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Removable Foreign Object Debris (FOD) Barrier for Electronics Components

IP.com Disclosure Number: IPCOM000228636D
Publication Date: 2013-Jun-26
Document File: 6 page(s) / 231K

Publishing Venue

The IP.com Prior Art Database

Related People

Scott Dukes: INVENTOR [+5]

Abstract

It is typical within the high reliability electronics packaging industry to spray or brush coat circuit cards after solder assembly with a conformable material to prevent electrical shorts or damage that can be caused by foreign object debris (FOD). This coating can also provide some resistance to moisture or salt-air exposure. However, recent advancements in miniaturization of electronics parts has led to the creation of high pin density package formats that may not allow for the complete coverage of these coating materials when applied in the traditional application methods. In addition, if excessive material is applied that fills the gap between contacts there could be premature failure of the soldered interconnects due to the large gradient in thermal expansion between the solder and the coating once cured. For some components, including high density interconnect parts and even connectors, the coating process can be manually intensive, difficult to inspect for a complete coverage and can create issues with mating of interrelated parts or potential ingress of the material into an electrical contact area not requiring coating. In the proposed solution, a gasket that is easy to install as a FOD (Foreign Object Debris) barrier is disclosed. The gasket barrier is designed so that it conforms to the exterior dimensions of the component on which it is installed.

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Removable Foreign Object Debris (FOD) Barrier for Electronics Components

Scott Dukes, Roy A Belaen, Jerry Keller, Neal Martinez, Kenneth Ferraro

ABSTRACT

It is typical within the high reliability electronics packaging industry to spray or brush coat circuit cards after solder assembly with a conformable material to prevent electrical shorts or damage that can be caused by foreign object debris (FOD). This coating can also provide some resistance to moisture or salt-air exposure. However, recent advancements in miniaturization of electronics parts has led to the creation of high pin density package formats that may not allow for the complete coverage of these coating materials when applied in the traditional application methods. In addition, if excessive material is applied that fills the gap between contacts there could be premature failure of the soldered interconnects due to the large gradient in thermal expansion between the solder and the coating once cured. For some components, including high density interconnect parts and even connectors, the coating process can be manually intensive, difficult to inspect for a complete coverage and can create issues with mating of interrelated parts or potential ingress of the material into an electrical contact area not requiring coating. In the proposed solution, a gasket that is easy to install as a FOD (Foreign Object Debris) barrier is disclosed. The gasket barrier is designed so that it conforms to the exterior dimensions of the component on which it is installed.


1. Introduction

There is a need to cover interconnects of circuit cards because of the potential risk of shorts caused by the released FOD, accumulated moisture or other contaminations. In order to cover the interconnects, a typical electronics circuit card goes through spray or brush coating with a conformable material such as urethane or acrylic based coating. Without affecting the utility of the circuit, these coatings should protect


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against any FOD and make circuit cards semi-resistant to moisture or salt-air exposure. However, it has been observed that in some cases where the coating material has been excessively applied (to force better coverage ), the solder joint fatigue life of the electronics part becomes degraded due to differences in the thermal expansion between the solder of the circuit card and the coating. As shown in FIG. 1 and FIG. 2 the coating could contract and expand, causing undue stress that can be transferred to the soldered interconnects leading to shorts and premature failure of the part.

Figure 1: Typical Grid Array Component of a Circuit Card

Figure 2: Effects of Thermal Cycle in Case of a Typical Coating

Further, in some cases, the density of the number of interconnects or parts on a circuit card could be so high that the process of coating could become manually intensive and the inspection after coating difficult. Additionally, there could be issues such as impediments to connecto...