TECHNET Archives

December 2012

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:
Fri, 14 Dec 2012 11:05:58 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (110 lines)
Inge,

That is an interesting thought!

Steve C

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
Sent: Friday, December 14, 2012 10:04 AM
To: [log in to unmask]
Subject: Re: [TN] Component issue - epoxy die attach

The critria was THEN (about 1965)  *FIVE MOLECULE LAYERS OF WATER ON A CHIP.
* Considering the extremly tough coatings the semis have today, I am of the
opinion that the 5,000 ppm is obsolete. I proposed many years ago, that we
should accept packages with He leakage 5x10exp-7 and so we did. We have made
tens of thousands hermetic packages and never had any issues connected with
humidity on inside. Medium value is of course higher, about 10exp-9.

Inge

On 14 December 2012 14:29, David D. Hillman
<[log in to unmask]>wrote:

> Hi Howard - Steve and Inge have provided you some good stuff so I can 
> only offer one additional detail. The reason for the 5000 ppm limit is 
> that is the' line in the sand' where you will get condensation inside 
> a hermetically sealed package as you go thru temperature swings. There 
> are a bunch of  very fun mathematic equations which can be used to 
> show that below 5000 ppm you won't get condensation as you go thru the dew
point.
> With a reading of 5600, you may want to evaluate "are you good enough" 
> in terms of would water cause you issues in your product use environment.
> Good Luck.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
>
> From:   "Watson, Howard A" <[log in to unmask]>
> To:     <[log in to unmask]>
> Date:   12/13/2012 05:25 PM
> Subject:        [TN] Component issue - epoxy die attach
> Sent by:        TechNet <[log in to unmask]>
>
>
>
> Hello 'netters,
>
> I debated posting this, as it seems to me to be an obscure problem, 
> but then, I'm always amazed at your knowledge base. I have a JFET 
> 2N6550 component to be used for space application. Unfortunately, it 
> is not manufactured at JANS space quality, so we buy the commercial 
> grade, plus an option 2 screening, which upscreens the part to "like" 
> JANTXV. I think this is called re-branding. Then, we send it to a lab 
> for further upscreening to JANS. The problem is that the parts are 
> failing the moisture test of the residual gas analysis (RGA). I found 
> out that epoxy is used for the die attach, and likely the epoxy is 
> outgasing during subsequent baking as part of the testing. My first 
> question is who knows of a standard for die attach of this component 
> type stating that epoxy is forbidden for military and space use?  The 
> epoxy  used by the manufacturer is Ablestik p/n 84-1LMI; Material # 
> 1119570.  I just found out today that they do have the capability of 
> eutectic die attach, and I'm pursing this option, expecting a huge expense
and lead time.
>
> Secondly, I had two independent labs perform the RGA. The first lab 
> had results averaging ~28,000 PPM.  The second lab results averaged ~5600
PPM.
>   The standard is no more than 5000 PPM.  They both performed the 
> testing to the same MIL-STD-750.  I can't understand the wide range of 
> results, but my second question is who knows of any studies related to 
> the negative effects of excessive (>5000 PPM) moisture inside 
> hermetically sealed devices used in space?  By the way, they all passed
the seal tests.
> Perhaps some of you are knowledgeable in this area.  Thanks in advance 
> for your help.
>
> Howard Watson
>
> ______________________________________________________________________
> 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] 
______________________________________________________________________

ATOM RSS1 RSS2