Electronics+Exam+Questions+1


 * Year 10 Electronic Products - Questions & Answers **

**Circuit board design and construction (15 marks)**
a) What do you understand by the term PCB? (1 mark) Printed Circuit Board (1 mark) b) When designing a PCB it is important to understand how the pins are numbered on IC’s. How would you find pin 1 on an IC? (2 marks) Top of surface there is a notch, mark or dot (1 mark) Pin 1 is always on the top left and are numbered around the pins in an anticlockwise direction(1 mark) c)  Draw an 8 pin IC show how the other pins are numbered (2 marks) Notch (1 mark) All numbers (1mark) d) Explain two safety considerations when making a PCB (2 marks) Using UV Light Box (1 mark) Developer to develop exposed board, protective clothing, gloves and goggles (1 mark) Etching using heated ferric chloride, protective clothing, gloves and goggles (1 mark) Wash thoroughly (1 mark) e) Before you assemble your circuit by soldering the components how would you ensure that it will operate as you want? (2 marks) Check all the tracks are complete on the PCB (1 mark) Check the components using a multimeter (1 mark)  Test circuit on computer simulator (1 mark) Breadboard building (1 mark) f) There are three different ways you could make you circuit board, what are these different methods of construction and what are the advantages of each method? (6 marks) >
 * Creating a design by hand or by computer and printing it onto photo resist(sensitive) boards (1mark) can be reused, manufacture in batches, exactly the same (1 mark)
 * Drawing with an etch-resist pen directly on top of copper clad board (1 mark) cheap, one off, and time consuming as one has to work accurately, component sizes have
 * Using rub down transfers and carbon transfers, stick back plastic and tape (1 mark) cheap, one off, more accurate than hand drawn (1 mark)
 * Silk Screen Printing (1 mark)
 * Photoengraving (1 mark)
 * PCB milling (1 mark)

**Industrial practices (15 marks)**
In the past many electronic products have been housed in aluminium cases. They are now made from moulded plastic a) Name a suitable process and material that can be used for the manufacture of a product case (2 marks) Vacuum forming high density polystyrene (HDP) (1 mark) Injection moulding (1 mark)  Blow moulding (1 mark)  Materials: ABS, nylon, high density polystyrene (HDP), polythene, acrylic (1 mark) b) Explain two advantages of using this material and process (2 marks) Good insulator (1 mark) can be fabricated easily, and with no finishing required (1 mark) c) Product cases are now designed on a CAD system. What do you understand by the term CAD? (1 mark) Computer aided design (1 mark) d) What advantages are there when using a CAD system? (2 marks) Speeding up the design process (1 mark) providing accurate information on how a design will function (1 mark) enables changes to be made quickly (1 mark), can provide simulations (1 mark), storing design data easily and accessible (1 mark) e) What must any manufacturer complete before it markets its products? (2 marks) Test for accuracy (1 mark) and tolerance (1 mark) and quality (1 mark) check national standards and laws (1 mark) f) What do you understand by the terms quality control and quality assurance? (4 marks) Quality control: Check product for defects (1 mark) and made to constantly high standards (1 mark) Quality assurance: Ensures quality control has been conducted (1 mark), and include following standards and laws (1 mark)

**Fault finding (3 marks)**
a) While the manufacturer’s first prototype worked, some of the circuits would not work when mass produced. One of the problems was broken tracks on the PCB. How would this be checked for before any components were soldered in place? (1 mark) Check the track for continuity by passing a current through each part of the circuit and using a multimeter (1 mark) b) Some circuits suffered from dry joints. What do you understand by the term dry joint and what may have caused this? (2 marks) When the solder does not connect the leg of the component with the pad of the copper circuit (1 mark) Either the solder wasn’t heated or cooled properly (1 mark)