O-shaped single extruded solid strip | When O-shaped seal meets continuous extrusion - EMI "ring guard" at the gap

1、 O-shaped single extrusion molding: When "continuity" becomes the core competitiveness

There are two main molding paths for conductive silicone rubber sealing strips: compression molding and extrusion molding. The difference between the two directly determines the application boundary of the product.

Compression molding is the process of placing mixed conductive silicone rubber raw materials into precision molds and completing vulcanization and shaping under high temperature and pressure conditions. The advantages are high dimensional accuracy and suitability for complex shapes, but each mold can only produce one product, resulting in low efficiency, high cost, and product length limited by the mold.

Single extrusion molding is the process of continuously extruding the mixed conductive silicone rubber raw material through an extruder, and forming an infinite length continuous strip product after passing through a vulcanization channel. Customers can cut to any length according to their actual needs, and there is no need for splicing during on-site installation.

The core advantage of the single extrusion molding process can be summarized in one sentence: cut as long as you want, and extrude as many meters as you need. For scenarios such as cabinet door frames and equipment panels that require long-distance continuous sealing, extrusion molding provides efficiency and cost advantages that cannot be replaced by compression molding.

More importantly, single extruded products are continuous and seamless. For the sealing ring formed by extrusion and bonding, the joint is precisely the weakest link of electromagnetic leakage - the conductive network is cut off at the joint, and the shielding effectiveness shows a "breakpoint". The continuous strip products formed by single extrusion fundamentally avoid this problem, maintaining the integrity and consistency of the conductive network along the entire sealing path.

2、 Data speaks for itself: the "hard index" of O-shaped single extruded solid bars

The performance of O-shaped single extruded solid bars ultimately needs to be answered by data.

Conductivity is the core indicator for measuring whether the conductive channel is unobstructed. When the volume resistance of conductive silicone is below 10 Ω· cm, it has electromagnetic shielding function. The volume resistivity of high conductivity silicone rubber is usually between 10 ΩΩ· cm and 1 Ω· cm. Advanced Institute Technology's O-type single extruded solid strip conductive silicone rubber, through precise compounding of selected conductive fillers and silicone rubber matrix, can control the volume resistivity at a lower level according to customer needs.

The shielding effectiveness determines how much electromagnetic waves the sealing strip can "block". The shielding efficiency of conductive rubber can reach 90dB-120dB in the range of 20MHz-20GHz. The formula using pure silver particles can even reach over 120dB. Parker's beautiful solid O-shaped conductive elastomer extruded gasket has a shielding efficiency of 90-120dB at 2GHz frequency. Laird's conductive elastomer extruded part has a maximum shielding efficiency of 120dB at 10GHz frequency. 120dB means that 99.99999999% of electromagnetic waves are effectively blocked - enough to meet the strict EMC standards of military electronic equipment.

The working temperature range determines the environment in which the material can work. Extruded conductive rubber products can be used for a long time in a wide temperature range of -55 ℃ to 170 ℃ (silicone rubber substrate). Some products can meet the temperature requirements of -55 ℃ to 200 ℃. This wide temperature range is sufficient to handle the vast majority of application scenarios from polar regions to deserts, from the ground to space.

The sealing performance can also withstand the test. Conductive rubber has good electromagnetic and water vapor sealing capabilities, and can provide good conductivity under certain pressure, with a suppression frequency of up to 40GHz. For solid elastomers, the recommended compression ratio is 5% -10%. This compression interval can ensure that the conductive particles fully contact and form a conductive path, without permanent deformation caused by overvoltage.

3、 Packing system determines performance boundary: from commercial grade to military grade

The selection of conductive filler for O-shaped single extruded solid strips directly determines the performance level and application scenarios of the product.

The silver plated copper system provides the highest level of shielding effectiveness (up to 120dB), suitable for high demand scenarios such as military electronics, aerospace, EMP protection, etc. Silver plated aluminum system has excellent galvanic compatibility in aluminum chassis scenarios and is a commonly used choice for communication equipment and military chassis. The silver plated glass system ensures good shielding effectiveness while having lower density and more competitive cost. The nickel/graphite system has outstanding cost-effectiveness and is suitable for cost sensitive scenarios such as commercial communication equipment and industrial chassis. Pure silver system performance ceiling, suitable for special scenarios with extreme requirements for conductivity.

Advanced Institute Technology can flexibly select conductive filler systems based on customers' requirements for shielding effectiveness, environmental tolerance, and cost budget, providing a full range of products from commercial grade to military grade.

4、 Three major application battlefields: from 5G base stations to military electronics

5G communication and data centers are one of the areas with the highest demand for O-shaped single extruded solid bars. In 5G base stations, communication cabinets, and RF modules, chassis gaps and interfaces are the main channels for electromagnetic leakage. O-shaped single extruded solid bars can be directly installed in standard O-shaped slots, while also completing EMI shielding and environmental sealing. With the popularity of 5G small base stations and millimeter wave devices, over 46% of newly developed conductive silicone grades are specifically designed for EMI shielding indicators of ≥ 80dB above 10GHz. The suppression frequency of conductive rubber can reach 40GHz, which is sufficient to cover the full spectrum requirements of 5G millimeter wave frequency band.

The military and aerospace industries represent the application fields with the highest reliability requirements for O-shaped single extruded solid bars. Conductive rubber products have been proven to be widely used in military electronic equipment such as aviation, aerospace, and ships through practice. The ultra-high conductivity silicone products meet the US military standard MIL-G-83528 (now MIL-DTL-83528), and are particularly suitable for small and medium-sized military electronic chassis, cabinets, shelters, and microwave waveguide systems. Extruded conductive rubber can be made into continuous pads with various conventional cross-sections - circular, D-shaped, U-shaped, P-shaped, etc. - and various cross-sections can also be customized according to user requirements. The product can meet the requirements of a wide temperature range of -55 ℃ to 200 ℃ and maintain stable performance even in harsh environments.

Automotive electronics and industrial control are the fastest-growing application directions for O-shaped single extruded solid bars. Vehicle electronic control units, sensors, medical diagnostic equipment, industrial control chassis, etc. have dual requirements for electromagnetic compatibility and sealing protection. Conductive rubber can be widely used in fields such as electromagnetic information leakage prevention (TEMPEST), electromagnetic interference (EMI), electromagnetic compatibility (EMC), electromagnetic sealing, pressure and environmental sealing.

5、 Selection points: How to choose the right O-shaped single extruded solid strip for your equipment?

When engineers select O-shaped single extruded solid bars, it is recommended to start from the following dimensions:

The packing system is the first choice. It is recommended to choose silver plated copper or silver plated aluminum systems for military and high-end communication scenarios; Commercial equipment and general industrial scenarios can choose silver plated glass or nickel/graphite systems. The cross-sectional size determines the installation adaptability. O-shaped single extruded solid bars support customization of multiple cross-sectional sizes. The matching cross-sectional diameter should be selected based on the actual size of the installation slot. The compression amount is related to the balance between shielding and sealing. The recommended compression ratio for solid elastomers is 5% -10%. Overvoltage may cause the conductive path to be squeezed apart and accelerate permanent deformation. Environmental tolerance determines long-term lifespan. It is necessary to evaluate the working temperature range (-55 ℃ to 200 ℃), chemical medium contact situation, and flame retardant level requirements.

Advanced Institute Technology provides full process technical support from material selection, sample trial production to batch delivery.

The global conductive elastomer market is estimated to be worth approximately $107 million in 2024 and is expected to grow to $176 million by 2031, with a compound annual growth rate of 7.4%. The global market for conductive silicone rubber is expected to reach 19.61 billion US dollars by 2034. Driven by the deployment of 5G/6G communication, military electronic upgrades, and the deep evolution of automotive electrification and intelligence, O-shaped single extruded solid strips are becoming the preferred solution for more and more engineers to meet long-distance EMI sealing needs, thanks to their unique advantages of "continuous length, no joints, and high efficiency".

Advanced Institute (Shenzhen) Technology Co., Ltd. will continue to deepen its expertise in the field of conductive elastomer extrusion molding, providing customers with higher performance and more reliable conductive sealing solutions through precision technology and continuous innovation.