IPC specifications recommend baking but very few flex users follow this
procedure. If the parts have stabilized in a reasonable air conditioned
environment for a couple of days and you follow good hand soldering practice
or automatic assembly. This applies to 1-4 layer circuits - if you are using
rigid-flex always bake in a clean oven.

Steve Kelly
PFC Flexible Circuits Ltd.
  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]]On Behalf Of Mick Thwaite
  Sent: Friday, September 08, 2000 4:02 AM
  To: [log in to unmask]
  Subject: [TN] Flex PCB's


  We are just starting to use flex PCB's in our production area.

  Is it true that the PCBs have to be dried prior to using as they absorb
moisture quickly?

  Is it also true that hot air is better than IR reflow?, and

  Does anybody have any good ideas on the materials to use for the vacuum
jig to hold down the panel during wire bonding?
  We have used vacuum holds as small as 1.00 mm but still find that the PCB
moves during bonding.....



  Mick Thwaite