Hi

I assume you have a misalignment in solder paste printing due to pattern inaccuracy on the PCB.
Some of the newer printers can actually record and report the data, if not use the vision system in the pick and place machine to measure how much stretch you have from one corner to the other.
There is a guideline in IPC-2222 9.1.5 but how good accuracy you will need on a specific product depends on board size and lead pitch. 0,125mm per 250mm is acceptable as a rule of thumb and achievablefor the PCB supplier. LDI may or may not give better accuracy depending on how much the supplier compensates to accommodate  inaccuracies on the inner layers.

Rgds
Grunde Gjertsen

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lyon
Sent: 23. mai 2014 12:19
To: [log in to unmask]
Subject: [TN] Misalignment

Hi all, We printed Top side of some boards with two vendors,but only one suppier found misalignment issue. what detailsFA we can do to prove the failure caused by FAb Lyon Yuan 发自 Android 网易邮箱

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