Cable, Wiring and Connector Guide

1. PCB Trace reference

Trace resistance guide based on

PCB board 1oz copper at temperature 100˚C. (worst case)

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Unit conversion table & calculator between inch, mil, mm, oz.

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also Download the wire gauge calculator from UltraCAD Design, Inc

If you are expecting a large current flowing through the traces, you have to keep in mind to provide a wider trace to increase the conductivity of the cable. Larger trace width means lower resistance.

For my PCB route software, the defined trace width for power is 1.27mm and signal is 0.38mm. Sometimes there is a need to route the trace through narrow space. In this situation, I would have to use the recommended trace width for power min, and signal min. Usually I will keep this narrow trace as short as possible to avoid higher resistance.

Seldom do I need to worry about traces carrying signal information. I am more worried about the conductor distributing the dc supply to individual circuit zone. Whenever possible, I would provide a wider traces for my 5V and ground supply.

When designing the PCB routing for my power supply, I would use the star topologies. This will ensure a evenly spread for the current distribution, hence lowering the burden of individual traces. I have actually experience such technical issue during my final year school project. The noise problem is somehow reduce after the attempt to improve on the trace routing. Another experience involve power up a remote system about 10m away. The distance is quite near and the power cable is rather thick to me. The voltage at the remote end is found to be too low to power the remote system. We have to double the cable conductor in order to resolved the problem. Our equipment conduct high current of about 20A if I remember correctly. The problem might not be obvious because the high current being drawn might happen during certain hard to determine event. For example, when your system trigger the lightings or motor which draws very high current for a short period of time. The voltage drop cause by the sudden high current draw might cause your system to fail. Therefore the design should always cater for the worst case. Always find out the maximum possible current drawn. Over design the system to ensure that the system will not fail in the worst case scenario. Just to make a note, that I have been referring to dc voltage supply.

For high voltage AC supply, I guess it is a different way of looking at it. My understanding in high voltage system is quite weak.

On the left is the reference table to estimate the resistance of the trace for my PCB routing. I have assume the worst case at temperature 100˚C with the copper layer of 1oz thick. Seldom do you need to refer to this table, unless you have encounter space restriction for your high current carrying traces. It is my usual practise to double the current carrying capacity. 2 times the maximum current I will be expecting. If you have the space, make it wider.

Electrical Resistance Equations:

Resistance = Resistivity x Length/Area

Question 1:

1oz copper PCB, Trace width 0.25mm, Trace length 0.1m, Operating temperature 25˚C

Solution 1:

Copper resistivity at  25˚C is 1.68×10^-8Ω.m

Resistance = 1.7×10^-8Ω.m  x  0.1m  /  (1oz x 0.25mm)

                 = 1.7×10^-8Ω.m  x  0.1m  /  (35um x 0.25mm)

                 = 1.7×10^-8Ω.m  x  0.1m  /  (8.75nm²)

                 = 1.7×10^-8Ω.m  x  0.0114×10⁹m^-1

                 = 0.19Ω

Question 2:

1oz copper PCB, Trace width 0.25mm, Trace length 0.1m, Operating temperature 100˚C

Solution 2:

Copper resistivity at  100˚C is 2.17×10^-8Ω.m,

Resistance = 2.2×10^-8Ω.m  x  0.1m  /  (1oz x 0.25mm)

                 = 2.2×10^-8Ω.m  x  0.0114×10⁹m^-1

                 = 0.25Ω

I have also provide the computation for copper resistance for your reference. Taking this opportunity to do further read up in order to explain in a simplified form.

Area is the cross sectional area of the conductor. Just like a water pipe, the larger the cross sectional area, the easier the current is able to flow through.

Resistivity defines the resistance of the material for a unit of length at a certain temperature. The resistivity for the material copper at 25˚C is found to be 1.7×10^-8Ω.m

The resistivity changes with temperature. The resistance will increase as the temperature increase. The term for this changing resistivity with temperature is known as the thermal resistivity of that particular material.

The material resistivity would therefore look like a graph curve. They are obtained through test and experiment. For some material, the graph curve could be approximated in the form of equation. This complicated formula describe the resistance behavior of the material under different temperature condition. For copper material, it can be represented from the following equation,

Copper resistivity = ρ₀(1+α(Temperature-T₀))

= 1.7×10^-8Ω.m  x  (1 + 3.9×10^-3Ω/˚C  x  (100˚C-25˚C))

= 2.2×10^-8Ω.m at a temperature of 100˚C

<ρ₀ is the material resistivity at T₀ temperature>

As you can see from the calculation on the left, the increase in temperature from 25˚C to 100˚C has increase the 0.1m copper trace by 0.06Ω. This is about 30% increase in the resistance.

To keep the topic simple, we will not go into the details of varying temperature. There can be other factor that can affect the resistance of the material.

Here is a quick and simple graph showing the change in temperature in relation with the trace width and the current flowing through it. (taken from the magazine elektor 2010-02). The graph assume the pcb copper trace thickness to be 35um (1oz) & that it is place in a open air environment (not enclosed inside a box/casing). For example, given the trace width of 0.6mm, and a 1.5A current flowing through it, we can expect the copper area to rise by another 10°C.

Some article reference:

PCB trace – HwB, trace vs current graph.pdf

Recommended digital and analog circuit layout on a PCB board.

Recommended trace corner layout.

Recommended plane placement.

Reference taken from “Op Amps for Everyone“.

More PCB layout recommendation can be found in the book “Op Amps for Everyone” from Texas Instruments.

2. Wire and Cable gauge

I have put up this wire gauge guide for my own reference. Very often there is a need to return to this reference to choose an appropriate cable for use. I have also written an article some time back. Myth about how the cable relate to their resistance. It is taken out from the main webpage but I have place a link here, for anyone who are interested to understand more.

NOTE: The following guideline is a brief guideline for copper ampacity (current rating or current-carrying capacity) of the cable used for power supplying purpose. The ampacity is defined as the maximum current the cable can withstand. Any current higher than that will generate enough heat to burn away  the cable. There are many factor affecting the current capacity of the cable, and it should be compensated accordingly. I would advise to select the cable, with at least double the current-carrying capacity for the intended equipment. Never operate near the cable current-capacity limits. You will never know when, the current overruns. Some of the factors that will affect the current-carrying capacity of a cable are:

– Conductive wire cross section area.

– Wire material. The temperature the material can withstand without melting out.

– Temperature. If the wire/insulator jacket can withstand higher temperature, the cable is able to carry more current.

     – place of installation or the surrounding temperature.

     – material of insulation jacket/skin/cover.

     – how much the cable can dissipate heat

– Stranded or solid wire type. Stranded wire can carry more current than a solid wire for AC type of signal/power. This is due to a phenomenon known as skin effect.

Reference:

– ayenbee AWG Wire Current Rating guide.pdf

– Wire Chart for 12Volt 24Volt.pdf

– A Guide to Wire and Cable Construction.pdf

230v Cable Size Selector- http://www.electacourse.com/cableselector.html

The factors involve are quite complex. The table is a simplified reference for myself to select the cables. Always allow a larger safety margin of minimum x2 when you chose your cable. Do take careful note of what you deploy.? There are many other factor, eg screw connections, plug contact which will affects the results. If the cable has the slightest warm, it is quite clear that the cable will be hitting it’s limit any time soon.

Wire Cable Description	Diameter (mm)	Area (mm2)	Copper Resistance 20˚C.Ω/km	Nearest SWG gauge (mm)	Nearest AWG gauge (mm)
	11.68	107.2	–	–	0000
	10.4	85.03	–	–	000
	9.266	67.43	–	–	00
	8.252	53.48	–	–	0
	7.348	42.41	–	–	1
	6.543	33.63	–	–	2
	5.827	26.27	–	–	3
	5.189	21.15	–	–	4
230Vac power cable 16mm2 (absolute maximum 69A) eg. Sub Mains	4.620	16.77	–	–	5
	4.115	13.30	–	–	6
230Vac power cable 10mm2 (absolute maximum 52A) eg. high power showers, cookers & other very high power devices	3.665	10.55	–	–	7
	3.264	8.366	–	–	8
230Vac power cable 6mm2 (absolute maximum 38A) eg. showers, cookers & other high power devices	2.906	6.634	–	–	9
	2.588	5.261	–	–	10
230Vac power cable 4mm2 (absolute maximum 30A, 6.9kW) eg. low power electric shower	2.305	4.172	–	–	11
	2.00	3.10	5.47	14 (2.05)	12 (2.05)
	1.90	2.80	6.05
230Vac power cable 2.5mm2 (absolute maximum 23A)	1.80	2.60	6.76	15 (1.83)	13 (1.83)
	1.70	2.30	7.57
Wire copper enameled, Pro-Power ECW1.5. current rating 2.74A eg. power speaker, transformer, motor	1.60	2.00	8.54	16 (1.63)	14 (1.63)
	1.50	1.80	9.7
230Vac power cable 1.5mm2 (absolute maximum 16A, 3.6kW)	1.40	1.50	11.2	17 (1.42)	15 (1.45)
	1.30	1.30	13.0		16 (1.29)
230Vac power cable 1mm2 (absolute maximum 13A, 2.99kW) eg. for light circuit	1.20	1.10	15.2	18 (1.22)
	1.10	0.95	18.1		17 (1.15)
Audio cable (shielded), Belden 8760 eg. power speaker drive	1.00	0.78	21.1	19 (1.02)	18 (1.02)
	0.95	0.71	24.3
	0.90	0.64	26.9	20 (0.91)	19 (0.91)
	0.85	0.57	30.2
	0.80	0.50	34.1	21 (0.81)	20 (0.81)
	0.75	0.44	38.9
	0.70	0.69	44.6	22 (0.71)	21 (0.72)
	0.65	0.33	51.7		22 (0.64)
	0.60	0.28	60.7	23 (0.61)
	0.55	0.24	72.3	24 (0.56)	23 (0.57)
Wire Cable Description	Diameter (mm)	Area (mm2)	Copper Resistance 20˚C.Ω/km	Nearest SWG gauge (mm)	Nearest AWG gauge (mm)
Category 5E network cable, 8060-OZZ7FNL from Alcatel 16 strand Ø0.2mm/strand Multipurpose 10core shielded. (RS232 communication, data signal), Belden 9540, Belden 9536 (6 core), Belden 9534 (4 core)	0.50	0.20	87.5	25 (0.51)	24 (0.51)
Category 5E network cable	0.45	0.16	108	26 (0.46)	25 (0.45)
Telephone line cable, GC5040 from Pro Power	0.40	0.13	137		26 (0.40)
	0.35	0.096	178	29 (0.35)	27 (0.36)
Ribbon cable, 1.27mm pitch					28
	0.30	0.071	243	31 (0.29)	29 (0.28)
Wire wrapping wire, Ok Industries	0.25	0.049	351	33 (0.25)	30 (0.25)
Wire copper enameled eg. small magnetic coil, speaker, solenoid, inductor, metal detector coil, small motor.	0.20	0.031	547		32 (0.20)
	0.19	0.028	605	36 (0.19)
	0.18	0.026	676		33 (0.18)
	0.17	0.023	757	37 (0.17)
	0.16	0.020	844		34 (0.16)
	0.15	0.018	970	38 (0.15)
	0.14	0.015	1120		35 (0.14)
	0.13	0.013	1300	39 (0.13)	36 (0.13)
	0.12	0.011	1520	40 (0.12)
	0.11	0.0095	1810	41 (0.11)	37 (0.11)
	0.10	0.0078	2190	42 (0.10)	38 (0.10)
	0.09	0.0064	2700	43 (0.09)	39 (0.09)
	0.08	0.0050	3420	44 (0.08)	40 (0.08)
	0.07	0.0039	4460	45 (0.07)	41 (0.07)
	0.06	0.0025	6070	46 (0.06)	42 (0.06)
Wire copper enameled (very fine) eg. transformer coupler for audio/signal, wire for earphone	0.05	0.0020	8750	47 (0.05)	43 (0.05)
Wire Cable Description	Diameter (mm)	Area (mm2)	Copper Resistance 20˚C.Ω/km	Nearest SWG gauge (mm)	Nearest AWG gauge (mm)

Cable Guide (typical cable type and name)          Click the chart for enlarge view.

Chart and images taken from Farnell, RS components and other websites.

      also Download the wire gauge calculator from UltraCAD Design, Inc

Other reference,

http://www.wiki.diyfaq.org.uk/index.php?title=Cables#Cable_Sizes

Refer to the most current National Electrical Code for further information on the electrical cable standards.

Special material for conductivity connection. Some references for non-traditional or advance conductor materials.

I happen to see some special wire product that I think I should put them in this website for reference.

The follow shows a rubber strip (a black layer sandwich in between the two white layer). It is call the elastomer connector. It is typically used to connect a flat LCD display panel to the pcb board without any soldering. It is quite cool when it was being shown to me for the first time. The LCD and pcb is connected with this elastomer connector sandwich in between.

Elastomer connector

(soft rubber strip that can conduct like a wire)

Conductive fabric or cloth

this pic is tken from other website

The conductive fabric actually can feels like a typical cotton cloth material. Some other feels like a nylon fabric, a bit like plastic. This is great for RF shielding, which we used it to test the performance of RF transmission through various material.

Glocom Marketing Pte Ltd

Conductive glass

reference: conductive glass

Singapore Safety Glass

Conductive paint

Conductive tapes

4. PCB Footprint reference

5. Tap drill guide (metric chart)

Commonly used screw size in Singapore, Metric (fine pitch)

Image of a machine cap screw

Enlarge image of the screw thread

->

References: http://www.aboveboardelectronics.com/catalogsmain.htm

Fasterner selection guide
http://www.aboveboardelectronics.com/abe_prodmain.htm
http://www.boltdepot.com/fastener-information/Type-Chart.aspx

Plastic fastener, Cable accessories

Enclosure bumper/rubber padding

Slide

Self Clinching Standoff

Installation Guide

Self Clinching Nut

Installation Guide

6. Common Connector Pin Out

This is a connector pin out reference.

3.5mm 4pins

Commonly use for:
– Earphone + Microphone

Earphone + Microphone:
Pin 1- Left Speaker
Pin 2- Right Speaker
Pin 3- Mic+
Pin 4- Ground

iPhone Mobile Phone Earpiece:
Samsung Galaxy
Samsung Nexus S
Pin 1- Left Speaker
Pin 2- Right Speaker
Pin 3- Ground, Push Switch
Pin 4- Mic+, Push Switch

Nokia Mobile Phone Earpiece:
Pin 1- Left Speaker
Pin 2- Right Speaker
Pin 3- Mic+, Push Switch
Pin 4- Ground, Push Switch

3.5mm 3pins

Commonly use for:
– Earphone
– Speaker

Earphone/Speaker pin out:
Pin 1- Left Speaker
Pin 2- Right Speaker
Pin 3- Ground

Notes: Speaker’s load is inductive. Measuring the resistivity from the pins will usually yield very low resistance (near to short circuit). Measurement by probing the pin in reverse will yield the same result.

Microphone pin out:
Pin 1- Mic+
Pin 2- Mic Power
Pin 3- Ground

Earphone/Microphone pin out:
Pin 1- Spk+
Pin 2- Mic+
Pin 3- Ground

3.5mm 2pins

Commonly use for:
– Microphone

Microphone pin out:
Pin 1- Mic+
Pin 2- Ground

Notes: Commonly available electret microphone contains active components. The positive terminal of a microphone can be detected using a ohm meter. Measure Mic+ (+ve Probe), Mic- (-ve Probe) will yield a higher resistivity than probing the reverse way Mic- (+ve Probe), Mic+ (-ve Probe).

Electret microphone equivalent circuit

Other type of microphone:
– The Carbon Granule Microphone
– The Piezoelectric Microphone
– The Condenser Microphone
– The Dynamic Microphone
– The Ribbon Microphone
– The Hot-Wire Microphone

reference:
http://mysite.du.edu/~jcalvert/tech/microph.htm

3.5mm 3pins, 2.5mm 3pins

Known to be use for:
– Walkie talkie

3.5mm 3pins, 2.5mm 2pins

Known to be use for:
– Walkie talkie

3.5mm 2pins, 2.5mm 3pins

Known to be use for:
– Walkie talkie

3.5mm 2pins, 2.5mm 2pins

Known to be use for:
– Walkie talkie

Mini DIN socket 6 pins (female receptacle)

Known to be use for:
– Walkie talkie

Walkie Talkie pin out:
Pin 1- Mic- / PTT Switch common
Pin 2- Mic+
Pin 3- PTT Switch
Pin 4- Speaker+ (left)
Pin 5- —unused— (right)
Pin 6- Speaker-

Mini DIN plug 6 pins (male pins)

Known to be use for:
– Walkie talkie

Walkie Talkie pin out:

Pin 1- Mic- / PTT Switch common
Pin 2- Mic+
Pin 3- PTT Switch
Pin 4- Speaker+ (left)
Pin 5- —unused— (right)
Pin 6- Speaker-

Mini DIN plug 4 pins (male pins)

Commonly use for:
– S-Video
– Walkie talkie PTT switch connector

Walkie Talkie pin out:
Pin 1- —unused—
Pin 2- —unused—
Pin 3- PTT Switch
Pin 4- PTT Switch

Mini DIN plug 4 pins (female pins)

DIN 5 pins

Known to be use for:
– Bike’s audio connector

Bike Audio pin out:
Pin 1- —unused—
Pin 2- —unused—
Pin 3- PTT Switch
Pin 4- PTT Switch

DIN 7 pins

Known to be use for:
– Bike’s audio connector

Bike Audio pin out:
Pin 7- PTT Switch (White)
Pin 3- Speaker L
Pin 5- Speaker R
Pin 2- Speaker Gnd
Pin 4- Mic-
Pin 1- Mic+
Pin 6- Mic shield

DIN 8 pins

XLR Plug 3 pins

Commonly use for:
– Studio Microphone

Studio Microphone pin out:
Pin 1- Shield
Pin 2- Positive Balance Signal
Pin 3- Negative Balance Signal

DC barrel jack/socket

DC barrel jack (OD=5.5mm, ID=2.1mm, length=11 to 12mm)

DC barrel socket

SMA RF connector (socket for WiFi Antenna)

7. Name of Connectors/Plugs

UK 3 pins Plug

EU 2 pins Plug

IEC 3 pins Socket

Male Plug -> IEC C14 (picture shown above)

Female socket -> IEC C13

Male Plug (with groove) -> IEC C16

Female socket (with groove) -> IEC C15

Check out here for more,

https://en.wikipedia.org/wiki/IEC_60320

Molex SPOX 5267 series connector header THT 2.5mm 4 way

Molex 5263 housing crimp receptacle 2.5mm 4 way

2.54mm pitch

molex KK 6410 series

molex KK 6471 crimp receptacle

2.54mm pitch

TJC8 connector (header and housing/receptacle pins)

Another name for housing is receptacle.

Pin Header PCB Crimp Style Cable Connector

TJC8 series(2.54mm pitch)Wire to Board Crimp style cable P.C.B connector housing terminal pin header

1. Pole: 1-40
2. Housing pins for wire size AWG28# – 22#
3. Header pins for PC board thickness: 1.6mm, 2.54mm pitch
4. Temperature range: -25C~85C
5: Voltage rating: 250V. AC/DC
6. Current rating: 3A
7. Contact resistance: 0.02
8. Insulation resistance: 800M
9. Withstand Voltage: 1000V. AC/1Min
10. Material:
Housing: PA66
Wafer: PBT
Terminal: Phos. Bronze Tin plated

Crimping tool, die sets size = ???

JST ZH connectors

B3B-ZR(LF)(SN)

S3B-ZR(LF)(SN)

ZHR-3

SZH-002T-P0.5

SZH-002T-P0.5 (0.08-0.13mm2, AWG28# – 26#, OD 0.8-1.1mm)
SZH-003T-P0.5 (0.032-0.08mm2, AWG32# – 28#, OD 0.5-0.9mm)

8. Name of Cable/Wire

Ribbon Cable & IDE connectors

Flat Flexible Cable (FFC)

Flex Jumper

9. Others