Alloy 171 for Electronic Interconnects
Copper Applications in Electronics & Communications
The use of copper and copper alloys strip and wire in the connector industry represents only a fraction of the total worldwide use of copper. However, copperbased materials, with its combination of inherent excellent conductivity, formability and spring characteristics make them strategic materials to the connector industry.
Current estimates for the U.S. connector market total 8000 tonnes per month (212 millions pounds/year) consisting of 27% Brass, 21 % Phosphor Bronze (PB), 16% High Performance Alloys (HPA), 13% Beryllium Copper (BeCu), Tin Brass 5%, CuNiX Alloys 5% and other alloys or unknown 13%.
|Consumption by market segment|
|Computer and business machines||22%|
Copper and copper alloy consumption by product category of electronic interconnect products is as follows:
|Consumption by product category|
|Printed circuit connectors||9%|
|Insulation displacement connectors||5%|
It should be noted that these figures represent total mill product and not finished product weight. The electronic interconnect industry's average scrap weight is approximated at 43%.
The use of BeCu for connectors began in the 1940's and was limited to military and telecommunication applications. During the 1950's and 1960's there was a significant increase in demand for BeCu driven by high reliability applications such as mainframe computers and telecommunications. The major demand generators were IBM and AT&T. The early use of BeCu was limited to the high strength Alloy 172, which required heat treatment after stamping and forming. Development of a "mill hardened" product during the 1960's eliminated the need for heat treating while still providing a formable material. The first major use of this mill hardened material was IBM's SLT contact for the 360 mainframe computer which was developed in the early 1960's and continued in production until 1980, reaching annual volumes of 800,000 lbs.
The use of BeCu in the connector industry peaked in the late 1980's due to a variety of factors:
- Decline in high reliability demands by the computer and telecom markets
- Improved connector contact design technology
- The development of new HPA
- Decline in military requirements
With BeCu reaching price levels 3-4 times of PB and HPA designers were driven to find alternatives to BeCu.
In response to market changes BWI developed and introduced a new alloy, (Alloy 174) in the mid-1980's with a price approximately one-half that of traditional BeCu. Alloy 174 offered the connector designer high reliability with affordable prices although still 2 times the price of PBA and HPA.
During the mid-1990's, as the automotive electronics market was developed, there was a major shift from brass terminals to the need for higher performing Cu Alloys. This change was driven by new automotive standards for higher performance and increased reliability particularly at high operation temperatures (in excess of 125C).
While BeCu Alloy 174 met the demands of these new requirements price was still a deterrent to all but the critical and safety related performance applications. This led BWI to the development of Alloy 171 in 1997. Coupled with a $117 million expansion of our primary strip manufacturing facilities BWI introduced Alloy 171 at a market price comparable to other available HPA being offered around the World. This new alloy system offers a combination of high strength, excellent and consistent formability with low stress relaxation at temperatures up to 200C.
Let us look at Alloy 171 close up.
- Chemical composition
- Physical properties
- Mechanical properties
- Stress relaxation
- Alloy 171 vs. traditional BeCu + Chemical composition + Mechanical and physical properties
- Alloy 171 vs. mid-performance copper alloys
Alloy 171 Close Up
|Nickel (Ni)||Zirconium (Zr)||Beryllium (Be)||Tin (Sn)||Copper (Cu)|
|0.5-1.4||0.5 max||0.15-0.50||0.25 max||Balance|
|Electrical Conductivity||50% IACS minimum||29 minimum m/ohm-mm2|
|Thermal Conductivity||128 Btu/(ft-hr-oF)||0.52 cal/(cm-sec-oC)|
|Elastic Modulus||20 x 106 psi||138 kN/mm²|
|Density||0.318 - -.323 lb/in³||8.80-8.98 gm/cm³|
|Temper||Yield Strength||Tensile Strength||Elongation||Formability (R/t)|
|ksi||N/mm²||ksi||N/mm²||(min)||Good Way||Bad Way|
- Stress Relaxation measured after 1000 Hours
- Initial Stress was 75% of 0.2% YS
Alloy 171 vs Traditional BeCu
|Alloy 171||0.15 - 0.50||-||0.5 - 1.4||-||0.25 max||0.50 max|
|Alloy 25 & 190
|1.8 - 2.00||-||-||0.20 min.||-||-|
|0.2 - 0.6||-||1.4 - 2.2||-||-||-|
|Alloy 174||0.15 - 0.50||0.35 - 0.60||-||-||-||-|
|ksi||ksi||% IACS min.||Percent R.S.||Good
|95 - 115||80 - 100||50%||86%||0.3||0.3|
|185 - 215||160 - 195||22%||88%||0.5||1.0|
|135 - 150||110 - 135||17%||80%||2.0||2.0|
|110 - 135||95 - 120||48%||85%||2.0||2.0|
|95 - 115||80 - 100||50%||80%||0.5||0.5|
|- Alloy 25 is formed and then heat treated to the stength level shown.
- Yield Strength is determined using the 0.2% offset method.
- Stress Relaxation is the % Remaining Stress after exposure to 150C for 1000 hours.
As we move towards the year 2000 there are new challenges facing the copper based raw material suppliers and our relationships with the connector industry. Most significant amongst these changing developments are:
- U.S. connector industry being challenged by China and other Asian connector manufacturers causing severe price erosion.
- Foreign competition for U.S. connector manufacturers is being compounded by the strong dollar.
- The new product development cycle has been reduced from a few years to a few months.
- The continuing consolidation in the connector industry has increased the purchasing leverage of the bigger players.
The resulting impact on the copper-based material suppliers takes the form of:
- Heavy price pressure resulting in reduced profits (i.e. the volume price for C510, phosphor bronze has dropped 50% in the last 5 years and, 30% in the last 9 months.
- Copper alloy companies are scrambling to develop new and modff ied alloys that are more cost effective. However, with the cycle reduction of new connector or product design often cannot incorporate these new alloys.
- Copper alloy producers are being pushed to provide more design support - FEA's etc.
- The copper industry, worldwide are forming alliances to be able to offer a global supply chain.
It is unlikely that in the face of lower profit expectations that any significant investments will be made in the near future. A frequently heard comment in the copper ailoy industry is: "What the World doesn't need is another Brass Mill"!
Maybe what the World needs is a closer working relationship between the connector industry and its strategic material suppliers.
Also in this Issue:
- Alloy 171 for Electronic Interconnects
- Copper's Role in the Safe Disposal of Radioactive Waste: Copper's Relevant Properties - Part I
- Q & A With Hans-Erhard Reiter of the ADSL Forum
- Copper and Aquatic Life
- Research on Copper Joining Techniques Evaluates New Designs and Brazing Methods