I fully agree with you Here a good spinning head and a lot of experience means more than 10 degrees By the way may I ask you if are you doing this in full time as a repair business?
This can be down to a few things, SoC, Ram, main PMIC or fuel gauge or EMMC data corruptions⊠more often then not though itâs the fuel gauge as itâs so fragile and people prior have tossed the board around a bit, you can often tell if there are any knicks, chips or cracks in the die.
If itâs Ram, sometimes you can get lucky and put downward pressure on the modules (BiskeyDump payload is good for this) and the board will spring to life indicating poor contact as a result of bad balls or pad traces below. If theyâre physically or electrically bad youâll often be able to tell by testing the two rails which feed them resistance relative to ground.
EMMC, if itâs unpatched you can rule it out by using Choi or EMMCHaccGen to re-gen the FW.
SoC and main PMIC is a bit harder to rule out and test but more often than not itâs just that theyâre dead or the pads below them have either been ripped/tore, or suffered liquid damage.
If you remember last weekend we âspent togetherâ to figure out my 170Ohm short on the 3,3V line It ended up a short on the CPU. I ordered the Stencil for the CPU, a Jig for reballing and balls. As soon as I receive it I try to reball it. This will be my first real reballing
The other one I already bought ca 1 year ago with zero experience and I messed it up that time. But since than I could repair all of them unil last week. This is why I have now the willingness to continue.
By the way I still owe you with the EMAG PCB cleaner âtestâ. I will try to do it tomorrow and come back to you with the results.
What type of jig did you wind up getting? I have three different types here two of which are not suitable as the jaws interfere with the stencil height.
What type of solder balls did you get, just curious, while the ones from china will certainly work Iâve found there consistency is pretty poor (not completely round) which makes getting them into the holes tricky, the name brand solder balls are a lot better and the alloy isnât called into question.
I donât know if this is a devation in the stencil or itâs a misunderstanding of the ball size by the chinese manufacturers but 0.35mm balls seem a touch on the small side to me, frequently two balls will fill one hole and you have to hold the jig and stencil at an angle to see and kind of brush over them with a cotton swab to knock the extra balls out⊠really annoying, i think Iâm going to get some 0.40mm balls and provided they fit in the holes, i reckon Iâll use them instead going forward.
Iâd reccomend just practicing on that SoC with the pulled pads, once youâve successfully done it four or five times youâll get the feel of it, just make sure to pre-flux the IC after wicking and cleaning, i typically put a blob of flux in all four corners and the middle and smear around with a cotton swab, too thick and the balls will piss off on you and to little and the balls wonât jump into place after youâve removed the IC from the jig and stencil and start to reflow the balls.
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I ordered balls kit from China. Do not really know what to expect
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That is a really good idea I will do so.
By the way with balls do you have to remove the stencil before melting them onto the pads or I can also heat it with the stencil on it?
I have that Jig, it works well for the big boy console chips but not in this case unfortunatley as it doesnât grip the IC well and the jaws protrude too much.
Something like this works well
Youâll have to lemme know when it arrives if the 0.4mm balls fit into the stencil well, as i donât have any on hand atm
Yeah you have to remove the stencil and take the IC out of the jig before reflowing the balls into place, otherwise the jig will sap too much heat, youâll cake the mechanism up in flux and/or balls which will ruin it and the 80x80 or 90x90 stencils are thicker than the direct heat stencils and will tend to buckel under the heat
I was hesitating betweend the jig you attached and the one I ordered. I would have to ask earlier but I do not want to bother you all the time
I will let you know for sure. Finally once I can also give you some information
Understood. I saw some videos this is why I asked. Im afraid that I will shift half of the balls with my shaky hands
Furthermore I also ordered a fume extractor because I did not have any. I invested quite a lot of money into this hobby now
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Even with the jig i reccomended above there is a fair amount of play on the stencil mount and it can shift the balls a fair margin off the pads, provided the balls are within about 50% of the pads theyâll find there place during reflow, itâs normal to have to manually reposition a couple after lifting the stencil or manually place ball because itâs decided to come off with the stencil/
Iâm a bit of a terror for not using these fume extractors⊠i should really invest in oneâŠ
The one youâve selected looks good to me and has to be better than those carbon filters on PC fans
I like this one pretty much. This is direct heat for solder paste.
Iâm a bit of a terror for not using these fume extractors⊠i should really invest in oneâŠ
The one youâve selected looks good to me and has to be better than those carbon filters on PC fans
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I am doing all these in our bedroom. I definetly need something reasonableâŠ
The jig seems to be some sort of fibre material, i havenât used them myself but see a lot of the youtube guys using them, particulaly for iphone related stuff.
The Stencil on the other hand isnât really suitable, as youâd have the same limitations as using a direct heat stencil which doesnât really work with solder paste for this size of SoC, so youâd have to use the pre-formed balls and as this isnât a conventional jig youâd make a bit of a mess (as you canât swirl the balls around the jig). I did something similar before the dedicated 80x80 or 90x90 Switch SoC stencil was available, would use a universal direct heat stencil taped oved the top of the SoC then used 0.35mm balls created a complete mess then reflowed them with the stencil in place then removed the stencil and excess balls etc.
Hello again Have a nice Sunday.
I have made my EMAG DOE today. With 2 different Fluxes. With a cheap chineese (I run out of my Chipquik and the Amtech has not arrived yet) and with a MGchemicals Rosin Flux. Test have been done with 10% and 5% solution and from the 5% version there is one with and without heating on the 3D printer.
The cleaning effect was amazing with both concentration but as You can see on the pictures the 10% version again caused quite severe etching/discolouration. At some point between the LED pads it even removed the white solder mask.
The 5% versions look way more shiny but still some slight discolouration can be seen.
As a result later on I will try to use 2,5% version (I was too lazy to test also this at the moment Sorry for that)
I donât think i would feel to comfortable using this solution on anything of value, I donât like the idea of something so aggressive getting inbetween board layers and despite an IPA rinse could potentially still be hanging around silently etching away and worse case later down the line causing possible issues.
There is also the possibilty it could alter passive values. Also if this is what itâs doing to easily visible areas it will be doing the same thing to the underside of components, the Max ICâs and the WIFI IC for example have an incredibly thin polymer layer isolating the pads, if for example a reball had already taken place on one of these ICâs then the coating is already in a semi compromised state (there no getting around this unfortunately and it is just the nature of it) and then i suspect this fluid even at a approx 2% concentration would eat away at the remainder.
Certainly seems to be a bit of an odd formulation, youâd hope the board (and joints) would come out better than when they went in. It might be worthwhile sending the seller a message regarding this as something doesnât seem right⊠maybe itâs a bad batch, over concentrated or something.
Hmmm. You might be right.
I already contacted with them and the response was this cannot be because of the cleaner vecause all their customers are using it with 5% concentration and its all goodâŠ
For sure they will not tell that it is bad for what is it made forâŠ
Maybe I will just send it back. It is from AmazonâŠ
God, can you imagine if you took their advice and left it in for the full 15mins they suggest in the datasheet⊠youâd likely have no solder mask left⊠maybe you should do it and send them a photo
I forgot to mention, itâs also not uncommon (for me at least) to complete all repairs on a board, throw it in the ultrasonic only to realise i have to repair something else that i missed or forgot about and have to throw it in the ultrasonic again⊠I donât think youâd get away with doing this with that fluid, particularly if it starts eating away at the solder mask
Would be interesting to see I will not fight with them just send it back and thats itâŠ
Yes, sure it is not uncommon that you figure out during testing that something else is also bad and you have to clean it again.
I will try to order than the fluid you recommended although I will not pay 28⏠for shipping and handling to MouserâŠ
By the way I also ordered the another bronze reballing jig you recommended.
One last question and I will not bother you anymore (for Sunday afternoon at least ) Which flux are you using? I used chipquik no clean flux until now. I run out of it and it is not on stock so I had to order something else. I had some cheap chineese but it does not help solder to flow at all and anyway who knows what it contains⊠Now I ordered originak Amtech 559 but it is coming from Ireland and will inly arrive in weeksâŠ
Yeah thatâs insane⊠Iâd mix my own version before i paid anything like that, doesnât seem to be anything special despite the complicated chemical names, seems to boil down to 80/90% distilled/deionized water, 5/10% IPA, <1% sodium/salt, and while itâs not mentioned in the SDS as itâs not a hazardous chemical there is a non foaming detergent in there too, Iâd probably just put a small amount of powedered washing machine detergent in, would guess this would work well
Check if you can get the Ambersil stuff from Farnell/Element14 in your country.
Cool, did you find the dedicated 80x80 or 90x90 SoC stencil for it too?
Iâm using two large tubs i got from china a while a go, ones Kingbo and the other is Amtech, will have to check the numbers on them but donât really think it matters as itâs highly likely theyâre fakes, even so, they work well, i think the knockoffs typically have a higher acidity which isnât too much of an issue as I use the ultrasonic afterwards, i think SDG youtube channel did a few tests regarding this and found the same.
I will check this also now. I remember that I checked quite a lot of places (Digikey, Mouser, Amazon etc) maybe not on Farnell⊠My badâŠ
For flux I want to use high quality no clean flux because I only want to use the Ultrasonic cleaner when the board is really messy already because as I told I am doing this in the bedroom and handling chemicals is not so straightforward hereâŠ
I have a good 500g Stannol 60/40 just opened. That is great.
I have exactly this Chipquik solder paste but I was not really happy with it. It is not consistent. Somewhere it is too dry, somewhere it is wet. I suffered a lot with it while reballing the few ICs I removed from the shorted 3,3V rail switch. As you also told the MAX IC is this âglassâ version and I only managed to reball it for the 10th times because of suffering the first time with the stencil and also with the incosistency of the paste. I hope it survivedâŠ
Fair enough, i donât use anything but no clean flux, you can typically tell (even if theyâre knockoffs) if theyâre water based by the way they behave when heated.
I used to use 60/40 myself but since then I just like the 63/37 alloy as it lowers the melting temps by a few degrees, might not sound like a lot but in actuality it makes a huge difference, especially when wicking off pads with a large thermal mass behind it.
I hear ya, they dry out and become inconsistent within just a day between uses, this is not a problem inherent with chip quik but all brands, i have a few other brands here which behave worse, I vigorously mix with a metal spudger prior to every use⊠and i mean aggressive, squashing it up against the sides of the tub, sometimes it will dry out too much and you have to mix in more flux to loosen it up, though it can be a challenge doing this and finding the right onsistency, too thin and it will buble out the stencil and too thick and it wonât combine when up to reflow.
Sometimes if itâs to thick to even mix, you can put the tub into a bowl of 80C water and let it warm up which makes it easier to mix, they also reccomment you keep it stored in a fridge, i donât do this tbh. I think itâs something even the distributors are aware of, as the last tub i ordered from Mouser last had electrical tape wrapped roung the tubs screwtop
I saw a Youtuber is using this Kingboo flux but he told that it is not No clean flux.
Regarding the Chipquik flux in Farnell. I see it is available but the 10ccm syringe costs 30⏠I bought it on Amazon for 15 before. And now I ordered the Amtech 30ccm syringe for 36âŹ.
I really did not expected that there is so much difference. I bought it a few years ago already. Anyway it must be way better than Lead free solders.
I really like âtalkingâ to you because you have an amazing knowledge and extreme amount of experience on this field.
My Chipquik solder paste arrived with teh same plastic tape around the lid. Maybe I should put it into a sealed bag to reduce the chance of drying.
I also saw that it should be stored in the fridge but I will defiently not put it into it. I do not want anything lead containing inside
Furthermore I checked this Ambersil ultrasonic cleaner but it is sold as a general purpose cleaner and not especially for PCB cleaning. Do you think it is free from corrosive substances?
Here a good spinning head and a lot of experience means more than 10 degrees 
Have a nice Sunday.
) Which flux are you using? I used chipquik no clean flux until now. I run out of it and it is not on stock so I had to order something else. I had some cheap chineese but it does not help solder to flow at all and anyway who knows what it contains⊠Now I ordered originak Amtech 559 but it is coming from Ireland and will inly arrive in weeksâŠ
I bought it on Amazon for 15 before. And now I ordered the Amtech 30ccm syringe for 36âŹ.