Diffusion Welding and Diffusion Bonding Equipment

HEAT: Heat is critical to achieving the correct temperature for diffusion bonding, which must remain below the melting point but high enough to activate solid-state welding. Accurately controlling this temperature is essential because deviations can either fail to activate the diffusion process or cause material deformation.

FORCE: Force is also an important parameter in a controlled diffusion welding process, and a vital one for a faster process or for a process over a large welding area. Diffusion Welding will happen uniformly and repeatably only if the force is CONSTANT over the entire surface, allowing the current to heat the parts homogeneously.

TIME: If both temperature and force are stable and the target temperature is reached, a timer will govern the welding cycle according to the predefined recipe. Excessive time can lead to material degradation, while insufficient time can produce weak bonds.

PLANARITY AND LARGE AREA DIFFUSION WELDING: Achieving perfect planarity across the welding surface ensures uniform heat and force distribution. This becomes increasingly difficult as the size of the part and the welding area increases. Factors such as material irregularities and thermal expansion can introduce distortions that affect the quality of the weld. TECNA’s patented planarity-control technology helps maintain uniform force distribution across large welding areas, improving process consistency for large-area diffusion welding applications.

The primary differentiator lies in how these parameters are controlled and combined to produce consistent, high-quality results, especially as the welding area increases in size.

What is diffusion welding?

Diffusion welding, also called diffusion bonding, is a solid-state welding process that joins two materials by holding their surfaces together under pressure at an elevated temperature for a controlled amount of time. The materials bond through atomic diffusion across the joint interface, typically without melting the base metals.

How does diffusion welding work?

Diffusion welding, also called diffusion bonding, joins two materials by holding their surfaces together under heat and pressure for a controlled amount of time. Unlike resistance spot welding or fusion welding, the materials generally do not melt.

What’s the difference between diffusion welding and resistance welding?

Resistance spot welding typically creates localized heat at the joint interface and forms individual weld nuggets in a very short cycle. Diffusion welding uses sustained heat, pressure and time across the bonding area to create a solid-state metallurgical bond through atomic diffusion, generally without melting the base materials.

What materials can be diffusion welded?

Diffusion welding can join titanium, aluminum, stainless steel, carbon and alloy steels, nickel-based superalloys, copper, magnesium, cobalt alloys, refractory metals, and many dissimilar-metal combinations. Because the materials are bonded below their melting temperatures, diffusion welding is particularly useful for high-value materials and combinations that are difficult to join using conventional fusion welding.

Can diffusion welding be used for copper busbars?

Yes. Diffusion welding is commonly used to join flexible copper busbars, laminated copper foil stacks and braided copper conductors. Controlled heat and pressure create a solid-state metallurgical bond between the copper surfaces without melting the base material or adding filler metal. The process produces strong, low-resistance connections and is particularly well suited for consolidating multiple layers of copper foil into solid terminal ends for EV batteries, energy storage systems and power distribution equipment.

Does Weld Systems Integrators offer diffusion welders?

Yes. Weld Systems Integrators (WSI) offers diffusion welding equipment, specifically TECNA diffusion welding systems for high-conductivity and large-area joining applications. WSI’s diffusion-welding systems range from open linear presses to large portal-frame machines, with effective welding areas up to 35.43 x 23.62 in. (900 × 600 mm), force up to 40 tons, and power up to 800 kVA.

How do I choose a diffusion welder?

Selecting a diffusion welding machine depends on the materials being joined, part dimensions, total bond area, required temperature, welding force, production volume and desired cycle time. Large-area copper busbars and laminated conductors also require precise control of platen planarity and pressure distribution to achieve uniform bonding across the entire weld area. When evaluating a diffusion welding application, WSI typically reviews:

• Materials and material thickness
• Number of laminations or foil layers
• Overall part dimensions
• Required bonding area
• Required welding force
• Temperature requirements
• Production rate and cycle time
• Part loading and automation requirements

Send us your part drawings and application requirements to determine the appropriate TECNA diffusion welding equipment configuration.

EV Battery Packs and Busbars

Diffusion welding is ideal for joining copper flexible busbars, laminated copper foil connectors, braided connectors, and battery current-carrying components. By forming high-integrity solid-state bonds without melting the base materials, it improves joint strength, electrical conductivity, thermal performance, and process repeatability for high-current EV battery applications.

Energy Storage Systems

Suitable for energy storage copper busbars, aluminum conductors, flexible connectors, laminated busbars, and composite conductive parts. Diffusion welding creates strong, metallurgical bonds with minimal electrical resistance, helping reduce contact resistance variation, minimize localized overheating, and improve long-term reliability in high-current energy storage applications.

Power Distribution Equipment

Designed for copper busbars, flexible braided connectors, switchgear conductive parts, and power connection assemblies. Diffusion welding enables large-area conductive joining with precise pressure and temperature control, helping improve joint strength, electrical conductivity, and long-term reliability for demanding power distribution applications.

Automotive Electrical Components

Designed for conductive connectors, power modules, EV electrical components, battery terminals, and high-current connection assemblies. The controlled diffusion welding process delivers consistent bond quality, excellent electrical conductivity, and repeatable weld performance while supporting process traceability and quality assurance for high-volume automotive manufacturing.

Flexible Busbar Manufacturing

Suitable for manufacturing flexible copper busbars, laminated foil busbars, and braided conductive connectors where bond integrity, electrical conductivity, and surface quality are critical to overall performance. Controlled heat and pressure deliver consistent welds that help minimize contact resistance while improving joint strength, dimensional stability, and production repeatability.