Ramping up through hole board production

[Szewczykm]

I have a board that I'm making in small quantities.  It's a roughly 3" x 4" board with through hole components on it that I assemble and solder by hand.  Does anyone have any advice about small dip soldering tanks for the workshop?

I've had a hard time finding anything in the small range.  I either find something that's really meant for wire tinning or a $100,000 machine.  Does anyone have experience with this they can share?

Thanks!

Mike

[Simon]

Do you really need one ? if you want to save on labor you could consider using SMD parts that don't need holes drilling in the board.

[george graves]

Is there a specific reason you can't convert to SMD?

I've been in the same boat for a while now, and an in the process of switching over to SMD.  That's really the only thing that can speed things up.  You can hand place a smd much faster then you can insert a TH, bend the leads, flip the board over, solder, and trim the leads.  You'll spend more time getting set up - but you'll gain that back with really fast assembly times.

[Szewczykm]

I forgot to add that.  I understand that I can switch to SMD and maybe bake the boards in a toaster oven like I've seen.  But there are over 30 through hole solder points that I can't make SMD, they are for screw terminals and other on board connectors.  I'd like to see if there's a small scale dipping product available out there.

[Simon]

drilling large holes is probably faster than all of those 0.5, 0.7 and 1mm holes and constantly changing drill bits, unless of course you subbing out the boards. But at least SMD saves you from having to keep flipping the board over and cuts board costs.

[Szewczykm]

The boards were subbed out.  No drilling.

I'm placing through hole parts, bending the leads to hold them in place, snipping them, then soldering them by hand.  I'm not sure if there's any way to save time with placing the parts in the board and snipping the leads, but I've seen processes where you spray or dip the board in flux then dip it in solder to make a hundred nice solder joints in a few seconds.  But most of the stuff I've found is for high volume robotic dipping stuff.

[Simon]

all you need is a container of molten solder, find a shallow container you can heat, fill it with solder, heat it up and then dip the board holding it with pliers, works for the Chinese making PC power supplies for 5 bucks

[Szewczykm]

all you need is a container of molten solder, find a shallow container you can heat, fill it with solder, heat it up and then dip the board holding it with pliers, works for the Chinese making PC power supplies for 5 bucks

Well, I don't have any Chinese workers at my disposal, so I'd prefer to find a commercial device.

[george graves]

I've never seen anyone that does DIY wave soldering - or "board dipping"  - but DX has a few soldering pots, I guess you could try.



http://dx.com/p/300w-temperature-controlled-soldering-pot-blue-golden-220v-48764?item=2

[george graves]

Here's some good info on a DIY wave soldering set up:

I assume that you know that this is a mass production technique so you are going to have to start with the idea of about 6 to 10 feet of space for the whole thing.

Second, you need to get a couple of bicycle chains you can splice together to make a conveyor belt. One of its critical features is adjustable speed so the board passes over the solder wave slow enough to get a good bond and fast enough to prevent excessive heat transfer to the components. Expect to ruin 5 or 6 boards on each production run getting this right since the thermal characteristics of each board type, copper pattern number of layers and size will change the optimal speed for each run.

Third, you need to build a solder pump. That means including some way to keep it at the temperature of the molten solder. You also need a reservoir of molten metal and a way to lower an ingot into the reservoir as you use it so the level is maintained for the entire production run.

Last is the design of the preheat and flux coating. Since you have massive amounts of heat available to melt all of the solder, the first is just a matter of spacing between the heat source and the board track and conveyer speed. The second can be handled by dissolving rosin in ethanol and spraying it on. Again, the spacing and conveyer speed has to be adjusted so the ethanol all evaporates before it hits the wave. That is why the process has to be run over a distance of 6 feet or more. Also, you need to plan on a run-out area after the actual wave solder so you can control the cool down of the board before anybody touches it. If you want to get fancy, you can spray the board with pure ethanol in this area to clean off any remaining flux.

It is strongly suggested that you plan on including a fume hood in the design over both the fluxing and defluxing stations for worker safety. Also, pay particular attention to fire safety in the design. You are going to be spraying volatile solvents in the vicinity of a heat source so make sure nothing can drip into something dangerous. Indeed, the liquid is not as big of a problem as the vapors. With the right mix of evaporating liquid flux, air and heat you could get a really spectacular explosion if you don’t plan on how to control every aspect of this.

At this point, I have to say, “Good luck” you’ll need it.

http://www.electro-tech-online.com/electronic-projects-design-ideas-reviews/110619-diy-wave-solder-possible.html

And there is this guy.  Looks totally impracticable - apparently he built it to desolder components.:
http://www.damir-pavkovic.iz.hr/index.php?option=com_content&view=article&id=30&Itemid=37

[Szewczykm]

I did find this:

http://www.esicotriton.com/pots/

If you look down the page some you'll see the Model 75T and the 80T.  The 75T would suit my current needs at $300 or so, but the 80T might be best at about $800 to make sure it fits whatever board size I might deal with in the future.

I'm wondering if anyone has experience with these.

[george graves]

Besides them being temp controlled, I wonder if you when out and got one of those dorm room single style burners, a old pot, and a bunch of solder, and give it a go.

Have fun stuffing a whole board at once and keeping everything in place.  I don't mean to be negative - just I can't see how this would work - but if would be cool if it did.

You might do something like this on your terminal blocks to help them stay in place.

http://www.sparkfun.com/tutorials/114

Anyways, I'll shut up and let others chime in.

[David_AVD]

How many boards do you want to make at once?  I'd say hand soldering would be more reliable than any DIY (or el-cheapo) solder bath.

[Szewczykm]

One board at a time.  I have also turned these products up:

http://www.wenesco.com/static.htm

When I'm done placing my parts, I can flip the board over without a problem.  Holding things in place hasn't been a big problem.  Also, I would probably build a jig to hold the board up off the table for placing thing parts where I'm not bending leads.

[EEVblog]

Have you priced getting an assembly house to do it?
They will either do it by hand or machine or selective wave solder.
Even here in Australia I'm only paying $0.35/minute for hand solder/assembly work.

Dave.

[mikeselectricstuff]

FYI the way they do TH boards in moderate volume is to hand or machine place parts, with  the PCB panel sitting on steel plate which has the same hole pattern as the PCB. The PCB+Plate is then put on a machine which runs a blade over the plate  surface to crop the leads the same length (the thickness of the plate).
It then goes through a wave soldering machine.
Sometimes shrink-wrap is used to hold parts in place during handling and soldering.
   

[Szewczykm]

I've tried three different places.  One place wanted $45 per board to assemble.  I can assemble 3 boards an hour at this point, I can't justify that huge cost.

One place didn't call me back and anoth said that my volumes were too low to be of interest to them.  So... I figured I'd become my own assembly house and employ friends and relatives and do it cheaper.

So, if there's a place I can go, that information would be appreciated also. 

I can easily picture the way the shear off the leads, that's pretty cool.  Shrink wrap is interesting but I'm having a hard time picturing it unless the plastic ends up moving through the pool of solder too.

[mariush]

I saw a youtube video just yesterday, it was actually in a thread here on the forum :

???4

Check at around 1:00, see how they put the board over flux and then just move the board and flex the sides a bit over the solder.

Otherwise, I nice method of speeding up the process would be to skip the bending of the leads, which also makes it harder (in the sense of taking longer time) to cut the leads after the components are soldered.

I guess you could get some foam style material and cut holes in it to match the height of the components you use. Put the PCB on some supports (so that the component leads will have room under the pcb) , put all components on the board, put the foam shape over so that components will not fall out when the pcb gets rotated, turn the pcb on the other side (the foam will keep the parts in place) and solder each leg of the components... then cut all the legs to size.

You could probably get some pliers that form the leads of components to a specific shape, therefore you'd be sure all parts would be at the same distance away from the board, making the shape easier to make.

You could probably make the shape out of some lego pieces.

Or even some cardboard springs to mind. Just grab a few cardboard pieces, use a blade to cut rectangles or squares into as many as needed (picture them stacked one on top of the other)

See this instructable below, or the article about autodesk, just picture the 3d model being a block of material with holes where the components would be, a sort of a negative of the area above the pcb.. :

http://www.instructables.com/id/Model-complex-solid-shapes-with-cardboard/#step1
http://autodesk.blogs.com/between_the_lines/2012/05/autodesk-123d-make-available-make-3d-models-real.html

[EEVblog]

So, if there's a place I can go, that information would be appreciated also. 

We need to know where you are based, country and city...

Dave.

[Szewczykm]

US.  50 miles northwest of Chicago.

[David_AVD]

Even here in Australia I'm only paying $0.35/minute for hand solder/assembly work.

That's very cheap.  We charge a lot more than that.  At that price $21 / hr price point, I guess that the assemblers are not skilled in electronics as such (apart from soldering)?

[Bored@Work]

For hand soldering you could use a jig like http://www.newark.com/ideal-tek/pcsa-2/pcb-assembly-jig-esd/dp/40K2016 Put as many PCBs between the bars as possible. Place all components, then close the lid. Foam in the lid keeps the components in place. Swing around. Cut the leads. It is easier to cut the leads now before soldering, especially if you use a flush cutter or similar which you have rigged to keep a certain distance from the PCBs. It also somewhat reduces the risk of cracked solder joints. After cutting, hand solder all components.

For bending the leads of axial components you could use a hand operated bending and cutting machine like http://www.cutbend.com/html/english/frame_e.htm to save some time.

[EEVblog]

That's very cheap.  We charge a lot more than that.  At that price $21 / hr price point, I guess that the assemblers are not skilled in electronics as such (apart from soldering)?

That's why they are called assemblers!
You generally don't have TO's or engineers assembling boards 
Although the caveat is that that price is part of my assembly package, so some of it may be subsided by other work, I don't know, but that's what the itemised quote showed.

Dave.

[mariush]

@BoredAtWork: Looks like what I was describing a few posts above.. But man, 400$ for that.... if you're handy with some screws and some pieces of wood, there's no reason you shouldn't be able to build that yourself.

As for bending leads, the machines are also kind of expensive, maybe too much for a few boards. Not to mention it takes 10-20 minutes to prepare them for desired width and all that and then you really need to form hundreds at a time to be worth it, otherwise you're better off with those plastic bands : http://evilmadscience.com/productsmenu/partsmenu/68-bender

If you want something simpler to do more complex shapes on the leads, something I've had my eye on fpr some time are the tools from Piergiacomi : http://www.piergiacomi.com/piergiacomi/en/products/hand-tools.html?ja_color=default
See the Special Tools section at the bottom.

I've seen them sold at various stores, at reasonable prices, like 10 euro for one tool, for example here:

http://www.renex.ro/pokaz_kategorie.php?cid=331
http://www.olamefusa.com/e_forming_handtools.htm (this page has probably the whole collection with nice pictures showing the way the leads are bent)

Hakko also used to have some of these tools, but I think they were OEM tools from some company and I couldn't find them anywhere at the well known online stores.

[David_AVD]

$45 a board sounds too much to be paying when you can do 3 boards an hour yourself.

Maybe there's ways to reduce the build time.  The layout of the board can influence this too.  Resistors in rows, same values next to each other (where possible), component values on the silk screened all make a difference.

We bought a axial bender/cutter machine years ago and it's paid for itself many times over.  You can process 1000 resistors in about a minute.  Imagine the RSI you'd get using a hand tool!

Loading the boards into frames (flip over type with a clip on foam cover) also improves production speed.  A good frame takes hardly any time at all to configure for a batch of boards as they have sliding rails and knurled nuts.

Using the right type of solder and soldering iron can make a massive difference to the speed of hand soldering too.