Fast and easy solder paste stencils

If you’re making your own boards with SMD parts, you might want to get a solder paste stencil. Usually made of laser-cut mylar or extremely thin steel, these stencils allow you to squeegee solder paste onto your board’s pads and make assembly a whole lot easier. [Rochey] needed a stencil for a board he was working on, and lacking a laser cutter he turned to what he had available – a few bits of plastic and a CNC machine.

[Rochey] began making his stencils out of laminating pouches and an xacto knife. This worked well, but it was time-consuming, and a bit fiddly when cutting 1 mm square holes. To speed up the process, [Rochey] put one of these laminating pouches on his CNC machine, exported the ‘Top Cream’ layer in Eagle to the CNC software of his choice, and had his machine attack the plastic with a 1 mm drill bit.

To [Rochey]‘s surprise, everything went as planned; in five minutes, he had a stencil with perfectly accurate holes that masked off everything but the SMD pads.

Thanks [Fabien] for sending this one in.

How to etch your own solder paste stencils

We’re kind of surprised we haven’t covered this concept before since it only uses techniques that are commonly avaialable for home PCB fabrication. [Ray] made this solder paste stencil out of a sheet of copper using the same etching techniques you would for a circuit board. He designed and printed a resist pattern, with toner everywhere except the places where there should be holes in the stencil. He transferred the toner to the copper using an iron.

The difference here should be obvious; this a thin copper sheet with no substrate. Because of that, you must protect the copper surface before etching. he covered the entire thing, both sides, in packing tape. After that it’s into the Cupric Chloride bath to dissolve the exposed parts. Once the tape and toner has been removed you can scree a precise amount of solder paste onto your boards.

This isn’t for everyone, but if you’re assembling many boards it’s not a bad approach. If the stencil is no longer used it can be recycled, but we do wonder how corrosion on the copper will affect the stencil’s performance.

The idea for this technique came to [Ray] from a guide that’s been around for years.

One-man SMD assembly line shares a lot of tips about doing it right

Need to use that antiquated hardware that can only be connected via a parallel port? It might take you some time to find a computer that still has one of those, or you could try out this USB to Parallel port converter. It’s not limited to working with printers, as the driver builds a virtual parallel port that you should be able to use for any purpose. But what we’re really interested in here isn’t the converter itself, but the build process. [Henrik Haftmann] posted a three-part series of videos on the assembly process, which you can watch after the break.

The build is mostly surface mount soldering with just a handful of components that need to be hand soldered. The first of his videos shows him stenciling solder paste onto the boards. From what we can see it looks like he built a nice jig for this using scrap pieces of copper-clad which match the thickness of the PCB, and hold it and the stencil securely in place. There’s a bunch of other tips you can glean from the videos, like the image seen above. It’s a clamp that holds the PCB and USB jack together while they are soldered.

If you’re ever thinking of assembling a bunch of boards you should set aside thirty minutes to watch them all.

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Solder paste dispenser hacked to run off compressed air cans

solder_paste_dispenser_air_can_hack

[John] got a shiny new solder paste dispenser for a steal, and before he hooked up the tool, he decided to take a look inside to make sure everything was on the up and up. Aside from a few questionable wiring practices he didn’t approve of, everything else looked to be in good working order.

The only thing that was bothering [John] is that he wasn’t too keen on keeping his noisy and large air compressor in his workshop, so he set off to find a different way to provide compressed air to the device. He settled on air dusters like those used for cleaning the crumbs out of your keyboard, but he needed to find a way to reliably get the air to his solder dispenser. He heated the air can’s nozzle until he was able to screw his dispenser’s hose barb into it, creating a tight seal. The modified nozzle was reattached to the can and placed in a simple jig that keeps the nozzle held down continuously.

[John] fired up his dispenser, and the 80 psi coming from the duster was plenty to get the solder paste flowing. Sure the rig might not be the most high tech solution, but we think it’s a pretty good means of getting quiet compressed air anywhere you need it.

Qube, not an Arduino clone

What allows the everyday user to tinker with microcontrollers, IO, interrupts, serial communication, and even analog readings? How about individual modules that add the ability to communicate over bluetooth or add LCD support? If you were thinking Arduino, you would be wrong. It’s actually [Nilok's] Qube, which at first seems like another Arduino clone however the Qube is based on PIC – not AVR. Another difference is the sweet black anodized case the Qube is planned to be put in.

While all this seems amazing at first, there is of course a catch – it looks like the first models are pre-order only for staunching price of $70! Sorry, but Arduino wins at half the cost.

Regardless, [Nilok] has documented the entire process and it’s amazing to read through; he even includes some guides on solder paste and bootloading USB. And who knows, maybe he’ll release open source. His site seems a little slow, we recommend the Google Cache.

SparkFun stencil and solder paste class notes

stencil

Hobby electronics manufacturer SparkFun has started offering various classes at their Boulder, CO facility. [Landon] has been attending as many as possible and posted about his experience during their Stencil and Solder Paste class. Solder paste is used when manufacturing boards with a reflow oven. He took quite a few pictures of the process and posted notes and audio. He says it’s definitely something you’d have to learn hands-on, but his numerous photos give you an idea of what’s involved. Below, you can watch a video of the paste clean-up pass and stencil removal.

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solder paste and reflow how-to


I was poking around spark fun electronics, and came across this interesting walk through showing spark fun’s solder stenciling technique. (I’d put on some gloves before handling that much lead paste) They top it off with some alternative ways of doing reflow work. My favorite has to be the target hotplate method. It’s a nice introduction if you’re interested in doing SMD work to save money and space on your projects [but not sanity. say goodbye to that] Me? I’ve used a 15 watt weller with a dremel modified small tip. It works great if you’ve got some one of those syringes of heat activated glue. Place, bake and solder.