This is the third time in my memory that the non-functional pad debate has cropped up on the Technet. I assume it is because of alot of new forum members. It's beginning to feel like picking a scab. I fall into the camp which advocates non-functional pad removal. I also work for a board fabricator. Judging by the tone of some of the comments, it looks like several people are engaged in "one-sided partnerships" with their customers/vendors. HADCO will request the removal of these pads, but will only do so after reaching this conclusion with the customer. We will encourage our customers to grant a "global waiver", or place a statement in their board specification allowing non-functional pad removal. We do this for two reasons: These pads may actually "float" during inner layer lamination, ending up causing a short. As to someone's comment to "get a better AOI system", HADCO has millions of dollars invested in state-of-the-art AOI equipment. Unfortunately, our equipment does not automatically remove unwanted shorts; it can only detect them. I suppose we could buy bigger trash barrels, or even hire an army of short removers. We choose instead to monitor our processes, and improve where improvement is possible. More importantly, pads on every single layer of higher layer count boards (8 layers and greater) cause excessive wear on the drills, which if left unmonitored, can lead to poorer hole wall quality. At the very least, it can add to the expense of drilling a board. I don't want to throw numbers at you for what savings are available if these pads are removed. I can tell you that drilling is the second biggest contributor to the cost of a circuit board (about 10%, smaller only to material, which is about 30%). Panels are stacked in multiples to a certain stack height (typically less than .200" thick) under each drill spindle. Our procedure calls for reducing the stack height by one panel if the drills are drilling into more than 20 ounces of copper/sq. ft. (about 7 ounces/sq. ft. per panel in a typical 3 panel stack) and non-functional pads are not removed. This will significantly decrease drill through-put, and should be reflected in the cost of the board. I might suggest that board consumers submit a specific board to their vendor(s) for quoting in both scenarios, one with a reduced drill stack height. In that way you can get your hard numbers. Someone referenced the Round Robin Small Hole Reliability Study published by the IPC several years ago. My take on this study is that it is outdated; at the very least, a new study should be commissioned reflecting current board chemistries, practices, and processes. Most reputable board houses have fine-tuned and refined their copper deposition processes to more ably handle microvias with success. Our definition of microvias has even changed greatly since then; 5:1 aspect ratios (board thickness to hole size) are standard fare now that we are learning to deal with aspect ratios in the 6:1 or even 7:1 range. They were not at the time of the study. Please understand that I am talking about boards in a volume environment. Finally, let me say that we have to have more "win-win" situations in this business. Designers and board fabricators need to work more closely together, each working for the other's success. Part of my job involves talking about "Design For Manufacture" with our customers. I have been very impressed with the hundreds of designers that I have met with over the last year. Most of these folks are as eager as I am to work together toward a common goal - to produce the highest quality product at the most cost-efficient price. We are all professionals, and need to approach each other that way. Best regards, Tom Coyle Field Services Engineer HADCO Corporation [log in to unmask]