Printed Circuit Design & Fab Online Magazine - Current Issue

Current Issue

Lenora Toscano

A rough topography aids reliability even while it complicates wet processing.

Read more: A ‘Promoter’ for Solder Mask Adhesion

Mark Finstad

Long, narrow flex circuits push manufacturing limits as catheter designs demand more connectivity.

I am asked quite often about the longest and narrowest flex that can be made, especially as new applications emerge that support minimally invasive surgery and pulse field ablation procedures used to treat atrial fibrillation (AFib). I will assume readers are looking for the longest and narrowest flex circuit that can be built for a reasonable price. Almost anything can be done “in a beaker” if cost is no object, but if you are looking for guidance on a flex that can be built in volume and not break the bank, there are limitations.

Read more: Flex Circuits for Use in Catheters

Nick Koop Successful flex and rigid-flex assembly depends on controlling moisture.

Questions about baking and assembly come up at least monthly, if not more often. Several factors can impact successful assembly with flex and rigid-flex.

Environment. As a rule, delamination is usually due to retained moisture. The rapid rise in temperature during reflow causes moisture to change from liquid to expanding vapor or steam. This expansion can result in delamination.

Read more: Managing Moisture and Heat in Flex and Rigid-Flex Assembly

Mark Finstad Flex circuits can use rigid board finishes, but some of them crack under pressure the moment you ask them to bend.

Is it possible for flex circuits to have the same final finishes available for rigid PCBs?

Yes, you can use any of the final finishes available for rigid PCBs, but whether you should use them depends on the application. Some standard finishes used on rigid PCBs are not suitable for flex applications. Here we go over some of the common and emerging finishes and the impact of using them on flexible circuits.