DE4120499C1 - Low cost copper@ alloy for e.g. semiconductor carrier - contains zinc@, silicon, iron@, aluminium@, phosphorus@ and copper@ - Google Patents

Abstract

Cu alloy contg. 13-18% Zn, 1-2% Si, 0.1-0.4% Fe, 0.1-1.0% Al, 0.02-0.1% P, remainder Cu and impurities, is used for electronic components, partic. semiconductor carriers and plug connectors. The alloy has a tensile strength of 400-1100 MPa, and electrical conductivity of 6-7 MS/m and a spring bending limit of 150-900 MPa at an elastic modulus of 120 GPa max. ADVANTAGE - Favourable combination of properties and price.

Description

The invention relates to the use of a copper-zinc Alloy with silicon, iron and aluminum as further components as a material for electronic Components, esp. for semiconductor carriers and connectors.

Materials for electronic components must have special combinations of properties exhibit:

• a) it is generally a high mechanical strength sufficient electrical conductivity is required,
• b) for connectors represents the rigidity, characterized due to the spring deflection limit and the modulus of elasticity (E- Module), another essential criterion,
• c) due to the progressive miniaturization and with it associated demand for good machinability the bending behavior of the material is increasing Importance,
• d) the functionality of a component even at higher ones Ensuring temperatures are both a high softening temperature as well as good relaxation behavior of fundamental interest.

So far, only a few materials are available for the range of high tensile strengths of R _m <800 MPa and electrical conductivities of <12 MS / m. Extremely high strengths can be achieved with copper-beryllium alloys (R _m <1000 MPa), but on the one hand these materials are expensive and on the other hand they are extremely problematic to handle due to the health risk.

The alloy C 68800 (CuZn23AlCO) achieves a high level of strength with a low modulus of elasticity (116 GPa) and  thus shows a soft spring characteristic. However, the bending and stress relaxation behavior of this material wish left.

Copper alloys with contents of 4-30% by weight zinc, 1-13 % By weight silicon, 0.01-1.0% by weight calcium boride and 0.01-1.0 Wt .-% phosphorus (DE-PS 37 35 522) are also by a low modulus of elasticity. They are mainly for the Manufacture of high-strength springy glasses parts used.

These alloys have tensile strengths between 500 and 800 MPa - in the cold-formed state is an increase to 1000 MPa possibly possible - one restricted for many applications Strength range on. In addition, you can only up to 30% cold worked. No information about the bending and stress relaxation behavior as well as the spring bending limit made.

An alloy of the following composition is also known: 5-20% zinc, 0.1-0.5% silicon, 0.1-1.5% iron, 0.5-1.5% aluminum, 0.1-0.4% phosphorus, balance copper (JP-OS 58/157 931).

However, this material has a relatively low tensile strength on. In addition, the relatively high iron content can cause rough Form Fe-Si precipitates, which affect the punchability. Information regarding spring bending limit, bending behavior and This material is not resistant to relaxation.

The invention is therefore based on the object of an inexpensive Specify copper alloy, which for the application areas mentioned a combination of particularly favorable properties having.

The object is achieved according to the invention by using a copper-zinc-silicon-iron-aluminum alloy which consists of
13-18% zinc,
1-2% silicon,
0.1-0.4% iron,
0.1-1.0% aluminum,
0.02-0.1% phosphorus,
The rest is copper and usual impurities (the percentages relate to the weight).

The composition of copper alloys of the type mentioned is Although known for example from US-PS 39 56 027, there However, there is no indication of the intended use.

The use is preferred embodiments of the invention of copper alloys of the composition according to the claims 2 to 7 recommended.  

The addition of zinc of 13-18% by weight increases the strength of the Material. At the same time there is a lowering of the modulus of elasticity achieved. However, a further increase in the zinc content has an effect negatively affects electrical conductivity. The silicon content increases both the strength as well as improved corrosion resistance. Because silicon but reduces electrical conductivity and ductility, a content of 2% by weight should not be exceeded.

By adding iron and tin, both the strength as well as the spring bending limit raised. Iron also increases the Softening temperature and grain refining. Regarding one Improvement in mechanical properties is a lower one Limit of iron and tin content individually or in combination of at least 0.1% by weight. An iron content of However, 0.4% by weight should not be exceeded, since on the one hand, the modulus of elasticity is undesirably raised high iron content in combination with Silicon reinforces to form larger iron silicide deposits leads, which negatively affects the punchability of the Can impact material. A tin content at the upper limit the specification has a positive effect on bending behavior and reduced stress corrosion cracking. Tin also improves the relaxation behavior and exerts a positive influence on the E-module off. Due to interaction effects between the individual alloy components lead to a tin content of more than 0.5% by weight to a general deterioration in the material properties.

By adding up to 1% by weight of aluminum, in turn the strength increases while an increase in the E-module is counteracted. Higher levels of aluminum reduce the processability of the alloy.  

The addition of phosphorus within the specified range improves the castability of the alloy melt. A concentration of 0.1% by weight should, however, with regard to the Hot rollability should not be exceeded.

The alloy used according to the invention can be hot rolled after casting and then cold rolled to a degree of deformation of 80-90%. Depending on the desired final thickness of the strip, soft annealing is required between the individual cold-forming steps. Depending on the degree of deformation, the mechanical properties can be specifically adjusted by tempering treatment. The tensile strength R _m is preferably 400-1100 MPa, the electrical conductivity λ is preferably 6-7 MS / m.

The alloy is further characterized by a spring deflection limit δ _FB of 150-900 MPa with a modulus of elasticity of 100-120 GPa. With the copper alloy to be used according to the invention, a material is thus provided with which a wide range of property requirements can be met in a strength area that has hitherto been insufficiently covered, as will be explained in more detail below with the aid of a few exemplary embodiments:

example 1

Alloy variant 1: Cu; Zn 15.5%; Si 2.0%; Fe 0.4%; Sn 0.5%; Al 1.0%; P 0.06%
Hot rolling: 800 ° C
Cold rolling at 1.50 mm
Soft annealing: 600 ° C / 1 h
Rolls with a final thickness of 0.30 mm, degree of deformation ε 80%
Starting: 200 ° C / 3 h

The resulting tape properties are in Table 1 listed.

Example 2

Alloy variant 1: Cu; Zn 15.5%; Si 2.0%; Fe 0.4%; Sn 0.5%; Al 1.0%; P 0.06%
Hot rolling: 800 ° C
Cold rolling at 0.38 mm
Soft annealing: 600 ° C / 1 h
Rolls with a final thickness of 0.30 mm, degree of deformation ε 20%
Starting: 200 ° C / 3 h

The resulting tape properties are in Table 1 listed.

Example 3

Alloy variant 2: Cu; Zn 15.5%; Si 2.0%; Fe 0.1%; Sn 0.1%; Al 1.1%; P 0.06%
Hot rolling: 800 ° C
Cold rolling at 0.75 mm
Soft annealing: 600 ° C / 1 h
Rolls with a final thickness of 0.30 mm, degree of deformation ε 60%

The resulting tape properties are in Table 1 listed.

Example 4

Alloy variant 2: Cu; Zn 15.5%; Si 2.0%; Fe 0.1%; Sn 0.1%; Al 0.1%; P 0.06%
Hot rolling: 800 ° C
Cold rolling at 0.75 mm
Soft annealing: 600 ° C / 1 h
Rolls with a final thickness of 0.30 mm, degree of deformation ε 60%
Starting: 500 ° C / 1 h

The resulting tape properties are in Table 1 listed.

Example 5

Alloy variant 2: Cu; Zn 15.5%; Si 2.0%; Fe 0.1%; Sn 0.1%; Al 0.1%; P 0.06%
Hot rolling: 800 ° C
Cold rolling at 1.60 mm
Soft annealing: 600 ° C / 1 h
Rolls with a final thickness of 0.30 mm, degree of deformation ε 87%
Tempering: 250 ° C / 3 h

The resulting tape properties are listed in Table 1.

Table 1 shows the properties of the samples made from the alloy to be used according to the invention with common reference materials for the specified area of application compared.

It is shown that the alloy C68800 with a low modulus of elasticity has comparable strengths as the examples listed here, but is clearly inferior in terms of the bending and relaxation behavior (cf. FIGS. 3 and 4).

On the one hand, the material CuZn37 also has one low modulus of elasticity and suitable electrical conductivity open, but on the other hand does not reach the high strength level by far and the favorable bending properties of the invention alloy to be used.

The favorable properties of the alloy to be used according to the invention are further explained using the following illustrations:

It shows

Fig. 1 ε, the tensile strength of the alloy variant 1 as a function of annealing temperature for different degrees of cold working,

Fig. 2 ε the spring bending limit of the alloy variant 1 as a function of annealing temperature for different degrees of cold working,

Fig. 3 shows the relaxation behavior of the alloy variant 2 in comparison with various copper materials and

Fig. 4 shows the bending behavior (bending radius based on the strip thickness as a function of the tensile strength) of alloy variant 1 in comparison with different copper materials.

From Fig. 1 it can be seen in particular that the softening temperature is above 300 ° C.

In the illustration of FIG. 3, the initial voltage was 0.5 σ₁ ≈ σ _FB, with a load time of 100 hours. The sample layer was parallel to the rolling direction, the samples were 80% cold worked and tempered. It shows that the relaxation behavior of the alloy to be used according to the invention is significantly better than that of the alloy C68800 (CuZn23AlCo) and is roughly comparable to that of the alloy CuSn6.

FIG. 4 finally makes the favorable bending behavior of the present invention clearly used copper alloy compared to other copper materials.

Claims (8)

1. Use of a copper-zinc alloy, with silicon, iron and aluminum as further components, consisting of
13 to 18% zinc,
1 to 2% silicon,
0.1 to 0.4% iron,
0.1 to 1.0% aluminum,
0.02 to 0.1% phosphorus,
Rest copper and usual impurities,
as a material for electronic components, especially for semiconductor carriers and connectors. 2. Use of a copper alloy according to claim 1 with 14 to 17% zinc for the purpose of claim 1. 3. Use of a copper alloy according to claim 1 or 2 with 1.5 to 2% silicon for the purpose of claim 1. 4. Use of a copper alloy after one or more of claims 1 to 3 with 0.1 to 0.3% iron for the purpose Claim 1. 5. Use of a copper alloy after one or more of claims 1 to 4 with 0.5 to 1.0% aluminum for the purpose according to claim 1.   6. Use of a copper alloy after one or more of claims 1 to 5, in addition to or instead of iron Contains 0.1 to 0.5% tin, for the purpose of claim 1. 7. Use of a copper alloy according to claim 6 with 0.3 to 0.5% tin for the purpose of claim 1. 8. Use of a copper alloy according to one or more of claims 1 to 7 as a material for electronic components, the
Tensile strength R _m = 400 to 1100 MPa,
electrical conductivity λ = 6 to 7 MS / m,
Spring bending limit σ _FB with a modulus of elasticity of maximum 120 GPa, 150 to 900 MPA and
bending radius related to the strip thickness for tensile strengths R _m up to approx. 900 MPa parallel to the rolling direction 4 and perpendicular to the rolling direction 2
is.