In message  <[log in to unmask]> [log in to unmask] writes:
> Hi Technetters,
>   Does anyone have any experience they could pass on
> regarding the automatic dispensing of UV cure epoxy.
> I am trying to dispense onto a substrate and then
> whilst holding the component being bonded in place
> with the bond head cure the material.  My only problem
> is that the dispense head is attached to the bond head
> and I am worried about the UV material curing in and
> around the needle.
>
> Thanks
>
> Bob Mewes

This kind of equipment is used quite commonly with no problems. The obvious use
is wire tacking, where a bridge bond of adhesive is placed over a mod wire to
bond it to the pcb. The application equipment consists of a pressure dispenser
and a UV spot lamp, melded together so the dispense needle and the light guide
are both in a single hand-held unit. There is usually a 2-stage foot pedal, one
side for dispense, one side for a timed light exposure for cure. Hit one side
of the pedal, dispense a blob of goo, hit the other and cure it.

If the dispense needle is too long, it may come beyond the light guide output,
but normal configuration is a bit like the following (poor) ASCII art:

  Needle    Light guide
    Ý Ý        Ý   Ý
    Ý Ý        Ý   Ý
    Ý Ý        Ý   Ý
    Ý_Ý        Ý   Ý
     O         Ý___Ý
     O        /     \
             /       \
           /          \

Works fine with the sorts of light curing goos mainly specified, i.e UV free
radical curing acrylated/urethanes. UV epoxies are generally slower and not so
popular.

Peter
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Peter Swanson                                              Oxfordshire, England
INTERTRONICS
[log in to unmask]                  http://www.intertronics.co.uk

Suppliers of materials and consumables to the electronics & related industries
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