Talk me out of installing a wave solder machine - Page 1
Forum section: electronics / general

author: Mangozac
author_rank: Frequent Contributor
timestamp: January 12, 2021, 10:37:05 pm
content: We have our SMT assembly line running great but of course there are still through hole components that need to be used: terminal blocks, connectors, headers, relays, transformers, electrolytic capacitors. We're currently doing this by hand but it's very slow and the team can't keep up. We're currently doing 20k boards per year with batch sizes of 100 to 1000 pieces and plan to double that volume in the coming years.I've been investigating installing a wave solder machine. We don't really have the space so it will be difficult to squeeze in but the increase in productivity would be enormous. It would at least quadruple the number of boards per hour that an operator could do.We had a really old, crappy Seho wave solder system a few years ago that caused nothing but headaches, including a lot of returns due to failed joints (investigated and found to be insufficient flux penetration up the leads). After sitting unused for years it was broken up for scrap metal a year ago. I'm now looking at brand new machines from reputable companies in China I've dealt with. Features include:Finger conveyor (no screwing round with pallets) up to 250mm widthAutomatic finger cleaning system (to remove flux and solder residue)Dual zone hot air preheater (they are claiming this is superior to IR preheaters)Spray fluxerDual wave (although for our applications only a single delta wave is probably all that's required)Lead-free capable (I'm fairly certain we'll be running it leaded though, not least because we still have 100kg of lead solder!)Discrete timer/PID controls so that in the event of failure repairs are easy. The biggest issue with the old Seho systems are their insanely complex proprietary controllers.So the drawcard of being able to quadruple our throughput without having to employ another person (not to mention the cost savings that would facilitate) is really helping me to forget our bad experiences with the Seho machine. But am I talking myself into a false sense of security?Alternative options:I have looked at selective solder systems and although more compact, they're also far more expensive and far more complex, meaning there's a lot more that can potentially go wrong.Automated dip soldering would probably suit but it's crude, has workplace safety issues and still needs a suitable fluxing systemBenchtop wave solder systems are very primitive and other than smaller footprint offer no advantage over a full size machineWho here is running a wave solder and has any comments for or against it?

author: jmelson
author_rank: Super Contributor
timestamp: January 12, 2021, 11:50:12 pm
content: I'm doing fairly small runs of boards. But, one board I do has FORTY connectors on it. It only has components on one side.http://pico-systems.com/osc2.5/catalog/images/products/CRAMPS.jpgSo, I got a big solder pot, and paint water-soluble flux on the back, mask some holes that should not be soldered, and drop all the parts into the holes.I made a "claw" out of thin galvanized steel to hold the board. I preat for two minutes on a 100 C hotplate and then dip into the solder pot for 10 seconds.Part of the trick is to ease the board in at an angle to allow air to escape, then hold the board flat for the ten seconds, then lift out VERY slowly at an angle.I get almost perfect soldering with this scheme, called "dip soldering". There are some fuse sockets and power transistors on the board, I paint those leads with the flux also, to improve wetting. Some day I have to look into somme kind of spray fluxer scheme, just a spritz bottle that can spray upward on the bottom of the board.Depending on your volume, this might solve your problem with a lot less investment. 20K boards a year, probably you SHOULD do a wave machine.That's 100 a DAY, every work day!But, as you note, they are not just push a button and go. There's a lot of setting up to get it to work properly. Preheat and fluxing are critical.Jon

author: IconicPCB
author_rank: Super Contributor
timestamp: January 13, 2021, 06:37:32 am
content: G'day Zac,Get Yourself a graduated heat resistant glass plate which can travel through the wave soldering machine.Use it to measure contact time of the wave with the PCBAlso get stick on temperature indicators. Stick them to the top surface of the PCB to measure temperature of the PCB as it travels through the machine tunnel.If You can get a nitrogen shroud over the solder pot; it will reduce the amount of dross in the pot which will in turn reduce the amount of dross inside the solder pump induction channel and naturally will result in a cleaner job.Also get a good supply of temperature resistant masking tape. Use it to form a dam on the leading edge of the PCB... mistiming does happen and when it does...it is followed by a flood.Oh and remember... peel-able solder mask is Your friend.

author: SMTech
author_rank: Frequent Contributor
timestamp: January 13, 2021, 10:53:19 am
content: Quote from: IconicPCB on January 13, 2021, 06:37:32 amThey are way more plug and play then you think, buy one, set it up, make your solder supplier help you dial in the process - because they will -its what they do.

author: Mangozac
author_rank: Frequent Contributor
timestamp: January 13, 2021, 11:05:45 am
content: Jon, I had considered "manual" dip soldering like that but as you describe, it's massively dependent on the skill of the worker. To be frank that's not something I want to rely on 😬Due to our previous experience we are familiar with the overall process and I'm confident in our ability to dial in the right settings with the help of the manufacturer. As I said, I believe our past issues were due to poor fluxing, so a spray fluxer should solve that issue.IconicPCB, those are valid tips and we already have a high temp glass plate that we used in the past for exactly that purpose.Nitrogen does make a lot of sense; I was looking at the price of used nitrogen generators but need to do more research on the ins and outs of them.

author: IconicPCB
author_rank: Super Contributor
timestamp: January 13, 2021, 11:47:03 am
content: A spray fluxer is a must with modern low solids flux.