A wide variety of materials can be used to make quality metal springs and metal clips. We focus on certain properties and the effectiveness of each metal to help determine which is best for each part and application. Here’s a brief overview of some of the most common metal choices.
Stainless steel is ‘regular’ steel, plus a little chromium and nickel. Up to 30% of stainless steel is actually not steel, giving this particular alloy a strong corrosion resistance. While that is one of the factors for a good battery contact, stainless steel is much more costly than other options.
There is quite a bit of diversity within the family of materials known as brass, an alloy of copper and zinc. Depending on the electrical and mechanical properties desired, you can add tin, lead, aluminum, beryllium, chromium, phosphorous, and many, many more materials.
Spring brass is distinctive from brass because of its zinc presence – roughly 30% or so. This is a popular choice where cost is a major factor because it is the most inexpensive brass.
BeCu is 98% copper and 2% beryllium. BeCu is well-suited for battery contacts and springs due to its material and electrical properties. Beryllium Copper can be heat treated to increase its hardness, can last under high stress and fatigue, and has great durability and high conductivity. Durability is always beneficial when developing products for a variety of uses. BeCu also has twice the electrical conductivity of phosphor bronze. While beryllium copper does have the highest stamping costs of all the copper alloys, it is widely regarded as the best for battery springs and contacts.
Plating is another consideration when it comes to battery contact materials. Plating, also known as finishing, allows you to further affect the material properties of your battery contacts and springs. It can increase conductivity while simultaneously adding corrosion resistance properties. There are a few different plating methods we offer:
- Pre-Plated Material: One advantage of pre-plating is that you can selectively plate a substrate material, which reduces overall costs.
- Reel-to-Reel: Reel-to-reel plating allows for total coverage or selective coverage of a substrate material.
- Barrel: Barrel plating is the most economical way to plate parts. It requires less prep time and many pieces can be plated simultaneously.
- Dip: Dip plating is another common way to plate substrate materials. Electrical contacts are dipped into the plating material while they’re still on the stamping strip, which uses less plating material. It is a time-consuming process.
- Rack: Rack plating is great for plating small or delicate parts that would become tangled or distorted in another process like barrel plating.
The actual plating material can add important characteristics and features to a copper spring or battery contact. Here are some metal finishes that are available:
- Gold: Provides extremely reliable metal-to-metal contact under virtually all environmental conditions.
- Nickel: Protects against corrosion and wear while adding a glossy, decorative finish.
- Nickel-plated cold-rolled steel: Cost-effective contact material that provides a fine contact surface for welding and soldering. In general, nickel plating should be continuous, nonporous, and thick enough to be wear resistant.
- Tin: Should be avoided for connectors due to possible galvanic corrosion along with fretting wear and corrosion.
Each metal is different and each offers unique benefits depending on usage and application of the product or part. Let APS help you select the best material for your next project.