IEC TR 63017-2015 pdf free download.Flexible printed circuit boards (FPCBs) – Method of compensation of impedance variations.
Size. spacing and number of via holes for test specimens shall not be limited, but sufficiently represented Especially, via holes oiler an important role to contact the NSMs with the ground plan of shield FPCB. The number of via holes shall be as agreed between user and supplier (hereafter referred to as AABUS).
The length of the test specimen shall be over 5 cm in order to obtain stable values from the measuring equipment. Each end of the test specimen should consist of SMA (subminiature A) connectors. For discernment of a Cu line-width, write each number to the bare end of the test specimen near the SMA connector.
The decision of width and thickness of a test specimen shall depend on to the pitch or the number of the Cu line or according to the requirements of the user. However, generally the structure of the test coupon shall be AABUS.
An impedance value for FPCBs shall be changed with respect to the Cu pattern width, layer structure, thickness and materials. The structure and materials of the test specimens is required depending on the users sample specifications. But the variation of these test specimens is not important, because the user of FPCBs shall check only the impedance variation effect by using NSMs for the users sample specification.
4.3 Test method
In order to measure the proper impedance value for the test specimen, the following procedures shall be empoyed.
a) Impedance values of the test specimen shall be measured by employing TDR. test specimen and coaxial cable according to IPC 2141A.
b) Measurement conditions shall be set by means of the TDR, such as dielectric constant. measurement point, rising time, pulse width. etc.
c) The impedance value of the test specimen shall be measured according to the Cu line width for bare FPCB.
d) The measurement of the above process according to Cu line width shall be repeated for the shield FPCB (see Figure 4).
NOTE The guideline of the test method is provided in Annex C.
e) The measuring value of the two types FPCBs (bare and shield) shall be presented in form of a diagram (line chart using excel).IEC TR 63017 pdf download.