JPS63192834A - Copper alloy excellent in thermal peeling resistance of tin or tin-alloy coating layer - Google Patents

Abstract

PURPOSE:To obtain the titled copper alloy having various characteristics suitable for semiconductor equipment lead material and conductive spring material, by providing a composition consisting of prescribed amounts of Sn, P, and Mn and the balance Cu with inevitable impurities. CONSTITUTION:The copper alloy of this invention has a composition consisting of, by weight, 2.0-10% Sn, 0.08-0.3% P, 0.2-0.5% Mn, and the balance Cu with inevitable impurities. The above-mentioned copper alloy has superior electric and thermal conductivities, heat resistance, workability, adhesive strength of plating, solderability, corrosion resistance, an spring characteristics as copper alloy for lead material of semiconductor equipment and conductive spring material. Further, this copper alloy is characterized by remarkably improved thermal peeling resistance of tin or tin-alloy coating layer.

Description

[Detailed Description of the Invention] (Objective) The present invention relates to a copper alloy suitable for lead materials for semiconductor devices such as transistors and integrated circuits (ICs), and conductive spring materials for connectors, terminals, relays, switches, etc. It is. In particular, the heat-resistant peeling property of the tin or tin alloy coating layer (Heat-resistant peeling property here means the property of a material provided with a tin or tin alloy layer having a peeling-resistant effect against the effects of heat and the like.

) relates to copper alloys with excellent properties.

(Prior Art and Problems) Conventionally, as lead materials for semiconductor devices, Kovar (Fe-29Ni-16Co) and 42 alloy (Fe- High nickel alloys such as 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 unit 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) Since various heating processes are added during packaging,
Good heat resistance.

(4) Most leads are manufactured by punching or bending lead material, so the workability of these is good.

(5) The surface of the lead is plated with precious metal.

Good plating adhesion with these precious metals.

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

(7) Good corrosion resistance from the standpoint of equipment reliability and lifespan.

(8) The price is for the device.

To meet these various required characteristics, improved alloys containing phosphor bronze and some additional elements have been widely used. However, in recent years, reliability requirements for semiconductors have become more stringent, and surface mounting types that support miniaturization have become more common, so the heat-resistant peeling of tin and tin alloy coating layers, which had not been a problem in the past, has become more difficult. has become a very important characteristic item.

That is, the lead frame and the printed circuit board are soldered together, but during use, the temperature of the lead frame and the soldering area rises up to about 120° C. due to external temperatures and heat generated by energization. If exposed to such temperatures for a long time, the tin or tin alloy layer will peel from the lead frame.
Since it is possible for a semiconductor to fail, the thermal peelability of the tin and tin alloy coating layer is one of the most important characteristics when high reliability is required from the viewpoint of longevity. Especially F P P (FLAT PLASTIC
PACKAGE) and P L CC (PLASTICLE
Since the surface mounting type represented by ADED CHIP CARRIER is not inserted into the printed circuit board but is in surface contact, the heat-resistant peelability of the tin and tin alloy coating layer becomes even more important.

In addition, conventional springs for electrical equipment, springs for measuring instruments, switches,
As materials for springs used in connectors and the like, inexpensive brass, nickel silver, which has excellent spring properties and corrosion resistance, or phosphor bronze, which has excellent spring properties, have been used.

However, brass has inferior strength and spring characteristics, and nickel silver has poor conductivity, so phosphor bronze is the most widely used material with high reliability. In the field of conductive spring materials as well, tin or tin alloy plating is applied for reasons such as reducing contact resistance and improving corrosion resistance, and since soldering is often performed, tin and tin alloy plating as mentioned above is used. Heat-resistant peelability of the tin alloy coating layer has become extremely important due to the recent demand for improved reliability.

Current phosphor bronze alloys are unable to meet these strict requirements for heat-resistant peelability of tin and tin alloy coating layers, so we developed high-strength, high-conductivity materials with improved heat-resistant peelability of tin and tin alloy coating layers. The appearance of copper alloys was awaited.

(Structure of the Invention) The present invention has been made in view of the above points, and provides a copper alloy that improves the drawbacks of conventional copper-based alloys and has various properties suitable for lead materials and conductive spring materials for semiconductor devices. This is what I am trying to do.

The present invention provides: (1) Sn2. O~IO, 0wt%, Po, 08~0.
3 wt%, Mn0, 2-0, 5 wt%
Including.

A copper alloy having excellent heat-resistant peelability of a tin or tin alloy coating layer, the remainder of which is composed of Cu and unavoidable impurities.

(2) Sn2. O~IO, 0wt%, Po, 08~0.
3wt%, Mn0, 2~0, 5wt% and Al, Be, Go, Cr, Fe, Hf, In, Mo, M
One or two of g, Pb, Si, Te, Ti, Zn, and Zr
A copper alloy having excellent heat-resistant peelability of a tin or tin alloy coating layer, characterized in that it contains 0.05 to 1.0 wt% of tin or more, and the remainder consists of Cu and unavoidable impurities.

It not only has excellent electrical and thermal conductivity, heat resistance, workability, plating adhesion, solderability, corrosion resistance, and spring properties as a copper alloy for lead materials of semiconductor devices and as a conductive spring material. It is characterized in that the heat-resistant peelability of the tin or tin alloy coating layer is also significantly improved.

(Detailed Description of the Invention) Next, the reasons for limiting the alloy components constituting the alloy of the present invention will be explained.

The reason for setting the Sn content to 2.0 to 1O, 0 wt% is as follows.
When the Sn content is less than 2.0wt%, the expected strength cannot be obtained even with the co-addition of P; on the contrary, when the Sn content is 10.0w
This is because when the amount exceeds t%, the workability deteriorates significantly and the price also increases. The reason why the P content is set to 0.08 to 0.3 wt% is that when the P content is less than 0.08 wt%, the improvement in strength and heat resistance due to P content is not remarkable, and when the P content is 0.3 wt%, This is because if the temperature is exceeded, the heat-resistant peelability of the tin or tin alloy coating layer will be significantly deteriorated. Conventional phosphor bronze is usually 0
．． Although it is around 1 to 0.15 wt%.

After conducting various studies on the effects of tin or tin alloys on the heat-resistant peeling properties, it was found that exceeding 0.3 wt% had a sudden negative effect, so the upper limit was set at 0.3 wt%.

The reason why the Mn content is set to 0.2 to 0.5 wt% is that Mn
The heat peeling properties of the tin or tin alloy coating layer are greatly improved by addition, but the effect is small when the Mn content is less than 0.2 wt%, and conversely, when the Mn content is less than 0.5 wt%.
%, the electrical conductivity decreases significantly, making it unsuitable for use as lead materials for semiconductor devices or conductive spring materials, particularly where electrical conductivity is strongly required.

Furthermore, Al, Be, Go, and Cr are added as subcomponents.

Fe, Hf, In, Mo, Mg, Pb, Si, Te
, Ti, Zn, and Zr improves the strength and spring characteristics, but if the content is Q, Q5w
If it is less than t%, we cannot expect much effect from Soya, and if it is less than 1,0
O
, OS ~ 1.0 wt%.

(Effects of the Invention) As described above, the alloy of the present invention significantly improves the heat peeling resistance of the tin or tin alloy coating layer by limiting the phosphor bronze-based components, and also has the excellent strength of phosphor bronze. It is a copper alloy that has spring characteristics, heat resistance, and electrical conductivity, and also has good solderability and plating adhesion. Note that plating adhesion can be improved by lowering the oxygen content in impurities. In this alloy system, it is recommended that the content be preferably 20 ppm or less by weight. In addition, its coefficient of thermal expansion is close to that of plastic, making it suitable for plastic packages as a lead material for semiconductor devices. Therefore, the alloy of the present invention is suitable as a lead material and a conductive spring material for semiconductor devices, and no prior art alloy has such comprehensive properties.

The material of the present invention will be explained below with reference to Examples.

(Example) Ingots having various compositions of the alloy of the present invention shown in Table 1 were melted and cast using electrolytic copper or oxygen-free copper as a raw material in a high-frequency melting furnace in air, an inert atmosphere, or a reducing atmosphere. Next, this was hot-rolled at 800° C. to form a plate with a thickness of 4 ai, which was then flat-faced and cold-rolled to a thickness of 1.0 m. After annealing this at 500° C. for 1 hour, it was cold rolled into a plate with a thickness of 0°8 m and evaluated as a lead material.

For evaluation, strength and elongation were shown by a tensile test, heat resistance was shown by softening temperature at a heating time of 5 minutes, and electrical conductivity (heat dissipation) was shown by electrical conductivity (%IAC3). Soldering is done using the vertical immersion method in a solder bath (tin 60°C) at 230±5°C.
%, button 40%) for 5 seconds, and the wetting state of the solder was evaluated by visually observing vA. Plating adhesion was evaluated by applying Ag plating to a thickness of 3 μm to a sample, heating it at 450° C. for 5 minutes, and visually observing the presence or absence of blisters on the surface. These results are shown in Table 1 along with comparative alloys.

In addition, in order to evaluate it as a spring material, 1.
After annealing the 0m material at 500℃ for 1 hour, it was cold rolled into a 0.3m thick plate, which was annealed at various temperatures from 150 to 500℃ to remove strain, and its strength and elongation were evaluated by a tensile test. The spring properties were evaluated using the Kb value. This is shown in Table 2 along with comparative alloys.

Regarding the heat-resistant peelability of the tin or tin alloy coating layer I, which is a feature of the present invention, various phosphor bronze base materials shown in Tables 1 and 2 were subjected to alkaline degreasing, electrolytic degreasing, and pickling neutralization. Under the following conditions, 1.5 μm thick tin or solder electroplating was applied to those with and without copper underplating, heated in the atmosphere at 105°C for 1000 hours, and then bent 90' back and forth once. A peeling test was conducted by examining the presence or absence of peeling of tin or tin alloy using a microscope. The results are also shown in Tables 1 and 2.

The plating conditions are as follows.

Natsumemushikoyu Natsumean Copper sulfate 210 g / Q sulfuric acid 100 g
/ Q bath warm 30
°C current density 5A/drrl' - Table 2 and double - Stannous sulfate 70 g / Q sulfur M
100g/fl Cresol Sulfone Wi 100g/Q Gelatin 2gIQ Beta Naphthol 1.5g/ff Bath
Temperature 20℃ Current density
4A/d Solder plating bath Tin phenolsulfonate 160g/Ω Lead phenolsulfonate 160g/fl Phenolsulfonic acid 150g/Q bath Temperature
30℃ current density 3A/d, , fan UTB Nα1 manufactured by Ishihara Pharmaceutical ■ 20g/QUTB N1
1l 20mQ/QUTB PS-A
C6mD, IQ From these Tables 1 and 2, it is clear that the alloy of the present invention has significantly improved heat peeling resistance of the tin and tin alloy coating layer, and has excellent properties as a high-strength, high-conductivity copper alloy. .

Margin below

Claims (2)

[Claims] (1) Sn2.0-10.0wt%, P0.08-0.
3wt%, Mn0.2-0.5wt%, and the balance is C.
1. A copper alloy having a tin or tin alloy coating layer having excellent heat-resistant peelability, characterized by comprising u and unavoidable impurities. (2) Sn2.0-10.0wt%, P0.08-0.
3wt%, Mn0.2-0.5wt% and Al, Be,
Co, Cr, Fe, Hf, In, Mo, Mg, Pb, S
i, Te, Ti, Zn, and Zr.
A copper alloy having excellent heat-resistant releasability of a tin or tin alloy coating layer, characterized in that it contains 0.05 to 1.0 wt%, and the remainder consists of Cu and unavoidable impurities.