Beginner to BGA  - Page 1
Forum section: electronics / beginners

author: taoybb
author_rank: Contributor
timestamp: September 22, 2024, 05:34:19 am
content: Hi, I got fews question about working with BGA IC.1) As I try search in this forum, I got a mixed signal from BGA being hard and some said it's easier than QFN. Why some said it's easier than QFN?2) I already got a decent soldering iron and hot air but lack of BGA rework station, option on BGA station for home use is quite limited here (except go with extra hiend model which is beyond I can afford). I don't do repair work but only prototyping DIY stuff and BGA would be only small chip (below 20*20mm) and only once or few times a year. I have my eyes on Yihua/Gordak 853A, is this option is adequate? Or should I go with Yihua 853AA (two 'A' instead of one). I also interest in Yihua 1000b but it seem to be overkill for my hobby(?).Thank you in advance

author: Psi
author_rank: Super Contributor
timestamp: September 22, 2024, 05:55:13 am
content: Unless you have a huge BGA, or a PCB with a huge amount of copper, all you should need to solder a BGA is a hot air rework tool. It requires some skills, but its no harder than anything else.The downside is, if you make a mistake, you then need to reball the BGA chip before you try again, which also requires some skill and a stencil + solder paste or solar balls.BGA isnt hard, just higher consequences of screwing it up and needing to spend time reballing it.Or you can just accept the cost of a wasted IC and get a new one.Screwing up a QFP/QFN usually just means you bridged some pads and need to grab the solder wick, which only takes a few seconds to fix. Perhaps worst case with QFN/DFN you just have to lift the part up re-tin the pads and put it back down.

author: pcprogrammer
author_rank: Super Contributor
timestamp: September 22, 2024, 06:30:45 am
content: Quote from: Psi on September 22, 2024, 05:55:13 amThat is the problem. Skills. Only when you have mastered it, it is not harder than anything else.Quote from: Psi on September 22, 2024, 05:55:13 amAlso skills are needed for this. It is what keeps me and for instance Nominal Animal away from BGA's. Only worth it if you plan on using a lot of BGA's for your projects.Quote from: Psi on September 22, 2024, 05:55:13 amWorst case is overheating the IC and killing it. That is why I prefer my IC's to have legs that I can solder with drag soldering. Risk of overheating is lower. Another issue with having to lift a part of is the risk of damaging the pads and tracks.If one has plans for assembling PCB's more often, in my opinion, a hot plate or even a reflow oven is a good investment.

author: zapta
author_rank: Super Contributor
timestamp: September 22, 2024, 07:11:36 am
content: How to you verify that all the pads are soldered well?

author: taoybb
author_rank: Contributor
timestamp: September 22, 2024, 08:07:24 am
content: Quote from: Psi on September 22, 2024, 05:55:13 amThanks you for your reply, I got high success rate to reflow QFN and wonder how will it be with BGA. As mentioned, my PCB is small 100*80mm but a lot of copper in it (8 layers) may be station is good to have?I do have a cheap hot plate but my board is required to got a lot of underneath capacitor for main chip, hot plate might not good for this task.. I guess.

author: taoybb
author_rank: Contributor
timestamp: September 22, 2024, 08:22:05 am
content: Quote from: pcprogrammer on September 22, 2024, 06:30:45 amThanks you for your reply, Oven is interesting but maybe not since it's all hobby. I do own a hot plate but mine not work very well with two sided component placement.The only thing that drag me to this point is my short temper about "What if I try to design my own SBC??" then here I amWhat a worst decision but I have to finish what I started and well may be it will be my new skill, I guess.

author: taoybb
author_rank: Contributor
timestamp: September 22, 2024, 08:22:39 am
content: Quote from: zapta on September 22, 2024, 07:11:36 amNo so sure too, Xray thing is way too expensive.

author: pcprogrammer
author_rank: Super Contributor
timestamp: September 22, 2024, 03:48:28 pm
content: Quote from: zapta on September 22, 2024, 07:11:36 amPower the board up. If it works the solder job is properly done. If it fails, well, then I guess you are up shit creek.

author: zapta
author_rank: Super Contributor
timestamp: September 22, 2024, 04:28:04 pm
content: Quote from: pcprogrammer on September 22, 2024, 03:48:28 pmWe need transparent PCBs and ICs. ;-)That's the reason I avoid BGAs. I wonder what those small repair shops that replace BGAs do.

author: janoc
author_rank: Super Contributor
timestamp: September 22, 2024, 04:45:26 pm
content: Quote from: zapta on September 22, 2024, 04:28:04 pmReplace it and pray that it will work. With small-ish chips it is usually not a big problem and you can always rework the part if needed.Trying to solder something the size of a modern GPU without having an x-ray on hand to inspect it is foolish.

author: Psi
author_rank: Super Contributor
timestamp: September 22, 2024, 11:55:14 pm
content: Quote from: pcprogrammer on September 22, 2024, 06:30:45 amTrue, but I've never killed an IC with heat from hot air rework in all my 25 years working with SMT parts.Or, if i have, it's so rare that i don't remember it or i attributed the failure to some other reason.So it's pretty much a non-issue.Sometimes small parts like SOT-723 fall part and a leg cracks off. But that's more of a mechanical failure from being a bit too aggressive with the tweezers while the plastic is soft from heat. Not really a heat based failure.

author: pcprogrammer
author_rank: Super Contributor
timestamp: September 23, 2024, 05:27:51 am
content: Quote from: Psi on September 22, 2024, 11:55:14 pmFor you it is a non issue, but for others it can be an issue.Because my first attempt with QFN (F1C100s) failed that way. Also damaged one pad in the process. It probably is a careful balance between the temperature, type of solder and flux, duration of the heating, impatience when removing the faulty part first and with it rip of pads.For the designs I make as a hobbyist, I try to stick to parts I know I can handle.

author: dietert1
author_rank: Super Contributor
timestamp: September 23, 2024, 07:24:08 am
content: As an exercise one can start with leadless packages.Some days ago i managed to solder L12 3x4 DFN packages with a heatgun. Process was similar: Wetting PCB pads and package pads with solder ("balls"), adding some flux and then solder with heatgun (Yihua 959 D II) at 270 °C max. It required a minute or so to reflow the solder. I worked under the stereo microscope watching how the IC fell into place.Those are ISL85415 switchers with a bottom heat transfer pad ("EPAD") and i managed to solder two of them without creating shorts.One day i will try a BGA package. Until now our PCBs with BGA MCUs were made by a service provider. They charged about € 5000 for a 25x test run.Regards, Dieter

author: Psi
author_rank: Super Contributor
timestamp: September 23, 2024, 07:55:48 am
content: Quote from: pcprogrammer on September 23, 2024, 05:27:51 amOf course. Everyone destroys parts in many different ways when first learning how to solder them. That won't change, it's how we learn.

author: zapta
author_rank: Super Contributor
timestamp: September 23, 2024, 03:26:45 pm
content: Quote from: dietert1 on September 23, 2024, 07:24:08 amFor QFN packages, I just make one big hole in the PCB. Easy to solder and easy to inspect. The picture below is after soldering the top pads and before soldering the bottom big ground tab.

author: dietert1
author_rank: Super Contributor
timestamp: September 23, 2024, 10:41:48 pm
content: Quote from: zapta on September 23, 2024, 03:26:45 pmThat quote is fake. Please correct the confusion.

author: leham
author_rank: Regular Contributor
timestamp: September 24, 2024, 01:45:51 am
content: I'd like to add from personal experience, that techniques can change for BGA when you get down to the small ones (mobile phones and laptops).Stuff like the surface tension of your flux and air turbulence can cause issues, if you are someone that likes to learn from the deep end, starting there helps a lot.Thats how I learnt

author: dietert1
author_rank: Super Contributor
timestamp: September 25, 2024, 05:05:29 pm
content: https://youtube.com/shorts/6_NE8_7E-Fs?si=qH01nkB1BycEhBB4

author: pcprogrammer
author_rank: Super Contributor
timestamp: September 25, 2024, 06:32:52 pm
content: Quote from: dietert1 on September 25, 2024, 05:05:29 pmIf only it was that easy. Maybe with a lot of experience or a pre heater is being used underneath the PCB, or the footage is sped up. There are a lot of these kind of youtube videos and from my personal experience with desoldering/soldering quad pin ic's is that it is not that quick and easy.

author: dietert1
author_rank: Super Contributor
timestamp: September 25, 2024, 09:22:48 pm
content: Quote from: pcprogrammer on September 25, 2024, 06:32:52 pmYes, that footage is a time-lapse and the person is a professional. Anyway it demonstrates the elegance of using a heat-gun and the steps of that work, like protecting a nearby electrolytic cap from heat and the usage of "ingredients". Psychology says it helps to see something being done successfully.For me that happened yesterday. Only after watching a youtube-video about the Qualia ESP32 S3 driving a HD458002C40 TFT i got my own STM32H730 graphics card drive that TFT correctly.Regards, Dieter

author: Psi
author_rank: Super Contributor
timestamp: September 26, 2024, 08:31:29 am
content: He appears to be using more than 1 'Paul' of flux.

author: pcprogrammer
author_rank: Super Contributor
timestamp: September 26, 2024, 08:51:18 am
content: Quote from: Psi on September 26, 2024, 08:31:29 amYeah, and using the copper mesh to remove solder the way he does, you best make sure it is well heated al the time while lifting. Otherwise a good recipe for lifting pads and tracks.

author: taoybb
author_rank: Contributor
timestamp: September 29, 2024, 12:38:14 pm
content: Thank you guy, after read more reply from you, search more post, watch more video and read some post again and again. I knew that BGA isn't easy but I had to do it anyway. So I had to do it right from beginning. Yesterday, I just get a Seamark machine, decent flux from Amtech and Mechanic (phone repair shop reccommend that one), reballing kit and some old board for practice before starting on a real board. Wish me luck

author: tooki
author_rank: Super Contributor
timestamp: September 29, 2024, 01:15:11 pm
content: Quote from: pcprogrammer on September 26, 2024, 08:51:18 amIndeed!! There's a reason that wiping with desoldering wick is NOT recommended!

author: dietert1
author_rank: Super Contributor
timestamp: September 29, 2024, 01:29:05 pm
content: There is a difference between working with a soldering iron and a heat gun.A pointed soldering tip made for fine work doesn't conduct heat very well, so most people use it with higher temperature (like 350 °C or even higher) and work rapidly to not overheat parts. Of course with this method there is a risk to destroy parts or the PCB.With a heatgun running no hotter than 270 °C it's all much slower. You take the time you need and the risk of damage is small.Regards, Dieter