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Parker Chomerics is delighted to debut CHOFORM® 5575, an all-new form-in-place EMI gasket at electronica, the world's leading trade fair and conference for electronics. Located in Munich, Germany, electronica brings together nearly 80,000 visitors from 90 countries to discuss the industry’s latest market and technology topics.
CHOFORM 5575 is a silver-plated aluminum filled, electrically conductive form-in-place gasket. Form-in-place gaskets are dispensed using an automated system and provide reliable electromagnetic interference (EMI) protection for packaged electronic assembles. They are ideal when isolation and complex cross section patterns are required, such as on automotive advanced driver-assistance systems (ADAS) modules or telecommunications boxes.
CHOFORM 5575 brings exciting new technology, providing premier EMI shielding over a broad frequency range in high temperature environments up to 125° C (257° F). CHOFORM 5575’s patented silver-plated aluminum filler technology allows for exceptional galvanic corrosion resistance when mated to an aluminum substrate, making this an ideal product for aluminum castings or airframes.
CHOFORM 5575 joins the family of Parker Chomerics CHOFORM dispensed form-in-place (FIP) EMI shielding gaskets, which are known to provide the lowest total cost of ownership for small cross section and complex pattern applications. From engine control modules (ECMs) to telecom infrastructure, to advanced avionic systems, CHOFORM is the designer’s first choice in form-in-place EMI gasket technology.
Be sure to visit Parker Chomerics at electronica, November 13-16, 2018 in Munich, Germany, in hall A2, stand 432 to see CHOFORM 5575, as well as the latest EMI shielding and thermal interface materials products from Parker Chomerics.
This blog was contributed by Jarrod Cohen, marketing communications manager, Parker Chomerics Division.
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There are many electromagnetic interference (EMI) shielding elastomer gasket mounting techniques that offer designers reliable, cost-effective choices in both materials and component assembly. These options offer aesthetic choices and accommodate packaging requirements such as tight spaces, weight limits, housing materials and assembly costs. Most EMI shielding elastomer gaskets attach using easily repairable systems. Take a look at the list we've compiled of the seven most common elastomer EMI shielding gasket mounting systems below.
This quick, efficient attachment strip offers superior flexibility in attaching molded elastomer sheets, cut parts, and extruded conductive elastomers. But beware, Parker Chomerics does not generally recommend the addition/use of pressure sensitive adhesive.
Friction fit in a grove prevents the over-deflection of the gasket. A retaining groove will be required to be designed into the application, and this mounting choice is ideal for molded and extruded conductive elastomers.
Adhesive compounds are ideal for spot bonding non-conductive or conductive adhesive and are ideal for all conductive elastomer materials. It is important to select an adhesive suitable to adhere to either silicone or fluorosilicone, regardless of whether it is a non-conductive or conductive adhesive.
Form-in-place (FIP) automated technology such as Parker Chomerics CHOFORM® applies high-quality conductive elastomer gaskets to metal or plastic housings with robotic precision. FIP is widely used in compartmentalized enclosures and other tightly packaged electronic devices in military, telecom, transportation, aerospace, and life science applications.
Friction fit on tangs requires special design consideration, but it does accommodate thin walls and intricate shapes.
Spacer gaskets are fully customized, integral spacers made from either conductive elastomer or plastic, and provide economical EMI shielding and grounding in small enclosures. Locator pins ensure accurate and easy installation, manually or robotically.
Rivets or screw mounting requires integral compression stops and mounting holes on the flange.
For more information, visit Parker Chomerics Division or contact us directly.
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Pressure sensitive adhesive, more commonly known as PSA, is adhesive which forms a bond when pressure is applied, to join the adhesive with an EMI gasket. As the name "pressure-sensitive" indicates, the degree of bond is influenced by the amount of pressure which is used to apply the adhesive to the surface.
When it comes time to focus in on gasket electrical conductivity, it is generally not recommended to use PSA with an EMI shielding gasket. This is because the strip of adhesive inhibits true contact of the EMI shielding gasket with the mating surface, thereby decreasing the performance of the gasket. However, if a PSA system is deemed necessary, then the following guidance should be considered.
Depending on how they are used, a PSA system may reduce the gasket through flange conductivity and/or shielding effectiveness to varying degrees. Applications such as an EMI connector gasket which requires the lowest electrical resistance ground connection should not incorporate a PSA system.
Overall, the use of PSA as an attachment method for elastomer materials is meant to aid in initial assembly operations vs. a long term means of permanent attachment. Generally, you can expect the minimum deflection of the gasket may need to be increased to obtain desired shielding results.
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Thermal Interface Materials (TIMs) are useful for thermal management in electronic components, as they enhance heat transfer from a heat-generating component to a heat dissipater, or heat sink. One important aspect when selecting a TIM for your application is knowing the material’s ability to transfer heat, which is often given by way of thermal conductivity and/or thermal impedance.
Across the industry, manufacturers often publish thermal conductivity in units of Watts / meter-Kelvin as well as thermal impedance in units of °C – inches2 / Watt on their datasheets. So, what is the difference between these two, and how should you consider them when selecting a TIM?
Thermal conductivity is a material property and describes the ability of the given material to conduct heat. Therefore, when a material’s thermal conductivity is high, the material is a better thermal conductor. This property is independent of material size, shape or orientation in a homogeneous material, and because of this, thermal conductivity is an idealized value.
To understand thermal impedance, we must first understand thermal resistance and thermal contact resistance.
Therefore, the thermal impedance of a material is the sum of its thermal resistance and all contact resistances. When a material’s thermal impedance is lower, the material is a better thermal conductor in that application. Based on this, it is understandable that factors such as surface roughness, surface flatness, clamping pressure, presence of adhesive, non-homogeneous, and material thickness all have large impacts on the material’s thermal impedance. Thus, thermal impedance is a better “real world” thermal property, as it accounts for more variables specific to the application.
In summary, when comparing different TIMs for a specific application, you can begin with thermal conductivity for general comparisons, but having thermal impedance versus pressure data will be far more accurate to your “real world” conditions.
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For automotive engineers looking to reduce vehicle weight, metal-to-plastic conversion is a win-win. At the highest level, injection plastic molds are capable of producing multiples of millions of parts required for automotive programs with ease. Typically, a single tool can support a program for its entire life-cycle, meaning you only must go through the cost and design of tooling just once.
In traditional metal fabrication, you have stamping and die casting, both of which require tool refurbishment, at what can amount to a very significant cost. Although injection mold tooling can be relatively expensive, it is not more expensive than die cast tools and/or stamping tools.
Typically, injection molds will last many times longer than metal tooling. Injection mold tooling are also more flexible than other types of tools, allowing you to incorporate many types of features into a part so that no secondary machining, coating and/or forming is required after the molding operation. And depending on the type of plastic material you select; you can realize excellent strength to weight properties.
Metal has been used for decades now to machine and fabricate parts that need to last long past the product’s life cycle. Today, metal replacement parts, better known as metal-to-plastic replacement technology, offers a lighter, more cost effective solution that is often superior to the metal part it replaces.
Take for instance the cylinder head cover pictured. It has undergone a metal-to-plastic transformation, featuring multiple cable management mounts, coupled with the elimination of the spark plug tube mounting point, which has vastly decreased noise from the engine.
But most importantly, its weight has decreased 47% - a significant weight savings by automotive manufacturing standards.
Selecting the right injection molding plastic resource is critical, especially for companies that do not have in-house plastic expertise. Support engineers can ensure that the plastic part is properly designed for optimum molding capability, and look for opportunities to combine multiple parts into one, eliminating cost and manufacturing operations down the line. Plastic engineers can also support the design process with computer aided analysis, such as mold flow and finite element analysis (FEA).
Finally, plastic engineers can help with selecting the correct plastic resin, noting the user environment and required chemical resistance, operating temperature range, and whether there needs to be electrical properties such as conductivity, thermal properties such as heat dissipation and mechanical strength. Plastics offer more functionality with less weight. With plastics, there is a freedom of design not found in metal parts.
Learn more about Parker Chomerics’ injection molded plastic expertise, including engineering support today.
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