Blair,

My tests were 'worst case', without CC.  Being a 'hybrid house' I really didn't have CC'ing ability anyway ...  Yes, fun stuff!  Thoroughly enjoyed the activities!

I typically saw two failure modes WRT adhesive bonding of passives on PWB's.

1 - bare copper would oxidize under the adhesive, causing the device [with adhesive attached] to come off the board.  Typically, VERY easily.

2 - Adhesive would cleanly let go from device [or PWB], if solder coated.

I would imagine the CC would delay things somewhat, but would expect the same results in the end.

It seemed that 85/85 would kill just about anything, but can still envision things working 'okay' in a very benign shock and temp/humidity environment.

Only did testing on passives.  Could have done actives too, but all had soldered [tinned] leads and that typically was a big nail in the coffin to begin with.  Was more than capable of handling 510µm [20 mil] line and space, even at that time.  Also with little or no heel/toe fillets, I could not imagine them to be very robust.  

Would one use this approach in a cell phone?  I know that when cutting wood, my cell phone gets very 'humid' when in my shirt pocket, but it uses soldered assy.

I still believe the concept has merit, but really needs to be on an application by application basis.  

Comments Joyce?

Let's see if Inge has comment.  He is probably sleeping in today, you know how those retired folks are  :-)

Steve

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Blair Hogg
Sent: Tuesday, March 13, 2012 10:09 AM
To: [log in to unmask]
Subject: Re: [TN] Assembling with conductive adhesive

Steve,

You will get that hour back in November....

In a prior company we used conductive adhesives for die attach to thick film ceramic substrates for hermetically sealed hybrid devices. Wire bonds for the rest of the connections. Fun stuff. 

Saw the other comments on the stuff not holding up in non hermetic applications. 

I wonder if conformal coating ove rit would help?

Blair

On Mon, 12 Mar 2012 11:39:16 -0400, Steve Gregory <[log in to unmask]> wrote:

>Hey all,
>
>
>
>Wish I hadn't lost that hour of sleep this weekend, I'll try to find it 
>tonight. :o)
>
>
>
>Anyways, have any of you thought of trying to replace solder with a 
>conductive adhesive for PCB assembly? There's a few out there (Henkel, 
>Cookson, Ellsworth, etc.) that are touting them as solder replacements.
>
>
>
>When I read the technical datasheets, I'm thinking to myself, why isn't 
>this stuff more widely used? There must be a reason.
>
>
>
>I do know it's pretty expensive almost all of them are silver filled, 
>and I have read that the mechanical strength and thermal conductivity 
>is not as good as solder, but what other reasons are out there not to use it?
>
>
>
>Steve
>
>


______________________________________________________________________
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] 
______________________________________________________________________