About that Lexar video

21.01.2011 18:48

A few weeks ago Lexar, the company behind all sorts of flash drives, published this video with some really nice shots from both the Micron fabrication plant in United States and their assembly factory "somewhere in Asia". It's worth watching.

A couple of interesting things can also be seen there. There are two clips of a pick-and-place machine picking dies from a diced wafer and placing them on PCBs around 2:30 into the video. It appears the machine is ignoring some dies. If those are chips that have been found defective at wafer testing then the yield of their process is around 65 % (I count 80 % good wafers in first shot and 50 % in the second). There's also screenshot visible of what looks like a wafer test result and that puts yield at 86 %

A little later in the video there's a close-up of the placing and bonding process and you can see that two identical dies are stacked on top of each other and slightly shifted so that the bonding pads of the bottom one are left exposed.

And lastly, the video states that it takes more than a month to make a memory chip. I'm not sure what to think of that. What part of the process could take that long? Shipping to Asia for assembly?

Posted by Tomaž | Categories: Life

Comments

The processing of the silicon from bare wafer to finished takes about 3-6 weeks, depending on the number of processing steps. I seem to recall from a TI rep that it takes ~8 weeks to process a wafer for a DSP. Dicing and packaging take about another 3-4 weeks, although that's probably mostly due to logistics. Although it is very much hands-off work, each step in the process takes several hours, with plenty of polishing, cleaning, and deposition operations. Wafers must be heated and cooled several times, but extremely carefully and slowly.

Posted by eswint

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