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In hardware development, you arrange physical atoms. In software development, you arrange abstract states. In both cases, you plan the interactive sequence of the system.

Electrical Design

Good electronics meet material safety standards such as RoHS, REACH, and JEDEC halogen-free (J-STD-609). Good parts are also flame-resistant (UL94-V0 is good) and EM-compatible (CISPR) as both low-interference and high-tolerance. Part moisture-sensitivity (MSL-1 is ideal) has minimal effect on operating performance (when assembled after correct handling) but better insensitivity provides flexibility (time, environment) for pre-assembly storage and processing.

For reliability, avoid pure-tin (ex. solder, plating) to eliminate the tin-whiskering failure-mechanism. Use PCB materials with low thermal expansion (CTE, cycling) and high electromechanical stability (CAF, electro-migration). For power electronics, prefer PCB materials with high thermal-solidity (Tg is glass-transition, Td is decomposition) and high thermal-conductivity (0.7W/mK is good non-ceramic benchmark). For signal electronics, prefer PCB materials with low dissipation-factor (Df), low relative-permittivity (Dk), and consistent impedance-control. Build PCBs with quality plating (ENIG is good) to a consistent fabrication class (IPC-2 is good, IPC-3 is better) and conduct pre-assembly electrical-testing (ex. flying probe).

For usability, prefer part packages that can be manually soldered and desoldered.

For strategy, consider the immediate and long-term availability (current stock, factory lead-time, pending orders) of each part costed at prototype-quantity (1 to 100 typical) to production-quantity (1000 to 10K+ typical).



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