BS 62490-1:2010 pdf download – ESL measuring method — Part 1 : Capacitors with lead terminal for use in electronic equipment
1 Scope
This part of IEC 62490 provides the equivalent series inductance L (ESL) measuring method for capacitors with lead terminal type for use in electronic equipment.
The inductance values of capacitors provided for this document are within the range of 1 nH to 1 0 nH.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60384-1 :2008, Fixed capacitors for use in electronic equipment – Part 1: Generic specification
3 Terms and definitions
For the purpose of this document, the terms and definitions given in IEC 60384-1 and the following apply.
equivalent series inductance L
inductive part of the impedance of capacitors
NOTE 1 The unit of ESL is Henry (H).
4 Measurement jig, short compensation jig, and spacer
4.1 Measurement jig (test fixture)
The measurement jig shall have the following features:
a) the lead terminal holding method shall be screw up;
b) the measurement jig has two pairs of screw-fixation electrodes for fixing the lead terminals of the capacitor to be measured. In pairs, one of the electrodes is fixed to the measurement jig and the other is adjustable for fixing the lead wire. The adjustable electrode shall move only in a direction to hold the lead terminal and shall not rotate
around the electrode fixing screw.
4.2 Short compensation jig
The short compensation jig shall be the lead wire rod which has the following features of the materials and dimensions, which includes the diameter or the cross-section area:
a) materials shall be the same materials as the lead wire of the capacitor to be measured;
b) shape shall be as shown in Figure 1 ;
c) spacing section (pitch) shall be the same lead spacing as the capacitor to be measured. The tolerance on the lead spacing of a short compensation jig shall be ±0,25 mm;
d) the straight section (shank) of the jig length shall be 5 mm to 1 0 mm, depending on what the measurement jig is able to hold. The straight section of the jig shall be kept from bending.
4.3 Spacer
These spacers shall be firmly fixed onto the measurement jig. The spacer material shall be nonmagnetic. An example is shown in Figure 2.
5 Measuring method
5.1 Measuring instrument
The impedance analyser (balance bridge method) with the following specification or equivalent shall be used:
a) inductance value (ESL) can be measured at a frequency of 40 MHz or higher;
b) basic impedance accuracy shall be ± 0,08 % or better;
c) impedance value of 3 mΩ or less can be measured.
5.2 Measurement conditions
The measurements shall be made under the standard atmospheric conditions for testing, as specified in IEC 60384-1 :2008, 4.2.1 . In addition, if there is any doubt as to the validity of measurement, the recovery conditions, as specified in IEC 60384-1 :2008, 4.2.2, shall be implemented.
5.3 Preparation of sample The lead terminals of a capacitor to be measured shall be cut at a length of 5 mm to 1 0 mm. When cutting the lead terminals, the lead terminal shall be kept from bending. NOTE By cutting the leads shorter, they make stable contact with the measurement electrodes and provide highly repeatability and reproducibility.
5.4 Measurement points The measurement points of ESL shall be the places of the seating plane or flange of the capacitor to be measured. An example is shown in Figure 3. NOTE Although during measurement the spacer is used, the measured value is equivalent to the value that would be measured at the seating plane of the lead terminals of capacitors as shown in Annex A.
5.5 Frequency and signal level
Unless otherwise specified in the product specification, the frequency and signal shall be as follows;
a) the measurement frequency shall be 40 MHz;
b) the signal level of an oscillation of a measuring instrument shall be 0,5 V to 1 ,0 V in r.m.s.