Thanks On Mon, Apr 29, 2013 at 12:37 PM, Steven Creswick <[log in to unmask] > wrote: > 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 I am sure that late 80 early 90s formulation are out of date...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 Late 80s and even 90s papers would be outdated as materials 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? > > > > > > ______________________________________________________________________ > > This email has been scanned by the Symantec Email Security.cloud service. > > For more information please contact helpdesk at x2960 or > > [log in to unmask] > > ______________________________________________________________________ > > > > ______________________________________________________________________ > > This email has been scanned by the Symantec Email Security.cloud service. > > For more information please contact helpdesk at x2960 or > > [log in to unmask] > > ______________________________________________________________________ > > > > > > ______________________________________________________________________ > > This email has been scanned by the Symantec Email Security.cloud service. > > For more information please contact helpdesk at x2960 or > > [log in to unmask] > > ______________________________________________________________________ > > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > --------------------------------------------------------------------- > This transmission (including any attachments) may contain confidential > information, privileged material (including material protected by the > solicitor-client or other applicable privileges), or constitute non-public > information. 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