Intro
Recently I disassembled modern ebike brushless motor controller and found interesting approach of using multiboard with different stackup.
Construction
Detailed Multiboard Stackup
| 1 | Standard FR-4 board Logic components |
| 2 | Metal SMD spacers for high current path | Board-to-board connector/ribbon cable for signals |
| 3 | Aluminum Board (1L+) Power Components (Transistors, Drivers) |
| 4 | Any heatsink |
Real Example
This is a miniature controller for brushless ebike motor that designed as advanced multiboard:
Possible Issue
Using normal spacers (which not designed for soldering) cause desoldering when work at high power.
Source: http://invertor48.ru/publ/remont_svarochnykh_invertorov/2_remont_svarochnogo_invertora_fubag_in160/2-1-0-29
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Conclusions
- Such multiboard construction design need additional efforts, but can save a lost of space with excellent heatsink and electrical isolation
