Quality in Regard to Capacitors
Two manufacturers of multilayer ceramic capacitors have reported the identical quality assurance data
Vitramon, a business unit of Vishay Intertechnology Corp
Novacap, a Dover Technologies company
The managers of the reliability departments have indicated that 100% of their commercial grade capacitors are tested momentarily at a voltage equal to 250% of rated and all capacity and dissipation factor are measured.
The high reliability version of these capacitors cost about 10x ($1) the price of commercial units (average $0.10).
High rel components are tested at elevated voltage for one entire week.
The failure rate of new capacitors from these vendors is 0.2ppm. This applies to NPO, X7R, and Z5U ceramics.
More failures are created in assembly by poor handling and stressing causing minute fractures which lead to future breakdown.
Power bypass capacitors can cause the greatest damage due to heating in a failure mode because these capacitors are in very low impedance highest potential positions.
We will buy our components from a vendor such as ones interviewed. This will give some assurance that we have started with a probably good component.
We will use an assembly contractor which will dispense these components automatically one to the printed board to minimize handling. The assembly vendor will use a calibrated infra red oven to minimize soldering caused failures.
The completed assembly will be 100% tested and powered at operating condition for one week prior to shipping.