Mumtaz, Looks like a Au/Sn seal. Either reflow or roller welder seal technique. Certainly if reflow oven seal [>280°C], you have thoroughly stress relieved the wires. In either case, you likely have a good pre-seal bake/vac bake taking multi-hours I will tip-toe around your question by saying that if one were to do a Weibull plot of all the wires in the package, you will find two different populations - the short, 'down-bond' wires, and the long wires. Which set is stronger, really depends on the bond parameters and tool.... Normally, I will find the short ones to have the greatest pull strength, but ... it all depends. Would be nice if you could use a package having a much smaller cavity size, but I understand the economics of using what you have. Steve Creswick http://www.linkedin.com/in/stevencreswick -----Original Message----- From: Mumtaz Bora [mailto:[log in to unmask]] Sent: Saturday, November 13, 2010 11:51 AM To: TechNet E-Mail Forum; Steven Creswick Subject: RE: [TN] Wire Bond Pull failures Hi Wayne, Yes, This is forward bonding . I will look into the time/temp.exposures post seal. The wire bonding configuration is uploaded. Should the long corner bonds be expected to have low pull as #60 and #21. Thank-you for your feedback. Much appreciated. Mumtaz Bora Senior Packaging Engineer Peregrine Semiconductor 9380 Carroll Park Drive San Diego, CA 92121 858-795-0112-direct 858-731-9499 -fax [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick Sent: Saturday, November 13, 2010 5:33 AM To: [log in to unmask] Subject: Re: [TN] Wire Bond Pull failures Mumtaz, You have gotten good responses thus far. My assumption is, this is 'normal' forward bonding. If 'reverse' bonding, invert my comments on first/second - front/back radius. We are zeroed in on the Al/Al bond. I particularly echo Wayne's comments on looping and tail. Aluminum wedge bonding is particularly sensitive to details - definitely much less forgiving than gold ball bonding, for example. Absolutely! Be very careful when working on the loop formation. I suggest that rather than looking at the remnants of the pulled bonds, you first look at the intact bonds - paying particular attention to any looping differences and especially to the region of the first bond heel. In the program, look for differences in looping parameters, and if that corresponds to pre and post wire pull differences. You may find that your 'strongest' wires are the longest ones, etc. Look for those telltale cracks in the first bond heel and develop a 'feel' for the impact of the crack magnitude on resultant pull strength - and what your organization deems to be acceptable. Note - Most times, one can find what appear to be 'cracks' in ANY first bond heel, if one cranks up the magnification enough... I would also contemplate increasing the back radius of the tool subject to what you can/can not do with respect to looping. You indicate that the pulls are 'post seal'. What time/temp regime have they been subjected to? Since a little bit of heat can facilitate a large amount of stress relief, make sure your time/temp exposures are consistent. Steve Creswick http://www.linkedin.com/in/stevencreswick -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Mumtaz Bora Sent: Friday, November 12, 2010 9:15 PM To: [log in to unmask] Subject: [TN] Wire Bond Pull failures Hello TechNetters, I have some wirebonds on a Hi -Rel package that pulled below 2.0 gm minimum per Mil -Std -883. I have taken some SEM images of failed and good bonds. Customer has a concern with plane of fracture of the failed bonds even though it is break at "neck" . . It is Aluminum wire/to Aluminum bond pad wedge bonded ultrasonically and aluminum wire to gold plated post also bonded ultrasonic. Wire pull is post seal. I have uploaded the file of images on the TechNet groupsite .I will appreciate some feedback from wirebonding experts on the forum. http://ipc-technet.groupsite.com/main/summary <http://ipc-technet.groupsite.com/main/summary> Thank-you, Mumtaz Mumtaz Bora Senior Packaging Engineer Peregrine Semiconductor 9380 Carroll Park Drive San Diego, CA 92121 858-795-0112-direct 858-731-9499 -fax [log in to unmask] ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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