Posts about creating printed circuit boards.
It is time to solder through-hole and surface-mounted components.
I use Chip Quick solder paste for SMT components. When not in use, keep it in the freezer to extend its shelf life (it should not dry up). Chip Quick has a very low melting point and it’s perfect to use for SMT since you can apply tiny drops of it through a syringe it comes with. Apply small drops to pads and then position SMT components on them using tweezers.
Even tinned, the PCB traces will still corrode. Soldered joints will also oxidize since the solder is exposed to air.
After soldering, the board could be further protected by applying a coat of clear lacquer. The lacquer dries fast and can be soldered through afterward if needed.
I use this lacquer for final board protection:
http://www.testors.com/products/137179
This particular board did not need an enclosure. Instead, I mounted it on raisers. Holes for raisers were already drilled.
If you do have an enclosure, you may want to try to fit it: drill the holes and/or cut openings using a tool like a nibbler.
This is general guidance for the initial testing.
Thoroughly examine the board for physical defects: are all traces complete or there are breaks?
Are all pins soldered and is the quality of the solder joints acceptable? The soldering point may be missing (forgot to solder it), may have a bridge or a short, or it may be a poor joint (cold point). Just redo it.
Is any component missing? (Something blunt but may happen!)
You may need a magnifying glass or a loupe with a strong light.
Check again the orientation of components: LED, diodes, connectors, chips – where is pin 1 located. Check the orientation of tantalum and electrolytic caps. On SMT components, this can sometimes be confusing.
The quality of the tools that we use to write software for projects like this is very important when selecting which MCU we may want to use. Atmel has a very robust IDE based on Microsoft’s Visual Studio (which is arguably the best development environment out there). Coupled with a JTAG interface, writing and debugging firmware with the Atmel toolset becomes a pleasure.
Their ASF (“Atmel Software Framework”) is a good collection of ready-to-use projects and components. Investing time to learn that environment is the best way to become very efficient when using it.
There are a few things that I did not get to try this time around:
If a project is large enough, one could add a board ID that is readable by the software. That could be done by GPIO pins connected to, or “fused”, to certain voltage levels creating a short ID. This may be overkill for simple boards, but still, it is a known industry practice.
I really wanted to find out exactly how much etchant would I need for a given board. That would be at least a theoretical minimum to etch all exposed copper, so after some calculation, I made this table. In practice, you would probably want to double that amount to get it to etch faster, but that’s a good starting value to measure.
A weather station, Ambient Weather WS-2080 that I installed in my backyard has a receiver unit with a pretty nasty hardware issue: occasionally, its USB interface would hang hard. It could happen twice a week or once a month – it is very unpredictable and highly annoying. Once it happens, nothing short of a power reset of the receiver unit would fix it. You’d have to remove the battery or unplug the USB if you powered it through it. I’ve finally got around to fixing it. If you have a similar problem with that weather station, you may be interested to read on…
(This article was first written in March 2009 – now most of us have Android tables laying around performing this task and much more!)
For a long time, I wanted to buy an internet radio to get access to thousands of stations from all over the world. However, it seemed the market in the US was way behind that of Europe, where (especially in the UK) you could select among many models of digital, Ethernet-equipped radios. Many of them had features such as pausing and recording the audio stream.
Aren’t you also intrigued with these novel picture frames, but could never justify the price of one, with better models reaching hundreds of dollars and lesser models not really worth buying? Picture frames were one of the best-selling gifts in 2008, with an average price of $169 for a connected photo frame (EE Times, Feb 23rd, 2009), but people are mostly confused with the device. I’ve seen a few in people’s homes being used for several weeks and then collecting dust.
Continue reading
