EMS - Overlay Clad Metal

An important application for clad materials is in the button cell battery industry for use as both the anode lid and cathode cup. In each case, clad is the preferred choice because of its unique multi-layer properties especially as performance demands increase for higher energy, smaller cells for hearing aids and other electronic devices.

Tri-clad Cu/S304/Ni functions as the anode current collector with its corrosion resistant nickel exterior, strong stainless core and pure copper interior for cell chemistry compatibility with mercury free applications.For the cell cup or cathode, Ni/S430/Ni excels over plated options because of the durability of the clad nickel layer compared to more porous plated solutions. This is especially important to prevent corrosion in hearing aide applications.

EMS offers gauges as low as 0.004” and widths up to 12” in both standard and special clad ratios. As cells become thinner, clad materials made through special rolled tempers provide deep drawability and strength.

One of the most well known applications for multi-layer clad metals is for home and commercial cookware. Combining the corrosion, formability and food compatibility properties of stainless on both exterior surfaces with a center layer of aluminum or copper for quick and even heating produces an optimum cooking vessel.

EMS added Stainless Steel / Aluminum / Stainless Steel products to its cookware portfolio in 2012 by installing continuous, warm bonding to its traditional cold bonding capability. EMS can clad numerous layers such as 3 or 5 layer aluminum clad or single ply copper cores with Austenitic Stainless and induction ready Ferritic Stainlesses.

EMS can easily vary the thickness ratio of each layer and combine different metals to produce either a unique material or one of the more conventional clads available today. 2 layer clads such as Stainless Steel / Aluminum are also used for special applications like iron Soleplates. For Stainless Steel / Aluminum / Stainless Steel combinations, thicknesses are 0.070” – 0.160” and widths up to 24”. EMS can provide coil, sheet or even discs all in a deep drawable temper ready for forming. 2 layer Stainless Steel / Aluminum clad systems can be produced in a wider range of thickenesses 0.013” – 0.200” with a number 8, polished surface.

In addition, EMS can produce a Copper / Stainless Steel system which offers the simplicity of a 2 layer system with an aesthetically pleasing Copper exterior. Typical thickness is 0.060” – 0.090”.

Decades of design experience have proven clads give lower assembly costs and higher manufacturing yields compared to using thin braze foils or paste. Applications include oil coolers, transmission coolers, and charge air coolers for off-road equipment, HDD trucks and passenger cars. Industrial heat exchangers also benefit from self brazing clads.

Clad offers forming flexibility, tight fitting components, reduced braze filler usage and because of the copper and stainless metallurgical bond, superior braze quality.

Self braze clads combine a braze grade copper layer such as C102 or C122 on one or both sides of a core of Ferritic or Austenitic stainless. Many copper ratios are available with 5—10% of total thickness being most common. Carbon steel core material is also an option for simplifying the internal turbulator processing in some heat exchanger designs.

Thicknesses available range from 0.010” – 0.120” and widths up to 25”. Material is normally provided fully annealed for maximum formability.

Copper / Invar / Copper composites are used in printed circuit boards, hybrid enclosures, heat sinks and other applications where coefficient of thermal expansion (CTE) match or constraint of thermal expansion is required. The copper layer provides high thermal and electrical conductivity while the Invar core lowers the overall expansion during thermal cycling. By adjusting the copper to Invar ratio, the CTE can be tailored to the specific electronic device attached to the board, reducing solder connection fatigue and failure.

EMS produces two standard ratios: 12.5/75/12.5 and 20/60/20 in gauges from 0.006” – 0.062” and widths up to 24.5”. Standard temper is fully annealed allowing drilling, shearing and forming as needed for PWB assembly. Material is available in coil or sheet.

Copper / Invar / Copper composites are used in printed circuit boards, hybrid enclosures, heat sinks and other applications where coefficient of thermal expansion (CTE) match or constraint of thermal expansion is required. The copper layer provides high thermal and electrical conductivity while the Invar core lowers the overall expansion during thermal cycling. By adjusting the copper to Invar ratio, the CTE can be tailored to the specific electronic device attached to the board, reducing solder connection fatigue and failure.

EMS produces two standard ratios: 12.5/75/12.5 and 20/60/20 in gauges from 0.006” – 0.062” and widths up to 24.5”. Standard temper is fully annealed allowing drilling, shearing and forming as needed for PWB assembly. Material is available in coil or sheet.

Transition material covers a broad range of clad products whose purpose is to join dissimilar metals.

Benefits include reducing galvanic corrosion at dissimilar metal joints and ease in joining using methods such as welding.

Popular clad systems are Steel / Aluminum and Stainless / Aluminum two-layer materials, typically in 50/50 thickness ratios. A variety of steel, stainless and aluminum alloys such as G1008, HSLA, S301, S304, S430, A3003, A5052 and A1100 and other ratios ranging from 5-50% are available. With a wide range of bonding and finish rolling and slitting capability, EMS can provide gauges from 0.003” – 0.160” and widths up to 25” in coil or sheet.