A Gatcha with PCB Panel
Recently I started panelizing my own PCB designs to speed up SMT production.
I used to ask PCB fab house to panelize my designs, but Altium Designer has a board array feature that makes panelization very simple. Also PCBWay, my go-to PCB fab accepts panelized gerbers the same way single board designs. So I have become comfortable panelizing my own designs.
This PCB was for JT Filament – the through hole design has been available as kits, but I started offering pre-assembled version as well, so I wanted to produce SMT version for that.
The panels and the stencil were produced in two days and delivered via DHL Total turnaround was only 5 days. This is crazy fast. (No rush fees paid. Note that it’s not always so quick, but sometimes you get lucky.)
Panels and stencil delivered. Oh and the holiday gift.
I ran the first batch of 4 panels as a test. Stenciling, pick & place, and reflow went without a hitch. I was very happy.
Stencil and the PCB Panels
Using low temperature paste for reflow – to protect the filament LEDs.
Assembled and reflowed panels
After testing each circuit on the panels, I went on to break them apart… That’s when it hit me – those V-scores are not snapping like I expected. After trying out some forceful ways to break the panels and only getting two boards successfully separated, I started to panic.
I talked to the support person at PCBWay and realized that my panelization had two problems;
- The boards were too close together (the support between the V-score lines needed wider).
- The inner cutouts left only thin strips next to the V-score line. This part can break or twisted during the depaneling.
#2 seemed to be the major issue, and since I can’t change the board design itself, I had to change the panelization. I decided to use tab-route instead of V-scoring. Which means I will have to file away the mouse bite residue after depanelization. Oh well…
I am now waiting for the delivery of the new panels (while keeping my fingers crossed). Will post the result soon.
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Here’s how I do my SMD PCB assembly
I design a lot of PCBs, and assemble most of them myself. Small quantity PCB fabrication services have become so popular and abundant, I take full advantage of them.
Recently I use PCBWay a lot. Their pricing is close to the lowest (sometimes is the lowest), but the quality is still quite good. My favorite part of their service is that they offer different solder mask colors without extra charge. I don’t like green PCBs so this is a big plus!
For small boards for prototypes, batch based PCB service such as OSHPark still wins, as the shipping cost is much lower than from China. I use OSHPark for boards up to 2 sq inches, and PCBWay for larger.
Oh and PCBWay (and some other Chinese PCB fabs) offer stainless stencil for a very reasonable price. I can usually add one for $10 and it is very nice to receive PCBs and the stencil together.
Here are the photos from my typical PCB assembly using the nice stencil.
Step 1: Gather All Materials
Clear your work area and gather all components, material, and tools. Preparing the organized BOM printed helps to reduce errors.
Step 2: Frame the PCB and align the stencil
I use squares made of fiberglass to secure the PCB to the desk. Then overlay and align the stencil on top, and secure it with a piece of masking tape.
Compared to Polyamide (orange plastic film) stencils, stainless stencils are easier to align to the PCB. The pads kind of “snap” into place.
Step 3: Squeegee time
Now it’s time to spread some solder paste onto the PCB. Use plenty of paste and pull the squeegee at a steady speed.
Here the stainless stencil really shines, as the paste spread very smoothly without effort.
(Ok, I could’ve done a better job, but…)
Step 4: Ready to Pick & Place
Now the PCB has solder paste beautifully printed on, I’d get busy placing components.
Step 5: Ready to Reflow
Here the boards have all the components placed and ready to reflow. Sorry I forgot to take photos during the pick & place process.
I use a small reflow oven to reflow PCBs.
