DIY hot air reflow station

Add to you bench tools by building this hot air reflow station. [Tobi] had a difficult time and was getting frustrated with the reflow oven he was building. He ditched that and set out on this project after drawing inspiration from a hot-air pencil project.

Pictured above is the business end of the device. On the right you can see the tubing that delivers air from an aquarium pump. At the center of the probe is a glass tube containing the heating element. A thermocouple is monitored by an ATmega644 to maintain the desired air temperature which can be dialed in on the base unit. This thing can put out air that’s around 500 degrees Celsius which has cause some problems with melted tubing and singed spacers. The final design includes a cover that fits over everything and hopefully provides adequate thermal isolation for the user’s hand.

[Tobi’s] base unit include faceplates for the front and back milled out of copper clad board. This really makes the tool look a bit more trustworthy. He assures us that there is a demonstration video on the way.

Easy to build rig prevents reflow soldering mishaps


[Erich aka VK5HSE] performs quite a bit of solder reflow work, but has always been concerned about bumping his circuit boards once the solder has liquified and is ready to be removed from the heat source. He says that removing workpieces from toaster ovens often results in the unintentional jarring of a circuit board full of components sitting on molten solder, and he wanted to find a solution.

Using some off-the shelf components from a local hardware store, he built a rig that fits on top of a hot plate, allowing him to move hot circuit boards away from the heat source in a smooth controlled motion. The rig is pretty simple, not only preventing unwanted workpiece movement, but also making it easy to regulate the amount of time a circuit board is allowed to heat.

He suggests that his design is not absolutely ideal, and that it can easily be improved upon in several ways without adding significant cost to the project.

Heat gun GPU reflow fixes laptop

Solder connections on processors seem to be a very common failure point in modern electronics. Consider the Red Ring of Death (RRoD) on Xbox 360 or the Yellow Light of Death (YLoD) on PlayStation 3. This time around the problem is a malfunctioning Nvidia GPU on an HP Pavilion TX2000 laptop. The video is sometimes a jumbled mess and other times there’s no video at all. If the hardware is older, and the alternative to fixing it is to throw it away, you should try to reflow the solder connections on the chip.

This method uses a heat gun, which we’ve seen repair PCBs in the past. The goal here is to be much less destructive and that’s why the first step is to test out how well your heat gun will melt the solder. Place a chunk of solder on a penny, hold the heat gun one inch above it and record how long it takes the solder to flow. Once you have the timing right, mask off the motherboard (already removed from the case) so that just the chip in question is accessible. Reflow with the same spacing and timing as you did during the penny test. Hopefully once things cool down you’ll have a working laptop or gaming console again.

Skillet reflow controller

Using an electric skillet to reflow surface mount circuit boards is a popular alternate use for those kitchen appliances. The real trick is monitoring and controlling the temperature. [Mechatronics Guy] built his own skillet temperature controller using a thermistor, a solid state relay, and an Arduino.

He was inspired by [Ladyada’s] work which used a servo to adjust the temperature dial on the skillet’s power supply. This started by attaching the thermistor to the bottom of the skillet using JB weld. since this area will be heating up he also attached a terminal block for connecting the feed wires as the heat would melt any solder joints. Those wires travel back to a control box housing the Arduino and solid state relay. To gain finer control over the heating element the relay is switched on and off, resulting in low-frequency Pulse Width Modulation, which should help maintain a consistent temperature better than just turning the temperature dial on the cord.

Pair this up with the vacuum tweezers hack and you’re on your way to a surface mount assembly line. If you want to see this process in action check out this post. It goes from stenciling, to populating, to reflowing in a toaster oven.

[Thanks Rob]

Hackaday Links: December 7 2009

Ah the beauty of watching molten solder pull SMD components into place. Yeah, we’ve seen it before, but for some reason it never gets old.

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Ferrofluid is our friend. But having grown up watching the Terminator and Hellraiser movies we can’t help being a little creeped out by the effects seen in this movie.

Follow along with the NASA astronauts in this 20 minute HD tour of the international space station. It’s a cramped place to live but we can’t help thinking that it looks incredibly clean. After all, where would the dirt come from?

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This video from the past that is about the future of  travel does leave us wondering why our cars don’t have built-in radar for poor visibility? We’ve already realized the rear-view-mirror-tv-picture, but we’re going to need your help before the flying police/fire/ambulance-mobile is a common sight. Oh, the fun of seeing a high-tech push-button selector 3:30 into the video. Perhaps the touch-screen was a bit beyond the vision of the time.

Sometimes you have so many servants you need to find creative things for them to do. Only the most discriminating of the super-rich employ a person whose sole responsibility is to erase and redraw the hands of a clock each minute. This video is obviously a result of the global recession as the live time-keeper has been let go; a looping recording took his job!

Last time we checked in with [Marco Tempest] he was syncing video over multiple iPhones. Now he’s at it again with an augmented reality setup. A camera picks up some IR LEDs in a canvas and translates that into information for a video projector. We’d call this a trick, but it’s certainly not magic.

Double sided surface mount PCB population

Above is a video detailing one method for populating a two sided surface mount PCB. We covered using a stencil to apply solder paste for a PCB a few weeks ago. In the comments there was a debate about the virtue of using stencils as well as a question about how two sided boards are populated. This was a good question because reflowing a board twice can cause components on the underside to fall off.

[Wim L’s] comment mentions that there are a couple of methods for two sided population. In the video you will see that a stencil is not being used, but instead, paste is applied by a pedal actuated syringe. The paste is applied to the underside of the board first, then a teeny dot of epoxy is added to hold the component in place. Each part is then positioned normally and baked in a reflow oven. This process both reflows the solder, and cures the epoxy. When the board is reflowed a second time, the epoxy holds the bottom components in place as the top solder reaches its melting point.

This method of applying solder paste is slower than using a stencil. But if done correctly, every component can get the amount of solder needed.

How to populate a surface mount PCB


Let’s face it friends, everything is moving toward surface mount components. We’ve seen quite a few features here that cover using stencils to populate boards and using ovens to reflow. [Oleg] has put together a tutorial on the process he uses to populate and reflow his own boards.

[Oleg] is the creator of the USB Isolator and therefore has a need to frequently populate the same board. He’s using an acrylic frame that fits the PCB perfectly to hold it in place so that paste and be applied right up to the edges of the board. He ordered a laser cut Kapton stencil for applying the solder. The paste is squeegeed into the stencil holes, the stencil is removed, and parts are placed with tweezers and a steady hand. For the final step, the boards go into an old toaster oven for reflow.

[Oleg] uses temperature marker on his boards to monitor the progress of the reflow. This marker is basically a crayon that begins to melt at a specific temperature. When the board has cooled, the melted mark can be scraped away or removed with alcohol.

Of course this is only really useful if you have a bunch of high-quality boards to populate. But with the relatively low cost of getting professionally made boards we think the need for this type of assembly process is on the rise.