How Does Press Fit Technology Work?

Preparation of the Via for a Press Fit Power Element

Start with drilling hole for the via and then deposit the copper to connect all the layers of the PCB with the copper. We recommend a minimum of 25 to 60 micrometers of copper but 30 to 40 micrometers is optimal. Finish the via with a maximum of 15 micrometers of tin. Following these three steps will ensure the best connection between the pins of the press fit power element and PCB.

We have two different styles, one for a chemical tin surface and one for hot air leveling (HAL) plate on the PCB. They are very similar, just the final via diameter is a fraction of a mm difference.

The tin plating has a more even finish (left) compared to the HAL (right) which has a wavy finish. Since you cannot be sure where the waves are going to go, you have to compensate a little more to ensure a good connection.

What happens if the via is too small?

There will be some differences in the temperature rise but the main problem is damage to the PCB. In the upper left photo, the pin was inserted into a via that was too small, which could damage outside of the via and cause issues.

Is it acceptable to solder these components?

It is not recommended to wave solder these components because it can deconstruct the cold weld or delaminate the PCB. The pins of the press-fit power elements are not made for soldering. Also, due to the high heat absorption, the press fit process should happen last during PCB assembly. This part will act as a heat sync during the reflow process and the components around the power element may not receive proper heat needed to solder to the board.

Want to learn more about press fit? See our last post for an introduction to Press Fit Technology and check back to our blog for the next article about products and applications.

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