803774 Bergquist, 803774 Datasheet - Page 19

• Manufacturer Part Number: 803774
• Description: BOARD LED IMS SEOUL SEMI P5
• Manufacturer: Bergquist
• Series: Thermal Clad® IMS®r
• Type: Thermal Clad Boardr

Specifications of 803774

• Shape: Star
• For Use With/related Products: Seoul Semiconductor Z-Power P5
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Leakage Current HiPot Testing
Due to the variety of dielectric types, thicknesses and board layouts,
not all boards test alike. All insulated metal substrates closely resemble
a parallel plate capacitor during HiPot testing. Capacitance is equal to:
The capacitance value changes with different configurations of materi-
als and board layouts. This can be demonstrated where one board
fails the test and another passes, but when both are actually tested for
dielectric strength and leakage current in a controlled environment,
both pass.Therefore, it is very important to properly design the test-
ing and test parameters with the material characteristics in mind.Test
set-up and parameters that over-stress or do not consider reactance
of the material and its capacitive and resistive components, can lead
to false failures and/or test damage of the board.
Another test characteristic that is generally misunderstood with
insulated metal substrates is the leakage and charge current that take
place during the test. In most cases, the leakage current value on
insulated metal substrates is much smaller than the measurement
capability of a typical HiPot tester. What is most misunderstood is the
charge current that takes place during the test. Leakage current
measurements can only be realized once the board has been brought
to the full test voltage (DC voltage) and is held at that voltage during
the test. This current value and rate dI/dT is directly related to the
capacitance of the board. Therefore, a board that has an effective
capacitance higher than another board will have a higher charge
current rate than the one with a lower effective capacitance. This
does not reflect the leakage current or the voltage withstand of the
dielectric insulation instead, it represents the characteristic transient
response of the dielectric. Therefore, one is not able to determine
comparable leakage current based on the instantaneous charge
current. For accurate leakage test data, bring the board up to full DC
test voltage and hold.
MEASURED CURRENT - CHARGE CURRENT
where:
∈
A = Surface Area
d = Distance (Dielectric Thickness)
= Permittivity (Dielectric Constant)
C =
∈
A/d
=
Creepage Distance And Discharge
Creepage distance and discharge has to be taken into account
because Thermal Clad dielectrics often incorporate a metal base layer.
Circuit board designers should consider “Proof Testing” requirements
for: conductor-to-conductor and conductor-to-circuit board edge or
through holes. The graphs below depict flashover: without solder-
mask, with soldermask and under oil.
0.006" (152µm) Dielectric, 25mm circular electrodes
0.003" (76µm) Dielectric, 25mm circular electrodes
Typical Flashover Voltage in Various Media
Typical Flashover Voltage in Various Media
LEAKAGE CURRENT
FOR POSITION ONLY
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