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GENERIC PCB SUPPORT NEST FOR MPM AUTOMATIC SCREEN PRINTER

IP.com Disclosure Number: IPCOM000007416D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2002-Mar-25
Document File: 3 page(s) / 106K

Publishing Venue

Motorola

Related People

David Cahill: AUTHOR [+2]

Abstract

SOLUTION To achieve high quality solder paste printing proc- ess, board retention (i.e. vacuum) and support are vital during the printing process. These three objec- tives are easily achieved when printing single sided boards or the first side of double sided boards, as the under side of the board is flat and can easily be supported by a flat support nest. Supporting the PCB is much more diflicult when printing the second side as the underside of the board is now li.tlly loaded with components.

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Technical Developments Volume 24 March 1995

GENERIC PCB SUPPORT NEST FOR MPM AUTOMATIC SCREEN PRINTER

by David Cahill and James O'Toole

BACKGROUND

SOLUTION

  To achieve high quality solder paste printing proc- ess, board retention (i.e. vacuum) and support are vital during the printing process. These three objec- tives are easily achieved when printing single sided boards or the first side of double sided boards, as the under side of the board is flat and can easily be supported by a flat support nest. Supporting the PCB is much more diflicult when printing the second side as the underside of the board is now li.tlly loaded with components.

  The screen print vendor does do supply flexible support for PCBs but this is extremely slow to set up, setups are not repeatable and it may not always be possible to give adequate support to the board.

  At present individual support nests are built for each board type. Recesses for the components on the underside of the board are milled into the sup- port nest. This allows the board to sit flush on the nest. Vacuum slots are also milled in the support nest to hold the board stable on the nest during printing.

  This system gives good support but is expensive as individual blocks are required for different types of board and a new block may be required if compo- nents are moved on the board.

  This support nest was designed to give maxi- mum support and vacuum hold to the PCB and also to be flexible enough to support any board ofa given size. A support nest with internal vacuum is built up to within 15mm of the required height. The top plate of the block has a matrix of holes drilled in it. Hollow pins of 15mm are placed in the holes. The pins are located so that no pin is under a compo- nent. These pins also suppl...