Hardware Advices for Technicians Read Before Rework!

[Wites OM Tesla]

Advice#1 Most important in repair when you receive an device for repair is INVESTIGATION under stereomicroscope entire board to OBSERVE damaged,missing,corroded,burned etc components.

Advice#2 Not all filters or resistors can jumped with wire that is mistake,for example filter that stay near lcd connector for light if you jump it this will overload the ic and coil even PMIC and can burn as a result you will need to replace light coil or ic in place of small filter,this why to jump is NOT RECOMMENDED.

Advice#3 Never heat glued ic’s or chip as this is NOT RECOMMENDED,only reballing will fix 100% loosen solder balls after device was dropped,fall,kick etc.

Advice#4 If members want 100% help on this forum they need to post full info about faulty phone,water damaged,dropped,fall,kick,connected to copy China charger etc.Also explain what you try as for members will be more easy to advice in right way!

Advice#5 All readings that i ask here are done with multimeter switched at diode/beep testing or if not available 2 in 1 function then use only diode testing,to make a reading hold Black probe to GND Red to Positive track and vice versa Red to GND and Black to Positive,so the track you take readings must have 2 different readings that you compare with working board and can see if there is no short.

Advice#6 It is recommended before do hardware repair on board,to test faulty board with known good working housing and LCD/Touch.
Feel free to ask anything here about rework!

[~Leo~]

Nice thread my friend keep it up. It should be sticky

[ortizvr4]

Which is the most recomended flux to use on board and what is his function, sorry if this is a stupid question but I want to learn soldering well, because I tend to burn things out.

[enatse]

Originally Posted by ortizvr4

Which is the most recomended flux to use on board and what is his function, sorry if this is a stupid question but I want to learn soldering well, because I tend to burn things out.

I think available fluxes differ from country to coutry .. And I'd like to know too .. What i do however know is that you want non-conductive and non-corrosive flux, since corrosive flux will attacks PCB's, essentially melting them, which can cause great damage, and conductive flux might cause short's.

I've seen people recommend doing their own flux, though the recipe escapes me at the moment .. Anyway, I'd recommend a fluxpen, i'm sure those could be found anywhere ..

Linking a video that might help:
EEVblog #180 - Soldering Tutorial Part 1 - Tools - YouTube This one related to soldering in general, where he talks of what tools to use, what paste's and so on and so forth.

EEVblog #186 - Soldering Tutorial Part 3 - Surface Mount - YouTube Same guy (Dave) discusses
using and soldering SMD's (Surface mounted Devices) which is VERY relevant in working wihth any iDevice.

[osakun]

it should be sticky wites...sometime those small attention were missed by us....thank u for that wites

[jegerjon]

I was wondering what material people uses to replace the black resin around chips? Say you have removed the resin, reballed the chip, and want to add a new pool of resin, just to leave everything the way it was before. What materiel would you recommend?

[Wites OM Tesla]

Originally Posted by jegerjon

I was wondering what material people uses to replace the black resin around chips? Say you have removed the resin, reballed the chip, and want to add a new pool of resin, just to leave everything the way it was before. What materiel would you recommend?

OMG i never do that because next repair will be much easier if not for me then for that technician that will repair it.

[blu angel]

Pardon to ask but because jegerjon mention about the black thing paste or glue or resin as he called it that was removed?, is there a good chemical that can remove it?

-blu

[Wites OM Tesla]

Originally Posted by blu angel

Pardon to ask but because jegerjon mention about the black thing paste or glue or resin as he called it that was removed?, is there a good chemical that can remove it?

-blu

I have tried many solvents thinner,acetone,dichloroethane(harmful),paint stripper,bga ic athesive remover(Made in China) all this are good for cleaning the ic after you unsolder it from board,it will never soften under the ic.
I have told many times use heat gun with 180C of heat full air flow and a needle or dental tool and clean around that glue then unsolder the ic with 280C to 300C of course this temps are low because i not use board holder,if you use board holder then you need more temp,good luck!
If there is some chemical that will eat that black s..t under the ic let me know.

[blu angel]

Again pardon my ignorance but well it's just out of curiosity really because I haven't known any chemical either but I am just curious about this guy who's asking if where can he get that black thing or resin as he calls it after he removes it.. means like maybe he uses a chemical to remove it or just the hard way?

Anyway I go as far as 480c sometimes just to remove the damn thing... Or sometimes I just throw the board away

[Wites OM Tesla]

Originally Posted by blu angel

Again pardon my ignorance but well it's just out of curiosity really because I haven't known any chemical either but I am just curious about this guy who's asking if where can he get that black thing or resin as he calls it after he removes it.. means like maybe he uses a chemical to remove it or just the hard way?

Anyway I go as far as 480c sometimes just to remove the damn thing... Or sometimes I just throw the board away

480C is too much friend i will make an video soon as my camera not come yet and show you that is enough to give 180C of heat iPhone 4S board need more 200C of heat that glue is even harder.

[denimdragon]

Originally Posted by Wites OM Tesla

OMG i never do that because next repair will be much easier if not for me then for that technician that will repair it.

That is definitely what I do. If I know that I may see the phone again, I make sure I leave things like that alone. Just saves time.

[jegerjon]

Of course it is annoying when we have to remove it, but it helps holding the chip in place, minimize damage from water, and (often) give away cracked balls.
So far I have not been replacing the resin, because I don't know which glue/filler to use.

As for the way to remove the resin, I do about the same as Wites. ~180 degrees from preheater, and a little less heat from air gun but with maxium airflow. Then i pick it with a sharp tool. I find this method rather quick, as the huge air flow helps clean the area when you work through it.
I would be very interested in watching you do this in a video Wites. I think we can all learn from you!

If we knew what type of glue that black stuff is, we might be able to find a proper chemical for dissolving it!

[Wites OM Tesla]

Originally Posted by jegerjon

Of course it is annoying when we have to remove it, but it helps holding the chip in place, minimize damage from water, and (often) give away cracked balls.
So far I have not been replacing the resin, because I don't know which glue/filler to use.

As for the way to remove the resin, I do about the same as Wites. ~180 degrees from preheater, and a little less heat from air gun but with maxium airflow. Then i pick it with a sharp tool. I find this method rather quick, as the huge air flow helps clean the area when you work through it.
I would be very interested in watching you do this in a video Wites. I think we can all learn from you!

If we knew what type of glue that black stuff is, we might be able to find a proper chemical for dissolving it!

Yes i agree if we could know the recipe of this black resin we could find how to dissolve it even under the ic.

[blu angel]

well wites I will be waiting for that video you are talking about so we could all learn from it, much appreciated to do that for all of us..


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