Brad, Just a thought, I believe IPC docs do specify a formal Fab Dwg for complete documentation, however whether or not the IPC spec's defines needing one, unless one plans on providing a very complete set of total electronic files like IPC GenCAM or Valor to a fab house which also does provide the ability to capture your fab dwg intent within the file, I would say a fab house could make a board for you if you scratched out on a napkin what you needed, but I would not want to chance them wiping their mouths with it before fabing the board. If a company or designer needs to specify critical dimensions or anything else that may be required a certain way I would seriously suggest a proper Fab Dwg be provided or like using GenCAM or some other file structure to provide a complete picture of you rdesign intent to a fabricator regardless of what some spec may or may not state. Bob
Robert M. Wolfe, C.I.D. [EMAIL PROTECTED] ----- Original Message ----- From: "Brad Velander" <[EMAIL PROTECTED]> To: "'Protel EDA Forum'" <[EMAIL PROTECTED]> Sent: Friday, May 17, 2002 12:08 PM Subject: Re: [PEDA] Too many hole sizes > Are there any IPC Certified designers who can confirm or deny the need for a > fab dwg? > What is the current IPC comment on the issue, come on guys I know > you're out there! Is the fab dwg not just part of the "complete" fabrication > information, what is the IPC training telling you guys to do about fab dwgs > these days? This is a test, are you a IPC man/woman or a mouse? > > Georg, > here is the best example that I can give. Contrary to some very > opinionated individuals, not all PCB inspectors have computers, nor CAD > software, nor the training to operate CAD software, in a 'LOT' of PCB > fabrication shops. Trust me, I have been in and out of many PCB shops in 3 > States and one Province for over 20 years. We aren't talking about the > Merixs, Tycos or Praegitzers here, just normal small - med size fab shops. > How does this inspector check drill sizes or locations? From manually > reading the numeric information? Is the fabricator CAM shop supposed to make > a drill drawing for him? Do you trust the fab shop to generate this drawing, > if they make a mistake who's fault is it, you didn't supply the required > information so they were forced to generate their own? They are not perfect, > neither are you but you didn't even have a chance to check/inspect their > handiwork! What can they use for even their trained CAM operators to confirm > the correctness of the information which they are viewing on their computer > screens? > > When the PCB is received at your company's (or your assembly shop's) > loading dock, who checks it for valid hole sizes, dimensions or other > details? Is this a fully trained CAD operator, with system software to deal > with all forms of CAD data or a simple minimally trained inspector with some > pin gauges, calipers and the ability to read a technical drawing? If you > don't supply them with a Fab dwg, do you get called to the loading dock to > check the boards upon arrival because you are the only one in your company > who can access and use the electronic data files? > > Here some other very good examples for you Georg. Where do your > drill files locate themselves within you board outline? Where are any of the > holes with respect to the board outline? What are the dimensions of your > board outline? Does everybody go into the CAM files again and again to > generate their own measures of these items? Isn't that lost repetitive > operations that could be done just once, checked, verified and appropriately > tolerance by the individuals who understand the design? What tolerances > would be allowed by differing individuals who take their own absolute > measures of the CAD data in the file? The CAD data is absolute isn't it? Are > the fabricated parts absolute without tolerance? I wish. > > Sincerely, > Brad Velander. > > Lead PCB Designer > Norsat International Inc. > Microwave Products > Tel (604) 292-9089 (direct line) > Fax (604) 292-9010 > email: [EMAIL PROTECTED] > http://www.norsat.com > > Visit us at Booth 2G2-09 at CommunicAsia 2002 in Singapore June 18-21. > > > > > -----Original Message----- > > From: Georg Beckmann [mailto:[EMAIL PROTECTED]] > > Sent: Thursday, May 16, 2002 10:17 PM > > To: 'Protel EDA Forum' > > Subject: Re: [PEDA] Too many hole sizes > > > > > > I do not understand, what a drill drawing is good for. I only > > use the drill > > file and the > > board shop read this to the drill machine. > > Since I have a computer and CAD program, I'm happy > > not to fill out a drill drawing sheet with any hole marked > > with a secret > > label and wether I or > > the man in the board shop makes one or more mistakes when > > programming the ' > > punchhole - tape for > > the drill machine '. > > > > Georg > > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
