last highlighted date: 2023-03-28
Highlights
- ht High Voltage PCB Mater
- Industry standards such as IEC-60950-1 and IPC-2221 mention some recommended materials for high voltage PCBs based on CTI values. These values can also be determined using some standard tests, most notably with either UL 746A, IEC 60112, or ASTM D3638. CTI values are classified in six Performance Level Categories (PLC):
- Note: categories related to CTI
- Voids at low resin content, which will increase the chances of degradation mechanisms between layers in the PCB stackup. Higher resin content is generally preferred in high voltage designs, which means the fiber weave will be looser.
- Note: high resin for high voltage, high fiber for high speed
- In dicyandiamide (DICY)-based FR4 laminates, the glass transition temperature (Tg) value can be rather high, reaching around 180 °C. However, these resin systems can fail earlier at high voltage gradient, as data from Isola shows (se below). While both might offer similar CTI, the failure rate with the phenolic curing agent is longer as CAF growth is inhibited in the cured laminate.
- Note: selecting material for high v
- Scratches in copper layers increase the risk of arcing.