Third Day with DesignSpark PCB

Previous installments of this series, First Day with DesignSpark PCB and Second Day with DesignSpark PCB where done with DesignSparkPCB version 1.03, I have since upgraded to version 2.00. My DesignSparkPCB libraries are now available on BitBucket: Right now they only apply to this series, but they will be updated over time.

Today I will try and route the board without using the autorouter. I have used a lot of autorouters in the past and I have never gotten satisfactory results with them. I have learned the hard way that autorouters and I just don’t get along and I now route boards manually using interactive routing where possible. I really wish DesignSparkPCB included an interactive autorouter, but it’s still possible to do good layouts without one. It just takes longer and you have to use grids wisely, This is especially apparent with fine pitch surface mount components. I would not attempt to route complex BGA components with a package like DesignSparkPCB.

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Solder Demonstration Video

This video shows how easy it is to solder a TSSOP package by hand on a circuit board. I see lots of advice on the net about using really fine solder tips and microscopes, etc but there’s an easier way if you use the right technique. The most important thing is to use the right tip on your soldering iron. I use 1/4in knife tips 99% of the time. Don’t waste money on other fancier tips that are concave because they aren’t an improvement.

Here’s the steps:

  1. Align the part on the pads and solder down 2 corner pins on 1 side of the part. This can take a little time, but it’s important to get it right. I did that in about 1 minute when setting up for the video.
  2. Solder all pins down on the other side. Try to keep a small solder ball on the iron tip and don’t overdo it. I used No Clean 0.020 Tin/Lead. Don’t use lead free unless you have to.
  3. Flux up the pins and touch them up. I used a No Clean flux pen and a wiping motion with the iron. Sometimes you also need to use some solder wick as well to get rid of the big blobs.

I made a video to show steps 2 and 3. The iron is a Hakko 936 set to 650F. I discovered that making soldering videos is hard because the camera is so close to the board that lighting and working around the camera are issues. The video below is my third attempt, but I think I need a little more practice making them.

It’s probably not obvious, but using a bigger tip helps when soldering small parts. That’s because the iron can control the tip temperature better and there’s more thermal mass to heat up the pad. A small tip doesn’t have the same thermal mass and I find that they cool down almost instantly when you touch them to a pad. Now I only use the small tips when the knife tip physically won’t fit.

Decentralized File Version Control

I’ve been using Subversion for years to store all of my files. It works well for binary and text files and Subversion is capable of file locking which is an important feature for binary CAD files. I know that lots of people tell you no put binary files in version control software, but it does work if you use the right system. Right now there’s 10’s of gigabytes in my work repository with a working copy that’s about 2GB and there hasn’t been any problems so far. The advantages of using Subversion are:

  • Data security: All your data is in Subversion which means it’s easy to go back in time if necessary. If you setup a separate server you also get redundancy as well since now there’s multiple copies of the data.
  • File locking: This is important for organizations where multiple people work on the same files. By enforcing file locking rules, Subversion makes sure that only 1 person can edit a file at a time. Nothing is more frustrating than having your changes overwritten by someone else.
  • Remote file access: You can easily access Subversion over HTTPS or SSH.

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Second Day with DesignSpark PCB

One of the issues from my first day with DesignSpark PCB was the fact that my titleblock printout didn’t come out as expected. All of the text was shifted down a little and was the wrong size. I did a little more investigation and it turns out that if you use a stroke font instead of a True Type, the alignment doesn’t change when printing. The font size is also the same. However, in order to use stroke fonts you need to declare them in the design technology file for every size and type you intend to use. Even though it looks like you can edit the size of a stroke font by just clicking on it, you can’t.

The next step in my project is to draw the schematic. That was easy – the drawing and placement tools are pretty straight forward. Here’s what I ended up with.

Relay schematic
Relay schematic

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