Quick fixes for SMD population problems

Here’s a collection of tricks to get over some surface mount prototyping issues the next time you find yourself in a bind. But first we have to address the soldering atrocity seen on most of the components above. [Rxdtxd] admits he’s using a firestick for soldering his SMD parts. The non-brand 40W iron is just about the worst thing he could be using (well, we guess a candle would be worse). Try to overlook those joints and enjoy his solutions to a couple of other problems.

First up is what to do when you lift a fine-pitch trace like would be found on a TQFP footprint. The fix for this is to grab a junked transformer and use a bit of the enameled wire from the wrappings as a jumper. The wire is quite fine, and the insulation will burn off when soldered which means you don’t need to strip it first.

The second and third tricks both deal with resistors. As you can see above he placed two 1K resistors on a single resistor footprint to make his 2k resistor. The 0603 packages were both soldered standing on end, then connected with a lead from a through-hole component. The other resistor hack piles five components on top of each other to build resistance in parallel. This is not a great idea as it will fail over the long-term, but it will get you though the prototyping stage as long it doesn’t require precise tolerance.

Populate SMD boads using a toothpick and tweezers

Here’s a demonstration which proves you don’t really need special tools to populate a surface mount PCB. We’ve seen this board before, it’s the glass PCB server which [Cnlohr] developed and demonstrated by connecting the real world to Minecraft. It’s a tiny board and we were happy to have the chance to see his method for populating the parts before reflow soldering.

In the video after the break [Cnlohr] starts by dispensing a glob of solder pasted from its storage container. He mentions that as long as you store the stuff in the refrigerator it’s rather easy to work with. Because most of his projects are single boards it’s not worth it to have a solder stencil produced. Instead he picks up a bit of the solder glob on the end of a toothpick and applies it to each pad.

This isn’t really as bad as it sounds. The fine pitch TQFP footprints can just be dragged with a bit of the paste. After this application — which took around seven minutes — he grabs some tweezers (not the vacuum type) and begins placing each component. If he missed some paste he’ll discover it in this step and add where necessary. The last step is a trip through his toaster oven.

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$20 vacuum pen build on of the best we’ve seen


Everything you need to build a vacuum tweezers is laid out in this image. The parts should run you about $20 and when you’re done you’ll have the perfect tool for placing very small surface mount parts for reflow soldering.

This project uses the same concept as other fish pump tweezers projects but builds upon them with some interesting additions. The first step in the conversion process is to tear down the aquarium pump to reverse its flow. There are several steps but all-in-all it’s not very difficult. With the source of vacuum established [Technically Artistic] begins work on the business end of the tool. This is where the array of different pens see some action. The large blue one is the outer assembly, with the others combining to help connect it to the plastic tubing. The business end is made from a needle adapter for an air compressor, with an alligator clip cleverly modified to serve as a valve to release the parts from the tip.

USB microscope used for soldering very small things


Lasik eye surgery is pretty common these days, but there are of course easier and cheaper ways to solder SMD components. [techpawpanda] wanted a video camera to see what was going on when he placed and soldered very tiny components on his board, but commercial SMD video cameras were terribly expensive. He wound up using a USB microscope to place and solder these tiny parts, and we’re thinking his SMD soldering station is the bee’s knees.

[techpawpanda]’s video-based SMD station is built around a USB microscope available at the usual online retailers for $40. This camera is mounted on a wooden base with a USB hub allowing the camera to be plugged in along with a few USB LED lights and a USB fan for a rudimentary form of fume extraction.

The results are impressive – even at 11x magnification, [techpawpanda] can put paste on pads and place even the smallest SMD parts. All this in a device that is small enough to fit in a shoe box, or be tucked neatly away whenever it is not needed.

DIY SMD stencils made with a craft cutter

Unless you’d like to spend hours with a toothpick and a tub of solder paste, stencils are the way to go whenever you’re placing SMD parts. While most commercial and industrial SMD stencils are made out of laser cut stainless steel, [Peter] figured out a piece of plastic and a $300 craft cutter is equally well suited for the job.

[Peter] has spent some time making SMD stencils out of polyester film in the form of overhead transparency sheets. This turned out to be a wonderful material; it’s dimensionally stable, commonly available, and just the right thickness suggested for SMD stencils. The polyester film was cut on a Silhouette Cameo, basically a desktop-sized vinyl cutter aimed at the craft market.

Stock, the Silhouette Cameo rounds off corners, not something [Peter] wanted with features only fractions of a millimeter. He came up with a tool to convert the paste layer of a Gerber file into separately drawn line segments, allowing him to cut SMD stencils for 0.3 mm pitch components.

It’s a great piece of work to make very fine pitch stencils, but we’re wondering if this tool could be used on the much less expensive Cricut paper and vinyl cutter that is unfortunately locked down with some very restrictive software.

DIY pick and place builds boards, is awesome

In what can probably be attributed to the pains of placing a lot of SMD components, [gravelrash] built his own home-made pick and place machine.

Instead of being frustrated with tweezers, stereo microscopes, and having an inordinate amount of concentration, [gravelrash] built a pick and place machine from a Chinese CNC router. The build doesn’t use automated feeders for its reels of parts. Instead,[gravelrash] picked up five manual feeders from eBay, allowing his pick and place to hold 25 different reels of components.

There is, of course, a vacuum pump for sucking up SMD parts and a two-axis gantry capable of moving components from reel to board. The software is Mach3, a program normally used with spinning cutters to mill away wood, metal and plastic. [gravelrash] replaced this motor with a few vacuum controlled needles to pick up, move, and drop components onto the board.

While the build may not be as fast as some other pick and place machines we’ve seen, it’s almost as fast as hand-placing components with the added bonus of not tearing your hair out over very tiny parts.

Tip ‘o the hat to [Alexander] for sending this one in.

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Building up an inventory of SMD parts

Once you’ve been tinkering around with electronics for a while, you’ll realize the through-hole components that make breadboarding a circuit so easy won’t cut it anymore. Surface mount parts are the future, and make it incredibly easy to build a semi-professional mockup at home. The question arises, though: how do you store thousands of surface mount parts smaller than a grain of rice?

As [George] was building up his SMD inventory, he came across a few clever solutions. The first was a binder sold by Adafruit (and others) that holds strips of cut tape SMD components. [George] wanted something a little more modular, and when he came across an eBay auction for 5000 0805 resistors and 3000 0805 caps, he needed to find a storage solution.

[George] ran across these tiny modular boxes while shopping at Adafruit. These boxes are completely modular, interlock with each other, and have a hinged lid that will hopefully prevent the eventual, ‘SMD parts everywhere’ spill everyone his likely to have.

After printing out some labels for his boxes, [George] had a very tidy solution to his SMD organization problems. We’re wondering what other Hackaday readers use to organize their parts, so if you have a better solution send it in.