1. Copper strip is the highest barrier area of copper processing industry. As an important downstream of copper strip, connector consumes a large amount of plate and strip. As a chip carrier of integrated circuit, lead frame also belongs to connector. With the help of bonding materials, it realizes the electrical connection between the lead-out end of the internal circuit of the chip and the external wiring, and plays a bridge role in connecting with the external wire. In addition to high strength and high thermal conductivity, lead frame also requires good solderability, stamping property, etching property and adhesion of oxide film particles. It is usually made of copper iron series and copper nickel silicon series C70250.

2. Cu Ni Si and Cu Cr Zr alloy plates and strips belong to high strength and high conductivity alloy. Bowei alloy can be produced in batch in China, and Xingye Shengtai copper can produce Cu Ni Si alloy in batch. In China, only Dongfang tantalum industry can produce Cu be, but domestic companies cannot supply Cu ti. In particular, Cu Ni Si alloy has been widely used in electronic field due to its excellent high temperature stability.

3. The comprehensive properties of Cu Ni Si alloy are excellent, the permeability is increasing, and the potential is great. The trend of miniaturization and current carrying capacity of electronic products is obvious. In the case of high current connection, such as base station power connector, new energy vehicle connector and smart phone connector, the high conductivity copper nickel silicon alloy can inhibit the heat and temperature rise, forming a strong substitution for other copper alloys, such as brass, Tin Phosphorus Bronze, etc.

The smart phone connector is more heat-resistant than the car. The temperature environment inside the car: 120 ℃ for engine, 135 ℃ for engine surface, 120 ℃ for instrument panel surface, 105 ℃ for interior floor and 117 ℃ for rear deck. The temperature inside the car can reach 120 ℃ without air conditioning. The use of brass and tin phosphor bronze for automobile connector has been unable to meet the requirements. It is necessary to use titanium copper or copper nickel silicon with better stress relaxation resistance. At present, titanium copper is only produced abroad, and the processing cost is as high as 200000 yuan / ton. The processing cost of copper nickel silicon is between 20000 yuan / ton and 30000 yuan / ton.

5. High performance and low-cost products such as c42500, c41125, pw33520 (exclusive patent product of Bowei alloy) have been developed at home and abroad to replace Tin Phosphorus Bronze. The yield strength of pw33502 alloy developed in China is 570Mpa and the electrical conductivity is 34%, which is twice of the original C5191, which can meet the requirements of high transmission and low temperature rise. The bending performance in bad direction is better than the original C5191. Tin content is lower than that of C5191, and can be recycled. Compared with Tin Phosphorus Bronze, it has excellent comprehensive performance and high cost performance.

6. China's copper processing industry has experienced three stages, and now it has entered the stage of high performance materials represented by c7025. In order to meet the needs of communication, electronic and automotive industries. Xingye Shengtai copper has developed c7026 and c7035 copper nickel silicon materials. C7035 has excellent properties and can partly replace low beryllium copper alloy.

7. C18150 / c18400 - strength 600MPa, with 85% IACS conductivity and 330W / (m · K) thermal conductivity, is the best copper alloy in high conductivity and medium strength area, and has very high resistance to stress relaxation and high temperature softening. Application fields: high current connector, hybrid charging and discharging connector, fast charging and flashing charging of battery, high power relay, terminal and efficient thermal management scheme.

8. The development of high-performance copper alloy in the future may have the following four directions: (1) double 70 alloy, tensile strength 700MPa, conductivity 70% IACS, thickness 0.03-0.06mm; (2) environmental friendly materials, tensile strength > 1000 MPa, yield strength > 950 MPa, conductivity > 45% IACS; (3) new composite materials, using the characteristics and advantages of various metal varieties, to achieve the comprehensive performance improvement and cost optimization; (4) Magnetic conductive materials, CFA copper iron alloy products, general iron content of 15-50%.

9. The supply of high-end boards and belts in Japan is in short supply. Due to the rapid development of China's copper strip industry, Japanese enterprises can only produce high-end copper strip, such as copper nickel silicon series, copper chromium zirconium series, beryllium copper, titanium copper and so on. Japan's copper strip production (excluding Brass Belt) increased from 190000 tons in 1991 to 270000 tons in 2018, accounting for 33% of the copper processing industry. The increment mainly comes from: (1) semiconductor lead frame, etching type; (2) automotive connector; (3) reflow tin plating process with low insertion force; (4) tin bronze, Kosen alloy, titanium copper and beryllium copper for mobile phone. Due to enterprise merger and product upgrading, the processing costs of copper strip industry increased.

10. Japanese enterprises began a new round of investment due to the improvement of demand and the growth of automotive electronics. Japanese enterprises are optimistic about the downstream: the Internet of things, artificial intelligence, big data, automatic driving, electric vehicles and other emerging industries on semiconductors and sensors. These downstream will promote the demand for high-performance copper sheet and strip in the long term.

Risk tips: copper strip downstream demand deterioration; downstream technology update fast, enterprises are not up to the pace; trade war intensifies; enterprise production and operation risks.

1、 Copper strip for electrical connectors

The contents of this chapter are mainly from the speeches of the conference: Yang Fen's "basic technology research on the application of contact copper materials" and Peng Lijun's "systematic research on high performance copper alloy materials for electrical connectors".

In a typical equipment system, there are many complicated connectors and other interconnection devices, including ordinary wires, equipment circuit boards, printed circuit connectors, backplane wires and interconnection cables. Generally, there are six types of connection on electronic or electrical equipment: internal connection of components; connection of components to printed circuit board or wire; connection of printed circuit board to conductor or other printed circuit board (in frame) on the same internal frame of single machine; connection from one internal frame to another inside frame in the same single cabinet; and; External connection from one stand-alone device to another; connection between systems.

Lead frame is the contact to realize the second type of connection. As a chip carrier of integrated circuits, it realizes the electrical connection between the lead-out end of the internal circuit of the chip and the external wiring with the help of bonding materials, which plays a bridge role in connecting with the external wires.

In addition to high strength and high thermal conductivity, lead frame also requires good solderability, stamping property, etching property and adhesion of oxide film particles. It is usually made of copper iron series and copper nickel silicon series C70250.

As an important downstream of copper strip, connector consumes a lot of plate and strip. The main performance requirements of connector for copper strip are: high strength, high formability, high conductivity, excellent stress relaxation resistance. Other properties are: fatigue performance, indicating quality, etc. The main copper plates for electrical connectors are as follows:

According to the strength and unit price, copper alloy can be divided as follows: high strength easy forming alloy; medium high strength and high conductivity alloy; medium high strength alloy and general alloy. Cu Ni Si and Cu Cr Zr alloy plates and strips belong to medium high strength and high conductivity alloys. Bowei alloy can be produced in batch in China, and Xingye copper can produce Cu Ni Si alloy in batch. In China, only Dongfang tantalum industry can produce Cu be, but domestic companies cannot supply Cu ti. In particular, Cu Ni Si alloy has been widely used in electronic field due to its excellent high temperature stability.

Cold deformation strengthening

The common strengthening methods of contact copper materials are: cold deformation strengthening, precipitation strengthening, excess phase strengthening and refining structure strengthening.

Cold deformation strengthening is also known as cold work hardening, and the deformation of metal materials at the recrystallization temperature is called cold deformation. After cold deformation, the material is strengthened, and the strengthening strength changes with the deformation degree, deformation temperature and material properties.

The same specification of C5191, qsn4-3 and other Sn-P bronze have higher tensile strength and hardness than H62, HPb59-1 and other brass. However, the cost of adding tin to the tin phosphor bronze increases, and the conductivity is low and the bending performance is poor. Therefore, we have developed c42500, c41125, pw33520 (exclusive patent products of Bowei alloy) and other high-performance and low-cost alternative products at home and abroad. The yield strength of pw33502 alloy developed in China is 570Mpa and the electrical conductivity is 34%, which is twice of the original C5191, which can meet the requirements of high transmission and low temperature rise. The bending performance in bad direction is better than the original C5191. Tin content is lower than that of C5191, and can be recycled. Compared with Tin Phosphorus Bronze, it has excellent comprehensive performance and high cost performance.

Resistance to stress relaxation and heat resistance

Metal stress relaxation refers to the phenomenon that the total strain (elastic strain and plastic strain) remains unchanged at constant high temperature, while the stress gradually decreases with time. The stress relaxation resistance of copper alloy used for contact parts is an important technical characteristic that determines whether the material can be used reliably. Electrical connector is often due to the stress relaxation of jack contact material, resulting in poor contact or instantaneous power failure. C70250 has good stress relaxation resistance.

The heat resistance of copper alloy materials for contact parts is usually measured by measuring the change of contact pressure (stress relaxation) at the same temperature for a long time. According to the introduction of JX company in Japan, after heating 150 ℃ for 1000 hours, the contact pressure of connector is compared with that before heating. Only 8% of brass and 50% of Tin Phosphorus Bronze. However, Cu Ni Si alloy still has 80-90% and Ti Cu can still maintain 95%. However, the processing cost of titanium copper is about 200000 yuan per ton, which is much higher than that of copper nickel silicon (20000-30000 yuan per ton).

Automotive connectors are more resistant to heat than smartphones. The temperature environment inside the car: 120 ℃ for engine, 135 ℃ for engine surface, 120 ℃ for instrument panel surface, 105 ℃ for interior floor and 117 ℃ for rear deck. The temperature inside the car can reach 120 ℃ without air conditioning. The selection of brass and phosphor bronze for automobile connector can not meet the requirements. It is necessary to use titanium copper or copper nickel silicon with better stress relaxation resistance.

High conductivity copper alloy

Generally, the yield strength of high conductivity copper alloy strip is more than 500MPa, and the conductivity is about 80% IACS. It is mainly used in high current connection occasions, such as base station power connector, new energy vehicle connector and smart phone connector. The power supply of the connected machine inside the smart phone is increasing, and the power consumption of each core is increased from 0.3A to 1.5-3.0a, which requires copper alloy to maintain high strength and high conductivity. C52100 Tin Phosphorus Bronze with conductivity of 12% was originally selected for usbtype-c male terminal, and high conductivity copper nickel silicon alloy with conductivity of 65% was used to inhibit the heating and temperature rise.

Application of balance direction copper alloy

Generally, the better the conductivity of copper alloy is, the more difficult it is to maintain high strength. The balanced direction copper alloy plate and strip is mainly used in the occasions where the material strength and conductivity have certain requirements. Generally, the yield strength is above 650mpa and the conductivity is about 65% IACS. For example, heavy-duty connectors and type-C bus terminals require high conductivity and good plug-in resistance. Due to different user design concepts, some pay attention to conductivity and others pay attention to yield strength. Therefore, there are two types of high conductivity copper nickel silicon alloy for users to choose: conductivity 65% IACS, yield strength 650mpa, or conductivity 90% and yield strength 490mpa.

High strength directional copper alloy

Generally, the yield strength of high strength copper alloy strip should be above 900MPa and the conductivity should be about 20% IACS. It is mainly used for signal connection, such as VCM, headset, SIM card connector, etc. The thickness of the smart phone of a manufacturer has thinned by more than 20% in five years. As a result, most of the board to board connectors assembled inside the mobile phone are flat and thin spaced. All other connectors of the mobile phone also require miniaturization. The mechanical strength and bending process formability of the original brass and Tin Phosphorus Bronze are difficult to meet the increasingly stringent requirements. Only by using copper nickel silicon alloy or titanium copper and other high-performance copper alloys can the requirements of high strength, good bending processability and high conductivity be met. Compared with the original Tin Phosphorus Bronze, the contact pressure of copper nickel silicon alloy can be increased by 12%, while that of titanium copper can be increased by 22%. The price of titanium and copper is much higher than that of copper nickel silicon.

Beryllium copper and its substitutes

Compared with bronze and brass, beryllium copper has higher strength, strong stress relaxation resistance and greater elasticity, which can provide maximum force in limited space. It also has high conductivity and thermal conductivity, excellent corrosion resistance and good process performance. In the annealed and cold rolled state, it can be formed in any direction. As a result, beryllium copper is widely used in aviation, aerospace and other high reliability connector fields.

However, the production and smelting process of beryllium copper has serious environmental pollution. Whether it will be gradually banned in the world has always been a problem that leaders and experts in the connector industry should pay attention to. In the increasingly stringent environmental protection situation, the research and development of beryllium copper substitutes has always been a concern in the industry. The world's major copper processing enterprises have developed copper nickel tin series, copper nickel silicon series and titanium copper alloy and other alternative materials, some of which have occurred.

2、 Development trend of new copper alloy products

The content of this chapter is mainly from the conference report: Jiqing "industrial copper new copper alloy products release report".

China's copper processing industry has experienced three stages, and now it has entered the stage of high performance materials represented by c7025. In order to meet the needs of communication, electronic and automotive industries

High performance copper alloy should have high strength, excellent conductivity, stress relaxation resistance and thermal conductivity. It is a key leader in aerospace, satellite navigation system, 5g communication, new automobile, network base station, smart home, large-scale integrated circuit, etc High strength, high conductivity, high elasticity, high temperature resistance and stress relaxation resistance are very important properties of high performance copper alloy, and its preparation technology represents the advanced level of copper processing technology.

Based on c7025, Xingye Shengtai developed c7026 and c7035 materials. The strength of c7035 can reach 900MPa, and the conductivity is 42-45% IACS. The production process is environmentally friendly and can be used as a substitute for low beryllium bronze.

In the following data, xyk-5 represents c7025, xyk-31 represents c7026, and xyk-32 represents c7035. In addition to high strength and high conductivity, these three materials also have strong resistance to stress relaxation and high temperature softening

Medium strength and high conductivity alloy:

C18150 / c18400 - strength 600MPa, with 85% IACS conductivity and 330W / (m · K) thermal conductivity, is the best copper alloy in high conductivity and medium strength area, with very high resistance to stress relaxation and high temperature softening. Application fields: high current connector, hybrid charging and discharging connector, fast charging and flashing charging of battery, high-power relay, terminal and preferred materials for efficient thermal management scheme.

Comparison of c18150 / c18400, c18080 and c18070: the elastic modulus of the three materials is basically close, and the strength of xyk-36 is higher than that of c18070 and c18080.

Under the condition of 150 ℃ / 1000h, the order of heat stress relaxation rate performance is: xyk-36 (c18150 / c18400) > c18080 > c18070.

The order of high temperature softening resistance is xyk-36 (c18150 / c18400) > c18080 > c18070.

The order of bending formability is as follows:

C18080>C18070>XYK-36(C18150/C18400)。

The development of high-performance copper alloy in the future may have the following four directions: (1) double 70 alloy, tensile strength 700 MPa, conductivity 70% IACS, thickness 0.03-0.06 mm; (2) environmental protection materials, tensile strength > 1000 MPa, yield strength > 950 MPa, conductivity > 45% IACS; (3) new composite materials, using the characteristics and advantages of various metal varieties, to achieve comprehensive performance improvement and cost optimization; (4) Magnetic conductive materials, CFA copper iron alloy products, general iron content of 15-50%.

3、 Current situation of copper processing industry in Japan

In the late 1991, Japan's copper production reached its peak, 1 million 200 thousand tons, surpassing the United States to become the number one in the world. Among them, 340000 tons of copper rods, 240000 tons of copper tubes and 390000 tons of copper strips (including 200000 tons of brass strips). After 1991, Japan's copper processing output decreased slightly, but remained at the level of about 1 million tons. In the 2008 financial crisis, it dropped to 650000 tons, and then recovered to the level of about 800000 tons, which has been maintained up to now.

Several trends of Japanese copper processing industry in 2008: (1) merger. (2) Transform to produce high value-added products.

From 2016 to 2018, the supply of plate and strip began to fall short of demand. The output of copper strip (excluding Brass Belt) increased from 190000 tons in 1991 to 270000 tons in 2018, accounting for an increase from 15% to 33%. The increment mainly comes from: (1) semiconductor lead frame, etching type; (2) automotive connector; (3) reflow tin plating process with low insertion force; (4) tin bronze, Kosen alloy, titanium copper and beryllium copper for mobile phone. Due to enterprise merger and product upgrading, the processing costs of copper strip industry increased.

With the improvement of demand and the growth of automotive electronics, Japanese enterprises began a new round of investment. Japanese enterprises are optimistic about the downstream: the Internet of things, artificial intelligence, big data, automatic driving, electric vehicles and other emerging industries on semiconductors and sensors. These downstream will promote the demand for high-performance copper sheet and strip in the long term.

The output of major Japanese companies is as follows:

Kobe Steel: the monthly output is 4700-4800 tons, of which 97% is copper plate and strip used in the electronic field, and more than 75% of the output of the exclusive invention alloy brand.

Mitsubishi copper: production capacity 4500 tons per month, output 4000 tons per month. Acquisition of Yamaha (600-1200 tons per month), including c7035100-200 tons per month, 7025300 tons per month, c194100 tons per month, titanium copper 100 tons per month.

JX metal (daily mine): the production capacity is 4000 tons per month, including 1700 tons of tin bronze per month, 100 tons of white copper, 200-300 tons of tinned brass (to be abandoned), 300 tons of Kosen alloy and 300 tons of titanium copper per month; in addition, nkc164, nkc388, high strength nkt322 and high conductivity nkt180.

4、 History of nonferrous industry PE band and Pb band