Manufacturing Processes

• Photo etching is the method of producing a printed circuit board (PCB).
• the process is a follows:
  1. Print the PCB design onto a clear transparency sheet using a laser printer.
  2. Cut the PCB to size.
  3. Peel the sticker (protective layer) from the PCB.
  4. Place the exposed photo-board on top of the laser printed design inside a UV light box.
  5. Allow the PCB to be exposed for the required length of time.
  6. The board now goes into the developer tank which removes the now softened PCB protection layer.
  7. The PCB then goes into the Ferric Chloride tank to remove the excess copper.
  8. The PCB is then sprayed with photo-resist stripper to remove the final layer of protective film on the PCB.
• This is the best process for making PCBs in schools.
• It is however, a vey slow process and not suitable for mass production.
• All the chemicals need need regular replacement as they become saturated with copper.
• These chemicals will need to be disposed of safely.

• Once the etching process has been completed, the PCB will need to be prepared and populated with components.
• The PCB will need to be drilled using the appropriate size drill bit, usually 1mm, this will be slightly bigger for components with thicker legs.
• Components are then pushed through the holes and then soldered in place on the opposite side where the copper tracks are.
• You must ensure all the holes are drilled before placing components, as it is usually very difficult to drill holes after the components are placed.

• When you wish to produce a circuit as a prototype to test it before full scale production, one of the methods that can be used is 'breadboarding'.
• A breadboard also known as protoboard is a type of solderless electronic circuit building.You can build a electronic circuit on a breadboard without any soldering! Best of all it is reusable.

• When you need to produce a number of the same product at the same time, a single batch production might be used.
• For this process, jigs (fits over a piece of material to guide accurate cutting or drilling without the need for marking) or templates (a cut-out of a shape that can be drawn around onto the material to mark out quickly and easily) are used.
• A good example of this is vaccuum forming. This is a system which uses a mould to produce the same shape repetitively.
• Advantages:
  1. The jigs and templates speed up the process and can be kept for future use.
  2. There is no need for expensive specialist equipment.
• Disdavantages.
  1. Very labour intensive using the jigs and templates.
  2. Producting the jigs and templates can be costly.

• When you wish to produce a product large scale (in the thousands), you will need to use a mass production method.
• These are the processes you will usually find in factories.
• The setup costs for these factories is very high, but as you will be producing thousands of the product, the cost should be offset against this.
• Examples of mass production processes are:
  1. Injection moulding.
  2. Blow moulding.
  3. Stamping.
• Advantage:
  1. Can make products very quickly.
• Disadvantages:
  1. Very expensive to setup/
  2. Only cost effective if large numbers are made and sold.

Injection moulding:

Blow moulding:

Stamping:

• This is the next dtep from mass production, but the process runs 24 hours a day.
• This process is used when very high volumes are needed and the factory can not be shut down over night.
• When the process is very long and stopping and starting it can cause serious delay, then this process is used.
• A good example of this is the car industry. if any stage in the production line is stopped. Delays and backups are created in other parts of the line.
• Advantage:
  1. Makes larger numbers of products very cheaply and quickly.
• Disadvantages:
  1. Machinery is very expensive.
  2. Only worthwhile if very large numbers of the product are made and sold.