IC Sensitivity to Temperature and Flux Conductivity

[adoion]

How sensitive are ICs to temperature?
I recently replaced a digital signal processor IC (IC:cxd3098aq) Sony made on a PlayStation 2 and while doing so I heated the chip first to remove it, then I re-balled all the pads and then put the new chip on the pads applied some flux in the form of paste and then heated the chip again with the heat gun to melt the solder.

When I then checked the pins I noticed that not all of them were soldered right so I heated the chip again with the heat gun and also used the soldering iron to fix the remaining pins. And now I'm getting a strange noise zummiiing when I turn the PlayStation on and also the DVD drive doesn't work right.

1. How sensitive are ICs to what I've done?
2. I've read somewhere that even static electricity can kill an IC so I assume that they are very sensitive to current and so even the smallest solder bridge across two pins can melt it, is this true? but that ICs are much more tolerant to heat??
3. The flux I used was in the form of paste. And I got it smeared all underneath the chip, are those paste fluxes usually conductive?

Thanks a lot.

 

[analogdesign]

Does the new chip work, besides the noise? It sounds like it does and only the DVD drive is not working.

1. Depends. Some are sensitive, some are very robust. I suspect Sony would use the cheapest packages they could get away with. It is more likely you caused issues with the package than the die.

2. ICs are much more sensitive to static electricity during packaging than after they are packaged. However the ESD protection isn't perfect and if you were carrying a big charge it is possible you zapped it. If you zapped it would probably fail to come up.

3. Depends. Did you use electrical solder flux? Sometimes people use paste intended for plumbing, and that *is* conductive (and often fatal to the chips).

Sounds to me you warped the board with the heat gun, not the chip. It could be some of the support chips are no long seated correctly.

 

[adoion]

All of the things you mentioned came to my mind and I reflowed a BGA that was underneath the chip I worked on and checked all the surrounding packages as well, and yes I got a few blisters on the board but that shouldn't be to big of a problem, maybe I'm wrong correct me please if so.

I think that BGAs are the most robust to heat.

The thing is that the digital signal processor is intended to control the dvd drive and process the information that comes out of it, together with another (BGA) IC, these 2 make up the heart of the disk drive system. So if I burned a short on it its most reasonable to assume that the disk drive will be defective

And yes I used no corrosive flux intended for electronics :), but I don't know of what quality it is. It is very sticky and just won't go away that easy and after it does it leaves a fluid residue witch might be water.

 

[analogdesign]

BGAs are really really really hard to solder by hand. Did you do the reflow with a hand iron or a reflow oven? It's quite possible you have a short under there but it will be really hard to tell if that is the case. You could even have an open (a cold-soldered joint). It's just too hard to tell. I hate to say this but the best remedy is probably to lift the BGA again and push it down on the solder balls again really slow and carefully. Good luck!

 

[adoion]

Thanks man, I don't know what you mean by really hard to solder by hand, you just put the solder on the pins position the BGA and heat the thing for a while :). Any automatic device would do the same thing.

I might just get a new board for 10 USD, just wanted to know if the chip is fried and I believe it is, I noticed that the laser starts working for a while If I let the ps2 cool down and then as it heats up it starts to go bad.

I could get another chip but its just not worth the trouble since I can replace the whole board cheaper .

 

[davenn]

Thanks man, I don't know what you mean by really hard to solder by hand, you just put the solder on the pins position the BGA and heat the thing for a while :). Any automatic device would do the same thing.

trying to solder dozens of fine closely spaced pins with a normal soldering is somewhere between extremely difficult and impossible
Its so easy to bridge solder between pins and a pain to remove
A rework station with the appropriate fitted heat gun nozzle makes it a breeze of a job :)

as far as the sensitivity of any particular IC goes, well that info is usually in the device datasheet
they will all vary to some extent

Dave

 

[analogdesign]

trying to solder dozens of fine closely spaced pins with a normal soldering is somewhere between extremely difficult and impossible
Its so easy to bridge solder between pins and a pain to remove
A rework station with the appropriate fitted heat gun nozzle makes it a breeze of a job :)

Dave

This is what I meant. It is super easy to bridge and/or get cold solder joints if you heat a BGA with a hand iron. The heat you generate is not uniform that way it is in a reflow oven or with a heat gun nozzle.

Buy the replacement board.

 

[adoion]

heh, I would never touch a GBA with an soldering Iron.

To bad I can't find the datasheet for this chip.

Thanks guys

 

[davenn]

it may well be a propriety chip and as a result data hasn't been publically released