• Course update (technical, CIM) • Quiz • Wires, Ground loops • Thermal considerations • Energy • PCB Layout 6.101 Spring 2020 Lecture 12 1 6.101 Course Update • Course information source: – Course website mit.edu/6.101 – Note will be posted on piazza when new information on course website is posted • Staff communications – Zoom/Video conference – Piazza – Email – Telephone 6.101 Spring 2020 Lecture 11 2 6.101 Spring 2020 Lecture 12 3 Revised Calendar Course Update • Lab 5, lab 6: physical lab replaced with LTspice simulation. Lab posted. • Quiz: Open book quiz, 3+1 hour limit, date selected by class poll: Wed 4/7, Thu, Fri 9p‐1am EST – Lpset 1‐5, Labs 1‐5, Lecture 1‐12; upload answers by 1am • Final project (Technical) – Single person or team – Proposal, block diagram, checklist, etc.. review/conferences as scheduled (video conference) – Design verified with LTspice – PCB layout required but not fab • Up to $100 budget for project – Can order from Digikey (need to setup business account under MIT) 6.101 Spring 2020 Lecture 11 4
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Course information source• Course update (technical, CIM) • Quiz • Wires, Ground loops • Thermal considerations • Energy • PCB Layout 6.101 Spring 2020 Lecture 12 1 6.101
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• Quiz: Open book quiz, 3+1 hour limit, date selected by class poll: Wed 4/7, Thu, Fri 9p‐1am EST– Lpset 1‐5, Labs 1‐5, Lecture 1‐12; upload answers by 1am
• Final project (Technical)– Single person or team – Proposal, block diagram, checklist, etc.. review/conferences as
scheduled (video conference)– Design verified with LTspice– PCB layout required but not fab
• Up to $100 budget for project– Can order from Digikey (need to setup business account under
MIT)
6.101 Spring 2020 Lecture 11 4
Ordering Parts
• Up to $100 budget for project• Ordering from Digikey:
• Abstract and proposal uploaded as scheduled• Design presentation review with Dave and Laura• Project Design Presentations (Tue/Thu during class time) ‐ attendance required
• Final report due last day of class. Extensions can be granted to Friday.
• Capacitance between turns of wires and layers of wires
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L
C
Use HP Impedance Bridge to measure
* RF choke
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Reliability
• Product of – stress factor (2x safety factor recommended)
• capacitor operating voltage• resistor power rating
– temperature factor– the environment factor
• shock, vibration• packaging
– the quality factor– the adjustment factor
PCB – Printed Circuit Board
• Invented by Paul Eisler circa 1930’s• Used in WW 2 radios• Released after WW 2 for commerical use by US Army
• General commercial use in 1950’s• Zenith Radio/TV last to implement PCB’s in manufacturing process – 1960’s
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Zenith Marketing Spin
6.101 Spring 2020 Lecture 12 32
PCB – Printed Circuit Board
• FR‐4 glass epoxy, high strength a elevated temperature, self extinguishing
• FR “Flame retardant”• Type two layer or four (or more) PCB• 1oz PCB: (1oz cu per sq ft)• Silkscreen: labels components on PCB • Solder mask: lacquer like polymer applied to prevent solder bridges and oxidation
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PCB Files
• Netlist: a text file describing connectivity of the design
• Gerber file: de facto standard used by PCB industry software to describe the printed circuit board images: copper layers, solder mask, legend, drill holes
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PCB General Rules
• Where ever possible, make the botton layer a ground plane
• Be careful of autorouters – all grounds not the same!• Coupling between traces: incidental capacitive
coupling; 0.75mm x 7.5mm run with 0.188 thickness creates a 1pF cap