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 * Considering the extremly tough coatings the semis have today, I am of the opinion that the 5,000 ppm is obsolete.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] ______________________________________________________________________