The boards I ordered recently arrived and it was time for assembly. Because I am designing for minimal cost, I had to hand solder the accelerometer and gyroscope. Both were QFN packages so I couldn't simply use a soldering iron for the job. Instead I needed to learn how to use soldering paste and do basic reflow.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiju1WpGVZ_585xK_JxarmqyhaO3614G8BhduSwZrzajdd1KBHOh0ZwwwdRieYsJm7oO8Gy2oshGrF38F2OsfVwDekxFxkPBD1Fg74KSqLjAkBe08QnuLmNO0Kq0XdhlrloIZtOdEt4Izc/s320/IMG_0319.jpg) |
The boards from SeeedStudio. |
So I talked to a couple people and they suggested hot air rework. The problem was I didn't have a hot air rework station and didn't feel like shelling out $100 for one. So when I went to Fry's electronics to buy some soldering paste, I saw a $14 personal skillet and I remembered this great tutorial from
SparkFun. They found that a skillet is a fitting alternative to a toaster oven and in some ways works better. I decided to give it a try and I wasn't disappointed.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4YaEydxUyi8XpLHT0D4CBU8qz0ygKr-aRhmLXkU7N222pN_i7gBCi5zBP7TY0D_ZfIqKcTylfCx7Z_RerSZ8a14sDsaMqMkXMaq9AIbzW10-5h5gbjOLO7XdGgZjFObsFst3RktJI2GQ/s320/IMG_0317.JPG) |
The skillet from Fry's. Only $13.99! |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-DQwS35SIgsZ4bdUB-X3-opOxl8EDHjcr65Eytz8XjVyQpZhLuM_qAeXefexPQ860XAV-J1WsPqdPrT3bHtXOm_0R_xtxrB88nHSgLkS2ghpmZPWAvWzDqjMhz64O2CANK5Q1XNmrglQ/s320/IMG_0318.JPG) |
Cooking up some electronics! |
The most difficult part of the process was applying the soldering paste since I didn't have a stencil or syringe. Instead I used my pair of tweezers to "paint" it on the pads which I wouldn't recommend. It worked, but it was tedious and messy. (I have since ordered a syringe). After adding the parts to the board, I simply laid it on the skillet and watched as the parts reflowed and slid into place. Everything seemed to reflow fine save a one or two solder bridges which were easily fixed with a soldering wick.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-92ED0xYXfGNNo3DglMP-cKxxZ50vpoYqIgCGuR_AaK5kc5rlyddESMWCal73-WKHkgLZ2D_nLBZoneo1fwDmDOyNVMeZLGe1t9tvMFkBHpgnHdcntwQprLGAp2TNCaZQq6BtX-QhN6Y/s320/IMG_0294.JPG) |
The board after reflow. You can see some small solder bridges. |
One disadvantage of the skillet method (and toaster?) is that you can only reflow one side. This meant that I designed my board with all of the reflow parts on top so I could hand solder the bottom. This wasn't too hard as I only really had to solder the microcontroller which is pretty easy with the help of soldering braid.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFDUZm6idw_QRwj0fI07ke2HtspF5km4dlgTRJzm0XRaQThYH_Z040ebw0ytmcRy2gA-c82QfA4GUcqhuC5BnTYdYEXfLkPodSd52xmqd5wg9QzHri9l00WTehbmA5s2kxcVe9q0FOc7Q/s320/IMG_0316.JPG) |
The hand-soldered bottom of the board. |
The end result looked great and I was really pleased with skillet reflow. It was fast, cheap, and easy to do! Check out my next post where I will show how I tested the boards.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhA-Nj2xACMC692V8UJHl0mbF2Cx3EgS28ZT3YiYBxi90YQGDNq02zrPh5jUwr567XMwMXaUmq_y193zMZOJERFbJBXGZntAjVeSzbBBWFWvehiw1uODo_3LP-2WZpaaxIe6ocud0y3gMs/s320/IMG_0314.jpg) |
The finished product. |