Thursday, June 21, 2018
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Label with Built-In Breather Membrane Replaces Pressure Cap
PCS label construct.

Electronic housings of any kind that are exposed to the environment can present a number of design problems — and there are no easy solutions. You can either hermetically seal the housing or you can vent the housing. Hermetic sealing is expensive and difficult to do. Venting the housing is also not easy. You can use a mechanical vent or a membrane vent. The mechanical vent invariably allows water, dirt, oil or some other contamination into the housing thus reducing the life of the product. Membrane vents like those from Gore or Nitto Denko work well but must either be installed in the form of a pressure compensation (breather) cap or they can be put on self-adhesively or welded to the surface in the case of a plastic housing that will allow welding. All venting solutions require an extra step in the process and, in the case of caps, must be done with a precisely manufactured hole, to assure a good fit and seal. The design of the housing must accommodate the cap as well as protect it from damage and allow space for its assembly.

For example, the assembly process for automotive electronic transmission control units used to involve the complex step of fitting them with pressure compensation (breather) caps including an integrated protection membrane. These membranes are permeable to air but not water, oil or dust. These caps are necessary to protect the sensitive electronics from pressure changes that result, for instance, from changing climatic conditions, such as a hot car driving into a rain storm. Changes in pressure can result in an internal vacuum inside the electronic housing. This causes the intrusion of water, dirt, oil or other contamination that would destroy the unit if it were not for the vent cap.

It is necessary to insert these pressure caps into the housings through a very precise hole in the housing. Manufacturers are then forced to deal with the hole as well as the pressure cap. The pressure cap often gets in the way of the housing design or application. They must be protected from damage or becoming dislodged. The caps can be expensive to buy as well as capitally intensive to install automatically. Also, the caps serve no other purpose than to provide pressure equalization without allowing water or oil intrusion.

Schreiner ProTech has now come up with a simpler solution for a product used in the automotive sector. The TTR printable nameplate serves as a permanent component label and as well as a membrane-based pressure compensation seal (PCS). The PCS ensures optimum pressure compensation and also protects the electronics from dust, oil and moisture. The PCS and the nameplate are combined into a self-adhesive label. The label is automatically applied in a one-step process, which eliminates the time-consuming job of separately installing pressure compensation caps. By combining the PCS and the nameplate, Schreiner ProTech has simplified the manufacturing process in a major way. This saves costs and provides additional competitive advantages.

Technically speaking, this PCS/label combination performs the same as the breather caps. The air flow is: >6 l/h.cm2; water entry pressure >0.6 bar; oleophobic grade 7-8; Ingress Protection (IP) rating 67; and temperature range: -40 to +160°C. Typical housing substrates are stamped steel, die-cast metal, aluminum, PBT GF30, Nylon 66, ABS and others. Automatic dispensing and placement ensure correct positioning of the PCS over the vent hole. The vent hole does not require extreme precision but the outside surface must be flat so that a good seal can be obtained. It is possible to place the PCS Label manually but then some other kind of positioning aid either in the design of the part or a placement fixture is required.

These Label-PCS parts can be used in a variety of electronic devices that require protection from moisture, oil and dirt intrusion. The best part is that you can do two things in one step: label the part as well as provide pressure compensation for water, oil and dust protection. It provides cost savings on many fronts.

For more information contact: Schreiner ProTech North America, Inc. 21477 Southfield, MI 40833 888-888-8564 E-mail: Web:

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