JPH02141551A - High strength and high conductivity copper alloy having excellent adhesion for oxidized film - Google Patents

Abstract

PURPOSE:To provide the title copper alloy with high strength and high electric conductivity and to improve its adhesion for an oxidized film by incorporating specific amounts of Fe, Co and P into a copper alloy and regulating the surface roughness of the alloy to the specific value or below. CONSTITUTION:The compsn. of the high strength and high conductivity copper alloy is formed with, by weight, 0.2 to 4.0% Fe, 0.2 to 2.5% Co, 0.001 to 0.2% P and the balance Cu with inevitable impurities. The alloy having the compsn. is refined into an ingot, which is rolled to regulate the surface roughness to <=0.2mum in the center line average roughness Ra and to <=1.50mum in the maximum height Rmax. In this way, high strength and high conductivity copper alloy having excellent adhesion of an oxidized film can be obtd. If required, as auxiliary components, 0.001 to 3.0wt.% total amounts of one or more kinds selected from Al, Be, Cr, Hf, Mg, Mn, Ni, Sn, Ti, Zn and Zr are incorporated into the alloy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a copper alloy suitable for lead materials of semiconductor devices such as transistors and integrated circuits, and conductive spring materials such as connectors, terminals, relays, and switches. This invention relates to a high-strength, high-conductivity copper alloy with excellent 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, the number of ICs with high power consumption has increased due to the improvement in the degree of integration of half-core circuits, resins are often 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.

Generally, lead materials for semiconductor devices are required to have the following properties.

(1) Leads must exhibit excellent thermal and electrical conductivity, as they are required to act as an electrical signal transmission part and also have the function of discharging heat generated during the packaging process and circuit use to the outside. .

(2) Since the adhesion between the lead and the mold is important from the perspective of protecting the semiconductor element, the coefficient of thermal expansion of the lead 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 manufactured by punching or bending lead material, so the workability of these materials should be good.

(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) Prices are 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. .

[Problem that the invention seeks to solve]

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, and none of them can satisfy all of these characteristics. do not have. On the other hand, Cu −
Since the Fe-P alloy satisfies the above-mentioned required properties to a large extent, Cu-Fe-P alloys and improved alloys with some additive elements added thereto 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 had not been considered an issue in the past, has become an extremely important characteristic. It has become.

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 and the like to enter therefrom, significantly reducing the reliability of the IC. Therefore, oxide film adhesion is one of the most important properties for a high-strength, high-conductivity copper alloy used for lead frame materials and the like.

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

[Structure of the invention]

The present invention was made in view of this point, and in particular,
The objective is to improve the -Fe-P alloy and provide a copper alloy that has various properties suitable as a lead material for semiconductor devices.

That is, Fe 0.2-4.0wt%, Co 0.2
~2.5wt%, P 0.001~0.2%+1%, the balance consists of Cu and unavoidable impurities, the surface roughness is 0.20μm or less in center line average roughness (Ra), the same maximum height High-strength, high-conductivity copper alloy and Fe with excellent oxide film adhesion characterized by an Rmax of 1.50 μm or less
0.2-4.0wt%, Co 0.2-2.5wt%
, P0.0O1-0.2wt%, and A as a subcomponent
1. Be, Cr, Hf, Mg, Mn, Ni
, Sn, Ti, Zn, and one or more selected from the group consisting of Zr in a total amount of 0.001 to 3.0w
t%, the balance consists of Cu and unavoidable impurities,
A high-strength, high-conductivity steel alloy with excellent oxide film adhesion, characterized by a surface roughness of 0.20 μm or less in center line average roughness (Ra) and 1.50 μ+i or less in maximum height (Rmax). It is in.

[Detailed description of the invention]

Next, the reasons 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 through aging treatment and improves strength and heat resistance, but the reason for setting the content to 0.2 to 4.0 wt% is that
If it is less than 4.0t1t%, the above-mentioned effect will not be obtained, and if it exceeds 4.0t1t%, deterioration of workability, plating adhesion, and significant decrease in electrical conductivity will occur. Like Fe, CO is a component that forms an intermetallic compound with P and improves strength and heat resistance when subjected to aging treatment.
, 5vt% is because if it is less than 0.2wt%, the above-mentioned effect will not be obtained, and if it exceeds 2.5vt%, the workability will deteriorate and the electrical conductivity will drop significantly. P is a component that forms an intermetallic compound with Fe and CO, but the reason why the content is set to 0.001 to 0.2 wt% is that 0.001w
This is because if it is less than t%, the above-mentioned effect will not be obtained, and if it exceeds 0.2wt%, solderability, oxide film adhesion will deteriorate, and electrical conductivity will decrease.

In addition, A1. Be, Cr, Hf,
Mg, Mn, Ni, Sn, Ti, Zn, Zr
The total amount of one or more selected from the group consisting of 0
．． 001-3. (The reason for adding ht% is that it can be expected to have the effect of improving the strength without significantly reducing the conductivity. If the total amount added is less than 0.001wt%, the above-mentioned effect cannot be expected, and on the contrary, 3. This is because if the content exceeds 0 wt%, a significant decrease in electrical conductivity will occur.Among these subcomponents, Zn and Mn are elements that improve solder heat resistance and peelability when added. Alternatively, it is recommended to add 0.01 to 1.0 wt% of both.

In addition, the surface roughness is 0.20μ in center line average roughness (Ra).
The reason for setting the maximum height (Rmax) to be 1.5 μm or less is to improve oxide film adhesion by smoothing the surface.

〔Example〕

Next, the present invention will be specifically explained. Ingots (3
0mm x 60mn x 120nwn) was melted, the ingot was prepared, hot rolled at 850°C to a thickness of 8nn, solidified and cold rolled to a thickness of 1.5mm, and then heated at 850°C for 10 minutes. Perform solution treatment, 1
Cool at a rate of 0'T:/see or higher, and after pickling, the thickness is 0.
Cold rolling was performed to 25 nm+. These test materials were aged in a vacuum annealing furnace at 400° C. for a predetermined period of time to prevent surface oxidation. 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 (%IACS). Solderability was evaluated by immersing the product in a solder bath (60% tin, 40% button) at 230±5° C. for 5 seconds using a vertical dipping method, and visually observing the state of solder wetting. The plating adhesion was determined by applying Ag plating with a thickness of 3μ to the sample at 450°C.
The sample was heated for 5 minutes, and the presence or absence of blisters on the surface was evaluated visually.

The springiness was evaluated by measuring the spring limit value.

Regarding oxide film adhesion, the material was heated at 200 to 500℃ to
An oxide film was formed on the surface by heating in the air for a minute, and an adhesive tape was attached to the oxide film, and then it was peeled off and evaluated based on whether or not the oxide film peeled off.

As is clear from Table 1, the alloy of the present invention &1 is a basic alloy type, and has a tensile strength of 59.1 kgf/WIs2 and an electrical conductivity of 48.2% IACS, and has both high strength and high electrical conductivity. There is. In addition, the surface roughness Ra is 0.082 μ-, R
Since the maximum thickness is adjusted to 0.283 μm, the adhesion of the oxide film is also good. Furthermore, it can be seen that other properties are also excellent. Nα3 of the alloy of the present invention is 0.21wt%h and 0.11wt%B as subcomponents in the basic alloy system.
This alloy has a slightly improved strength compared to Nα1, which is the alloy of the present invention. Although the electrical conductivity is slightly lower due to the improved strength, other properties are equivalent to &1 of the invention alloy.

The comparative alloy Nα1 has a small amount of Fe added, and the comparative alloy &6 does not have P added, so both have inferior strength compared to the invention alloy. Comparative alloy &2 is based on the basic alloy, but has a large surface roughness, and
Since No. 4 has a large amount of P added, both have inferior oxide film adhesion compared to the invention alloy. Since the comparative alloy Isao 3 has a large amount of Fe added, its plating adhesion, repeated bending properties, and electrical conductivity are inferior to the alloys of the present invention. In addition, the comparison alloy N
Since a5 has a large amount of Co added, its repeated bendability and electrical conductivity are inferior to those 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 has excellent oxide film adhesion. In addition, other properties are also good.

〔Effect of the invention〕

The alloy of the present invention is suitable as a lead material for semiconductor devices or a high-strength, high-conductivity copper alloy.

Margin below =11-

Claims (2)

[Claims] (1) Fe 0.2-4.0wt%, Co 0.2-2
．． 5 wt%, P 0.001 to 0.2 wt%, the remainder consists of Cu and unavoidable impurities, the surface roughness is 0.20 μm or less in center line average roughness (Ra), and the same maximum height (
A high-strength, high-conductivity copper alloy with excellent oxide film adhesion, characterized by an Rmax) of 1.50 μm or less. (2) Fe 0.2-4.0wt%, Co 0.2-2
．． 5wt%, P 0.001 to 0.2wt%, and further subcomponents such as Al, Be, Cr, Hf, Mg, Mn, Ni
, Sn, Ti, Zn, and Zr.
Contains 0.001 to 3.0 wt% of the species or two or more species in total, the balance consists of Cu and unavoidable impurities, and the surface roughness is 0.20 μm or less in center line average roughness (Ra), and the same maximum height A high-strength, high-conductivity copper alloy with excellent oxide film adhesion, characterized in that (Rmax) is 1.50 μm or less.