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FLUXING TOOL INCORPORATED INTO PART FEEDER; SPECIFICALLY FOR ASSEMBLY OF C-5 CHIP CARRIERS

IP.com Disclosure Number: IPCOM000006176D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2001-Dec-11
Document File: 2 page(s) / 117K

Publishing Venue

Motorola

Related People

Kiron P. Gore: AUTHOR [+2]

Abstract

C-5 chip carrier assembly, with the exception of the underside fluxing process, is a traditional pick and place operation that can be performed by chip shoot- ers, robots, or fine pitch machines (referred to as FPMs from here on). The specialized fluxing operation required for C-5 warrants the flexibility provided by robots who currently perform C-5 assembly. In addition to being a catalyst in the reflow process, flux also provides tackiness required to hold a C-5 carrier in position during transportation. A special tool consisting of a rotating disc with a levelling blade provides the required flux thickness for this process. The robotic C-5 assembly process currently requires 10.0 se&part of which 3.0 sets is used for fluxing. The current process uses reels or tray to feed carriers.

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MOlYlROLA INC. Technical Developments Volume 13 July 1991

FLUXING TOOL INCORPORATED INTO PART FEEDER; SPECIFICALLY FOR ASSEMBLY OF C-5 CHIP CARRIERS

by Kiron P. Gore and Ved V. Gundotra

PROBLEM DEFINITION

  C-5 chip carrier assembly, with the exception of the underside fluxing process, is a traditional pick and place operation that can be performed by chip shoot- ers, robots, or fine pitch machines (referred to as FPMs from here on). The specialized fluxing operation required for C-5 warrants the flexibility provided by robots who currently perform C-5 assembly. In addition to being a catalyst in the reflow process, flux also provides tackiness required to hold a C-5 carrier in position during transportation. A special tool consisting of a rotating disc with a levelling blade provides the required flux thickness for this process. The robotic C-5 assembly process currently requires 10.0 se&part of which 3.0 sets is used for fluxing. The current process uses reels or tray to feed carriers.

THE SOLUTION

  This concept provides a method to perform the fluxing within a tube feeder which reduces the cycle time by 3.0 sets/part. The fluxing is accomplished simultaneous to the operation of extracting a part from the tube and presenting it for pick-up. More impor- tantly this concept now provides the capability of performing C-5 assembly with FPMs (in leu of robots) operating at a much faster rate of 1.0 sets/part. FPMs

operate at 0.002" accuracy which is identical to a robotic placement accuracy. The optimal fluxing process calls for small quantities of flux on individual pads in lieu of being sprayed or brushed onto the entire foot print. Excessive flux causes the carrier to float and migrate in boiling flux as the carrier passes through reflow. An alternative could involve dispec- ing flux on every individual pad. This process is very slow. The limitation of using FPMs for C-5 was the inability to customize them to incorporate fluxing between pick-up and placement. This concept overcomes the limitation.

  Chip shooters, operating at 0.4 sets/part, can also be used for C-5 assembly. Their 0.006" placement accuracy, however is inadequate for C-5. Also, they cannot use stick feeders and their process cannot be modified to include fluxing.

  A 500K/YR capacity factory requires a total of 8 robots for C-5 assembly. These robots require 290 Sq. Ft. of floor space. Robots are expensive and slow in comparison FPMs. 2 FPMs have the capability of accomplishing the task of 8 robots at half the cost and occupy 90 Sq. Ft. of factory space.

  Therefore the use of FPMs with this concept results in a cost saving ,of 50%, floor space saving of 65%, and a 75% reduction in the number of machines required.

Summarizing, this concept solv...