EQUIPMENT USED INTHE MANUFACTURE OF ELECTRONIC PRODUCTS
The process by which a heated thermoplastic sheet is made to take the shape of a pattern or former by means of suction. The plastic sheet is first cut to size and clamped into place. The heating elements are then pulled over the plastic which is then heated for approximately 20 seconds. The heating elements are contained inside a shielded sliding housing, even so the housing can get very hot after a short while and must not be touched , the handle on the front must be used at all times. When ready the heating elements are pushed back and the lever on the left is pulled towards you, this raises the former which pushes upwards into the softened plastic sheet. Operating the vacuum switch completes the operation by pulling the plastic tightly down over the former so that the plastic now takes on the shape of the former. It should be noted that after use all the metalwork on the top of the vacuum former gets hot so care must be taken at all times.
The bench top band saw also seen in this picture is used to cut the finished PCBs down to size. Safety glasses must be used with this machine, the PCB must be held tightly and guided accurately to ensure an accurate finish to the edges of the board. The blade guard must be as low as posible so as to ensure that as little of the blade is exposed as possible. Dust extraction should be used to avoid breathing in the dust created when cutting the PCBs, alternatively a dusk mask should be used.
The profile cutter is a machine for accurately removing the waste plastic from around the casing once it has been vacuum formed. The guide acts as a safety guard for the rapidly rotating blade as well as ensuring that the blade follows the profile of the shape being cut accurately.
It is important that the safety guard is used at all times in order to avoid severe damage to the fingers of the user. It is also advisable to wear safety glasses when using this machine in case plastic particles get thrown out in the cutting process.
|Printed circuit board (PCB)|
A thin board made from an insulating fibre board that is covered on one or both sides with a conducting layer of copper and used as the chassis of an electronic circuit. The electronic components are mounted on the board with the copper forming the connection between them. The copper surfaces are changed into strips by etching away material between the connecting lines. Very complex circuits can be built on these boards.
When using the UV exposure box it must be noted that UV light can cause damage to eyes if looked at directly, to ensure that your eyes are not exposed to UV light makee sure that the lid of the UV exposure box is closed before switching it on.
After the PCB has been exposed to UV to soften the photo-resist compound it needs to be removed to leave the pattern of the tracks prior to the etching process. This involves immersing the exposed board in a developing fluid which is caustic such that contact with skin and eyes must be avoided at all times. Safety glasses and rubber gloves must be used for this stage of the process.
|Bubble etch tank|
A tank containing liquid ferric chloride that is used in the production of printed circuit boards (PCBs). The PCB is immersed in the liquid which is heated and then agitated by a stream of bubbles; unwanted copper cladding on the PCB is removed by a process known as etching. Care must be taken to prevent spillage and splashes of the ferric chloride because it is very corrosive. Safety glasses and rubber gloves should be worn when inserting the PCB in or removing it from the tank.
Once the PCB has been etched holes are drilled through the solder pads, for the insertion of component wires, using a 1mm drill bit. Obviously the PCB must be held tightly and contact with the drill bit must be avoided at all costs. Safety glasses should be worn when using any drilling machine.
A hand tool used as a heat source for soldering. Soldering irons have a copper bit or tip for the efficient transfer of heat to the work being soldered. Most soldering irons used in electronics are electrically heated. The tip of the soldering iron can cause serious burns if it comes in contact with skin, so utmost care must be taken. If contact occurs the area affected must be put under clean running water as soon as possible to bring about cooling of the area.
Soldering electronic components to a printed circuit board is best carried out using a small electrical soldering iron and multicore solder.
Place the tip of the iron so that it heats the component leg and the PCB at the same time, then after 2 or 3 seconds introduce the solder and allow it to flow quickly around the joint. Avoid breathing in any fumes released as a solder joint is made, especially if you are asthmatic. Remove the iron and let it cool.
An electrical measuring instrument that will measure voltages, currents, resistance, capacitance and transistor current gain. Readouts are normally now in digital form.