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SIDE WARD INSERTION GRIPPER FOR AUTOMATED ASSEMBLY IN HORIZONTAL PLANE

IP.com Disclosure Number: IPCOM000007875D
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2002-May-01
Document File: 4 page(s) / 195K

Publishing Venue

Motorola

Related People

Kiron P. Gore: AUTHOR

Abstract

Components with solder joints under constant strain typically require hold downs that are pressed into the PCB for strain relief 1) Tight fits create problems for both manual and automated assembly. Diameters of the hole and the post vary along with distances between their centers resulting in varying insertion forces. This makes manual assembly difficult and miss-insertion sensing unreliable.

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Technical Developments

SIDE WARD INSERTION GRIPPER FOR AUTOMATED ASSEMBLY IN HORIZONTAL PLANE

by Kiron R Gore

designed to fit over the conveyor and help ease the manual assembly process, especially when the fit was tight. This created more problems because exces- sive force often broke the PCB extensions. This proc- ess was very cumbersome, unreliable, resulted in
0.14 DPU and a 5% scrap on PCBs. A solution was urgently needed.

PROBLEM DEFlNlTlON

  Components with solder joints under constant strain typically require hold downs that are pressed into the PCB for strain relief

  1) Tight fits create problems for both manual and automated assembly. Diameters of the hole and the post vary along with distances between their centers resulting in varying insertion forces. This makes manual assembly difficult and miss-insertion sensing unreliable.

  2) On the other hand a slightly lose fit does not do a good job on strain relief and could result in breaking of the solder joint.

3) Thru holes in PCBs take up valuable space on top, bottom and inner layers as well.

THE SOLDTlON

  Similar to forked leads being pressed onto the edge of a leaded module, a side ward insertion (sur- face mount) design was created for easy assembly; whether manual or robotic. Instead of being a press fit close to the edge of the board, the new design easily slides on and clips to the edge of the board. Side ward insertion forces are low, consistent and therefore easy to sense with simple and reliable tech- niques. A side ward insertion gripper was then designed for automated assembly of the new part in the horizontal plane. Because of consistent inser- tion forces, miss-insertion sensing during automated assembly is now simplified and therefore reliable.

  This unique side ward assembly gripper (with built-in miss-insertion sensing) gave us, for the first time ever, the distinct advantage of avoiding the use of tight fit thru hole components which are difficult and unreliable to assemble manually or robotically.

CASE IN POINT-JEDI ANTENNA CONTACT

  This sheet metal L shaped part is reflowed close to the edge ofthe board while the main body hangs over the edge to make contact with the antenna bush- ing. Refer to Figure 1. For adequate RF perform- ance a strong contact force is required between the bushing and part. Therefore the solder joint is under constant stress. Initial design ofthe antenna contact had the part molded in a plastic housing with two strain relieving posts that were press fitted into holes in the PCB. Refer to Figure 2. Assembly was man- ual. The interference varied considerably resulting widely varying insertion forces. Every board had to be inspected in house. Boards with a loose fit were scrapped and the ones with too tight a fit had to be reworked. The rework sometimes produced scrap because the holes would get too large. A tool was

  This unique side ward insertion tool is designed to vacuum pick-up in the vertical position, and slide the component on to...