So I'm thinking about what to use as the guts of the gen2 reworkctf board.
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@jpm I'm targeting OSHPark 4 layer design rules but nothing will be fast enough to care about impedance so it should be totally doable on JLC.
There will be an 0201 and probably an 01005 on the board, but as bare footprints where the challenge is "populate it by hand". No components necessary for functionality of the board as a whole will be smaller than 0402.
The challenge isn't "populate the BGA" lol.
The challenges will be more like "ball C3 was accidentally left unconnected, route it to this resistor as you see fit".
There will be two difficulty levels of that challenge, one you are allowed to do on a bare PCB before stuffing the BGA.
The higher point version of the same challenge you are not allowed to do until the BGA is already populated (simulating late discovery of the defect), at which point you either have to do some kind of root-canal back drill operation without removing the chip, or pull the BGA, reball it, rework the site, and put it back on.
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So I'm thinking about what to use as the guts of the gen2 reworkctf board.
I want a BGA of relatively large (0.8 or 1 mm) pitch to allow practicing of BGA site rework without being 11/10 difficulty level right out of the gate.
The STM32H750XBH6 is $12.39 at digikey in single units, sub $10 in higher volume, although currently sold out until April (I have enough on the shelf to prototype with), 0.8mm depopulated 265-BGA.
The cheapest Xilinx part in a 1mm FTGB196 is the XC7S6-1FTGB196C at $20.94 qty1 price.
Any other ideas? A lot of the really low cost parts are like 0.5mm or WLCSP which defeats the point of using a large pitch to make the challenge not too crazy difficult.
@azonenberg if you look you can find some $1 ST BGAs at Mouser. Also try looking at Arrow, they have low prices on select ST parts.
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@jpm I'm targeting OSHPark 4 layer design rules but nothing will be fast enough to care about impedance so it should be totally doable on JLC.
There will be an 0201 and probably an 01005 on the board, but as bare footprints where the challenge is "populate it by hand". No components necessary for functionality of the board as a whole will be smaller than 0402.
The challenge isn't "populate the BGA" lol.
The challenges will be more like "ball C3 was accidentally left unconnected, route it to this resistor as you see fit".
There will be two difficulty levels of that challenge, one you are allowed to do on a bare PCB before stuffing the BGA.
The higher point version of the same challenge you are not allowed to do until the BGA is already populated (simulating late discovery of the defect), at which point you either have to do some kind of root-canal back drill operation without removing the chip, or pull the BGA, reball it, rework the site, and put it back on.
@jpm This is not a "learn to solder" board it's a "practice the skills you'll need to do circuit edits on high end multilayer boards full of BGAs and fine pitch parts" board.
Being able to populate QFNs and BGAs by hand is a prerequisite you are assumed to have down cold before you even pick up the challenge board.
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@azonenberg if you look you can find some $1 ST BGAs at Mouser. Also try looking at Arrow, they have low prices on select ST parts.
@0h00000000 most of the really cheap stuff is WLCSP or 0.5mm IME. Got any 0.8mm parts to suggest? specifically STM32s?
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@0h00000000 most of the really cheap stuff is WLCSP or 0.5mm IME. Got any 0.8mm parts to suggest? specifically STM32s?
@azonenberg TFBGA64 STM32L0 - $2.76 at qty 10.
$2.38 at qty 1:
https://www.arrow.com/en/products/stm32l071rbh6tr/stmicroelectronics.html -
@azonenberg TFBGA64 STM32L0 - $2.76 at qty 10.
$2.38 at qty 1:
https://www.arrow.com/en/products/stm32l071rbh6tr/stmicroelectronics.html@0h00000000 That's an 0.5mm pitch package
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@0h00000000 That's an 0.5mm pitch package
@0h00000000 Drilling out new vias or adding tracks between balls on 0.5mm is much harder than 0.8 or 1 (something *I* haven't attempted to date). I'm not going to put that on this challenge.
Maybe a sequel if some Chinese phone repair guy thinks it's too easy.
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@0h00000000 Drilling out new vias or adding tracks between balls on 0.5mm is much harder than 0.8 or 1 (something *I* haven't attempted to date). I'm not going to put that on this challenge.
Maybe a sequel if some Chinese phone repair guy thinks it's too easy.
@0h00000000 The smallest / cheapest 0.8mm packages I know of are like the UFBGA144 for F4s.
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So I'm thinking about what to use as the guts of the gen2 reworkctf board.
I want a BGA of relatively large (0.8 or 1 mm) pitch to allow practicing of BGA site rework without being 11/10 difficulty level right out of the gate.
The STM32H750XBH6 is $12.39 at digikey in single units, sub $10 in higher volume, although currently sold out until April (I have enough on the shelf to prototype with), 0.8mm depopulated 265-BGA.
The cheapest Xilinx part in a 1mm FTGB196 is the XC7S6-1FTGB196C at $20.94 qty1 price.
Any other ideas? A lot of the really low cost parts are like 0.5mm or WLCSP which defeats the point of using a large pitch to make the challenge not too crazy difficult.
Not serious (terrible availability):
LCMXO2-1200UHC-4FTG256C | Lattice | Price | In Stock | LCSC Electronics
LCMXO2-1200UHC-4FTG256C by Lattice - In-stock components at LCSC. Price from $4.3437. Free access LCMXO2-1200UHC-4FTG256C datasheet, Package, pinout diagrams, and BOM tools.
LCSC Electronics (www.lcsc.com)
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Not serious (terrible availability):
LCMXO2-1200UHC-4FTG256C | Lattice | Price | In Stock | LCSC Electronics
LCMXO2-1200UHC-4FTG256C by Lattice - In-stock components at LCSC. Price from $4.3437. Free access LCMXO2-1200UHC-4FTG256C datasheet, Package, pinout diagrams, and BOM tools.
LCSC Electronics (www.lcsc.com)
@azonenberg ECP5-12F used to fit this bill but they've hiked prices and reduced availability
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@azonenberg ECP5-12F used to fit this bill but they've hiked prices and reduced availability
@ldcd i feel like i could probably save a dollar or two with a slightly smaller stm32 but the h750 is one i have on the shelf which counts for something too
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@ldcd i feel like i could probably save a dollar or two with a slightly smaller stm32 but the h750 is one i have on the shelf which counts for something too
@azonenberg the H7s are just really nice all around
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@azonenberg the H7s are just really nice all around
@ldcd yeah it's just overkill lol.
I might borrow an idea from @cccpresser and break out some IOs to connectors so it becomes a useful devkit not ewaste when you're done with the challenge. That makes a bigger mcu easier to justify
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@ldcd yeah it's just overkill lol.
I might borrow an idea from @cccpresser and break out some IOs to connectors so it becomes a useful devkit not ewaste when you're done with the challenge. That makes a bigger mcu easier to justify
@azonenberg @cccpresser I mean yeah I think that's absolutely a good idea
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@azonenberg @cccpresser I mean yeah I think that's absolutely a good idea
@ldcd @cccpresser yep it is, it never occurred to me on the first iteration but for rev 2 I'll definitely be doing it
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@ldcd @cccpresser yep it is, it never occurred to me on the first iteration but for rev 2 I'll definitely be doing it
@azonenberg @cccpresser 0.4 but long pads https://www.digikey.com/en/products/detail/epc/EPC8009/4990585
Could have a little switch mode for funzies.
I think having a dev board you've done some rework on makes people more likely to use it
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@azonenberg @cccpresser 0.4 but long pads https://www.digikey.com/en/products/detail/epc/EPC8009/4990585
Could have a little switch mode for funzies.
I think having a dev board you've done some rework on makes people more likely to use it
@ldcd Lol.
I specifically need a large-ish pitch BGA (which makes sense to be the main processor of the system) for BGA site rework challenges though.
I think I'm gonna run with the H750.
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@0h00000000 That's an 0.5mm pitch package
@azonenberg ST "TFBGA" should be .8mm, but the dist may have the info wrong.
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