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Method of attaching SMD component at the bottom of flex

IP.com Disclosure Number: IPCOM000178066D
Original Publication Date: 2009-Jan-14
Included in the Prior Art Database: 2009-Jan-14
Document File: 3 page(s) / 216K

Publishing Venue

Motorola

Related People

Moses Teh: INVENTOR [+2]

Abstract

This document described the method of using Trap-Door Design in the flex circuit that allows a portion of the flex to be folded & bend over manually. This process allows parts from top side to be relocated to the bottom side of flex. It also allows the Trap-Door to act as a Shield or Insulator for certain sensitive component.

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Method of attaching SMD component at the bottom of flex

By Moses Teh, Max Lim

Motorola, Inc.

APS Energy, G&PS

 

ABSTRACT

This document described the method of using Trap-Door Design in the flex circuit that allows a portion of the flex to be folded & bend over manually. This process allows parts from top side to be relocated to the bottom side of flex. It also allows the Trap-Door to act as a Shield or Insulator for certain sensitive component.

PROBLEM

Flexible Printed-Circuit Board, which is flimsy in natured, required a carrier (pallet) for transportation during Paste Printing, Parts Placement & Reflow during SMT process. In order for Flex to be placed really flat on the reflow pallet for maximum support, the bottom side of Flex must be totally free of any part. In another word, it does not allow parts to be placed on the bottom side of the Flex during board assembly process.

However, due to specific requirement, certain component needs to be located at the bottom side of flex for ease of flex to plastic housing assembly. Current method employed the following approaches:

 

  1. extending the flex’s outline (see Figure 1)
  2. creating an extension leg (see Figure 2)

These approaches even thought it is feasible, has resulted in flex size increase that incurred extra cost.

 

SOLUTION

The new method is using Trap-Door Design. It is basically a U-shape slit cut with two 1.5mm thru’ holes at the end of the slit cut to act as a Tear-stop. Trap door can be incorporated anywhere within the flex’s outline. No modification of flex’s outline is required and thus incurred no extra cost.

This approach provides the following solutions:

  1. Relo...