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(转)
曾经率先破解微软Xbox主机的著名美籍华裔黑客黄欣国(Andrew Huang,网名“Bunnie”)近来把注意力从破解转移到了对X360“三红”问题的研究上,在其个人博客上撰写了多篇关于“三红”问题的文章。在最近更新的一篇日志中,他介绍了自己将故障X360主板送检并研究的过程,并放出了一些新的照片。
黄欣国在文中表示,他将一台“三红”的X360送往了美国微电子故障检测中心(MEFAS)进行故障检测。在对主板焊点进行“染色探察”的过程中,发现主板及GPU的焊接部分存在许多严重质量问题,而这也就是导致主机故障的重要原因之一。
“染色探察”的基本原理,是将测试主板浸泡在红墨水中,再使用专业设备对GPU焊点的可靠程度进行检测。合格的焊点锡球表面在浸泡后依然呈现焊锡本来的颜色,但如果焊接处存在的任何微小缝隙,那么红红墨水就会渗入其中并留下标记。
通过对比图片可以发现,出现故障的X360主板GPU上的焊点有很多不合格,当主机运行时产生的热量或气体钻进这些缝隙当中,就为日后的电子故障埋下了隐患的种子。
但令人感到奇怪的是,GPU上的所有焊点中只有一部分有质量问题而并非普遍不合格,而通常情况下许多同类电子产品也都存在类似的焊接问题,但却没有哪个像X360这样爆发大面积故障,因此GPU脱焊应该只是引发“三红”的原因之一。
Xbox360 RROD (Again)
January 21st, 2008
Nate just linked me to this post interviewing an inside source in Microsoft about the causes of the RROD. Now that I’m involved in hardware manufacturing of consumer devices, it’s a fascinating case study of what not to do, so I’m paying attention and taking notes.
A while back I posted that I was looking for an RROD Xbox360; I actually sent it off to MEFAS to get digested for solder joint inspection on the GPU through a process called “dye and pry”. In this process, the motherboard is flooded with red ink, and then the GPU is mechanically pried off the board. The red ink flows into any of the tiny cracks in the solder balls, and at least in theory, when you pry the GPU off the cracked regions will shear first so you will be left with visible red spots at the points of failure.
I was a bit puzzled by these results because you didn’t see any “catastrophic” failure — pools of red ink over a connection interface — just partial cracking. Partial cracking isn’t terribly uncommon, and many products work quite well despite such artifacts. However, after reading the article linked above, if Microsoft shorted safety margins around many of the design parameters to get the product out on time, it makes sense that the summation of many partial failures could lead to a total system failure — failures that have symptoms that vaguely cluster together but are diffi*** to point to any single root cause. Heisenbugs. Yuck.
Complex systems are a bitch to get right — and reliable. I think about that every time I step onto an airplane, or when I read about the space program. Respect to the engineers at Boeing and NASA!
BUNNIE 的博客:点击进入原文博客链接
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