reflow flux and other shit

[xboxhaxorz]

Re: reflow flux and other shit

regarding increased chances of permanent damage, this is correct if the operator is doing an improper rework

however some boards will work after a reflow that are in fact already damaged due to delamination and corrosion and will return in say a few dys to a few wks and you would only know if you did a reball or the use of x ray machine

our policy is if a board returns a 2nd time we do not reflow we reball it or replace gpu and sometimes we discover either bad gpu or bad board its not that common but it does happen

[GR-TEK]

Re: reflow flux and other shit

I run a laptop repair shop and I use CS-FLUX . Everyone says that reballing is better but reballing has very increased chances of permanent damage on the PCB pads or the GPU. I have tryed practically all kinds of flux on ebay and I can only sugest CS-FLUX for reflow. It is very hard to explain what makes it the best flux for this kind of work but you can get an idea from this video on youtube

http://www.youtube.com/watch?v=p8HN8iw2BHY

it is avaliable on ebay here
http://www.ebay.com/itm/390792468898

Since I descovered CS-FLUX I have almost 100% of success on reflow and practically zero returns. Comparing it with flux like Amtech and KINGBO I can say that it is of similar quality but CS-FLUX when heated turns into liquid and covers all area under the GPU. The other brands although they also turn into liquid when heated they are still quite viscus and they can't go through the GPU complitelly.

[xboxhaxorz]

Re: reflow flux and other shit

flux wise, you need kingbo flux

[EdT]

Re: reflow flux and other shit

there is nothing wrong with lead free solder as long as its done properly. They've been using ROHS LF solder for, I believe almost a decade. Most of the BGA chips in todays consumer market use it. Only a fraction has issues. HP DVxxxx had issues cause of poor cooling and, by make, chips that run too hot (why nvidia does not make chipsets anymore, nor should they)

but lead free is still used by Nvidia on video cards, and its up to the card manufacturers to ball them on good. I've been using the shit out of my 730M with no issues, and i'm pretty sure it has LF solder, and used the living shit out of my old GTX 285's and only one died (due to a PSU failure killing it)

It is more complicated than that, 10 years is not a lot of field data and even accelerated testing only simulates it up to 20 years. LF solder also requires higher temperature in the vicinity of 225-235DegC to wet properly which then increases the chance of component damage for RoHS specified components which are designed to withstand 250DegC bake temperature. In most production lines the reflow oven temperature is cranked up to 240DegC sometimes because of difficulties in good wetting. LF is "alright" for Class 1 consumer non mission critical applications, I wouldn't trust it for Class 2 or Class 3 applications !

[Uranium-235]

Re: reflow flux and other shit

there is nothing wrong with lead free solder as long as its done properly. They've been using ROHS LF solder for, I believe almost a decade. Most of the BGA chips in todays consumer market use it. Only a fraction has issues. HP DVxxxx had issues cause of poor cooling and, by make, chips that run too hot (why nvidia does not make chipsets anymore, nor should they)

but lead free is still used by Nvidia on video cards, and its up to the card manufacturers to ball them on good. I've been using the shit out of my 730M with no issues, and i'm pretty sure it has LF solder, and used the living shit out of my old GTX 285's and only one died (due to a PSU failure killing it)

[EdT]

Re: reflow flux and other shit

You have to know what was the original solder that was used, lead or lead free before you can determine the type of flux to use ! Most consumer electronic products are now RoHS if they are to be sold in Europe, RoHS solder is a horrendous nightmare and probably accounts for 80% of the defects we see in electronics today, God forbids if we are going to start seeing planes falling from the skies in a couple of years !

I know for a fact that Airbus and Alstrom uses RoHs solders in their planes while NASA and Boeing still does not, we should soon see whose right when the body counts starts piling up !

http://www.militaryaerospace.com/art...he-making.html

[Uranium-235]

Re: reflow flux and other shit

thank you. I was lucky this was not an nvidia chip. I do have a DV 9000 board in storage, but no way to test it if I did reflow it

[momaka]

Re: reflow flux and other shit

The balls look different, shinier.

That's a sign of a good reflow. Congrats on the fix!

[Uranium-235]

Re: reflow flux and other shit

no, this is a 17" regular top

[Th3_uN1Qu3]

Re: reflow flux and other shit

Should hold for a good while if it's not dropped or thrown around. Now i know which type of Vaio you're talking about, it's an ultrabook, right? I pulled the shorted APU from one of those. Happened due to the laptop being dropped really hard and the heatsink shorting the APU.

Main issue with them is the board is really really thin and will easily develop cracked joints if the laptop is poorly handled.

[Uranium-235]

Re: reflow flux and other shit

Its an AMD MCH (With a fusion APU). Ebay has a lot of those "BGA fix for $99" bids for this board model

[Th3_uN1Qu3]

Re: reflow flux and other shit

Either flux boiling or some moisture still trapped... Either way, if it works now, don't worry. It's not a nVidia southbridge by any chance, is it? If it's not a nVidia of the affected series (or a SiS ) there's a good chance it'll keep going for quite a while.

[Uranium-235]

Re: reflow flux and other shit

thank you. Coming from you of all people that means a lot

what about the crackling sound? anyone have any idea?

[Th3_uN1Qu3]

Re: reflow flux and other shit

Good job.

[Uranium-235]

Re: reflow flux and other shit

well I did it. Baked the board @ 212F, and heated it up with the heat gun. Didn't keep it on there for 10mins@220-240C. After a certain point, I would hear this crackling sound and I stopped, did it again and around 220 it did it again.

The balls look different, shinier. Works. For now.

[sasser]

Re: reflow flux and other shit

^Yes, I've seen it happen too on some boards I worked on. The state I am in, Virginia, it is quite humid in the Summer.

But my question was, why would hot air not do that vs. IR?

hye ..i do comparison between hot air bga machine and dark infrared machine. what i do is put the board on infrared machine and ir machine then read humidity meter. the reading is hot air got 10% with 70c currenct tempreture in 10minute but when heat on infrared i got 50% humidity. so my conclusion from that i see hot air machine blow up the hot air to pcb and move out the moisture. so that when u direct reflow on infrared machine without bake u can easily pop corn your bga cause shock with high temp.

[momaka]

Re: reflow flux and other shit

Probably the same way I do .

[Th3_uN1Qu3]

Re: reflow flux and other shit

Hot air will still blow up chips if they're humid enough. Guess how i know?

[momaka]

Re: reflow flux and other shit

^Yes, I've seen it happen too on some boards I worked on. The state I am in, Virginia, it is quite humid in the Summer.

But my question was, why would hot air not do that vs. IR?

[Th3_uN1Qu3]

Re: reflow flux and other shit

I don't know. My thinking is, regardless of whether you use IR or hot air, the board will be heated above 100C, and when that happens, moisture should evaporate all by itself (unless there is just too much).

If there's any significant moisture in it, heat it up too quickly and it will go POP... That's why it is recommended to "bake" boards and chips that have been stored in unknown conditions before attempting a reflow or reball.