New Industry Products

Infineon Introduces a New Series Of Welding Diodes

April 19, 2021 by Gary Elinoff

The new family of housingless power diodes are aimed at medium frequency resistance welding and at other applications requiring high current rectification

This generation of Infineon power diodes deliver high forward current and feature low conduction losses and high power cycling capabilities

Infineon’s new generation of welding diodes. Image courtesy of Infineon

This family of welding diodes are said by Infineon to offer the highest power cycling capability in the market. Their lower on-state voltage drop is claimed to permit 10 to 15% higher current than competitive devices.

Best In Class Performance to Lifetime Ratio

With these capabilities, the designer has a choice between increased current and longer lifetime for the application at hand, ultimately supporting a decrease in maintenance costs. This generation of diodes offers full mechanical compatibility, making them suitable for extending the performance of existing designs based on earlier Infineon welding diodes.

What is a Welding Diode?

Welding diodes are an essential part of mid frequency welding units. The image below is a simplified depiction of mid frequency welding.

Mid Frequency Welding. Image courtesy of How to Resistance Weld

The first part of the circuit is a bridge rectifier that converts 3-phase AC into DC. The IGBT circuit converts it into pulsating DC. The next step is the welding transformer, which turns the pulsating DC into high-power, mid-frequency AC, as depicted in sub-figure 4.

The two welding diodes are arranged to form a full wave rectifier, which generates a DC output. The DC is applied to the welding head. The weld current, being DC, has no zero-crossover, so there is no time where power isn’t being applied to the weld. This serves to speed up the welding process.

Another advantage to DC is that there are no inductive power losses, or any interaction issues with any magnetic material in the machine’s throat.

A Summary of the Welding Diodes

The four members of this generation of welding diodes are the, 65DN06B02, 56DN06B02, 46DN06B02 and the 38DN06B02. They are listed along with some older devices. All feature a blocking voltage of 600V and a maximum junction temperature (TVJMax) of 180℃

The 65DN06B02

The 65DN06B02 is 5 mm high with a diameter of 65 mm and is mechanically compatible with the current 65DN06. Continuous forward current is 12.8 kA. Surge current for 10 ms, with TVJ = TVJMax, is 95 kA. At 8000A, maximum forward voltage is 0.89V.

The 56DN06B02

The 56DN06B02 features a maximum forward current of 10.3 kA, 15% better than the current 56DN06B02. The units are mechanically compatible, and are sized at a height of 5 mm and a diameter of 56 mm. With TVJ = TVJMax, surge current for 10 ms is 70 kA. On-state voltage for this welding diode is 0.94V at 8,000 amps

The 38DN06B061

Following the pattern, the 38DN06B02 is also mechanically compatible with it’s predecessor, the 38DN06B. The combined dimensions are 38 mm diameter and a height of 4 mm. Maximum forward current for the 38DN06B02 is 5.8 kA, beating out its predecessor by 25%. With a forward current of 4500 amps, on-state voltage for the 38DN06B02 0.96V