1、 ENGINEERING MATERIAL SPECIFICATION Date Action Revisions 2012 07 25 N-Status No replacement A. Wedepohl, NA 2005 02 08 Revised Inserted 3.0; Deleted 3.1, 3.6, 4 1991 01 31 Released DE00E00107002086 J. Huebner Controlled document at www.MATS Copyright 2012, Ford Global Technologies, LLC Page 1 of 3
2、SOLDER PASTE, 62 SN, 36 Pb, 2 Ag NOT FOR NEW DESIGN WSF-M11A43-A 1. SCOPE The material defined by this specification is 62 Sn/36 Pb/2 Ag solder paste with a mildly activated RMA flux. 2. APPLICATION This specification was released originally for material used in the EEC-IV stencil printing systems a
3、s a printable solder. Any paste supplied for this application must be compatible with the IR reflow profile established on the production oven. 3. REQUIREMENTS 3.1 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Standard Requirements
4、For Production Materials (WSS-M99P1111-A). 3.2 SOLIDS 90 +/- 1% Place 10 - 50 grams of well mixed solder paste into a tared #0 Coors crucible and weigh to the nearest .01 gram. Melt the solder at approximately 25 C above liquidus of the alloy, remove from heat and allow to solidify. Extract melt fro
5、m residual flux with a suitable solvent (trichloroethylene), dry, and weigh within .01 grams. % TOTAL SOLIDS = WEIGHT OF SAMPLE AFTER DRYING X 100 ORIGINAL WEIGHT OF SAMPLE 3.3 VISCOSITY 800 - 950 Kcp.s (Equipment: Brookfield RVTD Viscometer) Solder paste shall remain stationary for a min of 2 h to
6、reach temperature and rheological equilibrium. Set bottom stop for helipath travel so that the cross bar is at a minimum of 28 mm below the surface of the solder paste in the test container. The bottom stop shall be a min of 10 mm above the bottom of the container. Set the upper stop at 3 mm below t
7、he surface of the solder paste. Immerse spindle in solder paste and record data for 10 minutes. Temperature of paste to be maintained at 25 +/- 0.25 C. Viscosity is to be based on the average of peak and valley of the last 2 cycles. If average for first two cycles is more than 10% higher than the la
8、st 2, test is invalid and additional equilibrium time is required. ENGINEERING MATERIAL SPECIFICATION WSF-M11A43-A Copyright 2012, Ford Global Technologies, LLC Page 2 of 3 3.4 SIZE/SHAPE/UNIFORMITY 3.4.1 Particle Size 200 - 325 Weigh 100 grams of paste in beaker. Remove solder paste flux with a sui
9、table solvent. Dry powder in an oven for 30 minutes at 80 C. Pass powder through a set of selected sieves. Weigh the contents of the sieves separately and calculate the percentage of particle size distribution. Alternate Method: ASTM B 214, microscopy; light beam scatter. 3.4.2 Solder Powder Particl
10、e Shape Spherical Solder powder particle shape shall be determined by visual observation of the powder with a binocular microscope at magnification sufficient to determine the percentages that are spherical, elliptical with length to width 1.5 to 1 or less and particles that have ratios greater than
11、 1.5 to 1. Powder with 90% of the powder less than 1.5 to 1 shall be classified spherical and all others as irregular or elongated. 3.5 SPREAD/SLUMP, SOLDER BALL AND TACK TIME Standard specimen for test shall be prepared using a clean, frosted glass, microscope slide 76 mm x 25 mm, min 1 mm thick. A
12、n equivalent allumina substrate may be used. Using a screen or stencil, deposit at least 3 solder paste pads with geometry .060 - 0.080 in diameter, 0.010 high. The printed pattern shall be uniform in thickness with no solder particles separated from pad. 3.5.1 SPREAD/SLUMP 2 specimens are to be pre
13、pared by procedure 3.4. Specimen 1 is to be stored for 50 to 70 minutes at 25 +/- 5 C and 50 +/- 10% relative humidity. Specimen 2 is to be placed in a convection oven for 10 +/- 2 minutes at 100 +/- 5 C within 5 minutes after printing. Measure the percentage in diameter as an indication of spread f
14、or specimen 1 and 2 as an increase of the solder paste/powder pattern greater than the original pattern. The pattern should not increase more than 15%. 3.5.2 SOLDER BALL TEST Reflow specimen 2 from 3.4.1 on a flat hot plate. Surface temperature to be maintained at 25 +/- 3 C above liquidus of solder
15、 paste alloy. Remove specimen and allow to cool to 23 +/- 2 C. Using a microscope, compare the reflowed solder paste with photographic criteria in IPC-SP-819. 3.5.3 TACK TIME 80% of peak value at 4 h Prepare test specimen as in section 3.4. Identify time after printing. Store prepared sample at 25 +
16、/- 2 C and 50 +/- 10% for 4 h. The samples shall not be stored in an enclosed cabinet or container which allows the solder paste solvent vapors to saturate the environment surrounding the printed paste, thus preventing natural drying of the material. A Chatillon tackiness tester or other equipment c
17、apable of accurately measuring force when tested at a similar velocity. (Ref IPC-SP-819 - SEC 4.6.4.2 for testing procedure). Initial measurements are to be taken immediately after printing and at the end of 4 h. Subsequent measurements are to be taken as needed to adequately define the rise and dec
18、line of tack force. ENGINEERING MATERIAL SPECIFICATION WSF-M11A43-A Copyright 2012, Ford Global Technologies, LLC Page 3 of 3 3.5.4 Wetting Specimen 76 mm x 25 cm x 0.8 mm of 1 ounce oxygen free high conductivity (OFHC) copper on epoxy/glass laminate. Specimen is to be cleaned with liquid copper cle
19、aner, rinsed with water and dried. A second specimen is to be prepared as above and then placed in deionized water for 10 minutes and air dried. Test pattern for solder paste is to be printed as in 3.4. Coupons to be reflowed by production compatible profile. After reflow, remove residual flux with
20、suitable solvent. Examine visually at 10X. Solder shall uniformly wet the copper and there shall be no evidence of dewetting or nonwetting of the copper and there shall be no solder spatter around printed pads. 3.5.5 Shelf Life Solder paste is to have usable shelf of a 6 month period, and is to be delivered within one month of production. 4. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements of this specification. Contact for questions concerning Engineering Material Specifications.
