Moisture Barrier Bags (MBB) and ESD Control

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13950While there is no direct link between protection from ESD and protection from moisture, many devices and components require protection from both. Statshield Moisture Barrier Bags (MBB) are designed to protect the contents from both moisture and ESD events. MBBs protect ESD susceptible devices by forming a faraday cage around the contents and they protect the contents from moisture with specialised layers of film that control the Moisture Vapour Transfer Rate (MVTR). In addition to the bags, Desiccant Packs and Humidity Indicator Cards must be used for proper moisture protection (read our article “How to use desiccants with Moisture Barrier Bags” for more information). The bag must be heat sealed with a vacuum-sealer to eliminate the amount of “moisture laden air” within the package.

Most manufacturers of the Moisture Sensitive Devices (MSD) will dictate how their product should be stored, shipped, etc. However, the IPC/JEDEC J-STD-033B standard describes the standardized levels of floor life exposure for moisture/reflow-sensitive SMD packages along with the handling, packing and shipping requirements necessary to avoid moisture/reflow-related failures. The ESD Handbook ESD TR20.20 mentions the importance of MBB in section Temperature.

While only specialized materials and structures can control the interior temperature of a package, it is important to take possible temperature exposure into account when shipping electronic parts. It is particularly important to consider what happens to the interior of a package if the environment has high humidity. If the temperature varies across the dew point of the established interior environment of the package, condensation may occur. The interior of a package should either contain desiccant or the air should be evacuated from the package during the sealing process. The package itself should have a low WVTR.

Further information on using MBBs:

  1. Surface Mounted Devices
    Surface Mounted Devices (SMDs) absorb moisture and then during solder re-flow operations, the rapid rise in temperature causes the moisture to expand and the delaminating of internal package interfaces, also known as “pop corning.” The result is either a circuit board assembly that will fail testing or can prematurely fail in the field. For more information on SMDs and moisture sensitivity, see the following articles:

  2. Lead-Free Solder
    The introduction of lead-free soldering has increased the problem because of the increased reflow temperatures required. Am article from called “Procedure for handling moisture sensitive PCB’s” details the new risks.

  3. PCB Laminate
    The moisture problem is no longer only isolated to the SMD, but is also a problem for the PCB laminate itself. Moisture in the PCB laminate can result in delaminating problems. For further information about moisture concerns in PCB laminates see Ray Prasad’s post on “Moisture Sensitivity Concerns in PCBs for Lead-free Assemblies“.

About Vermason

Vermason is a manufacturer of ESD protection products and was founded in Letchworth in 1979. Our mission is to maintain our position as the primary ESD solutions provider for the electronics industry in Europe. Vermason strive to manufacture quality ESD Control products with innovation, leadership and partnerships which deliver long term commercial benefits. We understand the many challenges our customers face regarding quality and reliability. We support these requirements with products and services of exceptional value which help them gain competitive advantages in their markets. We also appreciate that the control of ESD is one of many necessary links in a long chain required to bring a customer’s project to a successful completion. We endeavour to make that happen. We sustain our vision and mission by constantly seeking renewal via continuous education, application of new technologies and good business practices. Employees are expected to serve the customer with the highest level of technical knowledge in the industry.

Posted on 2015-12-17, in Uncategorized. Bookmark the permalink. 3 Comments.

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