TECHNET Archives

April 2013

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Steven Creswick <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steven Creswick <[log in to unmask]>
Date:
Mon, 29 Apr 2013 12:37:22 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (217 lines)
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I am sure that late 80 early 90s formulation are out of date...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 Late 80s and even 90s papers would be outdated as materials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. Any use of this information by anyone other than the intended
recipient is prohibited. If you have received this transmission in error,
please immediately reply to the sender and delete this information from your
system. Use, dissemination, distribution, or reproduction of this
transmission by unintended recipients is not authorized and may be unlawful.

______________________________________________________________________
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] 
______________________________________________________________________

ATOM RSS1 RSS2