Post B6e1Z51AGABxBFBZjM by azonenberg@ioc.exchange
(DIR) More posts by azonenberg@ioc.exchange
(DIR) Post #B6de0TcEW1reO83TuK by azonenberg@ioc.exchange
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Prepping some chips for a decap run as I do the lab cleanout.First on deck (other than the VSC8512 I prepped a while back) is a DisplayLink DL-5900. Seems to be some kind of USB displayport adapter? No idea where it came from.
(DIR) Post #B6deP7etHxtvWr3BBo by funkylab@mastodon.social
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@azonenberg it's proprietary display-over-USB-Ports thing
(DIR) Post #B6dfbXHhwAumR5godc by azonenberg@ioc.exchange
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Next is a Qualcomm MSM7500, seems to be part of a very old phone chipset with an ARM1136JF-S.Maybe from an embedded cellular module or something? It was sitting as a loose chip in my microscope-food bin and I have no record of its origin.It's very sticky on one side, some kind of adhesive or thermal compound residue that didn't come off with acetone. I have no special interest in the part so didn't bother trying to clean it further (plus it wasn't obscuring any markings)The underside is... weird. It's 28 balls square with three concentric rings, each consisting of two rows of balls then a void space, then a bunch of power/ground balls in the middle. This much is normal.But there's some strange gaps in the soldermask between the rings, and almost all of the balls seem to have connections going to these void areas. I wonder if there is some kind of test point or plating ground or something in this area that is removed late in the packaging process? Never seen anything like this before.
(DIR) Post #B6dfrEFYTYKg2BAKrw by nblr@chaos.social
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@azonenberg DisplayLink was notorious for their „attitude“ towards Open Source. Something along the lines… „you didn‘t build drivers for our old models, so you desve no documentation for the new ones. Support the EOLed stuff first, then we‘ll see.“ Total asshattery.
(DIR) Post #B6dg6D4h7wdmjWEHQ0 by xabean@infosec.exchange
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@azonenberg *boggles* how is that milled such to have very hard square corners
(DIR) Post #B6dgAL0HadDqTy8N5E by azonenberg@ioc.exchange
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@xabean I don't think it's milled I think it's lithography.meaning the soldermask had voids printed into it when it was applied, this wasn't cut out ex post facto
(DIR) Post #B6dh6SgNCKjL5sXMPY by azonenberg@ioc.exchange
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Next is another Qualcomm part with a very similar part number, the RFR6500. Seems to be an early generation CDMA receiver from circa 2005. This must have come out of one of my old phones, although I don't think I ever used a CDMA based carrier in that time frame (T-Mobile was GSM based).I had a Samsung SGH-T439 as my first phone, perhaps this was the chipset from it?Nothing noteworthy package wise, just a 56 pin punch singulated QFN.
(DIR) Post #B6diHTUWdA7Kk4oJwu by SiteRelEnby@transfem.social
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@azonenberg@ioc.exchange Plating ground probably makes sense, electrically it looks like it'd short everything if it was in place while the chip is powered up so test point doesn't seem as likely maybe?
(DIR) Post #B6diHTeo0wLBFxcWyO by azonenberg@ioc.exchange
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@SiteRelEnby well it's more a question of whether it was a whole slew of test points, but then why would you not just probe the pins?Plating ground makes the most sense but then why would you have a hole in the solder mask?Did they electroplate rather than electroless plate the pads, then somehow mask off the pads and etch the plating ground? because it couldn't have been mechanically removed, the corners are too sharp so at least the mask patterning had to be lithographic
(DIR) Post #B6diWvMVI4vZWcQRRw by SiteRelEnby@transfem.social
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@azonenberg@ioc.exchange That is weird, mechanical removal was my guess.
(DIR) Post #B6diWvbkNP7YHtYcD2 by azonenberg@ioc.exchange
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@SiteRelEnby Well i cant rule out mechanical copper removal but there's no way the soldermask was removed mechanically, that opening was lithographic for sure
(DIR) Post #B6die3Qhh2uqZdn2MS by azonenberg@ioc.exchange
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Next, probably also from the same device, a Qualcomm PM7500 PMIC.112 pin dual row QFN (gross)
(DIR) Post #B6dmaBi5MgMkugKdrE by azonenberg@ioc.exchange
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And with that I think I have enough components to keep this wet lab session busy.Time to fire up the fume hood...
(DIR) Post #B6dn0ZgYqbEGniCWcC by azonenberg@ioc.exchange
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Everything but the acid is prepped. Time to glove up and get spicy, won't be posting for a while
(DIR) Post #B6dnpF2pLiMpYLm9tw by azonenberg@ioc.exchange
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Hmm, I perhaps could have seen this coming.As soon as I added the acid to the VSC8512, with the large copper plane that I had sanded the soldermask off of to image, it started reacting aggressively even at room temperature and throwing off more NO2 than I was comfortable with.I ended up pouring the acid off to a separate beaker to let things calm down a bit. Will give it a few minutes then see how much copper is left... I might want to do a pre-etch with a dilute nitric solution or something so i can remove the remainder of it without it getting too energetic.
(DIR) Post #B6do4y3EIZ17TwSkOO by azonenberg@ioc.exchange
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Like, I knew it was going to react - my plan was to let it sit there at room temp until most of the copper was gone, and only begin heating to attack the organics after I had taken off the copper.But with this much copper it seemed to be entering thermal runaway, self-heating and increasing the rate of reaction to the point that I was worried about whether the filtration in the fume hood would be able to cope with the amount of NO2 it was throwing off.Maybe I should get like a cold water bath or something to put the beaker in when I resume? I wasn't expecting it to get this spicy at this scale (~5 ml of acid iirc).
(DIR) Post #B6doFAUMuUFUx81LRA by azonenberg@ioc.exchange
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For reference usually I see very thin wisps of NO2 at the lip of the beaker by the watch glass that become invisible as soon as they mix with the air, this was throwing out enough that I saw visible brown puffs moving up from the beaker and remaining visible all the way up to the top of the hood. Faint, but visible.
(DIR) Post #B6dpfbpXye5nEb6BBA by azonenberg@ioc.exchange
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A more normal amount of NO2 generation (now that I feel safe taking off my gloves and letting it sit for a bit, i can take pics)
(DIR) Post #B6drWOVQLdnDD9Q6Ou by dianea@lgbtqia.space
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@azonenberg this picture reminds me when I handled 93% sulfuric acid, took about 15 seconds to penetrate each layer of nitrile gloves. I started peeling gloves... That concentration fumes quite a bit too...
(DIR) Post #B6drWOitXYZHsvirOi by azonenberg@ioc.exchange
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@dianea I wear much much heavier gloves lol.MAPA Chem-Ply N-540. They're dual layered neoprene with black over a red core so you can easily see abrasions or pinholes in the outer layer before they fail completely
(DIR) Post #B6dsAyFor8H1fLTAO0 by azonenberg@ioc.exchange
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@dianea see here
(DIR) Post #B6dsHHe7fb2VXwqb3I by azonenberg@ioc.exchange
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@dianea and normally a thin disposable nitrile underneath just so I can take them off and have some protection when I need more dexterity to use tweezers or something but the sample might not be 100% deconned yet.Obviously I change the inner gloves before putting the outer ones back on if I do that
(DIR) Post #B6dwyj0uC4Xyh5TQfY by dianea@lgbtqia.space
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@azonenberg yeah, those are more like the ones I wear around anhydrous ammonia (and a respirator) but thicker butyl gloves
(DIR) Post #B6dwyjA7dnv59fmn2G by azonenberg@ioc.exchange
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@dianea yeah sounds about right. I considered butyl but iirc neoprene was slightly better against hydrofluoric acid or acetone or something else i work with. Or maybe just less expensive butyl is pricey
(DIR) Post #B6dy3dbroQmXKufWAS by maty@mastodon.gamedev.place
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@azonenbergdon't drink the qualcomm soup.
(DIR) Post #B6e1Jc9VIa2dJOiC5Q by azonenberg@ioc.exchange
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Took a quick break but the PM7500 is done, cleaned, and imaged.Sure looks like a PMIC. Lots of big metal polygons and multi-bonded nets that are probably inputs and outputs for LDOs and buck converters.Made on an older, 3-metal planarized process.https://siliconprawn.org/map/qualcomm/pm7500/azonenberg_mz_mit20x/
(DIR) Post #B6e1PGsHK1ox3cLtT6 by azonenberg@ioc.exchange
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I wonder if any of these people still work at Qualcomm?
(DIR) Post #B6e1UkdU660coC2sc4 by azonenberg@ioc.exchange
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I've figured out what foundry made a lot of chips based on various hints from fiducials and metal fill etc.But this is the first time I've seen someone actually write the foundry and process on the mask set. Makes the ID simple lol
(DIR) Post #B6e1Z51AGABxBFBZjM by azonenberg@ioc.exchange
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Random logic showing 3 metal layers and what looks like maybe poly resistors
(DIR) Post #B6e1cOuujParlVqUaW by azonenberg@ioc.exchange
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Poly resistors
(DIR) Post #B6e1guisQ6KtZGMphQ by azonenberg@ioc.exchange
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These also look like poly resistors but are a different color, maybe they have two poly layers with different silicide doping or one of them is a resistive metal layer or something
(DIR) Post #B6eAs4LbsJEkBusWdU by azonenberg@ioc.exchange
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DisplayLink DL5900 is pretty boring from the top layer.Made by TSMC on a recent-ish node, guessing maybe 90 or 65 nm but hard to say without deprocessing. Image was slightly overexposed, need to reshoot and grab closeups but the microscope is busy on other samples. Will follow up tomorrow.Some acid damage on bond pads some of the top metal power grid. Had to leave it in the acid a LONG time to get it off the BGA substrate.https://siliconprawn.org/map/displaylink/dl5900/azonenberg_mz_mit20x/
(DIR) Post #B6eB9nxtWVrqauF7OC by azonenberg@ioc.exchange
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Qualcomm RFR6500 is full of RF analog with a small amount of digital control circuitry. Code name is "firebird".Some interesting CD test patterns along the edges that don't look like anything I've seen before. Wonder who fabbed it?Closeups coming tomorrow, still busy shooting overviewshttps://siliconprawn.org/map/qualcomm/rfr6500/azonenberg_mz_mit20x/
(DIR) Post #B6eBT22jPE0Bl5foQ4 by azonenberg@ioc.exchange
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Qualcomm MSM7500 is a multi-die package with a logic die, something that looks analog, what appears to be an inert spacer die, and a DRAM die in a 3-level sandwich with two levels of FR4 substrate. The DRAM die was mounted face down, it seems like they wirebonded the DRAM to one substrate then the logic/spacer/analog to another and then attached them face to face or something.Slightly cracked the logic die during handling.Photos coming later, DRAM die is running on the microscope now but I need to get to bed and the analog die still has a bit of gunk on it so I might throw it back in the acid tomorrow before imaging.
(DIR) Post #B6eBXBR4QVAy302NXM by azonenberg@ioc.exchange
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Microchip VSC8512 die is exposed, and I will probably do a low res overview before any further processing to avoid the risk of damaging it, but it's still stuck to the FR4 substrate and I want to get it off so it's going back in more acid tomorrow.I hate decapping large BGAs compared to molded leadframe packages, the laminate always takes sooo long to decompose if you don't have FNA.
(DIR) Post #B6eBgj4siPBOzcD18q by azonenberg@ioc.exchange
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So that's it for tonight. I have to cook two chips tomorrow anyway, so I might throw some other non-BGA parts in as well because they'll be quick. Not sure what yet.
(DIR) Post #B6eDHf9wLXwdVbkfdg by lasse@social.tchncs.de
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@azonenberg awful font face; looks like 'LAYCUT'
(DIR) Post #B6eDQqBiiASUJtxcuW by azonenberg@ioc.exchange
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@lasse All of the letters with void spaces have slits attaching to them.I suspect either the mask or something in the lithography process doesn't like having small floating features, so similar to how spray-paint stencils work all of the floating bits have a "tail" to attach them.But I agree the O should have been attached at 12 and 6 o'clock to make it more obvious
(DIR) Post #B6eE2LSRPkJA12fJGS by lasse@social.tchncs.de
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@azonenberg yes, something like that. It's obvious on the 'CO' in Qualcomm, but otherwise not so much.
(DIR) Post #B6eQ5NG8N6cVvD7TM0 by azonenberg@ioc.exchange
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Couldn't sleep, went down to shut off the microscope illuminator so I didn't wear out the LED and also crop the stitched image.The die was pretty warped from stresses during decap and/or packaging, I had to focus stack to get it to turn out decently without horrible blurring.Here's the overview. It's made by Samsung and marked "256M-G-QL". Never seen a staggered "brick" layout like this before. It also has bond pads on the edges, not down the centerline as is typical on modern DDR.https://siliconprawn.org/map/qualcomm/msm7500-dramdie/azonenberg_mz_mit20x/
(DIR) Post #B6eqDJcqMa6DmEBmlM by adistuder@mstdn.social
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@azonenberg active circuits or silicon doodle (three deer)?
(DIR) Post #B6f6BuTaSXVc7MxgB6 by azonenberg@ioc.exchange
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@adistuder That definitely looks functional, but not a clue what it is without more analysis, higher resolution, and probably delayering. But I think they're power related