[jules]

I'm working on a DIY project that uses double sided boards with soldering seats [not sure if this is the correct term] on both sides and with the hole between the two sides gold plated. It's possible to make one big solder connection that forms a blips on both sides, interconnected through the hole. I've looked at a few finished jobs on similar boards and I notice that they are often only soldered on one side.

There's a couple of ways of creating a double sided joint that have worked for me. One is to hold the iron on one side of the board and feed the solder from the other. This worked very well for an Elma ladder [small board]. The other method is to keep the iron on the join for a few seconds [always seems like an age cos I don't like overheating things] longer than you'd do with a single sided board. This usually works but is hard to judge since you can only watch the side you're working on.

Realistically, I doubt that it's important to have the double connection but since it's there it's a pity not to use it.

What do others do/think and do you have any advanced tips on technique?

I'd appreciate your help on this one.

Jules

 

[Niteshade]

Hello- It sounds like a plated through hole. Try and get the solder to flow through to the other side. If if won't flow, you will have to try and warm the other side and apply a little solder. Never leave solder blobs (excessive solder) on the connections and keep track of the flux you leave behind. It can be cleaned with alcohol. Make sure your iron is the correct temperature and use 60/40 solder.

[jules]

Hi Niteshade,

Yes, they are plated through holes.

I've been giving it a bit more thought and I realize that for most connections, the electrical connection only happens on one side, so connecting through does add surface area and strength but depending on the particular component extra area may or may not be useful. At the moment I'm thinking that I can give it a bit more oomph with heat tolerant components and those that can benefit from the greater contact area but maybe I should err on the side of caution with heat sensitive components or those that don't need a large contact area.

Your post does encourage me to go for the full, double sided join though one soldering action seems the best. I've tried the addition of a small amount from the other side and while it works, it's very easy to partly melt the primary join which just doesn't look pro.

I use Cardas solder. It's user friendly, makes a neat join and the flux cleans up easily with alcohol.

Thanks again

Jules

[BobM]

I would definitely try to put a litle solder on both sides if you can. Sometimes it flows through on its own.

Be careful though, working from the top side of the board can be difficult if pieces are close together. It is all too easy to lean the soldering iron against another component and burn/kill it inadvertently.

Enjoy,
Bob

[loudnclear]

I'm not sure why having solder on both sides of a thru-plated via is important to you. I've worked as shop manager at a business that manufactures hand soldered PC boards for 25 years now. If the solder bleeds to the other side, OK. If it doesn't, OK.

[Niteshade]

Solder should flow all the way through a plated through hole. That's how I was taught and it does improve the mechanical connection as well as the electrical connection. I worked for Philips a while back and this is the way they wanted it done. Nettest had the same soldering requirements.

I'm not sure why having solder on both sides of a thru-plated via is important to you. I've worked as shop manager at a business that manufactures hand soldered PC boards for 25 years now. If the solder bleeds to the other side, OK. If it doesn't, OK.

[loudnclear]

Well, you give the boss what he wants, however there is no need to turn the board over to fillet the solder joint on the component side. If the soldering is done with the correct temp and solder size it will penetrate the via completely. What do you do when you solder a potted module where the top pads are inaccessible? Out of sight, out of mind?

[Niteshade]

I used to work with DC-DC converters that are potted. The holes were large enough to allow wicking. My iron was always the proper temperature. I could see the solder filling the area around the wire. It would look concave until the area was filled. I also knew how much solder it would take to fill it. So, no there was no guessing.  I don't like flipping the board over to touch things up with non-potted devices- it is better to do all that from the bottom. If it didn't look quite right, I'd use a solder sucker or desoldering wick to clean it up and then try again. But...sometimes it's OK to do... It depends on the situation.


BTW: I don't like plated through holes from a repair standpoint and doubly so with potted modules. 

[jules]

It would look concave until the area was filled. I also knew how much solder it would take to fill it

and

If it didn't look quite right, I'd use a solder sucker or desoldering wick to clean it up and then try again.

Every little bit helps, thanks.

I've done quite a few more by now and they're working just like the picture  . Knowing how much solder you need for a particular hole/wire size and getting the timing right seems to be most of the battle. It takes a bit of getting used to the fact that the amount of solder that has to be fed into the joint is double that you'd use on a single sided board. I've re-done a couple but not by adding solder from the other side. Rightly or wrongly, I figure that process would have to leave some sort of boundary or maybe bubble between the fresh solder and the re-melted older lot that could be fine but seems less than perfect.

I don't like plated through holes from a repair standpoint and doubly so with potted modules

Oh ... wondered about that. Hard to wick or suck I guess.

[Niteshade]

It can get very nasty removing modules when they're soldered to plated through holes. At least with resistors, capacitors, etc... the leads can be clipped on the component side and then the soldered half of the lead can be pulled through. It destroys the component but can save a board.

[jules]

The summary for me is, that double sided is several degrees of difficulty harder than single because of the less visible cues but like any other skill, once you've got it, it's very satisfying.

Here's 1/6 of what I'm building:



It's the gain board of a 45W, pure class A solid state DIY project.

Thanks again Blair,

Jules

[Niteshade]

Nice! Where's the other 5/6's of it? 

What kind of kit did you get?

[jules]

There's that many bits I'm having to be very diligent to be orderly. The other 5/6 are safely labeled and packed  .

It's an audio-gd product:

http://www.audio-gd.com/enweb/pro/ST1-2.htm

I'll post the build process on AC at some stage.

Jules

[peranders]

It's not extremely important to have visible tin on the component side but it looks nicer and the solder joints gets also a bit better. Solder as usual from the backside but maybe you have to warm a bit longer if you have thick copper. Each pad may need 5-10 seconds depending on part and copper traces. My 4-layer 70 um board (link below) requires so much heat that you may wonder if there is something wrong with solder or soldering iron. In my case, just burn until it melts. You also see where I have faild to have tin in the whole hole. Especially heat demanding are the ground connections (see the resistor R3) which have heat relief pads, still hard to solder.

Picture here