Week 8 (Final Semester)

Title: PCB fabrication

Objective:

• To copy the diagram of the circuit on the PCB
• To master on how to fabric the PCB

Content:

PCB fabrication

1.    PCB Drawing: PCB drawing is designed using Protel DXP 2005. Once the PCB layout has been correctly design, it is now prints out the layout on the A4 size transparent OHP paper. Note that, two types of printers are allowed to print the PCB layout, one is laser printer and the other is carbon type of printer such as Photostat machine. Inkjet and dot matrix type of printer will not work.

2.    Prepare tools required:

þ Fluorescent light

þ UV PCB

þ Marker Pen

þ Blade

þ OHP transparent paper

þ Iron (III) chloride, FeCl₃ acid

þ Clean water

þ Thinner

þ Plastic Container

þ Laser printer

þ PCB cutter and trimmer

þ Soldering gun

þ Soldering lead

3.    PCB Cutting: Cut photo PCB size according to the film size.

4.    PCB Photo Etching: Expose the photo PCB in photo etching kit for 8-10minutes.

5.    PCB Developing: Wash the PCB using PCB developer (white powder) for 2 min.

6.    Acid Etching: Etching is a process that removes materials from such us unwanted copper from the PCB surface to achieve circuit design requirements. The etching process used in this project is called chemical etch or pattern etch.

Once the image printed on PCB copper board, now prepare the iron (III) chloride, FeCl₃ solution and ready to do the etching. Add in hot water (80C) and shake the water until you see unused part is ‘washed’ and left only the tracks. The etching process takes around 30 min.

 

7.    Thinner Washing:

This is a process to remove the black ink on the PCB board. The black ink has to remove in order to solder the components. The green coating on PCB can be removed by alcoholic solution and leaving only the PCB trace. After remove the black ink, the PCB is then send for cleaning using normal water.

Analysis:

This project has two circuit, the circuit can do at the same time at the step acid etching and thinner washing to elude the waste. The acid etching is quite dangerous task, so must take safety precaution while doing it such as wearing a glove to cover the hand and the mask to evade from smelling the acid. If the route of the diagram is accidently  cut off, use the soldering iron to connect it back.

Conclusion:

This part of task is really important because the circuit is the heart of the project to operate. Without the circuit, the project cannot operate. After the fabrication is finish, the next thing to for the next week is drilling