We attach a flex to a ceramic substrate using a hot bar BUT using a 3M Z
axis adhesive tape.

The flex has very closely spaced pads and these were prone to shorting when
we tried hot bar soldering. We also found the adhesive gave a stronger joint
mechanically.

However cycle time for hot bar - whether solder or ACF - is not that good. I
would suggest about 1 minute per joint and it is done manually although a
certain amount of automation is possible.

One very large phone manufacturer told me the other week that they
absolutley loathe the hot bar process. A yield hit of 8% on a million phones
a month gets your name in the corporate spotlights...

Hope this helps,



> Technet,
>
> Does anyone have any guidelines for soldering flex circuit directly to a
> PWB?  We currently connect it mechanically and with a connector, but
> were toying with the idea of direct solder attach.
>
> Any experience, do's and don't, especially horror stories, appreciated.
>
> Thanks......DT
>
>
>



Eric Christison

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