IEC TR 63018-2015 pdf free download.Flexible printed circuit boards (FPCBs) – Method to decrease signal loss by using noise suppression materials.
3.2 Test specimen
3.2.1 Structure
Test specimens shall be designed by two structures, i.e. with and without NSMs in one FPCB board. The part without using NSMs is called bare FPCB. The part using NSMs is called shield FPCB, as shown in Figure 4. This test coupon shall also be designed as two types in order to have an object of comparison. The first design shall be composed of one bare FPCB with one shield FPCB. A design of this structure allows to compare the bare FPCB with the shield FPCB，as shown in Figure 4 a. The second design shall be composed of one bare FPCB with two over shield FPCBs. This structure allows to compare the bare FPCB with the two over shield FPCBs, as shown in Figure 4 b.
The test specimen shall be divided into two halves with one board (bare FPCB and shield FPCB) for equitable estimation with the same Cu line (LW1. LW1..). This structure has the merit of uniformly measuring at once a bare and a shield FPCB under the same conditions.
The Cu line is formed with a linear distance of direction, because the variation of shield effect is very weak for the curved line The width of Cu line shall be chosen freely in the allowance range of a manufacturing process. The size and spacing of via holes shall not be limited. Especially, via holes offer an important role to contact the NSt.1s with the ground plan of shield FPCB, as shown in Figure 2. However, the size. spacing and amount of via holes shall be as agreed between user and supplier (AABUS).
The length of test specimens shall be over 5 cm in order to obtain stable values from measuring equipment The width and thickness of test specimens shall be in accordance with the needs of the end user.
Figure 5 indicates one of the examples of a cross-section of a shield FPCB, where the shield region shall be formed just above the bare FPCB. The shield region contains the shield insulation layer. the shield conductive layer and the shield conductive adhesive layer. Where the shield conductive layer plays a role in an EMI absorber, the shield conductive adhesive layer plays a role for electric interconnection between the shield conduclive layer with the ground layer, and the shield insulation layer plays a role to protect the shield conductive layer from direct contact with the external device.IEC TR 63018 pdf download.