FEATURE EMC & CIRCUIT PROTECTION IMPLEMENTING CORROSION INHIBITING
ESD PAPER INTO THE EMS PROCESS Cortec Corporation describes an innovative new ESD paper that protects against corrosion and static discharge and serves many useful EMS purposes
T
wo important concerns for the Electronics Manufacturing Services (EMS) are
electrostatic discharge and corrosion. Either of these could damage sensitive electronics, and special precautions should be taken to protect components during manufacturing, assembly, and shipping. Options for protection have expanded with Cortec’s development of EcoSonic ESD Paper Powered by Nano VpCI. This large format ESD paper provides protection against both electrostatic buildup and corrosion. EcoSonic ESD Paper has ESD properties conforming to MIL PRF-81705D for surface resistivity and static decay rate. The anti-stat coating is made from environmentally friendly material and performs better on the static half- life test (a test performed in a low to no humidity environment) than conventional anti-stat coatings containing alkyl ammonium chlorides, typical ethoxylated amines, and phosphated esters, among others. Cortec’s VpCI technology supplies corrosion protection in the contact, vapour, and barrier phase on multi-metal components. VpCI molecules in the paper’s coating evaporate and then condense on metal surfaces in an enclosed space, forming a molecular protective layer that safeguards the substrate from the attack of corrosive species such as humidity, SO2, H2S, and the force of galvanic corrosion on dissimilar metals. When the enclosed space is open, the VpCI molecules evaporate into the air, leaving behind an unaltered surface. EcoSonic ESD paper conforms to the performance specifications of MIL-PRF-3420H (for vapour corrosion inhibiting ability of opaque wrapping materials). This paper is non-toxic and fully recyclable. The coated surface makes it an option for cleanroom environments. Its large format makes it useful for many more applications than the typical ESD paper formatted in standard copy paper size.
TEMPORARY WORK SPACE, TRANSIT, AND STORAGE Large format EcoSonic ESD Paper is a convenient way to make a temporary ESD-protected work surface. This is helpful at the assembly workbench, in the inspection room, or at the receiving warehouse where inspections are occasionally required on incoming ESD-sensitive materials. While not all surfaces may be ESD protected, EcoSonic ESD Paper solves that problem by providing a ready to use surface where components can be laid.
26 APRIL 2017 | ELECTRONICS Transit and temporary storage are two other
common situations where this paper is helpful. Added corrosion protection is especially important when components must be transported in totes to an outsourced vendor for special work. In-house, electronic components are frequently transported from one work station to the next in deep trays and may be left awaiting work for a day or two. ESD foam is typically used for interleaving between layers of components in trays. By replacing foam with this paper, parts will benefit from both ESD and corrosion protection between assembly stages. The greater strength of EcoSonic ESD Paper as opposed to ESD foam will also increase efficiency by allowing electronic components to be layered more deeply in transport trays without the normal risk of pinching other components through the delicate foam. Since this paper is less than 0.004 inches thick, it also saves on valuable storage space that would be consumed by the ESD foam. It is possible to increase efficiency by
incorporating this paper into the EMS reflow
Figure 1 & 2: EcoSonic ESD Paper
oven process. Since the ESD coating is heat stable up to 200°C, it can be used in the SMT assembly line process for PCB or FPCB assemblies. Rather than slowing the process by waiting for components to cool down after leaving the reflow oven, manufacturers can cradle the components in EcoSonic ESD Paper in order to take components off the assembly line more quickly and make way for additional parts to pass through. EMS environments require work instructions, process routing guides and instructions, standard operating procedures, records, and other documents to be circulated throughout the facility along with work pieces. By creating temporary jackets for these documents out of EcoSonic ESD Paper, manufacturers can avoid the potential contamination of reusing jackets made of plastic or other materials, while protecting against electrostatic discharge.
CORROSION PROTECTION FROM SHIPPING Since corrosion or contamination of electronics can mean future failure, end users are extremely sensitive to the presence of component variations, such as metal discolouration. Parts that are sent back to the plant due to corrosion often leave quality engineers puzzling because of the stringent precautions taken against corrosion and contamination during the manufacturing process. However, the cause may be the corrosive conditions of shipping in which electronic components are exposed to extreme fluctuations of humidity. EcoSonic ESD Paper is one option for ESD and corrosion protection during shipment. It can be used for packing, wrapping, and interleaving or used inside a metalised ESD or EMI shielding bag to provide corrosion protection. Ensuring that sensitive electronic
components are protected from electrostatic discharge is an important task for EMS environments. Finding a paper that combines ESD and corrosion protection is even more valuable. Add to this the large format, heat tolerance, and non-toxic/recyclable properties of EcoSonic ESD Paper, and EMS industries have a versatile tool for improving the efficiency and effectiveness of its electronics manufacturing and shipping processes.
Cortec Corporation
www.cortecvci.com T: +1 800-426-7832
/ ELECTRONICS
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