Art and Technology are Friends

Posts tagged “PCB

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.

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

Stencil and the PCB Panels


Using low temperature paste for reflow - to protect the filament LEDs.

Using low temperature paste for reflow – to protect the filament LEDs.

Assembled and reflowed panels

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;

  1. The boards were too close together (the support between the V-score lines needed wider).
  2. 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.


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

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

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.

View from the top

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

Ready to stencil

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.

Solder paste printed

(Ok, I could’ve done a better job, but…)

Step 4: Ready to Pick & Place

Solder paste printed

Now the PCB has solder paste beautifully printed on, I’d get busy placing components.

Step 5: Ready to Reflow

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. mention of JT Blinker

Mr. Watson of blog wrote about the LED blinker circuit using Joule Thief. I’ve sent him a PCB of my prototype, named JT Blinker – multivibrator and Joule Thief combined to blink LEDs with one 1.5V battery.

He had designed a similar circuit years ago, and has some insights about this type of circuits…

> read the article at Rustybolt

Some Old Works of Mine

I was doing some clean up and found some old works from years ago…


Wave JT – Kit and PCB

Wave JT is a tiny LED sequencer or “Larson Scanner” on steroid. It has over 16 sequence patterns, and speed can be adjusted by double/triple tapping the button. It’s the most versatile LED chaser.

Unlike other LED chasers, Wave JT controls each LED in smooth 7 bit (128 levels) brightness levels. The brightness curve is gamma-corrected like Aurora series, so the fades are visually pleasing.

Not only Wave JT versatile, it’s also energy efficient. Wave JT runs on a single AA battery, and the battery lasts for days!

> See more pictures and video

Please view technical details and assembly instructions at instructables.

Wave JT is made with 100% through hole parts. No surface mount parts!

Kit Contents
8x 3mm or 5mm Super Bright LED of your choice
1x 4.7k ohm (R1)
1x 100k ohm (R2)
8x 39 ohm (R3-10)
1x 10pF Ceramic Capacitor (C1)
1x 0.1uF Ceramic Capacitor (C3)
1x 33uF 10V Electrolytic Capacitor (C2)
1x 47-100uH Axial Inductor (L1)
1x Schottky Diode (D1)
1x 5.1V 500mW Zener Diode (D2)
2x MPS2222A or equivalent NPN BJT (Q1-2)
1x PIC16F1823 or PIC16F1824
1x Tactile Switch (SW1)
2x Battery Clips

Note: As of Oct. 1, 2012, all Wave JT kits are shipping with preprogrammed PIC. You do not need a PIC programmer to assemble Wave JT kits!

*** Purchase Here ***

Colour Night Joule Thief kit

Colour(Color) Night Joule Thief kit and PCB are available. Please use the buttons below to purchase.

Detailed information and building instructions are here:

*** Purchase Here ***

Night Joule Thief – LED Night Light Kit

Joule Thief circuit is combined with an ambient light sensor – Night Joule Thief is a little night light that keeps going with just one battery for weeks! Two white LEDs light up surprisingly bright.

* This is the original version of Night Joule Thief that uses white LEDs – not to be confused with the new color changing version.

Please view the instructables for technical info and assembly steps.

*** NOTE: The color of the PCB will be green instead of purple shown in some of the pictures. ***

*** Purchase Here ***