Solder Paste How-to Tutorial

The application of Solder Paste is an essential part of short run manufacturing and prototyping. After getting back bare boards from a PCB shop, its time to get down to business and populate those boards. This new tutorial set assumes you have access to things such as stencils for your boards, but does mention a couple of resources on commercially available ways to purchase stencils. Of course, if you have a laser cutter, we can help you out. After getting your solder paste chops down, make sure you check out our guide to toaster oven reflowing.

[Thanks to P. Torrone]

QFN or MLF soldering without solder paste

Take a few minutes to watch this amazingly informative video on how to solder QFN or MLF components without solder paste.  The quality of the video and the information within is quite nice. Even if you don’t intend to work with these parts, you could pick up some tips for soldering with hot air.

Flux paste applicator gun

[Luciano] didn’t want to drop a lot of cash into a flux and solder paste applicator so he built his own for about $5. He re-purposed a hot glue gun which you can usually find at a dollar store. After removing the heating element he inserted the body of a syringe. The plunger has been modified to use a knitting needle inside of some plastic tubing. After taking the picture above he made an improvement by adding a milliliter scale to the plunger, allowing you to meter out the paste and also gauge how much remains.

Laser cutting solder stencils

Do you have access to a laser cutter? If so, you can use [Riley Porter's] method to cut your own solder stencils. He starts with the Eagle files and exports the Dimension and tCream layers to a PDF. That file is then processed using Ghostwriter, Gview, and finally, Corel draw. The result is a 1200dpi file to feed to your Epilog laser. Now you’re ready to stencil on the solder paste and populate the PCB.

[Thanks Travis Goodspeed]

Hot air pencil for under $20

hotairpencil20usd1

Here’s a project from back in 2001 that might be of interest to some of you. It is a guide on how to build your own hot air pencil for SMD soldering.  He is using a super cheap 45W soldering iron from “the shack” combined with a pump type desoldering tool and an aquarium pump. He says it works pretty well, and we don’t see why it shouldn’t. This is a pretty elegant solution. There are also some more recent versions of this mod, but the idea is basically the same.

[thanks Stuart]

Eee PC bios resurrection

flashsolderedtoboard

Hot on the heels of our post about reading passwords from EEPROM, [n0th1n6] tipped us off about a similar hack used to resurrect an Eee PC from a bad bios flash. After discovering that a factory repair for a dead bios costs about $200, [CutenaCute_7] took on the challenge herself. She disassembled the computer and desoldered the bios chip from the board. After writing a program to flash the chip using C#, she temporarily soldered jumpers to make sure the flash worked. Looks like this is a zero cost hack, plus the time savings from not having to ship her computer somewhere. Bravo.

Double the RAM on D-Link router

d-link_double_ram

[Pelaca] upgraded the RAM on his D-Link DIR-320 router from 32MB to 64MB. This hack is simple enough: swap out the existing RAM chip for another one and change the bios to make use of the upgrade. The actual execution is not that simple because of the pitch of the TSOP II package; you’ll need to bring your mad soldering skills to pull this off.

This reminds us of when upgrading original Xbox RAM to 128MB was all the rage. It involved the same type of hack, adding four memory chips to unpopulated positions on the motherboard. The forums are thick with people complaining that their box not working after a failed upgrade attempt. Hopefully you’ll have better luck.

[Thanks Juan]

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