Introduction
The ever-increasing requirements for small volume envelopes contribute to integrating electronics to the mechanical design. Although there are numerous solutions this sheet provides the JPE standard in designing PCB’s.
Electrical layout characteristics
- Guidelines for outer layers (top/bottom), but also suitable for inner layers
- Copper base thickness: $18 \mu m$
- Suitable for PCB thickness of: $\le2.4 mm$
| Type | Minimal | Recomm. | Note |
|---|---|---|---|
| Trace Width | 0.15 mm | Recommended values: see “PCB trace widths” | |
| Edge-Trace | 0.45 mm | 1.0 mm | |
| Trace-Trace | 0.15 mm | 0.35 mm | |
| Trace-Pad | 0.15 mm | 0.35 mm | |
| Pad-Pad | 0.15 mm | 0.5 mm | |
| Pad-Hole | 0.20 mm | 0.5 mm | Also for Trace-Hole |
| Finished hole ø for PTH | 0.25 mm | Initial drill hole ø will be +0.1 mm to accommodate through hole plating | |
| Finished hole ø for NPTH | 0.35 mm | ||
| OAR PTH | 0.125 mm | 0.35 mm | |
| OAR NPTH | 0.30 mm | 0.5 mm | For non-plated hole but with pad on top/bottom |
| Via ø | 0.45 mm | 0.6 mm | A PTH to connect traces from/to different layers |
PCB trace widths
- Copper base thickness: $18 \mu m$
- Temperature rise of trace: $\le15^\circ$C
- Ambient temperature: $\sim 25^\circ$C
- For outer layer traces only (top/bottom)
| Signal type | Minimal | Recommended | Application |
|---|---|---|---|
| Low current | 0.5 mm | 1.0 mm | Low voltage DC power supply lines |
| High current | 1.5 mm | ≥ 2.5 mm | Mains, high power DC |
| Digital | 0.2 mm | 0.5 mm | I/O, logic, microcontroller, CPLD |
| Analog | 0.5 mm | 0.8 mm | ADC, low power op-amps |
PCB build up
A standard buildup of a 4-layer, thickness of 1.55 mm:
In a 2-layer design, the Copper Inner and Prepreg layers are left out but the base FR4 is thicker.
Mechanical design characteristics
| Type | Value | Note |
|---|---|---|
| PCB Dimensions | min. 5 x 5 mm | PCB does not have to be rectangular! |
| max. 425 x 425 mm | ||
| Board thickness | 1.55 mm | Industry standard |
| 1.00 mm | Also a standard for ceramic PCBs | |
| 2.00 mm | Heavy components | |
| Width for slots | min. 0.5 mm | |
| Radius inside corners PCB edge | min. 1.0 mm | |
| Drill size increments | 0.05 mm | |
| Standard tolerances | End-size drill ø NPTH: ±0.05 mm | |
| End-size drill ø PTH: ±0.1 mm | ||
| Contour dim. : ±0.2 mm | ||
| Position contour / holes: ±0.2 mm | ||
| Slot dimensions: width: ±0.1 mm length: ±0.2 mm | ||
| Surface finish on solderable pads and traces | HAL Lead-free | Good solderability, for standard PCB thickness |
| ENIG (chem. Ni/Au) | Flat surface, for connectors and contacts, expensive | |
| Immersion Silver (chem. Ag) | Flat surface, long shelf life, cheap |