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, 3.2, 3.7, 3.8, 4 1992 11 23 Released Released A2. Released A3 and A4 on 1993 03 31 L. Rumao Controlled document at www.MATS Copyright 2012, Ford
2、Global Technologies, LLC Page 1 of 4 SOLDER PASTE (62 Tin/36 Lead/2 Silver, RMA Flux, NOT FOR NEW DESIGN WSF-M11A44-A2 No-Clean, Stencil Printable) SOLDER PASTE (62 Tin/36 Lead/2 Silver, RMA Flux, NOT FOR NEW DESIGN WSF-M11A44-A3 No-Clean, Stencil Printable), HIGH VISCOSITY SOLDER PASTE (62 Tin/36 L
3、ead/2 Silver, RMA Flux, NOT FOR NEW DESIGN WSF-M11A44-A4 No-Clean, Screen Printable) 1. SCOPE The materials defined by these specifications are RMA 62 Sn/36 Pb/2 Ag solder pastes. These solder pastes are a homogeneous suspension of a prealloyed solder powder in a specially formulated screening and f
4、luxing vehicle system. 2. APPLICATION These specifications were released for conductive material used as a printable solder for surface mount connections and other applications where the use of a corrosive flux must be avoided. Post reflow cleaning may not be required. This solder paste was designed
5、 to be stencil or screen printed on circuit boards and reflowed using either convection or infrared soldering. 3. REQUIREMENTS This solder paste is a homogeneous suspension of a prealloyed solder powder in a specially formulated fluxing vehicle. All qualification testing shall be done at 25 +/- 2 C
6、and 50 +/- 3% relative humidity, unless otherwise specified. 3.0 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Standard Requirements For Production Materials (WSS-M99P1111-A). 3.3 COMPOSITION (IPC-SP-819, Section 4.4, 50 gram sample
7、 required) A2 A3 A4 Solder Metal, weight % 87.5 - 88.5 90.5 - 91.5 89.5 - 90.5 Vehicle Balance Balance Balance ENGINEERING MATERIAL SPECIFICATION WSF-M11A44-A2/A3/A4 Copyright 2012, Ford Global Technologies, LLC Page 2 of 4 3.3.1 Solder Metal Composition, Atomic Percent Tin 61.5 - 62.5 Silver 1.8 -
8、2.2 Zinc 0.003 max Antimony 0.30 max Bismuth 0.25 max Copper 0.08 max Iron 0.03 max Aluminum 0.005 max Other Elements 0.08 max Cadmium 0.005 max Lead Remainder 3.3.2 Vehicle Composition, weight percent (IPC-SP-819, Section 4.4, 50 gram sample required) Bake reflowed solder bead at 160 C for 5 hr and
9、 calculate flux percent using the following equation: Wp - Wc - Wb - x 100 = Wf % Wp - Wc Wp = Weight of paste before reflow Wc = Weight of cleaned solder bead Wb = Weight of baked solder bead Wf % = Weight percent of flux A2 A3 A4 Flux, % 66.7 62.5 57.0 Solvent Balance Balance Balance 3.4 INDIVIDUA
10、L COMPONENT PROPERTIES 3.4.1 SOLDER POWDER (Powder sample prior to mixing) 3.4.1.1 Particle Size (IPC-SP-819, Section 4.2.3) WSF-M11A44-A2 75 microns or less WSF-M11A44-A3 10 - 53 microns WSF-M11A44-A4 10 - 44 microns 3.4.1.2 Particle Shape Spherical; (IPC-SP-819, Section 4.2.3) Ratio = 1 - 1.5 ENGI
11、NEERING MATERIAL SPECIFICATION WSF-M11A44-A2/A3/A4 Copyright 2012, Ford Global Technologies, LLC Page 3 of 4 3.4.2 Flux Vehicle (Flux sample prior to mixing) 3.4.2.1 Copper Mirror No complete copper (IPC-TM-650, Section 2.3.32) removal 3.4.2.2 Halide Content, max (IPC-TM-650, Section 2.3.35) WSF-M11
12、A44-A2 50 ppm of vehicle composition WSF-M11A44-A3 900 ppm of vehicle composition WSF-M11A44-A4 840 ppm of vehicle composition 3.5 VISCOSITY (IPC-TM-650, spiral pump viscometer, 25 +/- 0.25 C) WSF-M11A44-A2 10 RPM (10 minutes) 1089 - 1331 mPa.s 15 RPM (10 minutes) 891 - 1089 mPa.s 20 RPM (10 minutes
13、) 765 - 935 mPa.s 30 RPM (10 minutes) 612 - 748 mPa.s WSF-M11A44-A3 3 RPM (5 minutes) 4320 - 5280 mPa.s 10 RPM (2 minutes) 2070 - 2530 mPa.s 10 RPM (10 minutes) 1700 - 2300 mPa.s 30 RPM (2 minutes) 1170 - 1430 mPa.s WSF-M11A44-A4 3 RPM (5 minutes) 2200 - 2800 mPa.s 10 RPM (2 minutes) 936 - 1144 mPa.
14、s 10 RPM (10 minutes) 765 - 935 mPa.s 30 RPM (2 minutes) 441 - 539 mPa.s 3.6 SHELF LIFE, min 6 months Store an unopened container of solder paste at 35 +/- 2 C for the specified shelf life time period. The solder paste shall meet the viscosity requirements per Section 3.5 of this specification. Shel
15、f life is based on date of manufacture. The solder paste is to be delivered within one month of the date of manufacture. ENGINEERING MATERIAL SPECIFICATION WSF-M11A44-A2/A3/A4 Copyright 2012, Ford Global Technologies, LLC Page 4 of 4 5. GENERAL INFORMATION The information below is provided for clari
16、fication and assistance in meeting the requirements of these specifications. Contact for questions concerning Engineering Material Specifications. 5.1 If the material contains a rosin based flux, a GC spectra of the extracted flux is required. 5.1.1 Extraction Method (a) Extract 2.0 g of paste with
17、 3.0 mL of 50% isopropanol/50% toluene solution. (b) Mix well and then use centrifuge to separate the metal particles from the liquid portion. (c) Collect liquid portion with pipette and save for GC sample preparation. 5.1.2 GC Sample Preparation (a) Pipet 100 microliters of the extracted flux mixtu
18、re and dispense into a GC sample vial. (b) Place the vial under a fume hood for 24 h to evaporate solvent. (c) To the sample vial, add 1 ampul Sylon BFT.* *The full name of Sylon BFT is Bis(trimethyl-silyl)trifluoroacetamide (BSTFA)/trimethylchloro-silane (TMCS). It may be obtained in ampul form fro
19、m: Supelco, Inc. Supelco Park Bellefonte PA 16823-0048 (d) Allow the mixture to stand for 5 minutes, then add 1.0 mL pyridine, and seal the vial. The mixture is ready to be injected into the gas chromatograph. 5.1.3 Equipment Parameters for Gas Chromatograph Column: DB-5 column, 0.25 micrometres ID,
20、 30 m long Column Flow Rate: 1 mL/minute, 1:80 split ratio Sample Injection Quantity: 1.0 microliter Injector Temperature: 260 C Detector (FID) Temperature: 260 C Air Flow Rate: 400 mL/minute H2 Flow Rate: 32 mL/minute He makeup flow rate: 30 mL/minute Temperature Profile: Hold the temperature at 70
21、 C for 4 minutes, ramp to 260 C at 10 C/minute, and hold on 260 C for 17 minutes. Total run time is 40 minutes. 5.2 If the material contains a polymer based flux, an IR spectra of the extracted flux is required. Extract the paste with acetone and collect the liquid portion. The extracted flux is to be applied directly to the KBr window.
