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• MISER; • SEAWINDS; • Pathfinder. and many others. Since the assemblies produced in this laboratory always fall in the high performance, high reliability category, cleaning is mandatory, not op-tional . With the demise of the ozone-depleting solvents that were the mainstay of the electronics industry for twenty years, it was necessary to turn to alternative chemistries an d cleaning systems to ensure cleanliness and high reliability of the surface mount assemblies (SMAs). The initial cleaning system chosen for the SMT Laboratory was a two-stage batch semi-aqueous (SA) cleaning system. Although this system worked satisfac-torily for a number of years, the decision was reached recently to replace it. Part of the reason was the increasing complexity of the SMT PWAs. Equipment to en-sure that the cleaning solution would successfully penetrate under the small standoff s and tight spacings found under the newer components now being in-creasing employed was considered mandatory. Another factor in the decision was that the initial equipment manufacturer sold off this portion of the business and no longer supported the equipment. It proved increasingly more difficult to maintain it in good working condition. In addition, isopropyl alcohol (IPA), used in the original equipment, came under increasing scrutiny by the South Coast Air Qual-ity Management District (SCAQMD). Because IP A is a volatile organic com-pound (VOC), its emission into the atmosphere is tightly controlled. The decision was made to investigate a new cleaning system and a chemistry that would sup-port JPL's need for clean PWAs to meet the newer challenges. 3. PERTINENT PROCESS INFORMATION The following JPL process information is pertinent to the discussion: • Rosin-based fluxes and pastes are used to produce all electronic hardware. Using the terminology of Mil-F-14256, the classification of these products is rosin mildly activated (RMA). • The solder paste is applied using a semi-automated screen printer ensuring that the paste is deposited in a uniform and consistent manner. Only stainless steel stencils are used in conjunction with a stainless steel squeegee. All boards are visually inspected for proper paste deposition after the stencil operation. • A laser-based solder paste height and width measurement system is used with a resolution of 0.0001 inch (2.5 jxm). This system provides real time informa-tion on the uniformity of solder paste deposition. All boards are subjected to this measurement prior to the reflow operation. • A batch reflow operation is used to create the solder joints of the SMT PWAs. The SMT PWAs are thermally profiled using aM.O.L.E.® - a thermocouple
DOI link for • MISER; • SEAWINDS; • Pathfinder. and many others. Since the assemblies produced in this laboratory always fall in the high performance, high reliability category, cleaning is mandatory, not op-tional . With the demise of the ozone-depleting solvents that were the mainstay of the electronics industry for twenty years, it was necessary to turn to alternative chemistries an d cleaning systems to ensure cleanliness and high reliability of the surface mount assemblies (SMAs). The initial cleaning system chosen for the SMT Laboratory was a two-stage batch semi-aqueous (SA) cleaning system. Although this system worked satisfac-torily for a number of years, the decision was reached recently to replace it. Part of the reason was the increasing complexity of the SMT PWAs. Equipment to en-sure that the cleaning solution would successfully penetrate under the small standoff s and tight spacings found under the newer components now being in-creasing employed was considered mandatory. Another factor in the decision was that the initial equipment manufacturer sold off this portion of the business and no longer supported the equipment. It proved increasingly more difficult to maintain it in good working condition. In addition, isopropyl alcohol (IPA), used in the original equipment, came under increasing scrutiny by the South Coast Air Qual-ity Management District (SCAQMD). Because IP A is a volatile organic com-pound (VOC), its emission into the atmosphere is tightly controlled. The decision was made to investigate a new cleaning system and a chemistry that would sup-port JPL's need for clean PWAs to meet the newer challenges. 3. PERTINENT PROCESS INFORMATION The following JPL process information is pertinent to the discussion: • Rosin-based fluxes and pastes are used to produce all electronic hardware. Using the terminology of Mil-F-14256, the classification of these products is rosin mildly activated (RMA). • The solder paste is applied using a semi-automated screen printer ensuring that the paste is deposited in a uniform and consistent manner. Only stainless steel stencils are used in conjunction with a stainless steel squeegee. All boards are visually inspected for proper paste deposition after the stencil operation. • A laser-based solder paste height and width measurement system is used with a resolution of 0.0001 inch (2.5 jxm). This system provides real time informa-tion on the uniformity of solder paste deposition. All boards are subjected to this measurement prior to the reflow operation. • A batch reflow operation is used to create the solder joints of the SMT PWAs. The SMT PWAs are thermally profiled using aM.O.L.E.® - a thermocouple
• MISER; • SEAWINDS; • Pathfinder. and many others. Since the assemblies produced in this laboratory always fall in the high performance, high reliability category, cleaning is mandatory, not op-tional . With the demise of the ozone-depleting solvents that were the mainstay of the electronics industry for twenty years, it was necessary to turn to alternative chemistries an d cleaning systems to ensure cleanliness and high reliability of the surface mount assemblies (SMAs). The initial cleaning system chosen for the SMT Laboratory was a two-stage batch semi-aqueous (SA) cleaning system. Although this system worked satisfac-torily for a number of years, the decision was reached recently to replace it. Part of the reason was the increasing complexity of the SMT PWAs. Equipment to en-sure that the cleaning solution would successfully penetrate under the small standoff s and tight spacings found under the newer components now being in-creasing employed was considered mandatory. Another factor in the decision was that the initial equipment manufacturer sold off this portion of the business and no longer supported the equipment. It proved increasingly more difficult to maintain it in good working condition. In addition, isopropyl alcohol (IPA), used in the original equipment, came under increasing scrutiny by the South Coast Air Qual-ity Management District (SCAQMD). Because IP A is a volatile organic com-pound (VOC), its emission into the atmosphere is tightly controlled. The decision was made to investigate a new cleaning system and a chemistry that would sup-port JPL's need for clean PWAs to meet the newer challenges. 3. PERTINENT PROCESS INFORMATION The following JPL process information is pertinent to the discussion: • Rosin-based fluxes and pastes are used to produce all electronic hardware. Using the terminology of Mil-F-14256, the classification of these products is rosin mildly activated (RMA). • The solder paste is applied using a semi-automated screen printer ensuring that the paste is deposited in a uniform and consistent manner. Only stainless steel stencils are used in conjunction with a stainless steel squeegee. All boards are visually inspected for proper paste deposition after the stencil operation. • A laser-based solder paste height and width measurement system is used with a resolution of 0.0001 inch (2.5 jxm). This system provides real time informa-tion on the uniformity of solder paste deposition. All boards are subjected to this measurement prior to the reflow operation. • A batch reflow operation is used to create the solder joints of the SMT PWAs. The SMT PWAs are thermally profiled using aM.O.L.E.® - a thermocouple
ABSTRACT
One of these is based on an aqueous chemistry containing a mixture of some alkoxypropanols with one to three alkoxy units (ether linkages). The molecules are not particularly large (C2 to C4), so the hydrophobic portion is not too large. The hydrophilic part of the molecule is due to one alcohol group (-OH) and several ether groups (-0-). Overall the organic molecules exhibit excellent solubility in water. Thus, the cleaning agent in water is herein referred to as an aqueous cleaning solution. The material itself is easily biodegradable. It has zero ozone depletion potential (ODP), virtually no greenhouse warming potential (GWP), and is classified as non-flammable. The following information is supplied by the manufacturer of the aqueous solution. Although the concentrate is 91% by weight volatile organic compound (VOC), the material as used in the cleaning system is only 13.6% by weight VOC.
