I get these type complaints continuously from the CAD folks. We actually did a study in my last company and found that it was cheaper to add an additional layer for routing and have the testpoint access than it was to loose 20% of the testpoint coverage and deal with the problems coming out of test. If you lose test coverage at ATE, you move the problems into functional and systems level test. The costs skyrocket and scrap rate soars. You have to live with this product for the 1-2 weeks (or so) that it takes you to lay it out and get approvals. Manufacturing has to live with it for the life of the product. A day of your time spent adding testability translates in to (as Charles has said) thousands of hours of time saved. Rob Green Manager, Test and CAM Engineering ______________________________ Reply Separator _________________________________ Subject: Re: [TN] In Circuit Test Author: Charles Barker <[log in to unmask]> at smtplink-hadco Date: 8/27/99 11:12 AM Phil, I ditto Jeff's remarks. We are ramping up a new product now. The design engineer didn't pay much attention to ICT. He has had to go back and move stuff around on a very dense board! Not a pleasent task. This has slowed down our ramp-up rate considerably. We have also had to go out for a secind genertion test fixture to accompdate the changes, which takes several weeks and costs beacoup US $$$! As he mentioned, providing extra test nodes over and above the required ones would be a feather in your cap! Of course, you don't want to over do this point. If you have to spend an extra two or three days on a several week long project squeezing in all the needed nodes, you will save the manufacturing process hundreds or even thousands of hours in the long run. This is not something you would do for small run boards, of course. I'm talking anything complex that would be built in even just the hundreds per month. It will save many hours of a technician's (quite often not that well trained) time trouble shooting the finished critter. Good luck. Charlie Barker Sr. Manufacturing Engineer Input/Output, Inc. www.i-o.com Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to [log in to unmask] To: [log in to unmask] cc: (bcc: Charles Barker/US/I-O INC) Subject: Re: [TN] In Circuit Test Phil Dutton wrote: > > Hello, > I was just wondering how people are dealing with ICT. > There is a big trend here (over the past year) to provide 100% nodal access > for ICT. > A big problem is littering the secondary side of the boards with suitable > test pads, taking up valuable routing area. > Often with SMT, the only vias on many of the nets, are to provide the test > point. (single sided probing fixtures) > I can see there are some benefits of 100% ICT, but from a designer's point > of view, we seem to be trading off the benefits of finer pitch devices. > Welcome to modern producibility. You can't ramp up production without automated test, if there's any kind of complexity to the product. You can't effectively do automated test without access to every functional pin of every device. The fun part? You should be providing access to unused functional pins as well. It's an opportunity to excel! The next step is to work up good verification of fixturing rules and then proper data handoff... -- Jeff Seeger Applied CAD Knowledge Inc Chief Technical Officer Tyngsboro, MA 01879 jseeger "at" appliedcad "dot" com 978 649 9800 ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################