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Form-in-place EMI gaskets, also known as FIP EMI gaskets, is a robotically dispensed electromagnetic interference (EMI) shielding solution that is ideal for modern densely populated electronics packaging.

The most important distinction of form-in-place EMI gaskets is that they were developed for applications where inter-compartmental isolation is required to separate signal processing and/or signal generating functions.

Simply put, form-in-place gaskets are meant to reduce “noise” between cavities on a printed circuit board (PCB) or in an electronics enclosure. 

In addition, form-in-place gaskets provide excellent electrical contact to mating conductive surfaces, including printed circuit board traces for cavity-to-cavity isolation. Parker Chomerics form-in-place gasket materials are known as CHOFORM. 

  7 reasons why form-in-place EMI gaskets can be an ideal choice

1. Small form factor - form-in-place gaskets can be dispensed in smaller bead sizes than most traditional EMI shielding gasket solutions, 0.018” tall by 0.022” wide. 
    
2. Excellent adhesion - 4-12 N/cm adhesion on prepared surfaces such as machined metals, cast housings, and electrically conductive plastics.
    
3. High shielding effectiveness - Parker Chomerics CHOFORM materials can provide more than 100 dB shielding effectiveness in the 200 MHz to 12 GHz frequency range.
    
4. Quick programming - Because form-in-place EMI gaskets are robotically dispensed, a standard CAD file can be used to program the dispensing system and quickly map out the dispensing pattern.
    
5. Complex geometries - The positional tolerance of the gasket can be held to within 0.001” and is able to follow very complex geometries including sharp turns, corners, and serpentine patterns. Other gaskets such as die cut sheets or o-rings manufacture and/or fabricate into such shapes and patterns. 
    
6. “T” joints - Traditional extruded gaskets are difficult to mate at intersections or “T” joints. The robot dispensing systems produce reliable junctions between bead paths to provide continuous EMI/EMC shielding and environmental sealing.
    
7. Integrated solutions - CHOFORM technology combined with a Parker Chomerics supplied metal or conductive plastic housing provides an integrated solution ready for the customers’ highest level of assembly. This approach requires no additional assembly or process steps for the installation of gaskets and/or board-level auxiliary components. 

  Form-in-place EMI gasket limitations 

1. Large form factor enclosure sealing that can accommodate a groove. For larger areas such as machined covers that can accommodate a gasket groove, other EMI shielding solutions are better suited. In most applications, conductive elastomers such as the CHO-SEAL product line by Parker Chomerics will provide better shielding and sealing. Form in place gaskets can be dispensed in bead sizes only as large as about 0.062” tall x 0.075” wide.
    
2. Enclosures requiring submersion or durable weather sealing. Because of the small form factor, FIP gaskets will not meet stringent environmental sealing requirements such as IP 67 or higher. While silicone-based, the material is better at preventing dust and environmental moisture from entering an enclosure. FIP gaskets can be paired with additional sealing gaskets for enhanced weatherproofing. 
    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This blog post was contributed by Ben Nudelman, market development engineer, Chomerics Division.

 

 

 

 

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Material selection for military applications requires careful consideration, as there are strict requirements to ensure maximum durability, security and of course performance. In munitions, or missiles and missile launch systems, materials that provide electromagnetic interference (EMI) shielding and environmental sealing are critical for the functionality and field life of the application.

Let's look at three areas of a munitions application -- specifically nose cones, cable shielding, and connectors, as each of these areas exemplify why EMI and environmental shielding are a necessity.

  Nose cones

Nose cones are what goes over the top of missiles, planes and other airborne technologies to assist with aerodynamics and to protect the electronic components inside. In missiles, all the electronics are stored within the nose cone and the fuel is held inside the canister. If these two parts are not properly shielded from each other, contamination can become a catastrophic event.

Therefore, shielding the nose cone from EMI and other outside environmental dangers and shielding the components of the missile from each other is of utmost importance.

Another threat to missile electronic malfunction is external tampering from malicious forces. Unintended or intentional EMI can result in misfires, false trajectory, and other problems. Often, anti-jammers are installed to help prevent this problem in combination with EMI shielding materials.

  Cable shielding

Cable shielding is a woven fabric that goes over cables to prevent electromagnetic cross-talk between the cables and the components. Typically, a metal mesh is wrapped around the cables that will prevent any EMI from interacting with the cables or emitting from the cables.

Different amounts of layers can be added to increase EMI shielding effectiveness, however adding more layers will also add more weight. Cable shielding that is lighter, typically non-metal based, is ideal for applications where weight is of concern like in munitions.

  Connectors

Connectors are where wires are plugged into to keep electric circuits intact. In munitions, connectors can be a failure point because environmental agents can more easily enter which is why they require more attention to be shielded properly.

The complexity of military electronics has increased significantly on air, sea and land-based applications. The environments in which systems are required to operate are often extreme. Design engineers need to consider wide variations in ambient temperature, shock and vibration, and electromagnetic interference (EMI).

With a wide choice of shielding materials and a range of advanced shielded optical windows, Parker Chomerics helps ensure the protection of complex electronics from damage and compromised reliability caused by EMI.

Sensitive electronic components can be kept within their operating temperature range limits by using heat management materials that include highly conformable, thermally efficient gap fillers and gels.

Parker Chomerics offers the products, technical know-how, close customer support and supply chain capabilities to meet these challenges and deliver superior, reliable and cost-effective solutions.

 

 

 

 

 

 

This blog post was contributed by Paige Ludl, marketing co-op, Chomerics Division.

 

 

 

 

 

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Most thermal pads, also known as thermally conductive gap filler pads, thermal gap pads, or thermal gap filler pads, have many different layer materials or carrier substrate options to choose from. It can be confusing which layer is supposed to stay on the product and which layer gets peeled off and removed before application. In fact, it’s one of our customer’s most asked about questions and can cause a lot of confusion on the manufacturing floor.

So, which layer should you peel off and which should stay on the thermal gap pad? Read on to find out.

Parker Chomerics, like many thermal gap pad vendors, offers several different gap pad layer options that must be peeled away before the gap pad is installed into the application. 

Think of a thermal gap pad as a sandwich of layers -- there is always a blue poly backing that keeps the gap pad together, but there are five additional carrier substrate options which provide the following benefits:

Woven fiberglass

The woven fiberglass carrier option provides reinforcement and a clean break / low tack interface surface, allowing for re-use of the thermal pad if necessary or for prototyping.

As you can see from the diagram, you peel off the liner to expose the woven glass carrier which does not get removed from the thermal gap pad.

Example: THERM-A-GAP HCS10G.

  Aluminum foil with pressure sensitive adhesive (PSA) 

The aluminum foil with PSA carrier’s primary function is to allow a pressure sensitive adhesive on the thermal gap pad to affix the thermal pad in place.

As you can see from the diagram, you peel off the liner to expose the aluminum foil carrier which does not get removed from the thermal gap pad.

Example: THERM-A-GAP A579.

 

Polyethylenenapthalate (PEN) film 

The polyethylenenapthalate (PEN) film carrier permits the thermal gap pad to see a shearing motion and offers a clear, cost-effective dielectric film with fair thermal performance.

As you can see from the image at right, there is no clear film to peel off that exposes the PEN film carrier, which does not get removed from the gap pad.

Example: THERM-A-GAP 579PN.

  Thermally enhanced polyimide 

The thermally enhanced polyimide carrier permits the thermal gap pad to see a shearing motion and offers an excellent dielectric film with enhanced thermal performance. 

As you can see from the image at right, there is no clear film to peel off, the polyimide carrier does not get removed from the gap pad.

Example: THERM-A-GAP 579KT.

  No carrier   

The no carrier or “un-reinforced” option allows the thermal gap pad to have high tack surfaces on both sides, allowing for the pad to be highly conformable, but it does make cutting and handling of the product more difficult.

Once the liner is peeled back, there is no additional carrier on the thermal gap pad, the pad is now exposed.

Example: THERM-A-GAP 579.

 

Blue poly diamond carrier

Lastly, the base carrier liner, shown in blue, is persistent on the bottom of all thermal gap pad options, and must be peeled and removed prior to installation of the thermal gap pad.

This blue carrier is necessary, as it keeps the gap pad intact and more easily to handle prior to installation. We recommend keeping this blue poly carrier layer on just until the gap pad is placed for the final time.

 

 

 

 

 

 

 

 

 

 

 

 

This blog was contributed by Jarrod Cohen, marketing communications manager, Parker Chomerics Division.

 

 

 

 

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