SB.10 Electronics & Mechanical Systems Flashcards
Processes programmed into domestic appliances for functionality
Switch to start washing cycle
Buzzer/LED may indicate cycle is complete
Anodising aluminium
Process of electroylsis which makes surface of aluminium oxidise, converting into hard, durable finish. Aluminium can also be dyed during anodising adding colour (so cannot peel off)
Etching process
Used to create circuit in layers of copper
1. Using CAD, circuit is drawn & mask printed on clear acetate sheet
2. Copper coated, photo resist board cut to size
3. Acetate mask placed onto board. Board exposed to UV light causing chemical change in photo resist layer
4. Board is washed & then placed in etching tank removing excess copper
5. Only copper tracks protected by mask will remain, now ready for soldering
Cutting printed circuit boards
Cut using precision guillotine
Drilling printed circuit board
Pins & wires placed on a PCB need to be pushed through small holes & soldered in place
What is current
Rate at which an electric charge flows (A)
What is voltage
Pd of electrical force that drives the current (V)
What is pd of mains electricity
240V
What are resistors
Components that restricts flow of electricity
Res measured in ohms
Pick and place assembly of PCB
Robotic machines used to place components, many of which are extremely small & difficult to place manually. Quicker, better precison
Flow soldering of PCB
Solder paste from powdered solder & flux used to temporarily attach electrical components to their contact pads. Board is then heated, making paste melt which flows, creating solder joint.
Surface finishes of PCB: protective
Used in env that can be damp, dusty, exposed to temps. If unprotected, can oxidise making board unusable.
A lacquer, known as acrylic conformal coating, can be sprayed onto PCB for protection
Surface finishes of PCB: lubricants
Applying substance sa grease or oil to components provides smooth movement, less friction & reduce wear & tear
