Based on industry standards referenced, the solder mask material must meet or exceed a minimum breakdown voltage related to its thickness.
Minimum Requirements Based on Thickness
According to specifications like the one provided, the dielectric strength of solder mask is defined by a minimum voltage threshold it must withstand before electrical breakdown occurs. This minimum value is directly linked to the thickness of the solder mask layer.
The solder mask material shall meet or exceed the minimum value of 500 VDC per 25 µm [0.001 in] of thickness. This means that for every 25 micrometers of solder mask applied, it is required to withstand at least 500 Volts DC.
Furthermore, for layers with a thickness less than 25 µm [0.001 in], the material shall meet an absolute minimum breakdown voltage of 500 VDC. This ensures a baseline level of insulation even on thinner applications.
Key Specifications from the Reference
- Standard Requirement: Minimum 500 VDC breakdown per 25 µm [0.001 in] thickness.
- Test Method: Tested in accordance with IPC-TM-650, Method 2.5.6.1.
- Absolute Minimum: 500 VDC for thickness less than 25 µm [0.001 in].
Understanding Solder Mask Dielectric Strength
Dielectric strength, or breakdown voltage, is a critical property of solder mask. It indicates the material's ability to act as an electrical insulator, preventing short circuits between adjacent traces and components on a printed circuit board (PCB), especially when voltage is applied. The higher the dielectric strength, the better the insulation properties.
Here's a simple illustration of the minimum voltage requirement based on thickness:
| Solder Mask Thickness | Minimum Breakdown Voltage (VDC) | Notes |
|---|---|---|
| Less than 25 µm | ≥ 500 | Absolute minimum |
| 25 µm (0.001 in) | ≥ 500 | 500 VDC per 25 µm |
| 50 µm (0.002 in) | ≥ 1000 | 2 * 500 VDC |
| 75 µm (0.003 in) | ≥ 1500 | 3 * 500 VDC |
| ... | ... | ... |
These values represent minimum performance criteria; actual solder mask materials may have significantly higher breakdown voltages depending on the specific type and manufacturer.
