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| Chip making process |
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| srce:
--- Quote from: ZeroResistance on October 16, 2018, 04:54:34 pm --- --- Quote from: coppice on October 16, 2018, 04:38:58 pm ---You need to test a wafer, to locate the good dies. Then you package the good dies. Finally you need to test again, to make sure the packaging went OK. --- End quote --- If a wafer has 100 dies on it what would be the typically percentage of good dies? --- End quote --- Yield depends on process maturity and die size (as well as some other factors) If a wafer only has 100 dies - that suggests they're monster dies and thus the yield would be relatively low. For a more realistic die size on a mature process, you should be looking at 98%. You'll also have a packaging yield as well. |
| ZeroResistance:
--- Quote from: mikeselectricstuff on October 16, 2018, 04:25:48 pm --- --- Quote from: ZeroResistance on October 16, 2018, 04:03:52 pm --- --- Quote ---Just tried X-raying a 10F200 and 10F322 - unfortunately the die wasn't visible through the leadframe, but estimating from where the bond pads were, I'd guess 2-3mm^2 --- End quote --- What kind of equipment did you use to xray that chip? --- End quote --- Faxitron MX20 - unfortunately only does 35kv so barely makes it through the leadframe --- End quote --- Doesn't the leadframe surround the die, I mean the die is in the center and the leadframe is surrounding it but only on the XY plane? And there is just the plastic packaging on the top. So just needed to understand how that interfers with the Xray? |
| Richard Crowley:
--- Quote from: ZeroResistance on October 16, 2018, 04:59:23 pm ---What's is probe yield? --- End quote --- Dice are tested on the wafer before the wafer is sawed apart into dice. Probe-cards are used to make connection with all the bond-pads so that the die can be tested. They used to actual put a drop of ink on the bad dice, but now the good/bad information is stored in a database for that wafer. That way they don't waste time/materials packaging bad dice. https://www.mjc.co.jp/en/technology/column/probe_card.html |
| ZeroResistance:
--- Quote from: srce on October 16, 2018, 05:22:24 pm --- --- Quote from: ZeroResistance on October 16, 2018, 04:10:07 pm ---For the masks, and for getting it made at the foundry. Would Microchip need to place an order for 1 million pcs of the chip? How do these things work out, will the foundry charge by area of silicon, that would me 2 million mm^2 of area. --- End quote --- They charge a one off fee for the masks, then per wafer. --- Quote from: ZeroResistance on October 16, 2018, 04:10:07 pm ---Packaging would be a seperate expense right? --- End quote --- Yes --- End quote --- Do foundries have a minimum wafer quantity. I mean wemberlytech showed cost of a wafer as USD 1600. So do the foundries expect you to order something like 100 wafers. And if each wafer has 15000 dies on it. Do the foundries also charge you per die on that wafer. I guess it should have been area based, if a wafer is 200mm in dia that comes to 31400mm^2. So Do they charge on area of silicon? |
| Wimberleytech:
--- Quote --- This is pretty amazing, did you rattle that off in a few minutes. Just a bit out of depth with the terminology what does MLO mean? What's is probe yield? How many wafers do I have to order from the foundry to get these sort of rates? --- End quote --- This came from my files. In my former life, I was founder and CTO of a fabless semiconductor company. MLO = Materials Labor Overhead Probe yield: prior to packaging, each die on the wafer is probed and tested. Only some of these die will pass the probe test...thus the probe yield. After packaging, the die are tested again. Less then 100% of the packaged units will yield--package yield. To work with a foundry, you will have to commit to many thousands of wafers in production. For this example, I do not recall which package was being used (maybe 32 pin pqfp). |
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