In an earlier blog concerning CAPLINQ’s UL Certification policy, it was outlined how CAPLINQ supports its customers with the UL certification of polyimide and other tapes. This time, the differences between UL94 V-0 and UL94 VTM-0 will be described.

Certification Classification

For tapes and other thin materials, the certification classification typically used is UL94 VTM-0. The UL94 V-0 code is used for a self supporting material. The problem that arises with a very thin material is that it may not burn but it will shrink or distort as the flame is directed to the sample and if it cannot withstand a ten second application before in shrinks to the holding clamp, so it will not be classified as a 94V material. Cases like this are what UL 94VTM is used for. You take a sheet 200mm X 50m and form a cone with it to perform the flame test as shown in the figure.  Many thin materials that will not burn but will shrink to the clamp and need VTM testing.

Vertical Testing of Thin Materials (VTM-0, VTM-1, VTM-2)

This test is used for materials that are thin, or are too flexible or may distort, shrink or flex during ordinary vertical testing. Procedure: An 8×2 in specimen is rolled longitudinally around a 1/2 in diameter mandrel and taped on one end. When the mandrel is removed the specimen forms a cone. The cone is supported in a vertical position and a flame is applied to the bottom of the specimen. The flame is applied for three seconds and then removed until flaming stops at which time the flame is reapplied for another three seconds and then removed. Two sets of five specimens are tested. The two sets are conditioned under different conditions.

Vertical Flame Test for Thin Materials

For more information of UL classification or polyimide tapes, visit us or contact us for more details.

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