HP HP-Bench-Briefs-1984-07-09 free download

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an SERVICE INFORMATlON FROM HEWLETT-PACKAI JULY - SEPTEMBER 1984 K. Nixon and T Yagel; ground plane contaminated by a dis- Prior to cleaning, areas of the ground Hewlett-Packard Labs colored film. The contamination on the plane were marked off on each sample ground plane was assumed to be simi- and photographed for reference. A typ- Introduction lar to the contamination found on the ical example of the f3m discoloration is board's connector hgers. All compo- shown in Figure 1. The marked areas This article summarizes a connector nents were cut from these boards and were next soaked for one minute in finger cleaning study that was con- the ground plane was cut into several each of the cleaning solvents listed in ducted on Hewlett-Packard printed samples approximately 2cm-by-2cm. Thble 1,rubbed using a solvent-soaked circuit boards (also referred to as printed wire assemblies) returned from customer use. The purpose of this . work was to: Develop a procedure to clean circuit board connector fingers in repair centers and the customer's environ- . . ment. Improve electrical performance Improve the connector's visual ap- pearance. The cleaning procedure and any mate- rials used (solvents, cleaning solutions and/or cloths) must be readily avail- able, safe, and easy to use by field ser- vice engineers, customers, and bench technicians. Figure 1. Film residuetypical beforecleaning. The study consisted of three phases: 1)A preliminary screening of potential Table 1. Solvents used in the preliminary cleaning evaluation. cleaning solvents 2) A more detailed second evaluation Cleaning solutions Concentrations of the cleaners that performed best in the preliminary tests Xyleneiisopropyl alcohol. .. . . . 20:80,1OWc, reactive solvent 99.5%assay IPA (byweight) 3) A study of the effects of possible Methylethylketone (MEK). . . . . . . . . . . . 10Wreactive solvent remaining cleaning residues. 1,1,1-trichloroethane . . . . . . . . . . . . . . . . ..90.0%assay by weight