Circuit Board Fabrication Project

Transcription

1 Circuit Board Fabrication Project TEL Electronics Technology Name: What you will be able to do: Etch a printed circuit board from prepared artwork. Prepare the circuit board for component population Assemble and solder a circuit board Test the completed circuit for proper function Project Description: You will be creating a circuit board that will play a basic game. This circuit board contains a Microchip PIC Microprocessor that has been programmed with PicBasic to play a Simon Says game. The circuit board contains LEDs as outputs, pushbutton switches for inputs, a piezoelectric speaker, and the clock circuitry to drive the microprocessor. In this project, you will create the circuit board from basic artwork, assemble the circuit, program the microprocessor, and test the circuit. Finished Simon Board Printed Circuit Board Project Grade Worksheet Criteria Circuit Board Artwork Transferred Properly Circuit Board Etched Properly Circuit Board is Drilled Properly Components Mounted Properly Good Solder Joints Circuit Functions Properly Safety practices used TOTAL Value Student Grade Instructor Grade

2 Part I Circuit Board Artwork Preparation Task to complete PC Board Material Thermal Laminator Toner Transfer Artwork Safety Glasses Step 1 Toner Artwork Transfer 1. Cut a piece of copper clad board to a finished size of 2 ½ x 2 ½ 2. Clean the surface of the copper with steel wool. Do not touch the surface with your fingers. Residual oils and dirt will prevent the toner resist from sticking properly resulting in a bad board. 3. Preheat the laminating press. 4. Obtain a copy of the circuit artwork from the instructor. Avoid touching the surface with your fingers. Residual oils and dirt will prevent the toner resist from sticking properly resulting in a bad board. 5. Carefully align the PC board material on the artwork with the black artwork in contact with the copper. Feed the board and artwork through the laminator twice. 6. Place the board and carrier under a steel plate and allow the board to cool for a few minutes. 7. Place the board in a pan of warm water. Be sure that it is completely covered with water. Allow the board to soak for 2 to3 minutes without disturbing it. The paper should separate from the board without assistance. 8. Remove the board from the water without touching the copper. Inspect the board. If the artwork is intact, you can continue on to the next step. If patches of the artwork did not stick, you will need to repeat the steps above.

3 Part II Circuit Board Etching Task to complete Prepared PC Board with Artwork Etch Tank with Ferric Chloride Safety Glasses Rinse Water Safety Warning: You will be using a Ferric Chloride Solution to chemically etch the copper clad board. Ferric Chloride is a mild acid that can hurt you. The following safety rules must be followed: Safety Glasses must be worn at all times when working around the Ferric Chloride. Avoid breathing fumes from the etch tank. Do not attempt to operate the tech tank with the lid open. Do not handle or place on benches or counters circuit boards or tools that have Ferric Chloride on them. Rinse all tools and circuit boards thoroughly with water for 2 to 3 minutes to remove any residual ferric chloride. If Ferric Chloride comes in contact with your skin or clothing, you must rinse the Ferric Chloride off with water. Avoid touching your face or eyes after working with the Ferric Chloride until you have thoroughly washed. Clean up any drips or spills. Leave the workspace clean and in order after working in the etching process. Ferric Chloride leaves stains that are difficult to remove from clothes. Wear a lab coat or older clothes when completing this activity Report any problems to the instructor immediately! Failure to follow any of these safety precautions will result in losing etching privileges and receiving a grade of Zero on this project. Etching Process: 1. Fill out the Etch Tank use log. 2. Tape your circuit board to the glass board holder using a loop of masking tape on the back. The copper should be facing out. 3. Place the board holder inside of the etch tank. Make sure that the etch tank cover is in closed. 4. Start the etching machine. Check the board after 1 minute to see if it is done. If it is not, return it to the etch tank and etch it for 30 second increments after that. 5. When the board is fully etched, remove the board carrier from the etch tank and place it directly in the rinse tank using plastic tongs. Rinse it in water for 3 minutes. 6. Remove the carrier and the board and place them in the sink. You may

4 remove the circuit board from the carrier. Rinse them both thoroughly with water. Be careful of coming in contact with any residual Ferric Chloride that may be behind the board or in the tape. 7. Remove the plastic toner from the surface of the copper using steel wool. 8. Clean up the work area and wash your hands. Get the approval of the instructor for clean up on the Etch Tank use log. Part III Drilling and Board Preparation Task to complete Drill Press #58 Drill #68 Drill 1/8 Drill File Safety Glasses Safety Warning: Safety Glasses must be worn when using the drill press. 1. Using the diagram provided, drill the holes in the circuit board to the correct sizes. 2. Cut the circuit board corners off following the lines left by the toner transfer. 3. Using a file, clean up any rough or sharp edges on the circuit board. Part IV Circuit Assembly Components for Circuit Board Component QTY Cost Each Total Cost Microchip PIC 12F683 Microprocessor (not included in kit) 1 $ 1.12 $ Voltage Regulator (TO-92) 1 $ 0.27 $ Pin IC Socket 1 $ 0.14 $ µF Capacitor 1 $ 0.09 $ 0.09 Piezoelectric Speaker 1 $ 0.80 $ 0.80 Red LED 4 $ 0.09 $ KΩ Resistor 4 $ 0.01 $ KΩ Resistor 4 $ 0.01 $ 0.04 Pushbutton Switch 4 $ 0.13 $ 0.52 Battery Clip 1 $ 0.35 $ /4" 4-40 Machine Screw and Nut 2 $ 0.10 $ 0.20 Printed Circuit Board (not in kit) 1 $ 0.85 $ 0.80 Transfer Paper 1 $ 0.13 $ 0.13 TOTAL $ 4.80

5 Task to complete Safety Warning: Safety Glasses must be worn when using the soldering iron. 1. Place the 1KΩ resistors in the circuit board. They should be oriented to be right-reading from the bottom or right side of the board. Solder these in place. Trim off the excess leads. 2. Place the 10KΩ resistors in the circuit board. They should be oriented to be right-reading from the bottom or right side of the board. Solder these in place. Trim off the excess leads. 3. Insert the 8 Pin IC socket into the circuit board. Make sure that the notch that indicates which end has pin 1. Solder each of the pins in place. 4. Insert the LEDs into the board. This needs to be oriented with the anode (+) (longer lead) toward the outside of the board. Solder these in place. Trim off the excess leads. 5. Insert the 0.1µF capacitor into the circuit board. Solder this in place. Trim off the excess leads. 6. Insert the leads for the 7805 voltage regulator into the circuit board and solder them in place. The flat should face away from the 8 pin socket. 7. Insert the leads for each of the pushbutton switches into the circuit board. Solder the leads in place and trim them off. 8. Insert the leads for the Piezo speaker into the circuit board. The speaker has a positive and negative lead. Make sure to put the positive lead toward the bottom of the board. 9. Inspect the circuit board for cold joints and solder bridges. Make any repairs if necessary. 10. Test the circuit board by connecting 9VDC to the board at your workstation. The LEDs should turn on when the buttons are pushed, even without the microprocessor. 11. If the board works, connect the battery clip. Bend the leads to be in alignment with the bottom of the clip. Connect the clip to the circuit board with two 4-40 x ¼ screws and nuts. Solder the two wire leads to the rectangular power pads. 12. You are ready to program the microprocessor. Follow the separate directions to do the programming.

6 Part V Programming the Microprocessor PIC 12F683 Microprocessor PIC Basic and Microprocessor Programmer 1. On a classroom computer, open the program on the desktop: MicroCode Studio. Download the PicSimon program from the instructor s website ( to your computer s desktop. Go to File => Open => and open the file from your desktop. 2. Optional: Once the program is opened, you can create you own sequence. Locate the area in the program that with the double bars top and bottom that looks like the following: Initialize EEPROM Values ' Note that the game sequence can be changed by changing the values in ' the following lines. Each set of brackets must contain 32 numbers. ' Only 0,1,2,4 are allowed. Separate numbers with commas. EEPROM 0,[0,4,2,1,4,0,1,0,4,2,1,4,0,1,4,0,2,1,4,2,1,0,2,1,0,4,2,0,1,1,0,4] EEPROM 32,[0,1,0,4,2,1,4,0,1,4,0,2,1,4,2,1,0,2,1,0,4,2,0,1,1,0,4,4,1,2,4,2] EEPROM 64,[0,4,2,1,4,0,1,4,0,2,1,4,2,1,0,2,1,0,4,2,0,1,1,0,4,2,1,4,2,1,0,2] EEPROM 96,[0,1,4,0,2,1,4,2,1,0,2,1,0,4,2,0,1,1,0,4,1,2,1,4,2,1,0,2,1,0,4,2] Replace the sequence of numbers that you used with the numbers in the parentheses following the EEPROM command. Note the following: a. Put in only 32 numbers in each bracket set. b. Place a comma between each number c. Only used values of 0,1,2,4 d. Do not change any other part of the program 3. To program compile the program, select from the menu bar Project => then Compile and Program. 4. The programmer application will open. Insert your microprocessor into the programmer. Make sure that pin 1 is toward the left as marked on the programmer. Make sure that the programmer lists the PIC12F683 microprocessor as the one being programmed. Click on the menu option Program => Program. The chip will take about 20 seconds to program and verify. When completed, carefully remove the chip and place it in your own circuit board and test it. 5. Place the programmed chip into your game board. When power is turned on, the LEDs should turn on and off in a continuous loop. Press any button to start the game. Repeat the sequence provided by the game. If you miss a sequence the game will end, Phasers will fire, and the game will give you your score as a binary number.

7 Verify that this box has the 16F627A chip selected

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