This test consists of twenty multiple-choice questions. All questions are from the video: Lead Free Surface Mount Assembly (DVD-68C). Each question has only one most correct answer. Circle the letter corresponding to your selection for each test item. If you wish to change an answer, erase your choice completely. You should read through the questions and answer those you are sure of first. After your first pass through the test, then go back and answer the questions that you were not sure of. If two answers appear to be correct, pick the answer that seems to be the most correct response. When you are finished, check to make sure you have answered all of the questions. Turn in the test materials to the instructor. The passing grade for this test is 70% (14 correct answers or better). Good luck! 1
ANSWER SHEET Name: Date: Circle the letter corresponding to your answer for each test item. 1 A B C D 2 A B C D 3 A B C D 4 A B C D 5 A B C D 6 A B C D 7 A B C D 8 A B C D 9 A B C D 10 A B C D 11 A B C D 12 A B C D 13 A B C D 14 A B C D 15 A B C D 16 A B C D 17 A B C D 18 A B C D 19 A B C D 20 A B C D 2
1. The reason for the switch to lead free solder is a. Europe s legal mandate to change by July 1, 2006 b. to keep lead out of the landfills c. reduce manufacturing pollution 2. The most common method of absorbing lead into our systems is a. ingesting lead by touching food or make-up after handling tin-lead solder b. touching circuit boards c. being touched by others who have handled tin-lead solder d. breathing in airborne fumes or particles 3. The melting point for lead free solder is typically a. 50 degrees C higher than tin-lead b. 40 degrees C higher than tin-lead c. 30 degrees C higher than tin-lead d. 20 degrees C higher than tin-lead 4. The most common lead free alloy for reflow soldering is a. tin-silver b. tin-copper c. tin-silver-copper d. tin-silver-bismuth 5. The tin-copper alloy is typically used for a. wave soldering b. reflow soldering c. hand soldering d. special rework applications 6. A consideration in implementing a lead free process is a. components and circuit boards need to withstand higher soldering temperatures b. solder defects may increase due to poor wetting c. higher activity fluxes may be required 7. When lead free and tin-lead solders are mixed, there will be a. a mixed technology assembly b. cross contamination c. reliable solder connections d. hybrid solder connections 3
8. In a lead free process, the metal stencils typically contain a. apertures that are the same size as the circuit board lands b. smaller aperture to land ratios c. larger aperture to land ratios 9. Lead free solder paste may a. contain a more active flux than tin-lead solder paste b. dry out more quickly than tin-lead solder paste c. have a reduced shelf life compared with tin-lead solder paste 10. Which stencil printing parameter is likely to need adjusting for lead free paste? a. snap-off distance b. downstop c. squeegee speed and/or pressure d. off-contact printing 11. The surface mount assembly operation least affected by the switch to lead free is a. solder paste printing b. component placement c. reflow soldering d. cleaning 12. In reflow soldering, peak temperatures for many lead free alloys range from a. 235 to 260 degrees C b. 220 to 240 degrees C c. 210 to 225 degrees C d. 205 to 220 degrees C 13. A nitrogen atmosphere in the reflow soldering machine creates a. an environment susceptible to oxidation b. a larger process window for better wetting c. a greater probability of contamination d. unreliable solder joints 14. The purpose of board supports in a lead free process is to a. control the quantity of flux applied during wave soldering b. support the socketed components c. control sagging and warping due to higher soldering temperatures 4
15. The visual appearance of the lead free solder joints is a. smoother than tin-lead b. shinier than tin-lead c. grainier than tin-lead d. wetter than tin-lead 16. The maximum acceptable solder contact angle is a. any angle that doesn t cover the top of the component termination or lead b. 180 degrees c. 45 degrees or less d. 90 degrees or less 17. Non-wetting occurs when a. the solder has not adhered to either the termination or land b. the reflow or wave soldering temperature is too low c. there is poor flux activity 18. A convex fillet with solder flowing over the edge of the land indicates a. excessive solder b. dewetting c. a blowhole d. tombstoning 19. A solder bridge is a. a crossing within the grain structure of the solder alloy b. a leaching of the solder or flux between two adjacent lands c. an unwanted solder connection between two or more conductive features d. an arched connection between opposite sides of the connection 20. Class 3 requirements in the IPC-A-610 are for a. consumer products b. high reliability electronics where failure is not an option c. business and computer products d. none of the above 5