Pcb design guidelines
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A short guide to the design of PCB

A short guide to the design of PCB

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Pcb design guidelines Pcb design guidelines Document Transcript

  • PCB Design GuidelinesBelow are a number of Guideline Rules to follow and keep in mind when designing PCBs. These aregeneral rules that apply for the most PCB fabricators, but it is advisable to check with your fabricator.Board SizePCB manufacturers have a maximum size board they can handle. Typically this is also their panel size. ThePCB fabrication houses panel size is also important when mass producing boards. In this situation onewould want to fit as many boards as possible on a panel with as little wasted board space as possible (inorder to reduce costs). Normal board spacing for routing (how boards are separated on a panel) is 0.3",plus there is typically a 1.0" to 2.0" border on the board for handling it during processing.Board thickness may also be specified. A standard thickness and type of board is .062" FR4. Other typicalboard thickness are .010", .020", .031", and .092".Trace Width and SpacingThe chemical and photographic processes used to produce a PCB put requirements on the minimum widthof trace and the minimum spacing between traces. If a trace is made smaller than this minimum width thereis some chance it will open (no connection) when manufactured. If two traces are closer together than theminimum spacing there is some chance they will short when manufactured. These parameters are usuallyspecified as "x/y rules", where x is the minimum trace width and y is the minimum trace spacing. Forexample, "8/10 rules" would indicate 8 mil minimum trace width and 10 mil minimum trace spacing. Theserules (especially spacing) apply to any metal on the PCB, including pad to track spacing and line widths forstrings on the PCB.Typical modern process rules are 8/8 rules with values as small as 2/2 rules being available. For Press-n-Peel people have had success using 12/12 rules, but values a little larger are easier to make workconsistently. However, keep in mind that the board must be soldered and a trace within 8 mils (8/8 rules) ofa pad is easier to short than one with greater spacing when hand soldered. For hand soldering 10/10 rulesare much easier to solder (if the design density can allow spacing this large).Pad SizesThe biggest issues with pad size are solder ability and manufacturability. Solder ability is really just a matterof skill and will not be discussed here. Manufacturability is concerned with whether or not the pad will bebroken when the hold is drilled in it. This is mainly a function of the accuracy of the PCB manufacturersdrilling. If a drill hole is slightly off center the pad may be broken at one edge possibly leading to an open inthe circuit. A standard requirement for pad sizes is a 5 mil annulus. This means there must be .005" allaround the hole (i.e. a 28 mil hole would require a 38 mil pad). Something a little larger than this (maybe 10mils) is recommended for solder ability. AP Circuits states they have had relatively consistent success witha 2.5 mil annulus (i.e. a 20 mil hole with only a 25 mil pad), but they dont recommend it.Hole SizesMost PCB manufacturers have a wide selection of drill (hole) sizes available. Some charge per drill sizeused, others offer a standard set of drill sizes for no charge and then charge for any non-standard drill sizes.AP Circuits uses the latter approach. When choosing a hole size remember that the plate-through will causethe hole to effectively be more narrow. The plate-through thickness varies from .001" to .003". AP Circuits
  • plate-through thickness is approximately .015" (meaning the "finished hole" diameter is 3 mils smaller). Standard Drill Sizes Finished Hole Drill Number Hole Size Size 70 .028" .025" 65 .035" .032" 58 .042" .039" 55 .052" .049" 53 .0595" .056" 44 .086" .083" 1/8" .125" .122" 24 .152" .149"Hole DensityHole density is purely a cost issue. The more holes there are on a board the more wear and tearmanufacturing will put on the equipment (and thus the more the board will cost). Most PCB manufacturershave a maximum hole density and boards with greater density are charged more. For AP Circuits, there is aper hole charge for densities above 24 holes per square inch. Drill Chart Drill Drill Drill Inches Inches Inches No. No. No. 80 .0135 53 .0595 27 .1440 79 .0145 52 .0635 26 .1470 78 .0160 51 .0670 25 .1495 77 .0180 50 .0700 24 .1520 76 0200 49 .0730 23 .1540 75 .0210 48 .0760 22 .1570 74 .0225 47 .0785 21 .1590
  • 73 .0240 46 .0810 20 .1610 72 .0250 45 .0820 19 .1660 71 .0260 44 .0860 18 .1695 70 .0280 43 .0890 17 .1730 69 .0292 42 .0935 16 .1770 68 .0310 41 .0960 15 .1800 67 .0320 40 .0980 14 .1820 66 .0330 39 .0995 13 .1850 65 .0350 38 .1015 12 .1890 64 .0360 37 .1040 11 .1910 63 .0370 36 .1065 10 .1935 62 .0380 35 .1100 09 .1960 61 .0390 34 .1110 08 .1990 60 .0400 33 .1130 07 .2010 59 .0410 32 .1160 06 .2040 58 .0420 31 .1200 05 .2055 57 .0430 1/8" .1250 04 .2090 56 .0465 30 .1285 03 .2130 55 .0520 29 .1360 02 .2210 54 .0550 28 .1405 01 .2280 dBm - Volts - Watts ConversiondBm V Po dBm V Po dBm uV Po+53 100.0 200W +7 0.50 5mW -37 3.2+50 70.0 100W +6 0.445 4mW -38 2.85
  • +49 64.0 80W +5 0.40 3.2mW -39 2.5+48 58.0 64W +4 0.355 2.5mW -40 2.25 0.1uW+47 50.0 50W +3 0.320 2.0mW -41 2.0+46 44.5 40W +2 0.280 1.6mW -42 1.8+45 40.0 32W +1 0.252 1.25mW -43 1.6+44 32.5 25W 0 0.225 1.00mW -44 1.4+43 32.0 20W -1 0.200 0.80mW -45 1.25+42 28.0 16W -2 0.180 0.64mW -46 1.18+41 26.2 12.5W -3 0.160 0.50mW -47 1.00+40 22.5 10W -4 0.141 0.40mW -48 0.90+39 20.0 8W -5 0.125 0.32mW -49 800+38 18.0 6.4W -6 0.115 0.25mW -50 710 0.01uW+37 16.0 5W -7 0.100 0.20mW -51 640+36 14.1 4W -8 0.090 0.16mW -52 570+35 12.5 3.2W -9 0.080 0.125mW -53 500+34 11.5 2.5W -10 0.071 0.10mW -54 450+33 10.0 2W -11 64 -55 0.40+32 9.0 1.6W -12 58 -56 351+31 8.0 1.25W -13 50 -57 320+30 7.10 1.0W -14 45 -58 286+29 6.40 800mW -15 40 -59 251+28 5.80 640mW -16 35.5 -60 225 0.001uW+27 5.00 500mW -17 31.5 -61 200+26 4.45 400mW -18 28.5 -62 180+25 4.00 320mW -19 25.1 -63 160+24 3.55 250mW -20 22.5 0.01mW -64 141+23 3.20 200mW -21 20.0 -65 128+22 2.80 160mW -22 17.9 -66 115
  • +21 2.52 125mW -23 15.9 -67 100 +20 2.25 100mW -24 14.1 -68 90 +19 2.00 80mW -25 12.8 -69 80 +18 1.80 64mW -26 11.5 -70 71 0.1nW +17 1.60 50mW -27 10.0 -71 65 +16 1.41 40mW -28 8.9 -72 58 +15 1.25 32mW -29 8.0 -73 50 +14 1.15 25mW -30 7.1 0.001mW -74 45 +13 1.00 20mW -31 6.25 -75 40 +12 0.90 16mW -32 5.8 -76 35 +11 0.80 12.5mW -33 5.0 -77 32 +10 0.71 10mW -34 4.5 -78 29 +9 0.64 8mW -35 4.0 -79 25 +8 0.58 6.4mW -36 3.5 -80 22.5 0.01nWGetek® Laminates - Epoxy / Polyphenylene Oxide Resin (Type: NEMA FR-4, IPC-L-108B/04) Nominal Thickness GE E-Glass Dk@1MHz. thickness tolerance grade construction 0.0027" �0.0005" ML200D 1080 3.8 0.004" �0.0005" ML200D 2313 3.9 0.005" �0.0007" ML200M 2313/106 3.8 0.006" �0.0007" ML200D 2313/1080 3.9 0.007" �0.0010" ML200M (2)2313 3.8 0.008" �0.0010" ML200D 2313/2116 3.9 0.010" �0.0010" ML200D (2)2116 3.9
  • 0.012" �0.0010" ML200D 1080/7628/1080 3.9 0.014" �0.0015" ML200D (2)7628 4.2 0.018" �0.0015" ML200D 7628/2313/7628 4.1 0.021" �0.0020" ML200D (3)7628 4.2 0.024" �0.0020" ML200C 2116/(2)7628/2116 4.1 0.028" �0.0020" ML200D (4)7628 4.2 0.028"(Alt.) �0.0020" ML200C 1080/2313/(3)2116/2313/1080 3.8 0.031" �0.0030" ML200C 2116/(3)7628/2116 4.1 0.031"1 �0.0040" ML200D (4)7628 4.2 0.044"1 �0.0050" ML200D (6)7628 4.2 0.059"1 �0.0050" ML200D (8)7628 4.2 VSWR Vs. Return Loss Ret. Ret. Ret. Ret. Ret.VSWR Loss VSWR Loss VSWR Loss VSWR Loss VSWR Loss - - - - - 1.01 1.51 1.79 2.18 2.57 46.064 13.842 10.960 8.611 7.135 - - - - - 1.02 1.52 1.80 2.19 2.58 40.086 13.708 10.881 8.565 7.105 - - - - - 1.03 1.53 1.81 2.20 2.59 36.608 13.577 10.804 8.519 7.074 - - - - - 1.04 1.54 1.82 2.21 2.60 34.151 13.449 10.729 8.474 7.044 - - - - - 1.05 1.55 1.83 2.22 2.61 32.256 13.324 10.654 8.430 7.014 - - - - - 1.06 1.56 1.84 2.23 2.62 30.714 13.201 10.581 8.386 6.984 - - - - - 1.07 1.57 1.85 2.24 2.63 29.417 13.081 10.509 8.342 6.954 - - - - - 1.08 1.58 1.86 2.25 2.64 28.299 12.964 10.437 8.299 6.925 - - - - - 1.09 1.59 1.87 2.26 2.65 27.318 12.849 10.367 8.257 6.896
  • - - - - -1.10 1.60 1.88 2.27 2.66 26.444 12.736 10.298 8.215 6.867 - - - - -1.11 1.61 1.89 2.28 2.67 25.658 12.626 10.230 8.173 6.839 - - - - -1.12 1.62 1.90 2.29 2.68 24.943 12.518 10.163 8.132 6.811 - - - - -1.13 1.63 1.91 2.30 2.69 24.289 12.412 10.097 8.091 6.783 - - - - -1.14 1.64 1.92 2.31 2.70 23.686 12.308 10.032 8.051 6.755 - - - -1.15 1.65 1.93 -9.968 2.32 2.71 23.127 12.207 8.011 6.728 - - - -1.16 1.66 1.94 -9.904 2.33 2.72 22.607 12.107 7.972 6.700 - - - -1.17 1.67 1.95 -9.842 2.34 2.73 22.120 12.009 7.933 6.673 - - - -1.18 1.68 1.96 -9.780 2.35 2.74 21.664 11.913 7.894 6.646 - - - -1.19 1.69 1.97 -9.720 2.36 2.75 21.234 11.818 7.856 6.620 - - - -1.20 1.70 1.98 -9.660 2.37 2.76 20.828 11.725 7.818 6.594 - - - -1.21 1.71 1.99 -9.601 2.38 2.77 20.443 11.634 7.781 6.567 - - - -1.22 1.72 2.00 -9.542 2.39 2.78 20.079 11.545 7.744 6.541 - - - -1.23 1.73 2.01 -9.485 2.40 2.79 19.732 11.457 7.707 6.516 - - - -1.24 1.74 2.02 -9.428 2.41 2.80 19.401 11.370 7.671 6.490 - - - -1.25 1.75 2.03 -9.372 2.42 2.81 19.085 11.285 7.635 6.465 - - - -1.26 1.76 2.04 -9.317 2.43 2.82 18.783 11.202 7.599 6.440 - - - -1.27 1.77 2.05 -9.262 2.44 2.83 18.493 11.120 7.564 6.415 - - - -1.28 1.78 2.06 -9.208 2.45 2.84 18.216 11.039 7.529 6.390 - - - -1.29 1.40 2.07 -9.155 2.46 2.85 17.949 15.563 7.494 6.366 - - - -1.30 1.41 2.08 -9.103 2.47 2.86 17.692 15.385 7.460 6.341 - - - -1.31 1.42 2.09 -9.051 2.48 2.87 17.445 15.211 7.426 6.317
  • - - - - 1.32 1.43 2.10 -8.999 2.49 2.88 17.207 15.043 7.393 6.293 - - - - 1.33 1.44 2.11 -8.949 2.50 2.89 16.977 14.879 7.360 6.270 - - - - 1.34 1.45 2.12 -8.899 2.51 2.90 16.755 14.719 7.327 6.246 - - - - 1.35 1.46 2.13 -8.849 2.52 2.91 16.540 14.564 7.294 6.223 - - - - 1.36 1.47 2.14 -8.800 2.53 2.92 16.332 14.412 7.262 6.200 - - - - 1.37 1.48 2.15 -8.752 2.54 2.93 16.131 14.264 7.230 6.177 - - - - 1.38 1.49 2.16 -8.705 2.55 2.94 15.936 14.120 7.198 6.154 - - - - 1.39 1.50 2.17 -8.657 2.56 2.95 15.747 13.979 7.167 6.131 VSWR Vs. Return Loss (Continued) Ret. Ret. Ret. Ret. Ret.VSWR Loss VSWR Loss VSWR Loss VSWR Loss VSWR Loss - - - - -2.96 3.07 3.18 3.29 3.40 6.109 5.872 5.654 5.452 5.265 - - - - -2.97 3.08 3.19 3.30 3.41 6.086 5.852 5.635 5.435 5.248 - - - - -2.98 3.09 3.20 3.31 3.42 6.064 5.832 5.617 5.417 5.232 - - - - -2.99 3.10 3.21 3.32 3.43 6.042 5.811 5.598 5.400 5.216 - - - - -3.00 3.11 3.22 3.33 3.44 6.021 5.791 5.579 5.383 5.200 - - - - -3.01 3.12 3.23 3.34 3.45 5.999 5.771 5.561 5.365 5.184 - - - - -3.02 3.13 3.24 3.35 3.46 5.977 5.751 5.542 5.348 5.168 - - - - -3.03 3.14 3.25 3.36 3.47 5.956 5.732 5.524 5.331 5.152 - - - - -3.04 3.15 3.26 3.37 3.48 5.935 5.712 5.506 5.315 5.137
  • - - - - -3.05 3.16 3.27 3.38 3.49 5.914 5.693 5.488 5.298 5.121 - - - - -3.06 3.17 3.28 3.39 3.50 5.893 5.674 5.470 5.281 5.105 WIRE DATA CHART Diam Diam Diam DiamAWG AWG AWG AWG (In.) (In.) (In.) (In.) 4/0 0.4600 9 0.1144 21 0.0285 33 0.0071 3/0 0.4096 10 0.1019 22 0.0253 34 0.0063 2/0 0.3648 11 0.0907 23 0.0226 35 0.0056 1/0 0.3249 12 0.0808 24 0.0201 36 0.0050 1 0.2893 13 0.0720 25 0.0179 37 0.0045 2 0.2576 14 0.0641 26 0.0159 38 0.0040 3 0.2294 15 0.0571 27 0.0142 39 0.0035 4 0.2043 16 0.0508 28 0.0126 40 0.0031 5 0.1819 17 0.0453 29 0.0113 41 0.0028 6 0.1620 18 0.0403 30 0.0100 42 0.0025 7 0.1443 19 0.0359 31 0.0089 43 0.0022 8 0.1285 20 0.0320 32 0.0080 44 0.0020 PCMCIA CONNECTOR PIN OUT 16- 32-bit 16-Bit 32-bit Bit Pin Memory I/O+Mem CardBus Memory I/O+Mem CardBus Pin 1 GND GND GND 35 GND GND GND 2 D3 D3 CAD0 36 CD1# CD1# CCD1#
  • 3 D4 D4 CAD1 37 D11 D11 CAD24 D5 D5 CAD3 38 D12 D12 CAD45 D6 D6 CAD5 39 D13 D13 CAD66 D7 D7 CAD7 40 D14 D14 RSRVD7 CE1# CE1# CCBE0# 41 D15 D15 CAD88 A10 A10 CAD9 42 CE2# CE2# CAD109 OE# OE# CAD11 43 VS1# VS1# CVS110 A11 A11 CAD12 44 RSRVD IORD# CAD1311 A9 A9 CAD14 45 RSRVD IOWR# CAD1512 A8 A8 CCBE1# 46 A17 A17 CAD1613 A13 A13 CPAR 47 A18 A18 RSRVD14 A14 A14 CPERR# 48 A19 A19 CBLOCK#15 WE# WE# CGNT# 49 A20 A20 CSTOP#16 READY IREQ# CINT# 50 A21 A21 CDEVSEL#17 Vcc Vcc Vcc 51 Vcc Vcc Vcc18 Vpp1 Vpp1 Vpp1 52 Vpp2 Vpp2 Vpp219 A16 A16 CCLK 53 A22 A22 CTRDY#20 A15 A15 CIRDY# 54 A23 A23 CFRAME#21 A12 A12 CCBE2# 55 A24 A24 CAD1722 A7 A7 CAD18 56 A25 A25 CAD1923 A6 A6 CAD20 57 VS2# VS2# CVS224 A5 A5 CAD21 58 RESET RESET CRST#25 A4 A4 CAD22 59 WAIT# WAIT# CSERR#26 A3 A3 CAD23 60 RSRVD INPACK# CREQ#27 A2 A2 CAD24 61 REG# REG# CCBE3#28 A1 A1 CAD25 62 BVD2 SPKR# CAUDIO29 A0 A0 CAD26 63 BVD1 STSCHG# CSTSCHG
  • 30 D0 D0 CAD27 64 D8 D8 CAD2831 D1 D1 CAD29 65 D9 D9 CAD3032 D2 D2 RSRVD 66 D10 D10 CAD3133 WP IOIS16# CCLKRUN# 67 CD2# CD2# CCD2#34 GND GND GND 68 GND GND GND TRACE SPACING GUIDELINE Voltage Between ConductorsVDC or A1 A2 A3 A4 A5 A6 A7 Peak 0 thru .004 0.025 0.025 0.005 0.005 0.005 0.005 15 016 thru .004 0 .025 0.025 0.005 0.005 0.010 0.005 30 031 thru .004 0.025 0.025 0.005 0.005 0.015 0.005 50 051 thru 0.004 0.025 0.060 0.005 0.005 0.020 0.005 100 101 thru 0.008 0.025 0.125 0.015 0.015 0.030 0.015 150 151 thru 0.008 0.050 0.125 0.015 0.015 0.030 0.015 170 171 thru 0.008 0.050 0.250 0.015 0.015 0.030 0.015 250 251 thru 0.008 0.050 0.500 0.015 0.015 0.030 0.015 300 301 thru 0.010 0.100 0.500 0.030 0.030 0.060 0.030 500
  • More 0.0002/V than 0.0001/V 0.001/V 0.00012/V 0.00012/V 0.00012/V 0.00012/V 500 A1 - Internal Conductors A2 - External Conductors, uncoated, sea level to 10,000 ft. A3 - External Conductors, uncoated, over 10,000 ft. A4 - External Conductors, with permanent polymer coating (Solder Mask). A5 - External Conductors, with conformal coating over assembly. A6 - External Component lead/termination, uncoated. A7 - External Component lead/termination, with conformal coating.Electrical Design FactorsConductor CapacitanceC = 0.31 a/b + 0.23(1 + k) log10 (1 + 2b/d +2b + b2/d2) Where k = Substrate dielectric constant a = Conductor thickness b = Width of conductor in inches d = Distance between conductors in inchesConductor ResistanceR = 0.000227W Where W = Width of conductorCharacteristic ImpedanceZo = R + jwL / G + kwC Where Zo = Apparent Z of an infinitely long line in ohms R = Resistance in ohms L = Inductance in Henries G = Conductor per unit length of line in mhos C = Capacitance in faradsCharacteristic Impedance for a Micro StripZo = (h/W) (377 / (Sqrt. er) {1 + (2h/PI W)[1 + ln(PI W/h)]} Where h = Dielectric thickness
  • W = Micro Strip widther = Effective dielectric constant of substrate 1-800-319-3599 E-Mail: info@pcbdesignandfab.com