BGA IC rework - Page 1
Forum section: electronics / repair

author: JtroTechAB
author_rank: Contributor
timestamp: April 19, 2019, 10:14:55 am
content: Hello,I am looking for best/mostly used no clean flux for BGA rework.I went through various videos on you tube showing the soldering and desoldering of BGA ICs, reballing of BGA but they havent mentioned any particular brand or name of the flux. so kindly guide.Also,In my case I have MPC5554 & MPC5566 BGA package ICs which I want to desolder and solder again. For this I am preferring the method which is without the use of stencilso share videos or links which would elaborate the procedure like temperature of hot air, type of flux to be used etc.I am not preferring the use of stencil because the stencils are available in sets not the single dimension stencil. Like in one set you will get 27mmx27mm, 30mmx30mm, 35mmx35mm stencils & so on.where can I get the particular dimension stencil for e.g 27mmx27mm only.

author: PKTKS
author_rank: Super Contributor
timestamp: April 19, 2019, 01:48:55 pm
content: Well hard to match all your needs simple.The most used flux out there that can be recommendedwithout issues for HAND SOLDERING BGA (and most likelyfor machined BGA) is the AMTECH NC-559-V2_TFVery easy to find - a bit expensive - but for hand solderingit will give you enough time and very good results.There are indeed a plethora of others - first in mind is KESTERbut any other NOCLEAN should be functional neverthelessI use AMTECH myself for BGA and KESTER RMA for THT/SMDRegarding the STENCILs - IMHO - Don't do BGA without the proper oneTry AliExpress for a good complete kit of it like "BGA STENCILS" kinda...Cheap.. very easily done with solder paste - a bit tricky with BALLSnevertheless BALLS are the primary choice in large gridsLEADED BALLS!!! best and probably fail safe results.LEAD FREE is a trouble maker...Paul

author: testpoint1
author_rank: Frequent Contributor
timestamp: April 19, 2019, 02:41:17 pm
content: Quote from: JtroTechAB on April 19, 2019, 10:14:55 amamtech 559 is the best for lead BGA, but, if your IC worked in high frequency, you had better to clean it by supersonic machine, and if that is lead free BGA, LF-4300 can use, also need to clean it. btw, Amtech already be registered by another company in China, if you buy the Amtech flux from China, 100% is fake.

author: JtroTechAB
author_rank: Contributor
timestamp: April 20, 2019, 07:45:37 am
content: Thanks for the suggestions regarding the flux.Now, my second concern is the stencil.The Part nos. of BGA ICs which I have are:MPC5554MZP132 & MPC5566MZP132so according to their datasheet the specs. are as follows:its a 416 pin PBGAball pitch 1.0mm27mmx27mm sq.so while ordering stencil what should be the specs of stencillike 1) stencil thickness (here I need to take into account the ball diameter so how much it should be?)2) stencil hole diameter?very confused, please guide.

author: kosomsk
author_rank: Regular Contributor
timestamp: April 20, 2019, 11:27:58 am
content: Use universal stencil, from Ali/ebay. If pitch 1mm, then diameter ~0,6mm usualy

author: PKTKS
author_rank: Super Contributor
timestamp: April 20, 2019, 11:59:03 am
content: Yes IT IS INDEED CONFUSING (BGA SUCKS!!!)and quite sometimes a UNIVERSAL ( as said above) or justanother regular stencil will match your needs..that is why we have to have at least a KIT of them and try and testand hope for the better - YES BGA SUCKS!!!Indeed they are numbered and you need to crawl until find notonly the proper matching stencil number BUT ALSO THE PROPER BALL SIZErule of thumb in several cases lies at 0.5 to 0.7 LEADED BALLSBUT DON'T ASSUME THAT AS ALWAYS CORRECT.The more information you can dig on the BGA chip the betterusually you find all this info together: STENCIL number and BALL SIZEbest tips of advice I can thinkPaul

author: JtroTechAB
author_rank: Contributor
timestamp: April 20, 2019, 12:37:59 pm
content: Quote from: kosomsk on April 20, 2019, 11:27:58 am0.6mm is which diameter, stencil hole diameter is what you want to say?and what about the stencil thickness?

author: PKTKS
author_rank: Super Contributor
timestamp: April 20, 2019, 03:22:51 pm
content: Usually when talking about diameter we talk about the BALLSLEADED BALLSLEAD FREE is not very consistent - the paste may not createeven balls - LEADED BALLS are likely to have a vert uniformdistributionLEAD FREE is a crappy material which tends to present cracksLEADED BALLS are not that prone to cracks.You buy the LEADED BALLS in a KIT containing XXX balls of YYY diameterSTENCILS are NUMBERED and YOUR BGA CHIP should have a clueto what stencil is it made of. Otherwise you will guess using your kitYES BGA SUCKSYOU MAY BUY INDIVIDUAL STENCIL USING YOUR BGA CHIP CODEbut a universal match would fit just fine as wellBUT.. the height of the balls and the stencil fit should be consideredusually in the range 0.5 ~ 0.7 mm balls ...but always a best guess of common sense .. yes bga sucks.....Paul

author: PKTKS
author_rank: Super Contributor
timestamp: April 20, 2019, 03:34:44 pm
content: and 2 more cents of advice...Remember ... that this CHIP was placed by a machine...using a tight controlled pressurized LEAD FREE dispenser...with tight controlled temperature ramp with proper fluxin a proper clean and controlled environment ...And it failed....Now you have to rebuild that crappy BGA using your handswith a manual STENCIL you will guess... with a set o ballsyou will just sparse in the holes...2 very different scenarios.

author: PKTKS
author_rank: Super Contributor
timestamp: April 20, 2019, 05:06:28 pm
content: Uneven BALLS from LEAD FREE solder upon thermal stressmay easily crack - they are not very easily uniformly sparseusing hand soldering BGA.Even in proper MACHINED BGA the RAMP PROFILE is very trickyso that your gradient will not cause some balls to be higher thanothers leading to LEAD FREE CRACKS... by thermal stress deformationBGA ICs with low array pin count are easily handled by HAND BGA(like smartphones ICS) but large BGA array pin counts (GPUs CPUs and others)will require very care to do uniform ball setPhoto helps to understand the ball height issue

author: kosomsk
author_rank: Regular Contributor
timestamp: April 20, 2019, 05:24:17 pm
content: Quote from: JtroTechAB on April 20, 2019, 12:37:59 pm0,6 is a ball size (diameter), thickness whatever

author: PKTKS
author_rank: Super Contributor
timestamp: April 20, 2019, 05:32:45 pm
content: as the balls will MELT in the STENCIL...It is just another BALLPARK figure to match all the issuesconsidering you will remove the STENCIL by hand..after melting the sparse balls

author: kosomsk
author_rank: Regular Contributor
timestamp: April 20, 2019, 05:40:31 pm
content: See, cheapest bga reball kit, from Ali. Near 20 usd

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 21, 2019, 04:50:52 pm
content: I just (2 weeks ago) made my first attempt at BGA reballing.Yes it sucks, but with experience and decent equipment it may not be that bad.I ordered most of the equipment on Aliexpress: BGA clamp and universal stencils, extra specific stencils for DDR, flux, Pb/Sn ball assortment.For heating I have a (precision IR tool) ceramic glass cooktop with spacer and a cheap 858D hot air gun.I think I have done enough desoldering with this setup to now get the temperatures about right.Of course the heating and cooling slopes are not going to be as good as in an automated process.The test was done on a Samsung UE32C6710 TV with random wonky colours, and boot looping.The problem was thinned down to the DNIe BGA or associated DDR2. On trying to reflow the area I nudged one of the RAM's a little too hard and shorted some balls, after that the options were to give up or attempt a full re-ball.I used a dedicated DDR2 stencil with a center trench and 0.45mm balls.The stencil is convenient for placing the balls but then for melting them to the IC it's another problem:The stencils I have are not very heat resistant, heating them causes a warp/bulge in the middle, then some of the balls move out of position.Applying a thin layer of flux to the IC before placing the balls then removing the stencil was a little better, most balls stayed in position. Then the problem was getting the hot air temperature, distance and air flow right to melt the solder without the balls moving. I had to do quite a bit of reheating and placing the odd balls by hand...After resoldering the DDR and reflowing the DNIe the problem was not solved but worse, at least this time it was obvious the weak balls were under the DNIe.This I had to reball with the universal stencil placing every single ball with tweezers...Here too there were several corrections to make before all balls would melt correctly to the IC.For resoldering to the PCB, I used my own flux made of acetone diluted rosin. Preheat took about 7 minutes from underneath until the top side of the PCB was about 110°C, then preheat was cut and hot air applied from above until BGA self positioned.I checked aspect of outer balls with an endoscope camera.The final result is a working TV but much too much time was put into this. It was more a training approach than financial one.

author: PKTKS
author_rank: Super Contributor
timestamp: April 22, 2019, 10:02:02 am
content: Actually the FLUX is essential not only as a thermalgradient conductive layer but also as the primary wetting agentanytime when you melt or deal with ballsDon't spare FLUX.. wet the stencil - the bigger it isthe more prone to twist or deform it isand that will do crappy ballsBGA rework really sucksI wonder it the trade off of being a CHEAP alternativeto PIN arrays really worth the hassle of dealing with FAULTY chipsPaul