|FR4*||1850 kg/m3||20 GPa||0.25 W/mK||11 μm/mK|
* Flame-Retardant category 4
FR4 is suitable for use in a vacuum environment. However, to address outgassing issues consider the following:
To be able to solder components by hand (for one-of PCBs, prototyping boards) make sure to use SMD components that are not smaller than a 0805-package (2.0 mm × 1.25 mm). Equally do not use IC’s smaller than an LQFP-package (0.4 mm pitch between pins), or use an IC-socket (for example for Ball Grid Array (BGA) packages).
When selecting connectors and their positions on the PCB, consider the final integration of the PCB so that connectors are always easy to reach.
If (single) wires need to be soldered to pads on the PCB, use a pad dimension of: min 3.0 mm x 1.0 mm (for wires ≤ 0.3 mm2 ). Consider implementing a strain relief.
The Silkscreen layer can be used to display reference text and/or visual marks. Place PCB name, part number, revision and [month/year] reference on the silkscreen for PCB identification. Anything on the silkscreen layer will clip against solder mask, copper or holes (in that order).
|Line width||0.17 mm||≥0.2 mm|
|Character height||1.0 mm||≥1.4 mm|
Make sure to mirror text on silkscreen bottom layer! This also applies to component reference text on the bottom layer.
All major PCB manufacturers are able to use the Gerber RS-274X format. Export all PCB layers in separate files, common layers are:
Do a net list / DRC check and connectivity check before exporting the Gerber data!
If the PCB is to be assembled by machine (pick-and-place components and reflow soldering for example), the following additional actions need to be done: