| 277043511 | 2008-02-29 16:32 |
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QUOTE: 原帖由4楼楼主 philomal 于2008-02-29 15:34发表  哦，谢谢了，碰到一个用清洗标准来要求免清洗产品的客户，头疼！ 手头有一份离子测试的标准给你参考, 对于有离子测试的板, 常见的超标物质和对应的原因如下 - Acetate: Acetate usually comes from the solder mask. A high acetate level can be indicative of an incompletely cured solder mask. Incomplete cure can allow exposure of the copper traces to the environment resulting in corrosion and board failure. Chloride: Chloride ions are the single most damaging material that can be on the board. Bare board levels below 1.5 micrograms per square inch can be attained readily. Higher levels are usually due to insufficient washing of the board prior to either applying the solder mask or after Hot Air Solder Leveling (HASL). Chloride can also be transferred to the board by handling. The boards should be handled with gloves! Bromide: Bromide ions are usually present from decomposition of the flame retardant (FR) package in the laminate. Rarely are the levels as high as 1 mcg/in2 in the bare board unless the board has been overheated in the lamination process. Inevitably bromide levels increase after wave soldering or reflow, but should not exceed 5 mcg/in2. Nitrite, nitrate, and Ammonium: Both of these ions can be introduced in the various plating and etching processes as well as a component of the flux. Levels up to 2 mcg/in2are rarely a problem. Above that, problems can occur. Sulfate: Sulfate Ion contamination is rarely a problem. High levels are usually caused by poor housekeeping: dirty equipment, unpainted walls or unsealed floors. Sodium/Potassium Levels: A sodium/potassium ratio near one is usually caused by excessive handling of the completed board without gloves. Again the levels should be below 1-2 mcg/in2. Calcium/Magnesium Levels: The only acceptable level for these ions is zero. Calcium and magnesium come from the rinse water and are indicative of poor rinse water quality |
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