how to solder SMT pads connected ground plane? - Page 1
Forum section: electronics / beginners

author: ice595
author_rank: Regular Contributor
timestamp: January 06, 2016, 08:03:22 pm
content: So, long story short, I've just got my first "professionally" designed and manufactured PCB for a school project. (hence the switch to SMT parts from hobby level through hole stuff)I've chosen 0805 sized passives for the sake of hand soldering. I have some experience soldering SMT parts before. (mainly SOIC and QPF on breakout boards)I seem to find myself having a tough time soldering pads that are connected to heat sucking ground planes, I literally have to crank my iron up to 430 degrees C for the solder to flow nicely.The solder that I am using is just the cheapo 60/40 0.6mm diameter solder from my local electronic component shop. As for flux, I am just using paste flux.The soldering tip used was one of those chisel tips, although its probably too big for SMT parts. (the Hakko T12-D12 tip is on its way from eBay)Here are some pictures of my board. (see how one pad on C10 is connected to the ground plane)Is the thermal capacity of my soldering iron too low? Or will the new tip that I just ordered do the trick?Pads that just connected to traces seem to solder quite nicely at 330 degrees C.Or should I just get some solder paste and mod a toaster oven?

author: jpmkm
author_rank: Contributor
timestamp: January 06, 2016, 08:36:38 pm
content: You shouldn't have any problem soldering to those pads with a decent tip, and at quite a bit less that 430 degrees C. It sounds like you're not getting good enough heat transfer. I bet it will work just fine with the new tip. Does your solder not have flux in it?Are you using a genuine Hakko soldering iron or a "compatible" one?

author: ice595
author_rank: Regular Contributor
timestamp: January 06, 2016, 08:48:00 pm
content: Quote from: jpmkm on January 06, 2016, 08:36:38 pmnope, its one of those ghetto soldering stations that looks like a laptop power brick with a knob and LED display like this one belowit works with Hakko tips though

author: wblock
author_rank: Regular Contributor
timestamp: January 06, 2016, 09:12:31 pm
content: The station might not be able to keep up with the heat demand, even if the power supply and iron are capable. That C10 pad has the heat relief pattern (can't think what that is called), it's not just a hole connected continuously to the ground plane. Should be no problem with a decent iron.

author: PeterFW
author_rank: Frequent Contributor
timestamp: January 06, 2016, 09:42:23 pm
content: Quote from: ice595 on January 06, 2016, 08:48:00 pmThe problem is not the board, the tip or the solder.Your problem lies with the "soldering station", it has simply not enough power.Do not confuse power with heat, to put it simply:You need more WATT and not more "degrees celsius", i consider 60W the absolute minimum that a soldering station should have.

author: KL27x
author_rank: Super Contributor
timestamp: January 06, 2016, 10:07:47 pm
content: If that's a fake-o tip, that might also be a problem.I have some generic tips that came with my Chinese desoldering station, and I notice a small but significant difference in the required temp setting vs similarly sized/shaped Hakko tips, particularly compared to the T18 style (the generics are almost all 900M-clones with a thinner barrel; hopefully, the T18 will fit your iron, even.)I notice the difference on thermal pads even with my genuine 65W Hakko with a large tip. I wouldn't have to change the temp setting, but instead of near instant, I will deliberately hold the tip on there for a half a second. I guess this is where a Metcal or JBC pays off.If the new tip doesn't do the trick, I'd get a larger tip. Not smaller. But if you do a lot of soldering, maybe just suck it up and get a new iron.

author: Fat
author_rank: Regular Contributor
timestamp: January 06, 2016, 10:47:17 pm
content: It's unfortunate that you can't score an old Metcal. I picked one up on Ebay for $25 and then bought tips and a handle (another hundred), but it makes quick work on the ground planes!

author: ice595
author_rank: Regular Contributor
timestamp: January 06, 2016, 11:38:19 pm
content: I am sure I need a smaller tip though, just look at it. Its as wide as a 0805 part.

author: KL27x
author_rank: Super Contributor
timestamp: January 07, 2016, 01:55:02 am
content: This is my first option for populating a board. That's a 1206.Why? Because this is the biggest (CF) tip I can find, and I don't have my own wave-soldering machine, yet.This will do about 20 0805's without reloading.For a chisel, meh. I have tried to figure it out, but I dunno what you gain by using abigger or smallerchisel for SMD.

author: ice595
author_rank: Regular Contributor
timestamp: January 07, 2016, 02:15:57 am
content: OMG if that tip is any bigger it'll probably be a good substitute for a plumber's soldering iron

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: January 07, 2016, 03:43:16 am
content: Quote from: ice595 on January 06, 2016, 08:48:00 pmWhere did you get that station at and about how much ??Also look into getting cheap Chinese tip set and find what works for you and then buy genuine hakko tip..

author: Falcon69
author_rank: Super Contributor
timestamp: January 07, 2016, 03:58:10 am
content: Quote from: KL27x on January 07, 2016, 01:55:02 amIt's not the size of the tip, but how you use it.

author: KL27x
author_rank: Super Contributor
timestamp: January 07, 2016, 04:14:27 am
content: That's what she tell you.