Browse Prior Art Database

STACKED SHIELDING IN PORTABLE RADIO PRODUCTS

IP.com Disclosure Number: IPCOM000009433D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-23
Document File: 4 page(s) / 165K

Publishing Venue

Motorola

Related People

Kamlesh S. Lele: AUTHOR [+3]

Abstract

Printed Circuit Board (PCB) area is at a premi- um in today's competitive size driven wireless mar- kets. One of the design obstacles that impacts the size is proper shielding. This invention allows for more effective use of PCB space to be utilized in component layouts by reducing the area used by sol- der down shields thus resulting in smaller radio products.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 4

Developments Technical 0 M MOlOROLA

STACKED SHIELDING IN PORTABLE RADIO PRODUCTS

by Kamlesh S. Lele, John M. Restrepo and Jon Feenaghty

BACKGROUND

  Printed Circuit Board (PCB) area is at a premi- um in today's competitive size driven wireless mar- kets. One of the design obstacles that impacts the size is proper shielding. This invention allows for more effective use of PCB space to be utilized in component layouts by reducing the area used by sol- der down shields thus resulting in smaller radio products.

PROBLEM DESCRIPTION

  This idea deals with optimizing the PCB area that is used to support the shield track of solder down shields. Radio Frequency (RF) subsystems are very susceptible to noise emanating from other

Radio Housin

RF subsections and digital sections. Shielding is the primary means of reducing the effects of noise on circuitry. In addition these shields aid in keeping the case radiation levels acceptable for FCC type approval and the prevention of receiver desense due to Electra-Magnetic Interference (EMI). However, these shields take up PCB area and thus are a factor in gating the size of the radio product.

SOLUTION

  The invention is essentially a complete tradi- tional solder down shield and an addition of a Dependent Spring Board Shield placed near it. The Spring Board Shield rests upon the Main shield. See Figure 1 below:

Main Shiel$/

- pressure conlac( I

Spring Board Shield

Fig. 1 Stacked Shielding

0 Mommla. 1°C. 1999 52

[This page contains 15 pictures or other non-text objects]

Page 2 of 4

Development.s Technical 0 M MOTOROLA

  The pressure contact between the Main Shield, the Spring Board Shield and the Conductive Foam Pad provides contact with the radio housing via tra- ditional screw and screw bosses or snaps. Solid contact between the radio housing, and PCB solder down shielding has been proven to be essential in meeting FCC specification for case emissions and preventing desense of the radio's receiver due to EMI. The advantage of this type of shielding scheme is that there is no bulging of the radio hous- ing due to rigid non flexible shields with conductive foam pushing against the housing case. The Spring Board Shield provides plenty of contact while not stressing the housing.

  An alternate method of using Stacked Shielding would be not to have a Spring Board shield rather, use a Coplanar Shield that rests on top of the main shield. The main shield would be solder performed and during reflow the electrical contact would be established. This option yields the benefit of reduc- ing net board space consumption however does not yield the added benefit of making contact with the radio housing. This option could be used when making the contact with the radi...