Society of Robots - Robot Forum

General Misc => Misc => Topic started by: dmclifton on January 30, 2011, 09:48:37 PM

Title: Soldering Connections
Post by: dmclifton on January 30, 2011, 09:48:37 PM
I was working my way through the simple robot tutorial and merrily soldering along when I got to the point where this picture is shown: http://www.societyofrobots.com/images/sbs_connect1_large.JPG (http://www.societyofrobots.com/images/sbs_connect1_large.JPG)

It looks like one might simply take the soldering iron and pour solder in some sort of haphazard fashion across the various circuits in order to achieve this. I myself tired multiple different ways - from 'over-soldering' on one point and trying to 'drag' it across (which worked sometimes) to trying to lay the iron between the two points and solder applied to both sides (made a mess).

In the process I burnt myself (my own idiot fault after a good deal of frustration), burnt the board (too many failed attempts) and ended up with a mess of solder all over the place (at which point I learned about a neat tool - the solder removal tool - which is now on my radio shack shopping list). In any case, I don't think any of my attempts was the 'right' way to do it - none of it seems to match the precision of heating the joint and getting a nice clean connection when soldering single joints. I'm left with pools of solder all over a board, two rows of the 6-pin male connectors soldered completely together as my pools of solder collided, circuits sticking out the other end haphazardly and generally a need now to start from scratch with a new board (hopefully I didn't damage any of the other components).

Can anybody point me to where I might find better instruction on this? Every time I attempt various searches across google, I find that it seems people just don't seem to make videos about this - most seem to be about soldering onto pre-printed boards that don't need the connections, or soldering a connection via a wire - never this cross-hole soldering that I see here. Would really appreciate some pointers - I just can't seem to get it right.
Title: Re: Soldering Connections
Post by: rbtying on January 30, 2011, 11:00:38 PM
I'm not too sure how other people tend to do this, but I usually take clipped component leads (resistors are always too long, capacitors too) and use those to bridge the gaps.  Similarly sized solid-core wire will do fine, as well.  Just place it along the row of pins you want to connect, hold it down with a pair of needlenose pliers, and solder the pins normally - the wire will be included in the solder-blob and will conduct the electricity between pins for you.
Title: Re: Soldering Connections
Post by: dmclifton on January 31, 2011, 08:41:14 AM
As I'm starting out new, I don't have extra clipped component leads sitting around, but I'm sure I can find something suitable somewhere - maybe just some wire - thanks for the tip.

From a purely functional standpoint, how do you tend to go about holding all the parts together?

I'm imagining myself with the iron in one hand, the solder in the other, and the wire held by...a little clamp on the lead I'm not soldering? Does that work ok?

I am thinking when I stop by radio shack today I might pick up a couple extra boards and whatever small component is cheapest to practice soldering before I go back to the stuff I need to work ;D
Title: Re: Soldering Connections
Post by: rbtying on January 31, 2011, 08:59:34 AM
No need to go to Radioshack for boards - just open up some old electronics, they're through-hole and free.  You can practice desoldering components from the PCB, and then resoldering them in arbitrary other parts =).

Holding everything together: it's probably better to tin (to cover with a layer of solder) the wire/leads first, then use the iron and a pair of pliers/tweezers/forceps (any small-ended grabbing tool made out of metal) to hold the part while reflowing.  For parts with many pins, pick a corner ( I like pin #1 =) ) and just use enough solder that the part would not fall out, then hold the part in position and heat the joint, such that the pin can move into the desired position.  The third hand is more useful for soldering two parts directly together (connectors, for example), not parts to a protoboard. 

For long headers: as it is possible to melt the plastic out of shape on accident, it's not a bad idea to use a long female header strip (1x40 works well) connected to the male header strip as you solder it, to keep it all in a straight line. 

For stuff that still doesn't work, tape is sometimes a viable option - just be careful not to melt it. 

Remember that for through-hole parts, you can just bend the leads out a  little to help hold the part in the position you want, solder them, and then clip the leads when you're done. 
Title: Re: Soldering Connections
Post by: Crunchy Theory on January 31, 2011, 11:49:15 AM
I was able to achieve the result shown in your included picture by dropping a large blob of solder in two holes (just heat up the hole, and push the solder wire through it as it's melting), then bridge the space between the two blobs. I did this for all of the connections. It does take a lot of solder, though. And once I got the hang of it, it came out pretty clean - looking exactly like the picture.

It also seemed like the more times I had to retry, the messier it got and the worse the solder was able to cling to the board - resulting in some burning and discolouration.

I'd recommend using the current board you've got, practice will more of the remaining holes till you're able to bridge two holes on the first try and cleanly. Then purchase a second board and start fresh. It's a few more dollars, but I bet you'd be more happy with the cleaner end result.

Edit:

I always have the problem with solder not staying at the end of my round-pointed soldering iron tip, leading to some bad/messy solders. From http://store.curiousinventor.com/guides/Surface_Mount_Soldering/101 (http://store.curiousinventor.com/guides/Surface_Mount_Soldering/101) that Admin provided, the video explains that a flat-sided soldering iron tip does a better job at holding the solder at the end. This is on my list for the next round of purchases, so I haven't tried it yet. But it's something to consider.
Title: Re: Soldering Connections
Post by: want2learn on January 31, 2011, 02:50:04 PM
Re: soldering components

Back when I first learned to solder at college my lecturer told me this "Something with long leads can have the legs bent slightly before turning over to solder, this'll hold it quite well. Always start with the lowest profile components and work up from there, when you turn the board over onto your work surface, the wieght of the board does quite a good job holding components while soldering."
I still lay the board ontop of through-hole chips and solder this way.

Re: bridging joints

If your iron has a flat tip, heat two legs at the same time (the furthest ones from you) and flow the solder between them, when they're bridged move your iron down the line and continue as far as you need. With a little practice it'll be second nature.

I posted some soldering tutorials here before to help newcomers, maybe watch a few and see if they help any?
Here they are http://www.societyofrobots.com/robotforum/index.php?topic=6602.msg49719#msg49719 (http://www.societyofrobots.com/robotforum/index.php?topic=6602.msg49719#msg49719)

Jim
Title: Re: Soldering Connections
Post by: dmclifton on February 04, 2011, 09:19:55 PM
Thanks - I'm a programmer most of the time so may be largely a matter of 'don't give a software guy a soldering iron', but I'm working on it - thanks for all the tips.
Title: Re: Soldering Connections
Post by: dmclifton on February 07, 2011, 02:18:29 PM
So I was wandering through radio shack due to a bit of intense boredom while waiting for my male headers and ic socket replacements to show up from digi-key, and I saw this thing called a 'CircuitWriter' pen, from CAIG Labs, Inc. It seems to be the same thing as listed here:
http://www.radioshack.com/product/index.jsp?productId=3964901 (http://www.radioshack.com/product/index.jsp?productId=3964901)

Has anybody here ever tried one of these? Some googling seems to show them used by various folks in conjunction with arduino projects, and I found one example of somebody who literally used it for all their traces around a standard board by making small dots to connect the copper contacts around holes along the way. It doesn't seem like something that one would want to use too heavily, but I was curious if anybody happened to have tried using and had good/bad luck.
Title: Re: Soldering Connections
Post by: blackbeard on February 07, 2011, 02:44:12 PM
here's what i like to do to bridge joints.

1. stick your components on the board
2. take a piece of scrap stranded wire
3. unweave the stranded wire and cut off one strand about .5cm or smaller
3. using tweezers stick ON THE COPPER SIDE in the same holes that the components are in
4. repeat step 3 for as many joined holes you need
5. solder the components. the wire should act as a guide for the solder allowing the components to bridge
6. cut any strands sticking out the top of your protoboard with side cutters. alternatively if you have enough of the lead sticking out then you can just solder it to the lead
Title: Re: Soldering Connections
Post by: arrrrgon on February 08, 2011, 10:57:38 AM
This robot was my first attempt at soldering anything alone, so this is certainly not expert advice.  I first soldered the middle hole, then I touched the soldering iron to the 2 component holes at the same time until they got hot (like you would on a single component hole), and finally I touched solder in between and the solder took to both sides.  It doesn't work perfect, but it did work.  I would personally go with the other tips to connect a small piece of wire or metal between the two points if I did it again.  The major issue with the way I did it was that I occasionally spread the solder to one of the other pins because it's such a small area.  This can get very frustrating :)