JPH02122035A - High strength and high conductivity copper alloy having excellent adhesion of oxidized film - Google Patents

Abstract

PURPOSE:To obtain the title copper alloy having excellent adhesion of an oxidized film and suitable for a lead frame material, etc., by specifying the contents of Fe and P as well as the wt. ratio of Fe to P. CONSTITUTION:The compsn. of a high strength and high conductivity copper alloy is formed with, by weight, 0.03 to 0.30 to 0.30% Fe and 0.005 to 0.3% P as well as 0.1 to 0.5P/Fe, i.e., the wt. ratio of Fe to P and the balance Cu with inevitable impurities. If required, 0.01 to 1.0% total amounts of one or more kinds among Al, Be, Co, Hf, In, Mo, Mg, Ni, Pb, Si, Sn, Te, Ti, Cr, Zr and Zn are furthermore incorporated thereto. The surface roughness of the alloy is moreover preferably regulated to <=0.2mum in the center line average height of Ra and to <=1.5mum in the maximum height of Rmax. The alloy having the compsn. has excellent adhesion of an oxidized film and is suitable as the high tensile and high conductivity copper alloy used for a lead frame, etc.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a copper alloy that is suitable for lead materials for semiconductor devices such as transistors and integrated circuits, and conductive spring materials for connectors, terminals, relays, switches, etc. This invention 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-29Nj, -16Co) and 42 alloy (Fe-29Nj, -16Co), which have a low coefficient of thermal expansion and 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.

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 viewpoint of protecting the semiconductor element, the thermal expansion coefficients of the lead material and the mold material should be similar.

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

(4) Good oxide film adhesion because an oxide film is formed between the resin and the material when various heating processes are applied during packaging.

(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) Since many products are soldered to the so-called outer leads, which are exposed outside the sealing material after packaging, good soldering should show good soldering properties.

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

(9) The price must be low.

In addition, conventionally, the materials used for springs such as springs for electrical equipment, needle side springs, switches, connectors, etc. have been inexpensive brass, nickel silver, which has excellent spring properties and corrosion resistance, or phosphor bronze, which has excellent spring properties. Ta.

[Problem that the invention seeks to solve]

Oxygen-free copper, tin-containing copper, phosphor bronze, Kovar, and 42 alloy, which 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 satisfies these characteristics. is not, whereas CLI −
Since the Fe--P alloy satisfies the above-mentioned required characteristics 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 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 and the like to enter therefrom, significantly reducing the reliability of the IC. Therefore, the emergence of a high-strength, high-conductivity copper alloy with improved oxide film adhesion, which is the most important aspect of a high-strength, high-conductivity copper alloy used for lead frame materials and the like, has been awaited.

[Structure of the invention]

The present invention was made in view of this point, and in particular, CuFe
The present invention aims to improve P-based alloys and provide copper alloys that have various properties suitable for use as lead materials for semiconductor devices, conductive spring materials for connectors, terminals, relays, switches, and the like.

That is, in the present invention, Fe0.03 to 0.30% by weight
, PO,005 to 0.03% by weight, the weight ratio of Fe and P is P/Fe of 0.1 to 0.5, and the balance is Cu and inevitable impurities. High-strength, high-conductivity steel alloy with excellent properties and FeO,03-0,3
0% by weight, Po, 005-0.03% by weight, Fe
The weight ratio of
Ni, Pb, Si, Sn%Te, Ti, Cr,
Contains a total amount of 0.01 to 1.0% by weight of one or more selected from the group consisting of Zr and Zn, and the balance is Cu.
A high-strength, high-conductivity steel alloy with excellent oxide film adhesion, which is characterized by consisting of
The present invention relates to the above-mentioned high-strength, high-conductivity copper alloy with excellent oxide film adhesion, characterized in that x) is 1.5 μl or less.

[Detailed description of the invention]

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

The Fe content is set to 0.03 to 0.30% by weight because
This is because Fe and P form a compound and precipitate through the aging treatment to improve strength and electrical conductivity. Fe content is 0.
If it is less than 0.03% by weight, the above-mentioned effect cannot be expected;
If it exceeds 30% by weight, oxide film adhesion, plating adhesion, solderability, processability deteriorate, and electrical conductivity significantly decreases. The reason why the P content is set to 0.005 to 0.03% by weight is that if the P content is less than o, oos weight%, the above-mentioned effects cannot be expected, whereas if it exceeds 0.03% by weight, oxidation will occur. This is because film adhesion and processability deteriorate, and electrical conductivity significantly decreases. Roughly Fe and P with a weight ratio of P/Fe of 0
．． The reason for setting P/Fe to 1 to 0.5 is that when P/Fe is less than 0.1, the amount of Fe that does not become a phosphide increases, and when P/Fe is less than 0.1, the amount of Fe that does not become phosphide increases. This is because the amount of P that does not become phosphide increases if the amount is exceeded, resulting in deterioration in oxide film adhesion, solderability, processability, and a significant decrease in electrical conductivity.

Furthermore, A1. Be, Co, Hf, In, Mo, M
g, Ni, Pb, Si, Sn, Te, Ti,
Cr, 7. The reason for adding one or more selected from the group consisting of Zn and Zn is that these additions can be expected to have the effect of improving strength without significantly reducing conductivity, and the total content is If the amount is less than 0.01% by weight, the above-mentioned effect cannot be expected, and if it exceeds 1.0% by weight, a significant decrease in conductivity will occur.

In addition, 1 surface roughness is 0.20 in center line average roughness (lla)
The reason for setting the thickness to be 1.5 μl or less at the maximum height (Rn+ax) is to improve the adhesion of the oxide film by smoothing the surface.

explain.

Ingots of various component compositions according to the invention alloy and comparative alloy shown in Table 1 were obtained by a casting method in an inert or reducing atmosphere.

Next, after face cutting these ingots,
The material was heated for an hour, hot rolled into a No. 5 plate, and immediately after the hot rolling was completed, the processed material was cooled at a rate of 1° C./sec or more.

This plate having a thickness of 5 nu was cold rolled into a plate having a thickness of 0.25 mm, and was subjected to an aging treatment at 400° C. for a predetermined period of time. Note that the surface roughness was adjusted by changing the type of roll.

As evaluation items for lead materials and spring materials, strength and elongation were measured by tensile tests, bendability was measured by 90° repeated bending tests, each round trip was counted as one time, and the number of bends until melting was measured, and electrical conductivity (heat dissipation) was measured. It 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 state of solder wetting. Plating adhesion was evaluated by applying Ag plating to a thickness of 3 μm on a sample, heating it at 450° C. for 5 minutes, and visually observing the presence or absence of blisters occurring on the surface. Moreover, the springiness was indicated by the spring limit value. These results, together with comparative alloys, are summarized in the first
Shown in the table.

Regarding the oxide film adhesion, which is the first point of the present invention, after heating the material in the air at 200 to 500°C for 3 minutes to form an oxide film on the surface, and applying adhesive tape to the oxide film. , - Peeled off with care and evaluated based on the presence or absence of peeling of the oxide film. Table 1 shows the formation temperature of the oxide film at which peeling occurred.

As is clear from Table 1, alloys 1 to 9 of the present invention have excellent oxide film adhesion, solderability, plating adhesion, and repeated bendability, and have high electrical conductivity, tensile strength, and spring limit values. The adhesion of oxide films used in semiconductor device lead frame materials and conductive spring materials is too high, resulting in poor solderability, oxide film adhesion, and repeated bendability. Since Comparative Alloy 11 does not contain P, Fe does not become a phosphide, and its electrical conductivity, tensile strength, and spring limit values are insufficient, and its solderability, oxide film adhesion, and repeated bendability are poor. Comparative alloy 12 is P/F
Since the e ratio is too high, the conductivity is low and the solderability, oxide film adhesion, and repeated bendability are poor.

Comparative Alloy 13 has too high a content of Fe and P, so its conductivity is low, and its solderability, plating adhesion, oxide film adhesion, and repeated bendability are poor. Comparative alloy 14.15 has too rough a surface and thus has poor oxide film adhesion.

〔Effect of the invention〕

The alloy of the present invention has excellent oxide film adhesion and is suitable as a high-strength, high-conductivity copper alloy used for lead frames and the like.

Margin below

Claims (3)

[Claims] (1) Fe 0.03-0.30% by weight, P 0.00
Contains 5 to 0.03% by weight, and the weight ratio of Fe and P is P/F
A high-strength, high-conductivity copper alloy with excellent oxide film adhesion, characterized in that e is 0.1 to 0.5 and the remainder consists of Cu and unavoidable impurities. (2) Fe 0.03-0.30% by weight, P 0.00
Contains 5 to 0.03% by weight, and the weight ratio of Fe and P is P/F
e is 0.1 to 0.5, and furthermore, Al, Be, Co
, Hf, In, Mo, Mg, Ni, Pb, Si, Sn,
It is characterized by containing a total amount of 0.01 to 1.0% by weight of one or more selected from the group consisting of Te, Ti, Cr, Zr, and Zn, and the remainder consisting of Cu and inevitable impurities. A high-strength, high-conductivity copper alloy with excellent oxide film adhesion. (3) Surface roughness is 0.2 μm in center line average roughness (Ra)
The high-strength, high-conductivity copper alloy with excellent oxide film adhesion according to claim 1 or 2, wherein the maximum height (Rmax) is 1.5 μm or less.