Hand assembly 0.5mm BGA - Page 1
Forum section: electronics / general

author: AndyC_772
author_rank: Super Contributor
timestamp: February 12, 2025, 02:42:27 pm
content: Hi allI have a prototype in the works which includes a BGA. It has a ball pitch of 0.5mm and is 81 balls in a 9x9 matrix.I normally like to hand assemble the first few of any new design if possible, it's quicker and cheaper that way. To that end, I have a good selection of soldering equipment - hot air, a hot plate, good stereo microscope and so on.However, I've not soldered this type of component before and I'm not sure how best to go about it. The pitch is right on the limit of what I think I can place by hand, and of course there's a risk that hot air will simply blow the part away.Has anyone had any success soldering this type of package in a home lab environment? Care to share any tips please?Having the board assembled by our regular CEM is an option, and so is purchasing new equipment if it makes sense to do so.

author: bigendian
author_rank: Regular Contributor
timestamp: February 12, 2025, 03:19:14 pm
content: prepare to sacrify some pcb/chips to obtain a good result.I finally bought a professional station for BGA soldering, btw, i soldered much bigger chips with it.For your case, in the hope balls are fresh (the chip was not too old), i would try this- some pre-heat in oven, 120* or the like, of all the pcbs, half an hour- capton strip if you want all around to avoid to damage the pcb (with hot air station pop-corn effect should not be an issue)- some flux on the bga pads on the pcb- chip on it, well centered, if you can find some tool with a spring to keep it slightly pressed,it should autocenter when heat is ok- and hot air, until you think is ok ... this is the tricky part with a simple air stationOther techniques known to be working are to use a small oven and put the pcb + chip in it. But cannot help much on this, never tried.good luck

author: tszaboo
author_rank: Super Contributor
timestamp: February 12, 2025, 04:07:26 pm
content: Quote from: AndyC_772 on February 12, 2025, 02:42:27 pmI've replaced DRAM in BGA package by hand. Thats 6 rows, 96 balls. In an industrial computer, when the firmware developer obviously run out of RAM. Have extra parts available. Otherwise it's not that different from a QFN, hot air the part on it's footprint until it stays in place. If you have leaded solder use that.

author: m98
author_rank: Frequent Contributor
timestamp: February 12, 2025, 06:03:51 pm
content: Assuming you solder the whole prototype all at once, just use the hot plate for reflow. In order to somewhat stay in the proper reflow profile, you might need a little hot air assistance at the end. The only problem in my experience is the tendency of lead-free type-4 and type-5 solder paste to just oxidize on the outer surface when you have a too slow ramp-up. Leaving a functional solder joint covered in essentially unmolten solder paste. Depending on your available workspace, get one of the newer budget reflow ovens like the iTECH RF-A250.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 17, 2025, 12:03:50 pm
content: Thanks for the suggestions.For the sake of closure: I've decided to give this job to our CEM, as it'll be a useful exercise for them to get the PCB fabricated and assemble the job too. This is, after all, one of the things that a prototype is for.

author: tom66
author_rank: Super Contributor
timestamp: February 17, 2025, 12:33:23 pm
content: If it is a job where you would waste more than a few hours wondering why your MCU won't come out of reset, then you figure that the RESET_N pin is open because your soldering wasn't perfect, it would be a job for the CEM. I think you made the right decision.If it's a hobby project or you can afford to spend the extra time on it because you want to learn how to do BGA by hand then it can be more easily justified.BGAs aren't too hard to get right but they can be a major PITA if you do not get them perfect and are nearly impossible to diagnose without an X-ray. We had a number of boards in a batch show faults with our 400 ball FPGA. In the end we had to rent access to a 3D Xray machine from a nearby CEM and inspected the boards ourself. It became clear that the FPGA was not well soldered on the corner that interfaced with the DDR3 memory. But access to that machine was £300 per hour!

author: AndyC_772
author_rank: Super Contributor
timestamp: February 17, 2025, 03:30:53 pm
content: Hi Tom, it's definitely a professional project with an hourly cost associated. I've not done any "hobby" projects besides the odd cable or repair job in years!The main reason to assemble the board by hand is speed. In most cases I can order a bare board from JLC, have them on my desk a week later, and fully assembled a few days after that. That's a tremendous advantage in terms of development time compared to outsourcing the job.Some CEMs take longer than this to even prepare a quote.

author: bigendian
author_rank: Regular Contributor
timestamp: February 17, 2025, 07:28:00 pm
content: I generally try to avoid bga stuff as much as possible, becouse i am able to prototype easily here at home with qfp or qfn.Of course you would require some practice. If you have many chips, that is the case when they are not too expensive, you can still desolder by hot hair, clean the pcb, and retry with another chip. Perfectioning the technique is the key that will give you more successful cases.Anoither aspect is how fresh are the balls, components too much in a deposit >= 2 years are generally harder to be soldered.Sometime even if some soldering is not perfect, as i had one gpio of a cpu not well soldered, you can still be able to test other things.Avoid to re-solder same bga, they genrally nmay have issues after 2 or 3 resoldering processes.