Surface Mounting Hidden Pins - Page 1
Forum section: electronics / beginners

author: Inspired
author_rank: Newbie
timestamp: August 29, 2018, 02:06:09 am
content: I am new to electronics. I need to repair a device. The component is rectangle with without pins. The connections are hidden when it is mounted. The connections on the bottom are silver and flat. I was told that I need a device that uses hot air to mount it. Is it possible to mount the component with a soldering iron?

author: mdszy
author_rank: Unknown
timestamp: August 29, 2018, 02:10:45 am
content: Sharing a picture would help us immensely with answering your question.

author: NexusKoolaid
author_rank: Contributor
timestamp: August 29, 2018, 02:35:34 am
content: Sounds like he's talking about a BGA package.

author: digsys
author_rank: Unknown
timestamp: August 29, 2018, 02:40:17 am
content: Sure does. Sorry mate, it's even a tricky / delicate operationwitha proper heat gun / nozzle. BGAs (assuming) are bastids to solder / unsolderwithout good equipment incl solder pastes / fluxes etc

author: IDEngineer
author_rank: Super Contributor
timestamp: August 29, 2018, 02:55:21 am
content: Quote from: digsys on August 29, 2018, 02:40:17 amx2 on this reply. No way will you replace that package with just a soldering iron. You might get the old one off, but you'll probably damage the PCB in the process, and then... how will you heat the solder balls on the bottom of the new package, when they're literally hidden and inaccessible with a soldering iron?Not trying to be a downer here, just honest. Some things require the proper tools. BGA's are one of them.

author: amyk
author_rank: Super Contributor
timestamp: August 29, 2018, 03:04:06 am
content: A hot air station is not very expensive and will come in handy for a lot more than surface-mount soldering.

author: JS
author_rank: Frequent Contributor
timestamp: August 29, 2018, 05:03:32 am
content: Hey, might not be BGA, just QFN without the pads wraping around or something like that, still a PITA but better chances.In any case, get a hot air station and some no clean flux!JS

author: tester43
author_rank: Regular Contributor
timestamp: August 29, 2018, 02:14:14 pm
content: he is probably talking about QFN. Removal will be possible .... with destruction of element.Mounting will be possible with very good soldering iron and master skills

author: Inspired
author_rank: Newbie
timestamp: August 30, 2018, 01:01:23 am
content: The QFN comments helped so much.It is a DFN 2 or 3 pins if the middle surface is a pin. So, how hard would that be with a solder iron?You guys are awesome.

author: digsys
author_rank: Unknown
timestamp: August 30, 2018, 03:24:07 am
content: Rather than getting a heap of text based explanations, which may be difficult to visualize - just google something like "soldering DFN package" on youtube.There are HEAPS of people in your predicament ! You can then actually see visually what you're up against. It's not as bad as BGA, but dern close to it :-)

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 30, 2018, 03:28:41 am
content: The center pad is a nice feature, but makes repair without hot air an absolute pain.

author: digsys
author_rank: Unknown
timestamp: August 30, 2018, 04:38:35 am
content: Quote from: Mr. ScramYup, if they make no provision for it .. ie several you-tube videos show 1 -2 p/t holes mid-pad (I also do the same). When you have that access,it is much easier to apply some flux, and heat / solder under the IC. You'd have to have the pins? free first though. A pain, but doable.

author: JS
author_rank: Frequent Contributor
timestamp: August 30, 2018, 02:55:50 pm
content: I think dave did one with his soldering using many vias underneath. Vias aren't that hard to find as usually the center pad is for heat transfer and is likely to rout it to the other side to cool things down.JS