensile test, and the evaluation of "electrical conductivity (heat dissipation)" was carried out by measuring conductivity (% IACS).

The "punching workability" was evaluated by observing the fractured surface of the press after the punching, and was evaluated when the fracture surface ratio {(fracture surface / plate thickness) × 100} was 20% or more.
"Good" and less than 20% were judged as "poor".

Regarding the "bending workability", as shown in FIG. 1, a 10 mm wide test piece was repeatedly bent at 90 ° to one side at an inner bending radius of 0.3 mm (= plate thickness) at right angles to the rolling direction. Then, the number of times of bending until the break (one round trip) was measured. The test was performed with n = 5, and the average was used for evaluation.

The results of these evaluations are also shown in Tables 1 and 2. Now, as is clear from the results shown in Tables 1 and 2, all of the alloys Nos. 1 to 18 of the present invention have excellent strength, elongation, conductivity, and good punching workability and bending property. It turns out that it shows workability.

On the other hand, the comparative alloy No. 19 is the alloy of the present invention.
Compared to No. 1, comparative alloy No. 20 was compared to alloy No. 2 of the present invention, comparative alloy No. 21 was compared to alloy No. 7 of the present invention, and comparative alloy No. 22 was compared to alloy No. 22 of the present invention. Compared to alloy No.16, all of them contain the same amount of Ni, Si and other components and have the same crystal grain size but do not contain Ti, Zr, Hf or Th. Poor flexibility and bendability. On the other hand, in Comparative Alloy No. 26, the Ti content was as high as 0.05% or more, so that the punching workability and bendability were rather poor and the electrical conductivity was lower than that of Alloy No. 1 of the present invention. .

Also, in Comparative Alloy No. 24, the punching workability and bendability were poor due to too much Ni content, and the electrical conductivity was low. In Comparative Alloy No. 25, the Si content was too large. Low conductivity.

By the way, alloy No. 23 is an example in which crystal grains are coarsened. As is clear from comparison with alloy No. 9, if the crystal grain size is so large, punching workability and bending workability are increased. It can be confirmed that the property deteriorates.

[0027]

As described above, according to the present invention, the difficulties in punching and bending work pointed out by conventional alloys as a lead material of a semiconductor device and a conductive spring material have been overcome. Industrially extremely useful effects are brought about, for example, it is possible to provide a high-strength, high-conductivity copper alloy that greatly improves the performance of materials.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a 90 ° repetitive bending test method.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-319642 (JP, A) JP-A-2-47228 (JP, A) JP-A-4-48041 (JP, A) JP-A-1-31964 100249 (JP, A) JP-A-3-162553 (JP, A) JP-A-59-145747 (JP, A) JP-A-62-99431 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) C22C 1/00-49/14

Claims (4)

(57) [Claims] 1. Ni: 0.5% or more and less than 4%, Si: 0.1% or more and less than 1%, one or more of Ti, Zr, Hf or Th by mass: 0.0005% or more and less than 0.05% in total amount And the balance is composed of Cu and unavoidable impurities, and has an average crystal grain size of less than 25 μm, and is used for lead materials of semiconductor devices having excellent punching and bending properties . high strength and high conductivity copper alloy. 2. In terms of mass ratio, Ni: 0.5% or more and less than 4%, Si: 0.1% or more and less than 1%, one or more of Ti, Zr, Hf or Th: 0.0005% or more and less than 0.05% in total amount together including, the balance being Cu and unavoidable impurities, and the average and wherein the crystal grain size is less than 25 [mu] m, excellent punching workability, bending workability high for the conductive spring member having a Highly conductive copper alloy. 3. Ni: 0.5% to less than 4%, Si: 0.1% to less than 1%, one or more of Ti, Zr, Hf or Th by mass: 0.0005% to less than 0.05% in total amount , P, Zn,
One or more of Fe, Cr, B, Be, Co, Mg, Sn, Al and Mn: The total content is 0.01% or more and less than 1%, and the balance is Cu
And inevitable impurities, and having an average crystal grain size of 25
and less than [mu] m, excellent punching workability, bending re semiconductor device including the processability - de material for a high strength high conductivity copper alloy. 4. In terms of mass ratio, Ni: 0.5% or more and less than 4%, Si: 0.1% or more and less than 1%, one or more of Ti, Zr, Hf or Th: 0.0005% or more and less than 0.05% in total amount , P, Zn,
One or more of Fe, Cr, B, Be, Co, Mg, Sn, Al and Mn: The total content is 0.01% or more and less than 1%, and the balance is Cu
And inevitable impurities, and having an average crystal grain size of 25
High-strength, high-conductivity copper alloy for conductive spring materials with excellent punching and bending properties, characterized by being less than μm.