Acrylic Stencils Help With Component Placement For SMD Assembly

July 16, 2018 by Dan Maloney 12 Comments

Surface mount is where the action is in the world of DIY PCBs, and deservedly so. SMDs are so much smaller than through-hole components, and fewer holes to drill make surface-mount PCBs easier to manufacture. Reflow soldering is even a snap now thanks to DIY ovens and solder stencils you can get when you order your boards.

So what’s the point of adding another stencil to the surface-mount process? These component placement stencils are [James Bowman]’s solution for speeding up assembly of boards in production runs too small to justify a pick and place robot. [James] finds that placing small components like discrete resistors and caps easy, but struggles with the placement of the larger components, like QFN packaged microcontrollers. Getting such packages lined up exactly is hard when the leads are underneath, and he found repositioning led to smeared solder paste. His acrylic stencils, which are laser-cut from SVGs derived directly from the Eagle files with a script he provides, sandwich the prepped board and let him just drop the big packages into their holes. The acrylic pops off after placement, leaving the components stuck to the solder paste and ready for their trip to the Easy Bake.

[James] claims it really speeds up hand placement in his biggish runs, and it’s a whole lot cheaper than a dedicated robot. But as slick as we think this idea is, a DIY pick and place is still really sweet.

Multi-Board Solder Stencils Explained

July 7, 2018 by Jenny List 13 Comments

There was a time when reflow soldering was an impossibly exotic process at our level, something that only the most superhuman of hackers could even dream of attempting. But a demystification of the process plus the ready availability of affordable PCB and stencil manufacture has rendered into the range of almost all constructors, and it is likely that many of you reading this will have done it yourself.

Screen-printing solder paste onto a single board presents a mild alignment challenge, but how about doing it with many boards at once? [Eric Gunnerson] had this problem with a small-volume board he’s selling, and not being in the happy position of having his PCBs supplied on a panel, had to create his own multi-board alignment jig and stencil. His write-up provides a comprehensive and fascinating introduction to the process whether you are an occasional dabbler or embarking on a production run as he is.

The problem facing any would-be stenciler is that the board has to be held in place reliably in the same alignment as the stencil. With a single board, it’s easy enough to do the usual thing of taping scraps of PCB board to constrain its edges and hold it in place as a rudimentary jig, then lower the stencil onto it. Perhaps you’ve used one of those commercial stencil jigs, in which a set of magnets hold the stencil in place, or maybe you use pins to line everything up.

[Eric] takes us through the process of creating a laser-cut alignment jig for twelve boards, and cutting a matching twelve-board stencil. This includes all the software side using Inkscape, the selection of materials to match PCB thickness, and some of the issues with cutting Mylar sheet for the stencil without shrinkage at the corners. He’s using pins for alignment, and he even finds a handy supply of those in the form of shelf support pins.

We’ve visited the world of reflowing many times before. If you’d like a primer, here’s our Tools of the Trade piece on it, and if you aren’t daunted by larger projects, here’s an account of a prototype run of a significantly complex board.

A Case For The Desktop Vinyl Cutter

August 1, 2017 by Sonya Vasquez 61 Comments

As far as desktop workbench fab tools go, it’s too easy to let 3D printers keep stealing the spotlight. I mean, who doesn’t appreciate that mechatronic “buzz” as our printer squirts a 3D CAD model into plastic life? While the 3D printer can take up a corner of my workbench, there’s still plenty of room for other desktop rapid-prototyping gadgets.

Today, I’d like to shed some light on vinyl cutters. Sure, we can start with stickers and perhaps even jumpstart an after-hours Etsy-mart, but there’s a host of other benefits besides just vinyl cutting. In fact, vinyl cutters might just be the unsung heroes of research in folding and papercraft.

Continue reading “A Case For The Desktop Vinyl Cutter” →

Cameo Cutter Makes SMD Stencils

May 15, 2017 by Al Williams 17 Comments

You never know what you might find in an arts and craft store. A relatively recent addition to crafting is automatic cutting machines like the Cricut and Cameo cutters. These are typically used to cut out shapes for scrapbooking, although they will cut or engrave almost anything thin. You can think of them as a printer with a cutting blade in place of the print head. [Mikeselectricstuff] decided to try a Cameo cutter to produce SMD stencils. The result, as you can see in the video below, is quite impressive.

If you’ve ever wanted to do SMD soldering with a reflow oven, stencils are invaluable for putting solder paste on the board where you want it quickly. The board [Mike] has contains a boat-load (over 2,000) of LEDs and dropping solder on each pad with a syringe would be very time consuming (although he did do some touch up with a syringe).

The board he’s using doesn’t have any extreme fine-pitched parts. However, he did some test patterns and decided he could get down to a finer pitch, especially with a little tweaking. However, the stencil he used didn’t need any changes. All he did was export the solder paste layer as a DXF and bring it straight into the Cameo software.

This isn’t the first time we’ve seen one of these cutters pressed into stencil service. You can also get some use out of your 3D printer.

Continue reading “Cameo Cutter Makes SMD Stencils” →

BGA Hand Soldering Video

January 3, 2016 by Al Williams 31 Comments

By 2016, most people have got the hang of doing SMD soldering in the garage–at least for standard packaging. Ball Grid Array or BGA, however, remains one of the more difficult packages to work with [Colin O’Flynn] has an excellent video (almost 30-minutes, including some parts that are sped up) that shows exactly how he does a board with BGA.

Continue reading “BGA Hand Soldering Video” →

Shirt Printing With Freezer Paper

June 24, 2015 by Rich Bremer 15 Comments

There’s a pretty good chance that you’ve wanted to add a graphic or design to a t-shirt some time in your life. There are certainly ways to do it but most of us don’t have silk screening equipment or a steady enough hand to have the end product look cool. Lucky for us, [UrbanThreads] has put together a stenciling tutorial for personalizing garments. The process is easy and inexpensive. The results are good, although it can be time-consuming if the pattern is intricate.

To get started, a black and white graphic is printed on a sheet of paper. The design is then taped to a sheet of the secret ingredient: freezer paper. The two sheets are then placed on a table with the freezer paper up. Since the freezer paper is semi transparent, the printed out design shows through. It’s now time to use an exacto knife and trace the design while cutting through the freezer paper. The two sheets are then removed from each other and the freezer paper is put wax-side-down on the garment and ironed into place. The wax melts and acts as a temporary adhesive to hold the stencil down. At this point, fabric paint can be sprayed or dabbed on with a brush (avoid brushing back and forth as it may lift the stencil). Once the paint is applied, the stencil is removed and the paint is allowed to dry. According to [UrbanThreads] the freezer paper doesn’t leave any wax or residue on the garment.

For more garment modding, check out t-shirt bleaching or get ambitious with this DIY screen printing setup.

Home Theater, Tribute To A Friend

August 2, 2014 by Edward Becker 12 Comments

The Greg Williams Theater

Ever since purchasing this house, [Ed] Always wanted a to turn his living room into a home theater, but not just any old projector and a white wall would do. He wanted the whole experience. [Ed] Started with a slightly damaged 12′ wide 4:3 roll up projector screen, he removed the damaged bottom portion and built a static frame to support the now 16:9 screen. Before he could mount the screen, he needed to drywall over a window that was inconveniently located. With the screen now in place, [Ed] framed out the elevated seating platform and steps with some 2×12 topped off with plywood. Next, the carpet that was sitting directly below the platform and steps was removed and then secured on top. Down firing LED fixtures were installed in the steps, to give them that movie theater look and feel. To provide the image, a refurbished HD projector acquired from the Bay of Electronics, was installed in the loft above the living room.

With the theater functional, [Ed] turned his attention to theater decorations. Dimmable ambiance lighting fixtures, using laser cut acrylic and CNC routed starboard (a marine-grade polymer), were made to resemble a film strip. Next a coffee table was crafted out of an equipment road case filled with movie props. Studio logos were painted on the sides with the use of laser cut stencils, and with a glass top, gives the illusion it came off the set of a hollywood movie. The addition of a rebuilt movie poster marquee, movie posters, candy stand, pop corn machine, and with the existing soda fountain and the arcade in the loft, the home theater was almost complete.

In a fitting tribute, [Ed] designed and built a marquee sign to dedicate and name the theater after his cousin Greg, one of his closest friends and avid movie watcher, who had sadly passed away. Video overview of all the hard work after the break.

Continue reading “Home Theater, Tribute To A Friend” →