WORK IN PROGRESS
CHANGE PICTURES TO CORRECT EQUIPMENT
EDIT INFORMATION FOR NEW ETCHING CHEMICAL
FORMAT UVMASCK PRODUCTION
This instruction has been written for a supervised session performed in a chemical lab. Be careful when applying to a different environment.
This instruction is about producing printed circuit boards (PCB) from prepared board schematics to component placement. The technique of PCB manufacturing employed in this lab is that of chemical etching. it is a five step procedure:
Here is a list of supplies you probably need:
Optimally this process is executed in a chemistry lab. This is the list of needed tools:
The following substances will be used:
Make yourself familiar with safety precautions for these substances and read the safety data sheets for them.
As stated in the beginning the following steps are normally performed in a proper lab after special security instructions and under supervision.
Put on your safety equipment. This includes glasses, lab coat and gloves. Make yourself familiar with the tools.
Removal & disposal of water from Rinser
Removal & disposal of developing solution from developer
New Developing solution for developer
Removal & disposal of etching solution from etcher
New etching solution for Etcher
-The PCB design and layout should be completed by students and comply with both ERC and DRC respectively.
-Place ground planes on both top and bottom of PCB design (use polygon feature in eagle) to limit the amount of etching required.
-Select top layer of PCB and show only tracks, ground planes, Via's and Pad's and selected marking's to be shown on PCB, note anything that is shown will be etched on to the PCB.
-Save using Print to PDF ensuring the color is black, size is A4, removing attributes from the bottom of page and saving with a recognizable file name i,e PCB_top.
-Select Bottom layer of PCB and show only tracks, ground planes, Via's and Pad's and selected marking's to be shown on PCB, note anything that is shown will be etched on to the PCB.
-Save using Print to PDF ensuring the color is black, size is A4, removing attributes from the bottom of page, SELECT THE MIRROR FUNCTION and saving with a recognizable file name i,e PCB_Bottom.
-At least one side of PCB mask must be mirrored due to the geometric nature of applying the mask.
-Print both sides of PCB design on the top and bottom of an A4 paper. To do this print one side of PCB design on A4 sheet of paper, than place printed sheet of paper back in the printer's paper tray, ink side up with the already printed PCB design at the bottom of the paper tray.
-Check to see if design is correctly aligned, To do this fold paper in half and check for correct pad and via locations.
-If all is correct than repeat printing process with projector paper.
-cut projector paper and align PCB schematic on top of each other ensuring the inked sides of the sheets are inside together, and secure in place with sticky tape (the inked sides are a mat black in color and can be distinguished by touch).
-Ensure there is no or minimal alignment of the PCB designs as this may result in defective PCB manufacture. (Pro tip cut sheet off center i,e have one side bigger than the other. this allows for easier alignment and sticky tape application).
-Well done you have now created your PCB Mask and are now ready to start with the UV exposure process.
Congratulations your board is now ready to place and solder components. .
Via's Component Placement and soldering
PCB's use two types of technologies for connecting components that require different ways of soldering being THT and SMD. due to the nature of the PCB construction used in the labs will require via's to also be manually placed.
Available sizes for punching via's in the university: 0.6 mm (drill 0.9 mm, pad 1.5 mm) and 1.0 mm (drill 1.5 mm, pad 2.5 mm).
To place a via in your PCB - drill the correct size hole for the desired size via at the wanted location. -correctly select and set the manual via press in place on a steady surface. -place the desired sized via so it sits on the suitable sized pin of the press with the flange of the via resting at the bottom (use of tweezers recommended). -Place PCB so via sits in correct position and gently but firmly press down handle of press.
Through hole Technologies THT
Surface Mounted Technologies SMD