Which is Best: Pre- or Post- Reflow AOI? Landrex, Imagen to Present Both Arguments at APEX

Rarely do PCB manufacturers have the resources to purchase an inspection machine for every stage of the manufacturing process. As a result, they have to decide whether to deploy AOI prior to the reflow oven ("in-process") or after it ("end of line"). An argument can be made for both cases, according to Dr Pamela Lipson, CEO of Imagen Incorporated of Cambridge, Massachusetts. Dr Lipson and Lyle Sherwood, Vice President & Technical Director, Landrex Technologies of Santa Clara, California, will seek to answer this question, or at least let session attendees decide, during a technical session at APEX 2008. The paper and presentation, titled “To Be or Not to Be (Before Reflow): That is the Question (In AOI)” is slated for Tuesday, April 1, 2008.

“On the one hand, a high-performing post-reflow AOI machine has the capability of inspecting all fault types (solder related faults and component level faults) at the end of the line” Dr Lipson says. “At this point all boards can be manually fixed and some coarse level, time-delayed information can be fed back to the in-process side. On the other hand, one pays the price for finding faults at such a late stage in the process. By the time the fault has been found, multiple boards have been built - all possibly with the same faults.”

Lipson and Sherwood’s paper also presents the results of a study at a manufacturing site in the US which contrasts using post-place inspection to find and correct defects, and also to perform process control vs. using a post-reflow inspection system to find defects at the end of the line. The paper will quantify and contrast the benefits and drawbacks of each type of inspection alone, and will also discuss any synergies between the two inspection strategies.

www.landrex-us.com
www.imagen-inc.com