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10 PCB007 MAGAZINE I SEPTEMBER 2021 Feature Article by Happy Holden I-CONNECT007 In any conversation about streamlining ac- tivities in printed circuit fabrication, two im- portant performance characteristics always come up: lead time and lot size. I've been in- volved in PCB fabrication since 1970 and these two items have always been a center of conver- sation. Introduction When I worked at HP, printed circuit pro- duction was all manual until they installed their first NC-controlled, four-spindle drill to augment the four Excellon template-driv- en quad-drills. I was working mostly in plat- ing and lamination, but production control was always an interest, especially that which made up our lead time and lot size. Our multi- layer process had 20 significant work centers that panels proceeded through before ship- ping (this would significantly expand with the introduction of photoresist and new final finishes), each consisting of the six associated times (Figure 1). Input/Output Control of Lead Time [1] Over my career in printed circuits, I have seen the growth of electronic products and the rise of sophistication of the PCB to where it can have 32 to 46 significant work centers in manufacturing. If I visit a PCB fabricator, what I usually hear is, "is is how we manage our customers' technology demands." But what I usually see is: • Excessive inventories • Inability to make realistic delivery promises and meet them • Excessive expediting • Chronic lack of space in the plant • Work centers that are always behind schedule Why are there symptoms like this? e an- swer is simple: With all the fancy tools that have been developed, industry has failed to learn the fundamentals of lead time control, It's All About Time! Figure 1: Times associated with a production work center [1] .