What means "flexible"?
Flexible as in "compliant" to accommodate grossly mismatched expansions?
or
as in "bendy" to conform to mobile substrate?
or
something else?
There are products which meet both descriptions, check out the usual culprits like
Ablestik and Epoxy Technology (Epotek) etc. as suggested, but ask yourself do you really
need it. Keep in mind that no benefit is without a cost, so if you squeeze a new property
into your finite glue pot you displace or compromise something else. In the case of truly
bendy materials adhesion is degraded and usually outgassing is increased. [Increased
compliance materials are much easier to achieve.]
For example most people expect to need a "flexible" adhesive when bonding components to a
flex circuit, forgetting that the bond area is small so that flexibleness is not really an
issue, especially as the components themselves don't bend anyway. So what can happen with
a really compliant flexible [soft] adhesive, where the adhesive strength is reduced, is a
peel failure in the adhesive component bond as the adhesive follows the bending of the
flex circuit, but not the component. This is kind of the opposite of what most people
intuitively expect when experiencing bondline failures at the flexcircuit / component
interface. Typically what they really have is a low bond strength caused by inefficient
cross linking on cure at the reduced temperatures imposed by the flex circuit material. In
this scenario the requirement is not necessarily a more flexible material but a low
temperature cure type.
So when contacting prospective suppliers don't ask them for a flexible material, just have
to hand the normal parameters you would expect to specify for any application - service
and processing environment limits, basis materials, surfaces to be bonded etc., and derive
a recommendation from that. If you ask for a flexible material you are likely to end up
with one.
Possibly you will still need to adopt an empirical approach on final product selection but
you will reduce the number of iterations with this approach.
Do you have a specific problem or are you anticipating one on a new application?
Mike Fenner
----- Original Message -----
From: Paul Klasek <[log in to unmask]>
To: <[log in to unmask]>
Sent: 12 January 2000 21:53
Subject: Re: [TN] Flexable conductive epoxy
> Geee, Thanks Paul (what ever happened to Steves Club); I just hate riot spot
> lights.
> I just took my polymer file home (been indicated by boss that my foot high
> invisible desk is mildly contravening Co's clinical image) , soo all my
> grace, ablestick (a very good Paul there in apply lab), dexter, loctite,
> ciba, etc. contacts pile now in my home office.
> Give me up to weekend (only time to breathe), meanwhile go through my howls
> in IPC archives (we rechewed the contacts few times.
> Webs of above may lead you somewhere (not saying where) ; Inge may break the
> hibernation ;
> and almost silent goldens may utter few words .
>
> What is flexible ? Something you should do with conductive inks ?
> Sorry to be sus, but I just hate to see an axe used as hammer by friends
> (epoxies being generically flexible enough within their domain).
> DETAILS please (on or off line if yo shy), vacuum pump you have I suppose.
>
> cusn pk
>
> PS
> Just pondered, Paul, is there an open season on all of those WHY2K (!?!)
> false prophets across the puddle ?
>
>
> -----Original Message-----
> From: Paul Maciejewski
> [mailto:[log in to unmask]]
> Sent: Thursday, 13 January 2000 6:34
> To: [log in to unmask]
> Subject: [TN] Flexable conductive epoxy
>
>
> Hellooooooooooo! Techneters,
>
> I'm looking for a flexible conductive epoxy that will meet NASAs space
> requirements (little or no out gassing)
>
> Do you have any suggestions??
>
> Any leads would be appreciated, Thanks, Paul
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