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Assembling the Board
with randofo
Circuit Board Design Class
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Lesson 5: Assembling the Board
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The board has finally arrived! Hooray!

Now is time to assemble it. It is not until you actually begin to assemble the board that you can tell whether or not you designed it correctly. In theory, everything should be perfect and this should be the easiest part of the process.

However, chances are that for the first board you designed, you will likely encounter a mistake or two. If this is the case, don't fret. This happens to everyone sooner or later. So, let's start to put the board together and see how you did.


Assemble the Board

It is best to start with the parts that sit closest to the surface of the board, and work your way up. For instance, I install the resistors, diodes and ICs first. I then install the taller components like the capacitors and transformer last.

Assembling the board this way helps keep parts flush to the board when installing them as the weight of the board is holding the part down. If the part is not well sandwiched between the board and the work surface, it may end up dangling by its leads above the surface of the board.

The final components I attach are those that are external to the board itself. Obviously, not all circuit boards have parts external to it, but many do.

Power it up and see if it works. If it works, great! You are basically done.

If it does not work, keep reading.


In an ideal world, everything about your board would be perfect the first time around. However, there is the chance that no matter how much you checked and double-checked your work, something is wrong. In my case, the first board I made had an incorrect footprint for the transformer.

With some modifications to the transformer I was able to make this work. I just bent the mounting pins back, and jammed the leads through and I was able to make it work.

I ultimately decided to fix this footprint issue in the Eagle design software, and pay to have a second version manufactured.

Fortunately, the footprint issue was my only error. However, there are others you might encounter.

Another common problem is the board simply not working at all. The first step to resolving is to visually inspect the board and determine you have installed the correct components and all of your solder joints are good.

Assuming this all checks out, visually inspect the traces to ensure they are all routed correctly. If everything seems correct, this is where having additional boards comes in useful.

On an empty circuit board, test the connections for continuity with a multimeter to see if they are connected. You should definitely also check any vias for continuity to make sure they are actually passing the signal through the board from side to side. Often shoddy vias can be the source of errors.

If nothing at all seems to be wrong, perhaps the first board is simply corrupted or has a corrupted component. Construct the second board and see if it works. If it does, you are good to go. If not, you likely got a bad batch of a particular component or are somehow damaging something during fabrication.

Debugging corrupted components is well outside the scope of this class. Instead, I recommend when constructing future boards, lower the heat on your soldering iron, use proper anti-static part handling techniques (such as a grounding strap), and procure a new batch of components.

The other problem you may encounter is that the board mostly works but is doing something unexpected. In this case, it is time to go back to the breadboard, compare it to the board, and really consider what is happening in the circuit.


One Last Thing...

One unexpected thing that you might find is that the circuit on the PCB works better than the circuit on the breadboard. This is typically because there is less noise in the circuit on account of the shorter connections and a ground plane. In my case, the guitar pedal I am building sounds much better on the circuit board than it did on the breadboard.

If this is the case for you, think of it as a gift.

To complete this class, post a picture of the PCB you made in the comments below.

If you post an Instructable using your circuit board and it gets featured, I will also add it to the list of example projects for this class.

CLASS PROJECT

Share a photo of your finished project with the class!

Nice work! You've completed the class project