Research On The Hip Joint Quality Improvement Of I Series Of Lead-free Products

In order to comply with the electronic assembly products lead-free trend, Bclients start to introduce lead-free process for their products. But functional failurescaused by BGA HIP solder joint defect were reported after I series products publishedin market not long. Although the lead-free technology has been gradually promotingin the same industry, and there are valuable experience to leverage from many relatedagencies or manufacturers on lead-free process design and HIP improvement scenario,we still couldn’t introduce the improvement actions from other manufactures directlyas there are many different characters with used raw materials, product performanceand different process flow. Besides, due to short term lead free product introductiontimeline, lead-free related theory is mostly limited to support the principle of manyHIP improvement cases in same field. Under this circumstance, it is still questionableon whether the sharing experience valuable for our HIP issue solution.Based on this background and in order to eliminate HIP failure for I seriesproducts and improve product quality, we set up a dedicated quality improvementproject management team to start in-depth study for this HIP issue, which team isbuildup with senior specialists from each department and is leading by high levelmanagement. Our purpose is not only to find out the true root cause for HIP failure,but also need to create a well designed process flow to eventually eliminate thissymptom forever.This paper first elaborated the lead-free production technology status andcognitive status of HIP in the industry. Starting from the basic theory of lead-free technology, it introduces the major factors contributing to HIP defect, effectiveimprovement methods and correlated improvement results in industry.Secondly, to discover potential issues existing in current manufacturing processwhich might lead to this HIP defect, we conduct a comprehensive investigation andanalysis. In the subject of intensive investigation, we list down all related factors bydifferent levels through group brainstorming method combined with expert opinionderived problem analysis diagram. Then we combine expects opinion on weight ofeach factor to define the key contribution factors. After that, team members performfurther investigation and data collection to each critical factor, to understandimprovement opportunities and feasibility. Base on expects team’s direction andmulti-cases experience, DOE is recommended to find out the critical factors inprocess and come out the best solution (parameter set up) for production. Excludingjust-do-it improvement items and unchangeable items, only3key factors are includedin the DOE matrix, which finally make8groups of experiment conditions. Through aseries of data collection, multiple times of data analysis and comparison, alsoexcluding uncontrollable process factors (such as raw materials) and the productioncost, team determined to design respective optimal process improvement schemes fordifferent process flow products. At the same time, these improvement methods arestandardized by documentation to ensure same implementation for similar productprocesses to avoid similar problems occur again.Finally aimed at high efficiency and costly proper process quality control, wedecide only to use quality inspection methods instead of statistic quality managementmethods for short term. Although there are many testing methods to determine HIPdefect or not, but most methods are limited to use for production process control aspartial are destructive testing methods which will scrap units, such as cross sectionmethod, dye and pry test. Thus, we dedicate on coverage improvement by visualinspection and x-ray inspection and5DX testing method by adding inspection slice at the-6mil solder joint location is validated the best solution to cover HIP defectefficiently. Improved process flow is standardized at the closure of this qualityimprovement project.