JPH02145734A - High strength and high conductivity copper alloy having excellent adhesion of oxidized film - Google Patents

Abstract

PURPOSE:To improve the strength, electrical conductivity and adhesion of an oxidized film in the title copper alloy by specifying Fe, P, Zn and Cu and regulating the surface roughness to prescribed one. CONSTITUTION:The title copper alloy is formed with the compsn. constituted of, by weight, 1 to 3.5% Fe, 0.001 to 0.1% P, 0.05 to 5% Zn and the balance Cu. Then, the surface roughness is regulated to <=0.2mum center line average height (Ra) and <=1.5mum center line maximum height (R max). The above copper alloy has high strength and high conductivity and has excellent adhesion of an oxidized film.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a copper alloy suitable for conductive spring materials such as lead materials and connectors, terminals, relays, switches, etc. of semi-quaternary devices such as transistors and integrated circuits. In particular, it relates to a high-strength, high-conductivity copper alloy with excellent oxide film adhesion.

[Conventional technology]

Conventionally, lead materials for semiconductor devices include Kovar (Fe-29Ni-16Co) and 42 alloy (Fe-29Ni-16Co), which have a low coefficient of thermal expansion and have good adhesion and sealing properties with elements and ceramics.
High nickel alloys such as Fe-42Ni) have been preferred. However, in recent years, as the degree of integration of semiconductor circuits has improved, the number of ICs with high power consumption has increased, resins have been increasingly used as sealing materials, and improvements have been made to the bonding between elements and lead frames. As a result, copper-based alloys with good heat dissipation properties have come to be used as lead materials.

In general, lead materials for semiconductor devices are required to have the following properties.9 (1) The lead serves as an electrical signal transmission part, and also has the ability to release heat generated during the packaging process and circuit use to the outside. Because it is required to have both, it exhibits excellent thermal and electrical conductivity.

(2) Since the adhesion between the lead and the mold is important from the viewpoint of protecting the semiconductor element, the thermal expansion coefficients of the lead material and the mold material should be similar.

(3) Since various heating processes are added during packaging,
Good heat resistance.

(4) When various heating processes are added during packaging,
Good oxide film adhesion as an oxide film is formed between the resin and the material.

(5) Most leads are made by punching and bending lead material.

These must have good workability.

(6) Since the surface of the lead is plated with precious metals, the plating adhesion to these precious metals must be good.

(7) Exposed outside the sealing material after packaging;
Many items are soldered to the so-called outer leads, so good soldering is a sign of good soldering.

(8) Good corrosion resistance from the viewpoint of equipment reliability and lifespan.

(9) The price must be low.

In addition, in the past, inexpensive brass, nickel silver, which has excellent spring properties and corrosion resistance, or phosphor bronze, which has excellent spring properties, were used as spring materials for electrical equipment springs, measuring instrument springs, switches, connectors, etc. 6 [Problems to be solved by the invention] Oxygen-free copper, tin-containing copper, phosphor bronze, Kovar, and 42 alloys that have been used conventionally all have advantages and disadvantages in meeting the various characteristics required for semiconductor devices as described above. However, Cu-Fs does not satisfy all of these characteristics.
-P alloy satisfies the above required properties to a large extent, so Cu
-Fe-P alloys and improved alloys with some additional elements have been developed.

However, in recent years, reliability requirements for semiconductors have become more stringent, and surface mounting types have become more popular in response to miniaturization, so oxide film adhesion, which was not considered an issue in the past, has become an extremely important characteristic item. It's here.

That is, since heat is applied to the lead frame during the packaging process, an oxide film is inevitably generated.

When sealed with a resin or the like, the adhesion strength between the resin and the oxide film, and the oxide film and the base material are compared, and the adhesion strength between the oxide film and the base material is generally low. In this case, peeling may occur between the oxide film and the base material, allowing moisture etc. to enter from there, significantly reducing the reliability of the IC. This is one of the most important properties for a high-strength, high-conductivity copper alloy.

These strict requirements for oxide film adhesion cannot be met with the Cu-Fe-P alloys developed to date, and the development of high-strength, high-conductivity copper alloys with improved oxide film adhesion is required. It was waiting.

[Structure of the invention]

The present invention was made in view of this point, and in particular, Cu-
The present invention aims to improve Fe--P alloys and provide copper alloys with various properties suitable as lead materials for semiconductor devices.

That is, in the present invention, Fe 1.0 to 3.5vt%, P
O1001~0.10wt%, Zn0.05~5. Ov
t%, the balance consists of Cu and unavoidable impurities,
High-strength, high-conductivity copper with excellent oxide film adhesion, characterized by surface roughness of 0.20 μm or less in center line average roughness (Ra) and 1.50 μm or less in maximum height (Rmax). Alloy and Fe 1.0-3.5wt%, P 0.001-0
．． 10wt%, Zn0.05-5.0wt%, and A1. Be, Cr, Hf, Mg, M
n, Ni, Sn, Ti, Co, and Zr in a total amount of one or more selected from the group consisting of o, oot~3
．． Contains 0wt%, the remainder consists of Cu and unavoidable impurities, and the surface roughness is 0.20μ in center line average roughness (Ra)
The present invention relates to a high-strength, high-conductivity copper alloy with excellent oxide film adhesion, characterized in that the maximum height (Rmax) is 1.50 μm or less.

[Detailed description of the invention]

Next, the reason for limiting the alloy components constituting the alloy of the present invention will be explained.

Fe is a component that forms an intermetallic compound with P and improves strength and heat resistance when subjected to aging treatment.
The reason why the content is set to 1.0 to 3°5 tit% is that 1.0
This is because if it is less than 3.5 wt%, the above-mentioned effect will not be obtained, and if it exceeds 3.5 wt%, there will be deterioration in workability and soldering properties, and a significant decrease in electrical conductivity.

P is a component that forms an intermetallic compound with Fe, but the content is reduced to 0. The reason for setting OO1 to 0.10wt% is 0,
If it is less than 0.001wt%, the above-mentioned effect is not present, and 0.10νt
%, deterioration of solder heat resistance, oxide film adhesion, and significant decrease in electrical conductivity occur.

The reason for setting the Zn content to 0.05 to 5.0 wt% is that Z
Solder heat resistance is improved by adding n, but the effect is small when the Zn content is less than 0.05 νt%;
This is because when the n content exceeds 5.0 wt%, the conductivity decreases significantly.

Also, as subcomponents A1, Be, CI, Hf, Mg,
Mn, Ni.

The reason for containing one or more types from the group consisting of Sn, Ti, Co, and Zr in a total amount of o, ooi to 3, Ovt% is because it can be expected to have the effect of improving the strength without significantly reducing the electrical conductivity. So, the total amount added is 0.001
If it is less than 3.0 wt%, the above-mentioned effect cannot be expected;
This is because if it exceeds t%, a significant decrease in conductivity occurs.

Furthermore, the center line average roughness (Ra) of the surface roughness is 0.20.
The reason why the maximum height (Rmax) is 1.5 μm or less is to improve the adhesion of the oxide film by smoothing the two surfaces.

〔Example〕

Next, the present invention will be specifically explained.

Ingots of various compositions related to the present invention alloy and comparative alloy shown in Table 1 (30m x 60++n x 120
After melting m) and solidifying the ingot, hot rolling was performed at 850°C to a thickness of 8+os, and the thickness was 1.5n after cutting.
Cold rolled to ++. Thereafter, solution treatment was performed at 850°C for 10 minutes, and cooling was performed at a rate of 10°C/see or higher.
After pickling, cold rolling was performed to a thickness of 0.25 m. These test materials were heated in a vacuum annealing furnace at 40°C to prevent the surface from being oxidized.
Aging treatment was performed at 0°C for a predetermined period of time. The surface roughness of the sample material was adjusted by changing the type of roll used in the final cold rolling.

As evaluation items for lead materials and spring materials, strength and elongation were measured by a tensile test, and bendability was measured by a 90° repeated bending test, with each reciprocation being considered as one time, and the number of bends until breakage.
Electrical conductivity (heat dissipation) was shown by electrical conductivity (%IAC5). Solderability was evaluated by immersing the sample in a solder bath (60% tin, 40% lead) at 230±5° C. for 5 seconds using a vertical dipping method, and visually observing the wetting state of the solder w4. The plating adhesion was determined by applying Ag plating with a thickness of 3μ to the sample, and
The sample was heated at ℃ for 5 minutes, and the presence or absence of blisters generated on the surface was evaluated by visual observation.

The springiness was evaluated by measuring the spring limit value.

Regarding solder heat resistance and peelability, the material is coated with 5μ solder plating (
60%Sn, 40%PB) and kept in a constant temperature bath at 150°C for up to 2000hr, taking it out every 100hr and
The solder was bent back and forth once at 0°, and the presence or absence of peeling of the solder was examined.

Regarding oxide film adhesion, heat the material at 200°C to 500°C for 3 minutes in the air to generate an oxide film on the surface, apply adhesive tape to the oxide film, and then carefully peel off the oxide film. Evaluation was made based on the presence or absence of peeling.

As is clear from Table 1, Nα1 of the alloy of the present invention is a basic alloy type and has a tensile strength of 58.8 kgf/rm2. It has a conductivity of 48.1% lAC3, and has both high strength and high conductivity. In addition, the surface roughness is Ra: 0.088μrin,
Since the Rmax is adjusted to 0.275 μm, the adhesion of the oxide film is also good. Furthermore, including solder heat resistance and peelability,
It can be seen that other properties are also excellent.

Na3 in this alloy is 0.82w as a subcomponent in the basic alloy system.
By adding t% Co and 0.36vt% Al, the strength is slightly improved compared to Nα1 of the alloy of the present invention. Although the electrical conductivity is slightly lower due to the improved strength, other properties are almost the same as those of the alloy of the present invention, No. 1.

Comparative alloy &1 has a small amount of added Fe, so its strength is inferior to the invented alloy. The comparative alloy Ha 2 is based on the basic alloy, but has a large surface roughness, and N114
Because of the large amount of P added, the oxide film adhesion of both alloys is inferior to that of the alloy of the present invention. Comparative alloy &3 has a large amount of Fe added, so its plating adhesion, repeated bending properties, and electrical conductivity are inferior to the invention alloy.
Since this alloy does not contain Zn, its solder heat peeling resistance is inferior to that of the alloy of the present invention. On the other hand, comparative alloy island 6 has a large amount of Zn added, so its conductivity is inferior to that of the alloy of the present invention.

It can be seen that the alloy of the present invention has high strength and high conductivity, and also has excellent oxide film adhesion. In addition, other properties including solder heat resistance and peelability are also good.

[Effects of the Invention] The alloy of the present invention is suitable as a high-strength, high-conductivity copper alloy used for semiconductor device lead materials and the like.

Margin below

Claims (2)

[Claims] (1) Fe1.0-3.5wt%, P0.001-0.
10wt%, Zn0.05-5.0wt%, the balance consists of Cu and unavoidable impurities, the surface roughness is 0.20μm or less in centerline average roughness (Ra), and the same maximum height (R
A high-strength, high-conductivity copper alloy with excellent oxide film adhesion, characterized by a max) of 1.50 μm or less. (2) Fe1.0-3.5wt%, P0.001-0.
10 wt%, Zn0.05 to 5.0 wt%, and further subcomponents such as Al, Be, Cr, Hf, Mg, Mn, Ni,
Contains one or more selected from the group consisting of Sn, Ti, Co, and Zr in a total amount of 0.001 to 3.0 wt%, the balance being Cu and unavoidable impurities, and the surface roughness is equal to the center line average. A high-strength, high-conductivity copper alloy with excellent oxide film adhesion, characterized by a roughness (Ra) of 0.20 μm or less and a maximum height (Rmax) of 1.50 μm or less.