PURDUE UNIVERSITY PCB BLACK HOLE APPLICATION FOR THRU-HOLE PREPARATION FOR ELECTROPLATING RF LAB. Professor in charge: William Chappell MSEE 289

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1 RF LAB Professor in charge: William Chappell MSEE 289 Author: Bob Salisbury Date: 12/5/ /6/2007 page 1 of 6

2 1 SCOPE PURPOSE REFERENCE DOCUMENTS MATERIALS EQUIPMENT GENERAL REQUIREMENTS DEFINITIONS CONTROLS SET-UP PROCEDURE CLEAN UP TROUBLESHOOTING MAINTENANCE CALIBRATION TRAINING OUTLINE CERTIFICATION CHECKSHEET /6/2007 page 2 of 6

3 1 SCOPE 1.1 This specification provides instructions for using Black Hole material to prepare holes drilled in non-fluoropolymer printed circuit boards for plating. 2 PURPOSE 2.1 The purpose of this operation is to establish a conductive surface on the inside of the drilled holes onto which metal can be electroplated. 3 REFERENCE DOCUMENTS 3.1 Black Hole MSDS 3.2 Chemical Hygiene Plan And Hazardous Materials Safety Manual (REM) 3.3 Purdue University Guidelines: Handling And Disposal Of Chemicals. 3.4 Standard Operating Procedure for MSEE MATERIALS 4.1 Gloves, latex disposable, Microflex Diamond Grip or equivalent 4.2 Black Hole 4.3 Water 4.4 Wipes 4.5 Silica powder 5 EQUIPMENT 5.1 SAFETY EQUIPMENT Lab coat or apron Safety glasses Gloves 5.2 Tray, plastic, of size sufficient to lay sample flat in 5.3 Squeegee, plastic 5.4 Vacuum, small shop vac or equivalent OR low pressure compressed air gun 5.5 Oven, forced air convection, C 5.6 Scrub sponge 6 GENERAL REQUIREMENTS 6.1 All sections of Standard Operating Procedures apply. 7 DEFINITIONS 12/6/2007 page 3 of 6

4 7.1 Black Hole - A colloidal solution of carbon particles ranging in size from nm. Used to create a conductive film through printed circuit board holes to act as a seed layer for electroplating. 7.2 PCB - Printed circuit board. 8 CONTROLS 8.1 Lindberg / Blue M Oven Power - Toggle on front of oven Controller - Small display box on front used to set temperature of oven and read current temperature PV - Red numeric display shows current oven temperature SP - Green numeric display shows set point of oven Arrows - Push buttons under green display used to change set point Set / Ent - Light blue colored push button to left of arrows. Must be pressed after changing set point to tell controller to accept the new set point. 9 SET-UP 9.1 Don all required safety equipment. 10 PROCEDURE 10.1 Lay pcb flat in tray. Shake bottle of Black Hole ink thoroughly before using. Dribble a few drops of Black Hole ink on the surface of the sample. Amount must be sufficient to be able to spread over the entire surface with the squeegee While wearing protective gloves, hold board at a ~30 angle and use squeegee to spread the Black Hole material over the surface of the sample, forcing it through the holes. Verify that all holes have been completely filled by holding the board up to the light and looking at the back side. NOTE: Compressed air gun may be used to blow the holes clear in lieu of vacuum of step Just be sure to do this in such a manner as to contain the ink and not blow it all over the place. If you make a mess, you clean it up. So don t make a mess Use vacuum to remove bulk of the ink from the holes. Do not hold the vacuum flush against the board, but at an angle. The objective is not to remove all the ink from the holes, but only to remove the bulk of it. By holding the vacuum hose at an angle to the board, enough draft will be generated to draw out the ink without completely removing it from the hole sidewalls Hold the board up to the light to insure that all holes have been sucked clear. Also suck up any pools of ink that may remain on either side Transfer board to C oven and allow to dry for 30 to 60 minutes. 12/6/2007 page 4 of 6

5 10.6 Remove from oven and allow to cool. Hold the board up to the light and inspect all the holes to be sure none of them are plugged with dried black hole material. Any filled holes can be opened with a small drill bit, being careful not to scrape the walls of the hole Lay the board flat in the large tray and sprinkle some silica powder on it. Use the slightly dampened scrub sponge to scrub the surface of the board on both sides. This removes any of the black hole material that dried on the board outside the holes Rinse scrubbed board with warm tap water while lightly brushing with hands to remove the cleanser, then blow it dry with compressed air At this point, it is recommended that all the holes be inspected under microscope to verify that they are entirely coated inside and still have connection to the cladding metal on the faces. If they don t, the through hole application process can be repeated again to give the holes a second assurance coat The prepared board may be stored for up to six months prior to electroplating. 11 CLEAN UP 11.1 Rinse and dry all trays and tools used Return to stores all cleaned equipment and unused materials. 12 TROUBLESHOOTING 12.1 This section is not applicable to this document. 13 MAINTENANCE 13.1 This section is not applicable to this document. 14 CALIBRATION 14.1 This section is not applicable to this document. 15 TRAINING OUTLINE 15.1 Review specification with trainee Show trainee location of materials and equipment Demonstrate Set-Up and Procedure. Trainee shall participate as much as possible 15.4 Demonstrate Clean-Up. 12/6/2007 page 5 of 6

6 16 CERTIFICATION CHECKSHEET Trainee: Date: Task Description Pass Retrain 1 Trainee has read and understands this process specification. 2 Trainee has demonstrated knowledge of where all supplies are located. 3 Trainee has executed process with good results 4 Trainee has properly cleaned up the station. Certification Approved: Trainer: Date: Trainee: Date: This form shall be filed in Certification file for this operation in Lab Office and shall be maintained by Lab Safety Coordinator. 12/6/2007 page 6 of 6