µRuler User Manual

[timb]

µRuler Legend v1.0

oz		µm
ounce		micrometer/micron

Ounce to Micron conversion table for PCB copper thickness.

SMD FOOTPRINTS		POW
new + (old) SMD sizes in mm		Resistor Power

Size (in mm) of various SMD components plus the general power of resistors in that size.

mil		-->		mm		[Conversion Formulas]
thousandth of an inch		to		millimeters		mm to in/mil & vice versa

Table of mil to/from mm conversions plus formulas.

V		INT		MASK		BARE		>3km
volts		internal PCB layer		top PCB layer with mask		top PCB layer without mask		at altitudes above 3km

This table shows minimum PCB trace separation (in mils) for various voltages and locations.

mils		A/10°		A/5°		A/1°		mR/in
trace width		10°C above ambient		5°C above ambient		1°C above ambient		milliohms per inch

Maximum current for various trace widths (0.5oz copper) at several temperatures (°C) above ambient.

mils		A/10°		A/5°		A/1°		mR/in
trace width		10°C above ambient		5°C above ambient		1°C above ambient		milliohms per inch

Maximum current for various trace widths (1oz copper) at several temperatures (°C) above ambient.

mm		1°C		5°C		10°C
via size		1°C above ambient		5°C above ambient		10°C above ambient

Max current for various diameter 1mil thick vias at several temperatures above ambient.

SQ PIN		DIAmm
header size		equivalent diameter hole

Correct diameter hole needed for corresponding (square) pin size.

EIA SMD TANTALUM

capacitor number

capacitor letter

size in mm

Size (in mm) of SMD Tantalum Capacitors.

[neilrudden]

POW - is this a general power rating for a resistor in this size?

>3km if used at altitude greater than 3km

[chip273]

Please remove the red shadow text, it really hurts in the eyes.

[creyc]

Please remove the red shadow text, it really hurts in the eyes.

Fixed that for you. And WOW that's painful to read!

[timb]

Sorry guys, internet went out this morning after it posted. Yes, red text will be removed, that was just for my benefit while editing. I'll get this cleaned up shortly!

[EEVblog]

POW - is this a general power rating for a resistor in this size?
>3km if used at altitude greater than 3km

Correct on both.

[timb]

Almost done. mR/in is megohms per inch of trace, right?

[EEVblog]

Almost done. mR/in is megohms per inch of trace, right?

milliohms! - small m, not big M

[timb]

Almost done. mR/in is megohms per inch of trace, right?

milliohms! - small m, not big M

Doh!

Of course... Fixing that and adding descriptions for the last few tables and I should be done.

[timb]

Okay, initial post is done! Anything need correcting?

[samgab]

Okay, initial post is done! Anything need correcting?

"Ledgend"... really?

[timb]

Okay, initial post is done! Anything need correcting?

"Ledgend"... really?

Sorry I didn't notice a typo? The spellcheck either didn't catch it or I didn't notice. No need to be sarcastic, it's fixed now.

[don.r]

Nice work Tim. Can we have this stickyed?