Browse Prior Art Database

CORNER RELIEF HOLES FOR EXCISED CHIP CARRIERS

IP.com Disclosure Number: IPCOM000006075D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2001-Nov-30
Document File: 2 page(s) / 117K

Publishing Venue

Motorola

Related People

Ken Thompson: AUTHOR [+4]

Abstract

The manufacturing of organic based chip carriers (in specific, PCB material) is often done in reel to reel or strip form for the purpose of automated handling and processing. The cost and complexity of tooling required to excise these carriers from these strips needs to be minimized. A simple design method for rectangular formed carriers is described to aid in this purpose and to allow easier handling after excising.

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MOTOROLA INC.- Technical Developments Volume 12 April 1991

CORNER RELIEF HOLES FOR EXCISED CHIP CARRIERS

by Ken Thompson, Lonnie Bernardoni, Frank Alves and Kingshuk Banerji

  The manufacturing of organic based chip carriers (in specific, PCB material) is often done in reel to reel or strip form for the purpose of automated handling and processing. The cost and complexity of tooling required to excise these carriers from these strips needs to be minimized. A simple design method for rectangular formed carriers is described to aid in this purpose and to allow easier handling after excising.

Two main problems are resolved by this design:

  1) Eliminating more expensive tooling for punching (or blanking) PCB material to form tooling would allow faster turnaround time on punch tooling (this is typically the longest lead time item for production start-up), less punch maintenance, less bending stress imparted on the substrate corners, and improved cycle time due to reduced extraction time and cleaning of punch tooling.

  2) Replacing sharp substrate corners with a quarter diameter hole would reduce susceptability of sharp substrate corners to pierce or become snagged during future processing, thus reducing substrate bending and twisting. This pre-drilled corner feature overcomes the issue of chip carrier hang-ups in the cavities of tape and reel packaging and plastic tube feeders for automatic pick and place equipment presentation.

  The design method is the inclusion of a pre-drilled hole at the intersection of a PCB chip carrier's edges prior to the excising function known as punching (or blanking). These (unplated) holes are drilled into the substrate at the same time as other drilled (and plated) holes are processed. The size of the hole may be varied to fit the tolerances and cost of the punch used

for excision. The hole is passive in nature until the excision process.

  During the punching process, the PCB carrier is contained within an exterior border of PCB (See Figure l...