I have been looking at Henkel (Locktite) and Heraeus formulations. Hope to
experiment in the near future.


On Mon, Apr 29, 2013 at 1:13 PM, Guy Ramsey <[log in to unmask]> wrote:

> I found the same, little bit of info, on MatWeb. But nothing at Ellsworth
> or
> the Loctite website.
> I talked to an engineer about some first level assembly work this morning.
> It sounded like this was the product they were recommending. But, not by
> brand. I wonder if Henkel sold it.
>
> Guy
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
> Sent: Monday, April 29, 2013 12:37 PM
> To: [log in to unmask]
> Subject: Re: [TN] Conductive epoxy to install SMT parts
>
> Guy,
>
> No experience with, but sent you a couple datasheets directly.
>
> Might be interesting
>
> Would like to come up with a more direct data sheet for the first one
> attached
>
> Steve C
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
> Sent: Monday, April 29, 2013 12:10 PM
> To: [log in to unmask]
> Subject: Re: [TN] Conductive epoxy to install SMT parts
>
> Has anyone had experience with Loctite 3445 1?
> I can't get my hands on a data sheet.
>
> Guy
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
> Sent: Monday, April 29, 2013 9:07 AM
> To: [log in to unmask]
> Subject: Re: [TN] Conductive epoxy to install SMT parts
>
> I am sure that late 80 early 90s formulation are out of date... may be not
> withstanding leadfree temperature, but the stuff currently out of space are
> still running.  Not that much can be said for current 18 month warrantee
> part. (My VCR still running, that is almost 23 years old... however, my DVD
> player is already on its way out... )... Many formulation went away with
> the
> chief head to cottage... those are masters... (a phone call, they wipe a
> formula for you, and 1st trail, perfect... Try to get that done now? ).  My
> old penny (out of circulation).
>
> Joyce Koo
> Researcher
> Materials Interconnect Lab
> Office: (519) 888-7465 79945
> BlackBerry: (226) 220-4760
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Eva J
> Sent: Monday, April 29, 2013 8:59 AM
> To: [log in to unmask]
> Subject: Re: [TN] Conductive epoxy to install SMT parts
>
> Conductive epoxy is being considered as an electrical and mechanical bond
> since the component can not withstand reflow temperatures. The future
> application will be an ENIG finish on PCB with gold finish on the component
> termination. Late 80s and even 90s papers would be outdated as materials
> have changed. So no one is aware of recent papers regarding conductive
> epoxy?
>
> Thanks
> Eva
>
>
> On Sun, Apr 28, 2013 at 7:41 PM, Mike Fenner <[log in to unmask]> wrote:
>
> > It's not totally clear why you want to adhesive bond instead of solder.
> Are
> > you looking to adhesive bond special devices to otherwise assembled
> boards?
> > There maybe ways to solder using repair techniques for example.
> > If you wish to use adhesives you will need to consider conditions of
> > use, service life, and in production surfaces to be bonded as well as
> > max process temp and time. These will be different from solders.
> > Generally adhesive bonds are not as strong as solder, and in
> > non-hermetically sealed packages service life can be shorter (but
> > maybe sufficient in either case).
> > As already said epoxies do not bond well to tin or tin based alloys.
> > Gold is also a low energy surface and will give low bond strengths
> > with adhesives.
> > So bond strength could be an issue, this is in addition to any
> > problems that might arise from the Ag:Sn interface. Some suppliers do
> > claim to have addressed the long term conductivity issues.
> > Do keep in mind that whereas adhesives can be classified into generic
> > types, (epoxies, silicones, acrylates etc) they are all supplier
> > unique within that classification. This means you will need to check
> > or verify product performance claims with every supplier. [This is not
> > like solder pastes where although flux chemistry may be supplier
> > specific, a solder alloy
> such
> > as Sn63 is not.]
> > You will need to observe the cure schedules in the supplier data
> > sheets, treating them as minimum times/temps at the bond line or the
> > product will not develop data sheet properties.
> >
> > Regards
> >
> > Mike
> >
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
> > Sent: Thursday, April 25, 2013 3:31 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] Conductive epoxy to install SMT parts
> >
> > Eva,
> >
> > You should ask the formulator for this information.  Really attempt to
> nail
> > them down and get them to provide real, and detailed data - one real
> > live part types.
> >
> > In general, it is quite difficult to get most adhesives to adhere to
> > the diverse surfaces finishes presented in SMD work, at temperatures
> > that the SMD assembler [and components] will tolerate.  Making it more
> > flexible is only one factor to consider.
> >
> > Mechanical, thermal, or other environmental stresses typically quickly
> show
> > the weak links.
> >
> >
> > Side note - if "cured" over the weekend, I suspect that it is more of
> > a humidity cure RTV than an "epoxy" based system.  Do you smell acetic
> > acid [vinegar] during cure?  = bad idea.  Or do you smell more of an
> alcohol?
> =
> > okay.  Silicones have a nasty way of tending to migrate to places you
> don't
> > really want them to go... switches, connectors,
> >
> > Can your production live with a 48-72 hr cure?
> >
> > I would be sure to ask the formulator whether the material has an
> > epoxy backbone, or a silicone backbone so that I could get a better
> > grasp of its mechanical properties.  I am assuming that if it is a
> > silicone, under normal conditions, it will already be above its Tg,
> > and therefore already in it 'high expansion' state.  I also make the
> > generalization that it will
> remain
> > flexible until down in the -20 to 0°C range [subject to the specifics
> > of the material]
> >
> > Steve C
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Eva J
> > Sent: Thursday, April 25, 2013 10:01 AM
> > To: [log in to unmask]
> > Subject: [TN] Conductive epoxy to install SMT parts
> >
> > I am looking for guidance on conductive epoxy selection for components
> > on PCBs. I heard that there is a formulation of conductive epoxy with
> silicone
> > as a filler that is more flexible. Do you know of any studies or
> > evaluations available on conductive epoxy for electronics?
> >
> > We attached a 4 pin LGA component that has gold finish terminations to
> > a HSAL finished PCB. We syringe dispensed the conductive epoxy to the
> > land pattern. Optically machine placed part and allowed the conductive
> > epoxy to cure over the weekend.
> > During environmental stress test ( hot / cold cycling) one joint failed.
> > All of the LGAs were removed and what we found is the component came
> > off way to easily.
> >
> > I would like to continue using conductive epoxy to mount special
> > application
> > SMD's: however reliability is a concern. Any words of wisdom?
> >
> >
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