Use of fastener: Using screws and bolt help to keep the transistor stayattached to the heat sink. I used two screws to put it through the transistor.One screw at the hole at the top of the transistor and the other for the holeat the bottom of the transistor. The screws would go through the transistor,the washer, the heat sink and then the securing plate. Once the screws havegone through, you use nylon lock bolts to secure the screws in place and makingsure that the transistor is in place with the heat sink and is not moving.
The transistor collector gives the mountingscrews and bolts electrical conductivity to the other side. The mounting screwheads are in contact with the transistor so it had electrical conductivity. Prevention fromshaking/vibration:To prevent vibration and shaking when you attach a heat sinkto a transistor the washer, screws, bolts and the securing plate will work. The washer is a thermal conductor but is electricallyinsulating so when you attach the transistor (with the washer on it) to theheat sink, the heat will be transferred from the transistor to the heat sinkwith no electric conduction but the use of the transistors conducted parts(emitter, base and collector), are electrically conducted but it must not getinto contact with the heat sink. The washer’s texture is a bit lumpy so it willhave grip if any vibration and shaking goes on. The use of the securing plate does what it is named for. Thesecuring plate holds the transistor and heat sink in place and when it isattached to the heat sink it is clipped on and would not move from thatposition.
However, if any vibrations do happen, there is not a guarantee thatit will always stay in place. But the use of the screws and bolts willdefinitely guarantee that the heat sink and the transistor will always stayattached and in place. The screws go through the top of the transistor and thebottom of the transistor. It holds the transistor, the washer, the heat sinkand the securing plate in place. The use of the bolts makes sure that there isextra placement of the transistor to the heat sink. The screws and bolts willhold all the layers together including the transistor and heat sink together. Thebolts will not move when the vibrations is happening so the heat sink andtransistor will be attached together.
Heat transfer usingthermal compound:The thermal paste/grease is thermally conductive andelectrically insulated meaning that it would not conduct electricity. Thethermal paste will give a good thermal connection between the transistor andthe heat sink. When you are putting the paste on the washer on both sides, itis vital that the paste does not touch the prong of the transistor as if thisdoes happen then the prongs would not conduct. When you applying the thermalpaste to to the washer on both sides, you need to make sure that you put enoughon it because it is not good at conducting heat and if too much is applied, itcould cause an increase in thermal resistance. The thermal paste gets rid ofair gaps and spaces so it can maximize heat transfer.