Coil Bobbins Grades of SUMIKASUPER LCP

Grade Selection Guide for Usage in Bobbins

Optical Bobbin Structure and Properties Required for Material

A bobbin is a cylindrical or polygonal spool around which a coil of electrical wire (helix winding) is wound. Most bobbin material is composed of a resin that possesses insulating properties. Although metal is often utilized for bobbin terminals, its usage adds an additional component to the bobbin, thus increasing the cost of manufacture. To address this issue, resin terminal bobbins have been developed that are composed entirely of resin.

Figure : Optical Bobbin Structure and Properties Required for Material

In order for the electrical wire to conduct electricity, the wire is coated insulator material (such as urethane), the coating must be removed from the wire ends that contact the terminals. One of the methods used to remove the wire insulation is to dip the wire into a high temperature solder bath (300-400 deg C).

When metal terminals are present, most of the heat received from dipping the terminals into the solder bath will not be conducted into the bobbin itself, thus making possible the utilization of resin that has a relatively low heat resistance. However, bobbins with resin terminals must be composed of resin having high heat resistance, so that the terminals will not melt or become deformed. Yet, as recent developments have resulted in the further miniaturization and reductions in weight for consumer electronics products, smaller bobbins are also being produced. These smaller bobbins contain shorter terminals, allowing heat to be conducted more readily to the resin itself. Therefore, even bobbins with metal terminals must now be composed of resin having high heat resistance.

For this reason, high heat resistance (300-400 deg C x several seconds) and precision moldability have taken on added importance as properties that are required in bobbin applications, due to current demands for smaller, lighter bobbins. Furthermore, thermoplastic resins are now receiving increased appreciation from the perspective of environmental protection, thus making SUMIKASUPER LCP the main material of choice for bobbin manufacture.

Grade Selection Guide for Bobbins

The E5000 series, ultra-high heat resistant grades, are required for usage in resin terminal bobbins. The E5000 series can also be utilized for metal terminal bobbins, however, the by far the highest heat resistance may not always be needed. One point to be noted for E5000 is that although short-term heat resistance is high, the molding temperature is also extremely high, at 400°C. This high molding temperature may lead to problems within the injection molding machine due to the deterioration of any residual resin. Furthermore, both the molding machine and the molds require more frequent maintenance than if E4000 or E6000 series grades are utilized. Therefore, it is recommended that the particular heat resistance requirements for each bobbin be thoroughly understood, and if ultra-high heat resistance is not an imperative, then E4000 series or more preferably, E6000 series grades, should be utilized.

E52008 is improved in flowability of E5008 with keeping an ultra-high heat resistance, and is very fit for ultra-small bobbins for stepping motors whose thickness is less than 0.2mm.

Type of Bobbin Recommended Grade
Resin Terminal Bobbin E5000 Series(E5008L,E5008 and other grades)
Resin Termina Bobbin
(Ultra-small)
E52008
Metal Terminal Bobbin
(Small)
E5000 Series(E5008L,E5008 and other grades)
E4000 Series(E4008L,E4006L,E4008 and other grades)
Metal Terminal Bobbin
(Medium to Large)
E5000 Series(E5008L,E5008 and other grades)
E4000 Series(E4008L,E4006L,E4008 and other grades)
E6000 Series(E6006L,E6008 and other grades)
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