To all of the "Metal Shield" vs "Sticker" Oooooh this is a design flaw people. First, I've seen the video and the claims by the assembly person making these speculations are exactly that. Speculations. This person is NOT a mechanical engineer. This person is NOT an EMI Electrical Engineer. She is a skilled assembly person simply noting that the phones with the shield don't exhibit the problem where the ones with the sticker do. That being said, NEITHER THE SHIELD NOR THE STICKER were designed with the intent of keeping IC's from becoming unsoldered. The EMI shield does have the property that it provides mechanical strength to the PCB, thus minimizing what is probably mechanical flexing which is probably the part of the root cause of the solder balls becoming detached.
Being an IC designer for some 30 years and working in the PC industry for just as long, anyone who has done this kind of work would immediately recognize this issue as most likely 1) a solder ability issue and 2) perhaps a mechanical issue with flexing on the PCB that has problems with the IC becoming detached. My 2cents is it is a manufacturing issue relating to either the type of solder used or the process control or lack thereof relating to how the IC's were originally put on the board. If it was a rampant design flaw then a substantially larger sample of phones would be failing with this problem. Given the fact that this large failure rate does not exist, I'd point my finger to the solder reflow line and what was going on at the time of the failed units. It would not surprise me at all to know (us on the outside will never find this out) that the failing units may all in fact be traced to a specific line or a specific period in time and something happened on the manufacturing line to cause weak solder joints.
All of this being said, is it Apple's fault? Well, yes ultimately of course it is. Is it the design change from a shield to sticker the cause for the problem? I would say no. The design change exacerbated the problem but I don't believe it's the root cause, which, as an engineer, you are most interested in solving. The design change to the stickers from the shield, looking at both a manufacturing cost and a design profile design was probably a very desirable change. Making the change, however, allowed devices that came off the line with the weak solder joints to fail.
I'm not going to get into the muck of who should pay and who should not. Have at it. I just wanted to put my 2c in on what I believe is the real root cause of the problem. And.... like I said.... because of certain liabilities, you and I will never really know but I would guarantee you there is a manufacturing engineer or two at Apple and their assembly plant that know EXACTLY why these units failed and I'd be more that willing to bet EMI shields have NOTHING to do with the root cause of the problem.
