Originally Posted by quinney
It is not all that obvious. We know that the white version is delayed because of manufacturing
problems. We also know that many phones shipped with the screen bonding substance insufficiently cured, causing yellowish blotches on some screens. We don't know how many lots of black iPhones were rejected, because of spot checks. We don't know how extensive and well designed the final tests were. Finally, a certain portion of all manufacturing runs makes it out the door with defects. We don't have accurate statistics on the prevalence of the issue for iPhones, so
we can't say with certainty that it is excessive.
Originally Posted by Hodar
I guess being a genius has it's drawbacks.
When you make a non-conductive finish, the out-going test would be a resistance measurement step prior to going into final assembly. You NEVER ever (EVER!) allow something like a human's 'opinion' ("Gee, it looks like it had that step taken") bypass a test. No, you scan the Serial Number and measure the resistance on a go/nogo basis. Measure resistance, if less than 100K ohms = fail.
That way, you now only KNOW that the bezels are coated, you know the measured value of the resistance and to some measure, the quality of the coating. If a passing value is 101 Kohms and you are consistently reading 500K - 1 Meg ohm - well, then you know you have a good insulation. If you consistently read 102K; then you know your process is marginal.
Pretty simple stuff, actually.
And how does any of that refute anything of quinney's? He never said anything about human testing. Are you positive
that your automated conductance test has
to be completed on fully cured bonding? Or is it that the far more likely case, the automated lot testing is done after a specified time where the electrical and adhesive properties have adequately set even though the VOCs haven't all evaporated?
It is not uncommon for manufacturing processes to pass testing with some pre-known cosmetic changes still in process, such as off gassing and final adhesive curing. Many epoxies pass strength and hardness tests within minutes, yet continue to cure for days and display minor cosmetic changes in that time which have no effect on the passing rate during the testing.
It's far more likely some production engineer under-estimated the storage and shipping time that would be available for the bonding substance to clear up. So production got pushed to the consumer a couple days faster than the necessary cosmetic curing time. Not first string varsity work, but not end of the world either.