枕头效应的测试与预防

Testing and Prevention of Head-In-Pillow

在PCB上组装BGA或CSP时,产生的枕头效应(HIP)令电子制造业很苦恼。枕头效应是由于在再流焊接过程中元件或板子翘曲所引起的,且氧化作用会使枕头效应更为严重。行业急需用于评估可能产生HIP的方法。除了介绍染色法外,还介绍了另外两种简单的方法小滴焊膏法(Tiny Dot Paste)和焊膏上焊球法(BallOnto Paste)。小滴焊膏法重点评估焊膏的抗氧化能力。焊膏上焊球法评估抗氧化性和助焊剂组合能力。这两种方法均是快速、简易和高度仿真的方法,而后者在实际工艺仿真过程中效果更好一些。

Head in pillow （HIP）is ailing the electronic industry when assembling BGAs or CSPs onto PCBs. It is caused by warpage of components or boards at reflow process, and is aggravated by oxidation. Methods for assessing the potential for occurrence of HIP are highly desired by the industry. Besides using BGA rework station followed by tedious dye and pry treatment, two other simpler methods are introduced in this work, Tiny Dot Paste method and Ball Onto Paste method. Tiny Dot Paste method stressed on the assessment of oxidation barrier capability of solder paste, while Ball Onto Paste method assesses combined capability of oxidation resistance and excessive fluxing capacity. Both methods are quick, easy, and close simulation, with the latter being better in real process simulation.