The concept of QCB is based on scoring the non-connections rather than laboriously draw connections on the copper clad board. The complexity of technology of making traditional PCBs can be virtually reduced to pencil and paper technology using QCB. Though very complex circuits might not be possible with QCB, moderately complex circuits involving one or two ICs are indeed possible. Complex circuits might be developed using modular approach.
Salient features of QCB:
- Quick process
- Layouts can be easily documented
- Easy templates
- Easy and quick reproduction
- Pure mechanical process with no chemicals
- Professional quality
- Very small footprints possibles
- Very simple tools required
- Easy checking of circuit
- Easy conversion of schematic into circuit
- Low resistance circuit
Step 1: Tools and Materials
- Etchant of any kind
- Masking of copper clad boards
- Hefty PCB designing software
- A lot of time, tools, problem solving, cleaning, disposing off, etc.
- Copper clad board
- Schematic of the electronic circuit (even hand drawn wiring diagram will do)
- Inkscape and inkjet printer OR pencil and paper (plain, graph or sticker paper)
- HSS hacksaw blade (NOT shown in figure; cutter was tried earlier but was found to be inconvenient; HSS blade is best as it can cut any material with ease)
- Straight edge (anything straight will do)
- Manual pen type PCB drill (see figure) with 0.8 mm drill bit
- Center punch
- Glue stick
- Scrap piece of wood
- Some spare time
- Oregano (optional: It's free and easily simulates schematics)
- Multimeter or continuity tester (optional: For checking connections)
Step 2: From Schematic to Artwork
This step is the only time consuming step of this instructable. After that it is as simple as drawing lines on paper.
The basic concept behind a QCB is drawing non-connections rather than connections. This change in point of view reduces the number of lines to be drawn, makes circuit layout simple, makes use of simple drawing software possible.
Now the steps:
- First set the line thickness equal to 110% of thickness of hacksaw blade.
- Draw component profiles using simple shapes such that their dimensions correspond to the outer dimensions of your component. Save this file as it can be reused for any new circuit.
- Draw 0.8 mm circles. These circles will represent places for drilling holes for pins.
- Divide your components in two groups - IC and non-IC.
- Non-IC components include resistors, LEDs, transistors, etc. These components can be simply represented by rectangle or circles.
- ICs can also be represented by simple shapes but require a little work on their part. First, make small rectangles to represent connections for each pin. Like IC555 timer has 8 pins so draw 8 small rectangles. Now place the IC profile with 8 circles on top of these rectangles.
Step 3: From Artwork to QCB
- Cut and paste copper side layout on copper side of the copper clad board.
- It is recommended to first center punch on the black dots. Then drill all the holes.
- Now scribe all the black outlines using an empty ball point pen before starting to score.
- Next score all the black outlines using HSS hacksaw blade. In case you over score, the score may be corrected by shorting the two copper blocks while soldering.
- Finally, clean your QCB using appropriate emery paper.
- Optional: Check the continuity of copper blocks for any short circuits. If present you might require to score that path again.
- It is recommended to visually check the short circuits after soldering.
- QCB is ready for soldering.