BGA removal temperature - Page 1
Forum section: electronics / beginners

author: openthomas
author_rank: Contributor
timestamp: October 17, 2012, 03:33:10 pm
content: I need to remove some BGA chips from a board with a heat gun. Having trouble finding the correct temperature for the air in the datasheets. What is the term used ?

author: openthomas
author_rank: Contributor
timestamp: October 17, 2012, 03:38:33 pm
content: Also I have various sized round nozzles for the heatgun. What do I base the choice of nozzle size on ?

author: ablacon64
author_rank: Frequent Contributor
timestamp: October 17, 2012, 05:09:25 pm
content: It depends on the BGA. There are some that have a big metal shielding that require more heat. Also it depends on the size.A good way to start is to check the datasheet of the flux you're using, they normally have a recommended profile.

author: openthomas
author_rank: Contributor
timestamp: October 17, 2012, 05:51:13 pm
content: I need flux to remove a BGA chip ? How would that work ? I cant get it under the chip.

author: openthomas
author_rank: Contributor
timestamp: October 17, 2012, 05:56:17 pm
content: I noticed some people heat from beneath as well as with the heat gun. Is that essential ?

author: Short Circuit
author_rank: Frequent Contributor
timestamp: October 17, 2012, 06:03:51 pm
content: Copper areas under the BGA (such as powerplanes) act as heatsinks. Without bottom heating, it is practically impossible to remove the BGA without damaging the part and the PCB as well.

author: AndyC_772
author_rank: Super Contributor
timestamp: October 17, 2012, 06:15:24 pm
content: Do you need to salvage the chip, the board or both? If you need to save the chip, you'll need to bake the board first to drive off moisture, otherwise you'll risk the chip popcorning as you remove it even if you get the temperature just right.I'd personally start with a hot air nozzle about the same size as the chip, set the air temperature to about 350 deg C, then start by warming the board from a distance and gradually getting closer to the IC. If after a couple of minutes it hasn't let go, wind the temperature up to 400 degrees.Then again, I rework PCBs with a paint stripper. Normally I send boards with BGAs back to the assembly company, which has people with skills and equipment that are actually right for the job.

author: ablacon64
author_rank: Frequent Contributor
timestamp: October 17, 2012, 06:19:11 pm
content: Flux make it easier, I use tacky flux for soldering and desoldering when it comes to BGAs. It simply slips under the BGA as you heat the PCB.Yes, bottom heat is (almost) required for not damaging the part. As I wrote, it depends on the BGA, there are small BGAs (like 1x1 cm or less) that you can desolder with the heat gun only. But try to remove an Intel E8500 northbridge for instance. It would be a nightmare with a heat gun and no bottom heat.

author: openthomas
author_rank: Contributor
timestamp: October 18, 2012, 05:05:32 pm
content: Ok well I burned out my heatgun. Could not concentrate the heat. I used too large a nozzle, but even so I had to keep moving it around the chip. Turned it up to 480 still would not release the solder. Could only get the chip up to 160c. I did get one chip off but it blistered in two places right before the solder melted. Why does that happen ?So I am looking at puhui irda stations that heat evenly from above and below. Thoughts ?

author: ablacon64
author_rank: Frequent Contributor
timestamp: October 18, 2012, 05:10:42 pm
content: I had an IR6000 and think it's very good, but it was very difficult to find a good profile for some BGAs. I've heard Honton R390 or R490 are very good.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: October 18, 2012, 05:15:41 pm
content: Quote from: openthomas on October 18, 2012, 05:05:32 pmPossibly the popcorning that AndyC mentioned above.IC packages are not hermetically sealed, so they absorb water and other particles. When the heat rises too rapidly, the moisture evaporates and cracks the package. Baking of the IC allows for a slow evaoration of these moistures, after which it is safe to apply the rapid heat cycling from hot air soldering.

author: openthomas
author_rank: Contributor
timestamp: October 18, 2012, 05:58:45 pm
content: How much should I be spending to remove 50mmx50mm chips with irda. The heating from beneath is equivalent to baking regarding blistering ?

author: ablacon64
author_rank: Frequent Contributor
timestamp: October 18, 2012, 06:16:38 pm
content: Quote from: openthomas on October 18, 2012, 05:58:45 pmUntil you reach melt temperature, some machines last more than other (if I understood the question). Google for some lead-free and leaded soldering profiles.Quote from: openthomas on October 18, 2012, 05:58:45 pmNo, it's too fast. You need at least one hour to bake the pcb properly.

author: openthomas
author_rank: Contributor
timestamp: October 18, 2012, 06:29:06 pm
content: Could I simulate the baking by heating at low temperature for an hour with the lower heater ? Do I really need an oven ?

author: openthomas
author_rank: Contributor
timestamp: October 18, 2012, 06:29:42 pm
content: Sorry not time, money for a irda station

author: ablacon64
author_rank: Frequent Contributor
timestamp: October 18, 2012, 07:05:20 pm
content: Quote from: openthomas on October 18, 2012, 06:29:06 pmNever done that, although I've seen people say that it can be done with a hot plate.A DIY "oven" may do, a cardboard box covered internally with aluminum foil and an incandescent 150W lamp or so.

author: ablacon64
author_rank: Frequent Contributor
timestamp: October 18, 2012, 07:06:11 pm
content: Just beware not to burn your house down.