|reply or ask a question. If you are coming from a partner
site such as the SMTA or Solder.net, you'll need to complete
free registration to post.
Registration is Free and only takes a minute. Click Here
to register now.
Printed Circuit Board Assembly & PCB Design
SMT Electronics Manufacturing Forum Sponsors
One single sided copper clad board 180x130 mm
Iron-on toner transfer foil/paper or laser printer transparencies
Postscript capable Laser printer or Xerox copy machine
Etchant (Ferric chloride)
Scotch brit cleaning sponge for cleaning the board
Etch resistant pen (Decon) for touching up badly transferred
You can also expose the artwork on the board. In that case
you will need a photosensitized copper board and all the chemicals
to develop the board.
Download the 120k ZIP file with the Postscript/Acrobat files
and unpack it to a directory on your hard disk.
The archive contains the following files:
ARTWORK.PS / ARTWORK.PDF
is the unmirrored Artwork files in postscript/Acrobat format
Active threads from last 14 days :
SMT Production Start a new thread
Check box next to thread to receive posts via email
messages | views
Uncoalesced solder problem in fine pitch IC pads ramesh.r
09/06/08 1 158
AOI ION Federico 09/05/08 9 1585
problem in solderability omid 09/05/08 38 3757
MSL/MSD Tracking Bachman SMTA 09/05/08 7 259
noclean flux + wave soldering issue omid 09/05/08 15 453
power relay problems jeffrey miller 09/05/08 1 11
Miss Prints Jim 09/05/08 11 256 Electronics/PCB Layout
From Wikibooks, the open-content textbooks collection
< Practical Electronics
Jump to: navigation, search
PCB layout: The efficient laying out of traces on a PCB is
a complex skill, and requires much patience. This task has
been made vastly easier with the advent of readily available
PCB layout software, but it is still challenging.
1 Copper Thickness
2 Trace Width
6 Reference Handbook
9 further reading
11 External links
11.1 Manufacturer design tips
11.2 Other external links
12 Further reading
 Copper Thickness
The vast majority of PCBs are manufactured with "1 ounce
copper" on the outer layers. (If there are inner layers,
they are almost always manufactured with "1/2 ounce copper"[citation
The thickness of the copper layer on the PCB affects the
behaviour of the circuit. PCB copper thickness is usually
measured in ounces per square foot, or frequently, just ounces.
It can also be given in micrometres, inches or mils. The measurements
for common thicknesses are given below.
oz/ft2 屘m in mil
0.5 17.5 0.0007 0.7
0.75 25.5 0.0010 1.0
1 35 0.0014 1.4
2 70 0.0028 2.8
3 105 0.0042 4.2
As always, the thickness of a thin slab of metal with a given
top surface area is always exactly
The area is "1 square foot" (144 square inches),
the density of copper is 8.96 mg/mm^3 = 5.18 ounce/(inch^3),
and usually the mass is "1 ounce of copper",
 Trace Width
Different widths of traces have different properties that
could affect the operation of the circuit. For, example, a
thin trace has a higher resistance than a thick one, and can
therefore carry less current or will heat up more for the
Due to the large number of tables and charts, this information
is presented on different pages:
For current capacities, see Trace Current Capacity.
Most manufacturers can manufacture a minimum trace width of
0.010 inch. (Many can manufacture traces 0.008 inch wide).
Such minimum-size traces are more than adequate for most digital
and analog signals.
The manufacturer of each part recommends a "footprint",
a copper pattern for the part to be soldered to the PCB.
Most PCBs have many holes drilled in them.
Most PCBs with more than 1 layer have every hole "plated-through-hole",
even holes that don't need to be plated through-hole (tooling
holes and some through-holes). They do that because it takes
extra effort to plug "non-plated" holes before throwing
the PCB into the plating bath.
There are 3 general types of holes:
A via -- literally, a "way" to get from one layer
of copper to another layer of copper. The vias on a particular
PCB should all be the same size. Some people recommend
0.025" (0.6mm) diameter via holes, surrounded by a 0.042"
(1.0mm) diameter via copper pad  , if at
all possible. Some very dense SMT boards require smaller vias.
Some manufacturers can handle 0.012" diameter via holes,
surrounded by 0.024" diameter via pad 
High speed digital design
Protecting ideas and intellectual property
Component markings explained
Electronics construction ExpressPCB
The ExpressPCBWindows layout software makes designing PC boards
simple for the beginner and efficient for the professional.
Freeware hits: 13159 3,6 Mb
EAGLE Layout Editor Light Edition
The EAGLE Layout Editor is an easy to use, yet powerful tool
for designing printed circuit boards (PCBs). The name EAGLE
is an acronym, which stands for Easily Applicable Graphical
Freeware hits: 18321 6,5 Mb
FreePCB is a free, open-source printed circuit board layout
editor for Microsoft Windows, released under the GNU General
Public License. It is not quite finished, lacking some important
features such as a Footprint Editor, Design Rule Check and
Casing prototype circuits
Circuit board design and making
A Guide to Semiconductors Rate this link
How things work - physical explanations how common things
work Rate this link
SI Units Rate this link
Techlearner - Basics of electronics and computers, links to
industry, latest news on technology. Rate this link
The Vacuum Tube Era (1905 - 1948) - electronics history document
Rate this link
Twisted Pair - a site dedicated to those in pursuit of an
understanding of Electronics Rate this link
Unit Conversion Factors Rate this link
Using a multimeter - A meter is a measuring instrument. An
ammeter measures current, a voltmeter measures the potential
difference (voltage) between two points, and an ohmmeter measures
resistance. A multimeter combines these functions, and possibly
some additional ones as well, into a single instrument. Rate
Using the Multimeter to Measure Voltage and Resistance - Multimeters
are commonly used to measure voltage and resistance between
two points. Current is rarely measured because you must alter
the circuit to measure the current. Rate this link
Abbreviations used in Electronics Rate this link
Electronics Dictionary Rate this link
Lexicon of Semiconductor Terms - Intersil has assembled this
Lexicon of Semiconductor Terms, Abbreviations and Acronyms
to improve understanding of the exciting world of semiconductors.
Rate this link
Metric Prefix in Electronics Rate this link
What does k, M, m, n and p mean in component markings ? Rate
What's in a dB? Rate this link
A Guide to Semiconductors Rate this link
Basic Circuit Analysis - This page provides insight into Ohm's
law, Kirchoff's law, LED calculations and voltage dividers.
Rate this link
Basic electrical laws and circuits analysis techniques - Using
Circuit Magic to study electrical circuit theory. Rate this
How Semiconductors Work Rate this link
How to Understand, Present and Invent Electronic Circuits
Since there is no actual component put into a via, many PCBs
are manufactured with "plugged" vias (vias completely
filled with metal) and "tented" vias (vias completely
covered with solder mask).
A through-hole -- many components (called "through-hole
components") require a hole (a "through hole")
for each pin. The part manufacturer should specify a "footprint"
including the location and size of each hole. If there is
no recommendation, common practice is
round leads: add 6 mils to the nominal round lead diameter
to get the recommended PCB hole diameter. Rectangular leads:
find the lead diagonal (sqrt(x^2 + y^2)). Then add 6 mils
to get the recommended PCB hole diameter. ( 6 mils ~= 0.15
"The component lead - hole clearance should be 0,4 mm"
"The optimum pad diameter for a through-hole component
is twice its finished hole diameter."
A tooling hole -- ... preferably 0.125" ...[citation
needed] ... mounting holes ... A "tooling hole"
-- used to temporarily attach the board to test fixtures,
and later bolt the board into the final product case. Needs
to big enough for the mounting bolt. If the board is wave-soldered
(rather than reflow soldered), there is a risk that these
holes may get plugged with solder. So these holes are temporarily
plugged with a stopper -- either plugged when the PCB is manufactured
(becoming non-plated-through-holes, so solder won't stick),
or plugged during the wave-solder process.
The vast majority of PCBs have an overall thickness of 1/16
inch (1.58 mm). Some very dense SMT boards have an overall
thickness of 1/32 inch ( 0.79 mm ), which allows smaller via
holes to be drilled, allowing denser packing. Occasionally
boards are made with an overall thickness of 3/32 inch (2.3
mm), which makes it more rigid (but requires bigger via holes).
Often some or all layers are covered with a "copper
pour" ("ground plane" or "power plane").
Such pours typically have a signal-to-pour clearance of 0.010
inch  and clearance from the cut edge (perimeter
of the board edge) to pour of 0.020 inch.
(more layer stackup tips)
 Reference Handbook
A PDF file is being prepared which will contain many of the
diagrams and tables in a downloadable, printable format:
PCB Layout Reference
Usually an electronics or electrical engineer designs the
circuit, and a layout specialist designs the PCB. PCB design
is a specialized skill. There are numerous techniques and
standards used to design a PCB that is easy to manufacture
and yet small and inexpensive.
Most PCBs have between one and twenty conductive layers laminated
(glued) together in a sandwich with insulating plastic. PCBs
with more than two layers help construct complex or dense
circuits. They are not always used because they are more expensive,
and the inner layers are more difficult to inspect and repair.
In more complex PCBs, two or more of the layers are dedicated
to providing ground and power. These ground planes and power
planes distribute power well. They also prevent radio waves
from antennas unintentionally formed by tracks. These planes
are rectangular sheets of foil that occupy entire layers (except
for small holes to avoid unwanted connection to vias and through-hole
components). They distribute electrical power and heat better
than narrow traces. Sometimes solid metal PCBs with thin layers
of insulation are used. The power electronic substrate carries
away waste heat when air cooling is impossible.
Four-layer PCBs with a ground and power plane are often used
in high-quality, but cost-conscious audio, avionics and medical
electronics. Most consumer products have one or two layers.
Underfill 300balls BGA connector akareti 09/05/08 2 78
Pin Chain Lube for Vitronics SPM Sr.Tech 09/05/08 3 109
Best compromise aj 09/05/08 2 291
Humiseal 1C51/1C49 Help Mr McMeany-Head 09/04/08 1 489
3rd Party Juki Machines geron 09/04/08 1 18
looking for HASL TIN thickness specification eliezerk 09/04/08
Omniflo 5 high temperature warning AR 09/04/08 4 389
Solder not reflowing properly dyoungquist 09/03/08 20 943
Juki pick and place ? Sr.Tech 09/03/08 7 416
Imm Silver tarnish? blnorman 09/03/08 6 285
PCB becomes darken (yellownish) Kelson 09/03/08 10 985 Amateur
A Printed Circuit Board (PCB) design for Mel Bartels' Alt/Az
This PCB Layout does NOT include the new added feature of
field rotation! For a description of my fieldrotation daughterboard
go to my Fieldrotation page.
Many people asked me to sell them one of my circuit boards.
I do NOT manufacture or sell those boards! It is actually
quite easy to make them. I however will be happy to answer
any question about the process of building one.
Neither PCB's manufactured using my design nor the design
itself may be sold. The use of the content of this page for
any kind of publication needs the agreement of Mel Bartel's
Also see my CompuDob page that displays my 6" Computerized
? WebRing Inc. scope drive
<< Prev | Ring Hub | Join | Rate| Next >>
I assume that the reader is familiar with the basic process
of etching printed circuit boards. If not, I recommend to
look through the reference section at the end of this page.
The reader has to take all necessary safety precautions while
handling the chemicals for PCB etching!
Those include: Rubber Gloves, glasses to protect the eyes,
apron, suitable and well-ventilated working area.
MIR-ART.PS / MIR-ART.PDF
is the mirrored Artwork files in postscript/Acrobat format
reflow profile development Allan 09/02/08 3 34
ive solder profiles Mr McMeany-Head 09/02/08 19 925
Siemens S-27 Error Code Descriptions Mark W 09/02/08 1 18
Electro-mechanical assembly Q-Man 09/02/08 2 43
Land Grid Array (LGA) Rework pete 09/02/08 3 124
Mydata M100 Series Sr.Tech 09/02/08 5 464
BTU TRS-14 Yiannis 09/02/08 2 298
soldering ROHS boards with sn/pb components