Acer aspire 7520 problem (nvidia chip)

[primoz1]

I got a motherboard from acer aspire 7520 with integrated graphic, and I think the chip is bad, so I got a good chip from aspire 7520G with separete graphic card, the chips got same code Nvidia MCP67MV-A2 is that chip compatible for both motherboards ?

Thankyou ?

[Joun]

Re: Acer aspire 7520 problem (nvidia chip)

The thing is chips rarely go bad, its the solder balls under them that crack and don't make contact with pads anymore.The best thing to do is reball the chip motherboard allready had .

[mockingbird]

Re: Acer aspire 7520 problem (nvidia chip)

Any of these three things can lead to nVidia MCP failure:

1) The solder does indeed crack under the chip, but ONLY because the chip runs too hot. There are MANY chipsets that do just fine with RoHS solder (And mind you, there are many varieties of RoHS solder, some vastly superior than others)
2) Due to an inadequate underfill, the die is not allowed to flex enough when the chip is under thermal stress, in this case, the chip itself is irreparably damaged
3) Due to a poor chip design, the die leads (Not to be confused with the BGA "leads") seperate from the internal pads

In cases 1 and 2, reflowing CAN temporarily resolve the problem. But situation 2 is ultimately inevitable with those nVidia chips.

[primoz1]

Re: Acer aspire 7520 problem (nvidia chip)

Hi. On this board has already been done reball, I buy defected board but someone has do repair-reball before I buy this board.

For information this MCP67MV-A2 chips are identic for 7520 with integrated graphic and 7520G with separated card.

I replace MCP67MV-A2 from another board and now all work OK. Only graphic drivers must be raplaced.

Edit: What solder balls you use and where can I buy (if leadfree) mockingbird leadfree ar leaded ? I think maybe is leadfree better solution, because has a higher melting point and heating not afected on solder, of course must be a top quality.

Thank you all for suport again.

[mockingbird]

Re: Acer aspire 7520 problem (nvidia chip)

Good question.

Who sells good quality unleaded solder balls? I have no idea if you can even buy any. But one thing is for sure, if you buy it from China, it won't be good quality. Why? Because high quality RoHS BGA balls are only sold in large quantities.

Another problem is the tack solder. The tack solder is used to hold the balls in place after the chip is taken out of the stencil jig. Yes you can get fake Kingbo tack, but then there's a risk of the chip "popcorning".

I have heard theories that the chips popcorn because of moisture from storage, but my bet is that they're popcorning because of the counterfeit Kingbo tack.

[primoz1]

Re: Acer aspire 7520 problem (nvidia chip)

Hi. What is tack (Im from slovenia, and my english is not so good) are you got in mind flux ?

I use this kingbo flux one year, and is OK for desoldering chip and clean the board with desoldering wick wire, and also for reballing chip, but for soldering chip back on board is not OK. depends what size balls is on chip, if is smaller on 0.5 kingbo flux is boiling and make bubles and fu*ked up the balls under chip. This kingbo also produce a lot of smoke, which is not good for health.

So I use now only ERSA flux is very expensive 22 € or 28 US$ for 5 ml injection, but is OK. and almost not produce any smoke.

For leadfree solder balls I look on this site but Im little in doubt, they are not just glued jovy labels on the cheap Chinese stuff.

[mockingbird]

Re: Acer aspire 7520 problem (nvidia chip)

Tack means a sticky substance... the Kingbo is tacky, which means it is a kind of flux which is sticky...

Yea, you had fake Kingbo flux and it popcorned your chip.

Lead-free solder balls on that page is SAC305... Try to get SAC405. Supposed to be better.

[primoz1]

Re: Acer aspire 7520 problem (nvidia chip)

Hi. Are you got in mind this Kingbo flux
Thankyou

[mockingbird]

Re: Acer aspire 7520 problem (nvidia chip)

No, I'm talking about the Kingbo that comes in a syringe. If it comes from China, it's fake. To be honest, I've never ever used it personally, but I've seen it being used on many Xbox re-ball videos.

[primoz1]

Re: Acer aspire 7520 problem (nvidia chip)

Hi. I need one info more, laptop work OK. but battery wont charge, I change several battery's (all is OK) but still wont charge. Is any controler on board which is responsible for this ?

Thankyou.