The first thing I would try is to shorten the cure time to match Loctite's
tech. data sheet for 3609  ( 90-120sec. at 150C). I have been working with
our Loctite rep. trying to solve a hard to bond component issue. This was
their first suggestion. Your cure time at 4-5 min. will result in what
Loctite called a brittle cure. Shortening the time to the recommended range
of 90-120 seconds will result in a tougher and more flexible cure. Maybe
this will help, we've never had a problem bonding to any masks. We use 90sec
at 150C for both 3609 and 3614 for stencil printing.
 I have just recieved a syringe of 3618,  for hard to bond to materials,
which I'm told has been used at some of their customers to solve problems of
this type.

> ----------
> From:         Wade Oberle[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Wade Oberle
> Sent:         December 23, 1998 7:52 AM
> To:   [log in to unmask]
> Subject:      [TN] Surface Mount Adhesive
>
> Dear Technetters,
>         I am having a problem with SMT adhesive sticking to some types
> of solder mask.  Does someone out there have experience with using SMT
> adhesive on glossy boards vs. matte finish boards.  I am using Loctite
> 3609 or Epibond 7275 or Epibond 7275-1 with a cure cycle of 145-150
> degrees centigrade for 4-5 minutes.  Is there an SMT adhesive or cure
> cycle that works better with glossy boards?  We seem to have a problem
> with adhesion at room temperature and at wave solder temperatures.  We
> run a standard wave solder profile and have even increased the wave
> speed to 5.75 feet/minute from our norm of 4.5-5.0 feet/minute.  This
> helps but we run the risk of voids and poor solder connections on some
> components.
> If I cure the boards and then use a 'push' tester to measure the force
> required to remove the 'glued' components, is there a standard for
> minimum and maximum expected force for removal?  I have heard of some
> people using a custom socket and a torque wrench to measure the strength
> of the cured adhesive.  Is there a standard specification for this test
> method?  Which test method do you think is best?  The tests mentioned
> above are done at room temperature.  Is there a way to measure the 'hot'
> strength of the adhesive bond?
>
> Thanks in advance.
>
> Wade Oberle
>
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