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Flexible Circuits

Release time: 10/09/2018

Have anyone has experiance in SMT on flexible circuits?

 

I used to work for a flexible circuits house and was responsible for the SMT assembly flexible circuits area. What is your question?

 

I didn't pose the question -- but have some: As the substrate is flexible circuits -- how do you hold the flexible circuits substrate flat for paste application and then flat enough for larger (>1" long SMT components to be placed without coplanarity issues> Also, what types of finishes are common for the flexible circuits;i.e, ENIG, immersion Ag, etc.?

 

In a previous life, we built some flexible circuits for a customer. The configuration was a flexible circuits cable, with a flexible circuits at one end of it. We had fixtures made out of the same material that we had selective wave solder fixtures made from. Cut an indention in the material in the shape of the flexible circuits, and included a clip to hold the circuit securely in place.

 

I didn't work on it personally, but it seemed to work through screening, pick/place, and reflow (conveyorized line).

 

well we are running flex panel(150x270) with one connector(3 pin legs both sides) insert. Each panel consists of 28 parts and its used for disk drive industries. We are having a pallet to support with the top cover design such away the connector area is open and each open area a bridge are crossing to hold the connector. Im using lead free type(brand avantec) 1) facing problem on leg shifted 2) solder fillet

by the way do you think that aqueous cleaning system is playing important role??

 

 

We were using pallets (delmat with cavities for the flexible circuits) We put stips of double sided Kapton tape in the critical areas. The tape held up to the heat and kept the flexible circuits flat for the QFP's and BGA's. We based our flexible circuits assembly process for this flexible circuit around the carrier pallet. After the flexible circuit was loaded, we used the pallet for printing (Manual), placement and reflow. We then removed the circuit and ran through an in-line aqueous cleaner in a basket with spring clips to secure the flexible circuit to prevent damage.

We also had some applications where we used a vacuum table to secure the flexible circuits for placement but you need to maintain planarity throughout the entire process through reflow or you will see the same sort of problems.

 

I think every application has different requirements but we found that utilizing a carrier thoughout the process eliminated quite a few problems.

 

Please let me know if you would like to discuss this further.