Electrical Design
Resources
General
| Description | Link |
|---|---|
| Art of Electronics, 3rd Edition, Paul Horowitz and Winfield Hill | https://archive.org/details/the-art-of-electronics-3rd-ed-2015_202008 |
| Microcontrollers Intro (Jay Carlson) | https://jaycarlson.net/microcontrollers/ |
| ROHM EE Knowledge Base | https://techweb.rohm.com/ |
| Thermal Intuition (Texas Instruments, 2020) | https://www.ti.com/lit/an/slpa015/slpa015.pdf |
| Custom Silicon with Google | https://developers.google.com/silicon |
Circuit Design
| Description | Link |
|---|---|
| Linear Circuit Design Handbook (Analog Devices, 2008) | https://www.analog.com/en/education/education-library/linear-circuit-design-handbook.html |
PCB Design
| Description | Link |
|---|---|
| MFG Design Limits (Candor Industries) | https://www.candorind.com/design-limits/ |
Architecture
| Description | Link |
|---|---|
| Comparing Bus Solutions (Texas Instruments, 2017) | https://www.ti.com/lit/an/slla067c/slla067c.pdf |
Standards
| Description | Link |
|---|---|
| Canada Electrical Code | https://www.csagroup.org/store/product/CSA%20C22.1:21/ |
Reference
| Description | Link |
|---|---|
| Wire Gauge Chart (Powerstream) | https://www.powerstream.com/Wire_Size.htm |
Key Knowledge
| Topic | Keywords |
|---|---|
| basic | resistor, capacitor, inductor, impedance |
| x | ground shift, parasitics (leakage, distortion), reliability, whiskering, corrosion (ECM, CAF) |
| reliability | corrosion, ionic contamination, dendritic growth, intermetallics, dielectric breakdown, charge trapping |
| thermal | expansion, cycling, real-time distribution, operating range, circuit-longevity (based on temp average/volatility), flammability |
| electromagnetics | (EMI, EMC) |
| mechanical | form trade-offs (weight, 3D size), part protection, SMT/THT shock-resist, ingress protection, transient voltage suppression, moisture sensitivity, conformal-coat/encapsulation |
| signal integrity | impedance matching/continuity, capacitive coupling, skin effect loss, trace length loss, dielectric loss, dissipation loss |
| power integrity | decoupling capacitor (against inductive delay), inductive bounce/ringing/kickback, snubber |
| PCB fabrication | layers, surface finish, impedance control, vias (landless, blind, buried, tented, filled, plated-over), soldermask-defined pads |
| PCB assembly | reflow conduction paths, flux activation, first-side mass limit of two-sided assembly |
| MCU workflow | IDE, IPE, debugger, production programmer |
| quality assurance | optical inspection, QVL/PPAP, MFG revision errata |
| extra | FIT, cascading-events, silkscreen, connector mechanisms, universal footprints/pinouts, standard interfaces, one-firmware multiple-configurations |
| debug | single-wire-debug (SWD), JTAG |
| regulatory compliance | RoHS, REACH, WEEE, CE (EU), UL Listed/Recognized, FCC, TUV, Flammability (ex. UL94V-0), EMC, RED (EU) |
Qualified Vendor List (QVL), Qualified Parts List (QPL)
Tools
Main Design Program
Kicad (STRONGLY RECOMMENDED)
Free, open-source, cross-platform, sponsored by CERN
Normal Workflow:
- Prepare schematic symbols and layout footprints
- Design schematic (abstract circuit design)
- Import schematic into layout (each symbol should be mapped to a footprint)
- Design layout (physical board design, all layers)
Export Workflow for PCB Fabrication
- Export layer files (outline/copper/soldermask/silkscreen, gerber format) and drill file (absolute, mm, excellon format).
- Specify, as necessary, the layer stack-up (table) and any impedance control on which traces (table/graphic)
- Specify extra info:
| Specification | Notes |
|---|---|
| board material | |
| finished copper thickness per layer | (ex. 2oz) |
| finish plating | (ex. ENIG) |
| finished board thickness | (ex. 1.6mm) |
| fabrication class | (ex. IPC2) |
| soldermask color | green (RCMD) |
| silkscreen color | white (RCMD) |
| depanelization | (ex. individually routed boards; one-up) |
| electrical testing | yes (RCMD) |
| board dimensional tolerance | (ex. +0mm, -0.2mm) (if important) |
| tented vias | (if any in design) |
| soldermask-defined pads | (if any in design) |
Export Workflow for PCB Assembly:
Extras:
- Kicad Visual PCBA Plugin (for DIY PCB assembly): InteractiveHtmlBom
Assorted
| Function | Name | Notes |
|---|---|---|
| Oscilloscope | Siglent SDS2104X Plus (2020) | 100-350MHz, 8-bit ADC, 2GSa/s, 4-channel |
| DC Power Supply | Siglent SPS5083X (2021) | 80V, 45A, 1080W, 1mV/1mA |
Design Targets
System
| Scope | Specification |
|---|---|
| measurement standard | metric |
| DC voltages | 48V, 24V, 12V, 5V, 3.3V |
Parts
| Scope | Specification |
|---|---|
| nominal size | 1608 metric or bigger (smaller can be acceptable) |
| composition | RoHS (RoHS3, EU Directive 2015/863, without exemptions), halogen-free (IEC 61249-2-21), red-phosphorous-free, antimony-free, REACH (EU Regulation 1907/2006, without candidate substances) |
| operating temperature | -40C to 125C |
| reliability qualification | automotive (AEC-Q Grade 1) |
| quality assurance features | wettable flanks (for optical inspection; MOI/AOI) |
| moisture sensitivity (for assembly) | MSL 1 (low priority target) |
| lifetime | 10+ years |
| tin finish (if applicable) | matte-tin (reduced whiskering) |
Special:
- glow-wire connectors (thermal ignition safety)
- soft-termination MLCC (anti-crack)
- aluminum-polymer bulk capacitors (long-life)
PCB
| Scope | Specification |
|---|---|
| impedance control | for high-frequency, precision-analog |
| material performance | high thermal stability (ex. low-CTE, cycling tolerance, high electromechanical stability, high thermal conductivity (ex. 0.7W/mK is a good non-ceramic benchmark), good impedance-properties (ex. low relative-permittivity, low dissipation-factor) |
| surface finish | ENIG |
| soldermask color | green (optical ergonomics) |
| silkscreen color | white |
| fabrication class | IPC2, IPC3 |
| flame resistance | UL94-V0 |
| mounting | M3 screws |
| corners | rounded (5mm+ radius) |
| Footprints | pad rounded-corner (0.05mm), BGA pads soldermask-defined, thermal reliefs for THT and high-maintenance SMT |
| PCB Assorted | Trace-to-Via Teardrop, 0.15mm thruhole dia tolerance |
| PCB Silkscreen | reference-designator for each part-footprint (ideal), remove designators when space is limited (use fab drawing for assembly), complete perimeter outline per footprint (incomplete outline for space; dotted/dashed outline for flux-scatter, ex. high-rel BGA assembly), functional label for every external pin |
| PCB Silkscreen Text Size | 1.2/0.6 mm height (normal/minimum), 0.2/0.15 mm line width (normal/minimum) |
| PCB Spacing (min) | 0.2mm board-edge to silkscreen-edge, 0.5mm board-edge to hole-edge |
| Via Size (drill dia, ring dia) | landless (0.2mm, 0.2mm), compact (0.25mm, 0.35mm), thermal (0.3mm, 0.5mm) |
| External Conductor Clearance (IPC-2221, min) | 0.1mm (30V class B3), 1.5mm (100V class B3), 3.2mm (170V class B3) |
| Internal Conductor Clearance (IPC-2221, min) | 0.05mm (30V), 0.1mm (100V), 0.2mm (300V) |
| quality assurance | electrical testing |
PCB Silkscreen, Common Elements:
| Meaning | Example | Required |
|---|---|---|
| Company Name | Guidebolt | Always If Possible |
| Part ID | BC2023R4 | Always If Possible |
| Component Designator | R1 | Always If Possible |
| Component Value | 1K | Optional |
| Batch Date/ID | 202305C1 | Optional |
| MFG Origin | Made in Canada with Imported Parts | Optional |
PCB Assembly
| Scope | Specification |
|---|---|
| solder | lead-free solder (SAC305) containing low-activity no-halogen flux (category L0, no-clean, IPA-washable) |
| conformal coating | especially for condensing/high-altitude environments and compact high-voltage |
| underfill | for best shock and thermal cycling (especially for BGA, WLCSP) |
Protection
- Lightning Resistance
- ESD Resistance
- Overvoltage Protection (OVP)
- Overcurrent Protection (OCP)
- Reverse Polarity Protection (RPP)
- Electromagnetic Compatibility (EMC)
PCB Parts and Circuits
Basic
Resistor Standard: R1608M (SMT), AEC-Q200, 100V, Thin Film, Inorganic Passivation, -55C to 175C
MLC Capacitor Standard: AEC-Q200, 100V, Soft Termination, X7S/X8L
10A Diode: Diodes Inc, SBR10M100P5Q-13 (100V, 2uA leak-max 25C, 0.88V drop-max, 18ns switch, 245pF junction, -55 to 175C, 4x6.5/26mm2) (recommended)
Controller Area Network (CAN)
Standards: CAN, CAN-FD, CAN-SiC (CiA 601-4), CAN-XL, CANOpen
CAN-FD Transceiver: (testing) (target spec: CAN-FD-SiC, AECQ-G1, 8Mbps, -58 to 58V bus fault tolerance, exposed pad, ESD tolerance, UVLO, standby, VIO, hot-swap, thermal shutdown, 3x3mm)
RS485
RS485 Transceiver: Maxim Integrated, MAX14775EATA+ (-40 to 125C, 20Mbps, -65 to 65V fault tolerance, hot-swap, thermal shutdown, 3 to 5.5V input, SCP, reliable output state) (3x3x0.75mm, TDFN8, exposed pad, side pads) (Datasheet)
We wanted 100Mbps (ex. Maxim Integrated, MAX22501E) but we highly value 60V+ fault protection (given our 48VDC power standard) and our current node MCU frequencies are too low anyway (future goal, 1GHz+ low-power compact MCUs).
Single Pair Ethernet (SPE)
(SPE: IEEE 802.3)
SPE Summary, Microchip Webpage
100BASE-T1, TI, SZZY009, 2018 (PDF)
- video-audio bridge
- time-sensitive networking (TSN)
APU
ISA: Complex, Reduced (General), Reduced (Graphics)
AMD, Intel, Nvidia
- 8 Core, 16 Thread, 3+ GHz Base, iGPU
- Cache: L1-I 32KBx8, L1-D 32KBx8, L2 512KBx8, L3 16MBx1
- 64GB DDR5 RAM Support
- <30W TDP
General Memory
Commercial SATA 2.5FF SSD: SAMSUNG, 870 EVO, 4TB (0 to 70C, 2400TBW) (Datasheet)
Industrial M.2 NVMe SSD: (testing) (target spec: PCIe 3.0, NVMe 1.4, -40C to 85C, 2280FF, SLC, vibration/shock/altitude)
MCU
- integrated development environment (IDE) (develop MCU firmware)
-
integrated programming environment (IPE) (upload MCU firmware) (advanced mode, production mode)
-
AECQ-G1 (-40 to 125C)
- <100uA/MHz
- ECC Dual-Bank Flash
- ECC SRAM
- Ethernet MAC
SWD over USB-C:
- SWDIO (A2, B2) (digital signal, continuously unique, debug data)
- SWDCLK (A3, B3) (digital signal, single frequency clock, debug data rate)
- RST (A10, B10) (digital signal, simple momentary, debug start sequencing)
- VTG (A11, B11) (analog signal, constant, debug I/O voltage setting)
Embedded Memory
https://www.fujitsu.com/jp/group/fsm/en/products/index.html
Ferroelectric RAM (non-volatile): 4Mbit (AEC-Q100), 50MHz max, 10+ trillion writes/reads (4mA max at 50MHz), 120ns write cycle
Resistive RAM (non-volatile): 12Mbit, 10MHz max, 1 million writes (1.5mA typical), unlimited reads (0.15mA typical at 5MHz)
NRAM (carbon nanotubes):
Thermal
Thermal Jumpers: Vishay, THJP (170W/m-K, -65C to 150C) (preferred: 1608M/3216M, tin-plated nickel termination) (Datasheet)
XY Thermal Pads: (testing) (1800 W/m-K, -40C to 120C)
Z Thermal Pads: (testing) (28 W/m-K, -55C to 400C)
USB
USB-C 24-pin Connector: Wurth Electronik, 632723300011 (SMT/THT standard-mount, -40C to 105C, 6.2mm insertion length, 1.9mm pin length)
USB2 SPEC-DL WEBPAGE, 2021-07-01
USB4 SPEC-DL WEBPAGE, 2021-06-09
USB POWER DELIVERY SPEC-DL WEBPAGE, 2021-07-06
USB Type-C REV2.1 SPEC-DL WEBPAGE, 2021-05-25
USB Type-C LOCKING SPEC-DL WEBPAGE, 2016-03-09
Connector
General-Purpose Wire-to-Wire: Molex, CP-4.5 Series (600V/10A max, 16-20/22-26AWG, -40C to 120C, polarized/color-mating, locking, genderless terminals, halogen-free)
High-Current Detachable: Wurth Electronik, THT External-Thread, 74651173 (M3, 50A, -55C to 150C, tin-plated brass)
Medium-Current Permanent Wire-to-Board: Molex, Solder-Right (1.95mm low-profile, 28AWG to 14AWG crimp, dual THT mounting, 1.6mm thick PCB compatible, -40C to 105C) (40N pullout-min for 16AWG)
Low-Current Permanent Wire-to-Board: Molex, Board-In 2.5mm Series, Right-Angle Models (3A/125V max, -40 to 125C, 0.22 to 0.35mm2 wire, halogen-free)
Fuse
48V-Power Time-Delay Fuse: Schurter, UMT-H Series (C-UL-US/TUV/CQC, AECQ, -55 to 125C, 125VAC/72VDC, 5.3x16mm, 500A breaking) (Datasheet)
Class-J Time-Delay Fuse: Mersen, AJT Series (UL/CSA, 200kA-AC/100kA-DC interrupt, open fuse indication, dual-element) (aka 4TAR9 at Grainger Canada) (Datasheet)
Fuse Reducer: Mersen J636 (UL/CSA, 600V, adapts 30A fuse to 60A fuseholders)
Wireless
(Wifi: IEEE 802.11)
Wifi Antenna: 2.4/5/6GHz, <1.5 VSWR, 80%+ efficiency, omnidirectional, -30 to 85C, SMA-M
- 2400 to 2485 MHz
- 5150 to 5850 MHz
- 5925 to 7125 MHz
RF Bulkhead: SMA-F to SMA-F, 18GHz max, <1.22 VSWR, <2mohm, -65 to 165C, 50 ohm impedance
- stainless steel body
- beryllium copper contact
- gold finish (body+contact)
- PTFE insulation
- silicone seal
RF Cable: SMA-M to SMA-M, 8GHz max, <1.5 VSWR, gold finish, 50 ohm impedance
Infrastructure Parts and Circuits
20A 125V Duplex Outlet: Schneider Electric, Square D, X Series, SQR42204WH (tamper-resistant, matte white, outdoor, heavy-duty)
NEMA 15-50 Straight Plug: Hubbell, HBL8451C
NEMA 15-50 Receptacle: Hubbell, HBL8450A (requires 63mm-hole 2-gang wallplate, deep 2-gang box)
63mm-hole 2-gang Wallplate: Hubbell, SS701 (stainless steel)
Deep 2-gang 3/4-Hub Box: Thomas and Betts, 2IHD5-2 (requires 3/4-hub closure x2, 3/4-hub fitting)
3/4-hub closure: Thomas and Betts, PLG-2-RD (zinc) (can also be sourced from 3/4-hub box included-accessories)
1/2-hub AC90 fitting: Thomas and Betts, CI71 (zinc alloy)
3/4-hub AC90 fitting: Thomas and Betts, CI72 (zinc alloy)
Thomas and Betts, Iberville, Commercial Grade Fittings: PDF
PCB Assembly
Underfill
Capillary Underfill Dispensing Method (web article, GPD Global)
As summarized in Test-to-Fail Methodology for Accurate Reliability and Lifetime Evaluation of eGaN Devices in Solar Applications (PDF article, EPC), underfill significantly improves the failure rate to zero (88 devices, 1800 ramp-dwell cycles of -40C to 125C).
Henkel Loctite Board-Level Underfill Solutions (PDF)
Notes
Thermal Asymptote: When current flows through a trace, its temperature approaches infinity; when a soldering tip touches a pad, its temperature approaches the tip temperature.
Footprints are spaced to support part-holding with tweezers (0.8mm tip-thickness).
Same-net pads can be closer together. Different-net pads should be further apart.
Other Resources
(less common use)
| Description | Link |
|---|---|
| MIL-STD-202: Electrical Part Testing | WEB-PDF |
| AEC Qualification | WEB-PDF |