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electronic PCB design,circuit PCB design,PCB layout,shenzhen, China,Low cost

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Printed Circuit Board Assembly & PCB Design
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Materials needed
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 traces
Electric Iron
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.


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Layout
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

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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.

Contents [hide]
1 Copper Thickness
2 Trace Width
3 footprints
4 holes
5 layers
6 Reference Handbook
7 layers
8 traces
9 further reading
10 references
11 External links
11.1 Manufacturer design tips
11.2 Other external links
12 Further reading


[edit] 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 needed] ).

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",


[edit] 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 same current.

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.


[edit] footprints
The manufacturer of each part recommends a "footprint", a copper pattern for the part to be soldered to the PCB.


[edit] holes
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[1] recommend 0.025" (0.6mm) diameter via holes, surrounded by a 0.042" (1.0mm) diameter via copper pad [citation needed] , 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 [citation needed] .Acronyms
Basic tutorials
Theory
Cooling
Analogue electronics
Digital electronics
High speed digital design
Analogue-digital conversion
Protecting ideas and intellectual property
Electronics symbols
Materials
Component markings explained
Electronics construction ExpressPCB
1
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
2
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 Layout Editor.
Freeware hits: 18321 6,5 Mb

Free PCB
3
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 Autorouter.

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Electronics basics


Basics


General

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 this link
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

Acronyms

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 this link
What's in a dB? Rate this link

Basic tutorials

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 link
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 mm )[2]
"The component lead - hole clearance should be 0,4 mm" [3]
"The optimum pad diameter for a through-hole component is twice its finished hole diameter."[4]
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.


[edit] layers
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 [citation needed] and clearance from the cut edge (perimeter of the board edge) to pour of 0.020 inch[5].

(more layer stackup tips)


[edit] 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.


[edit] layers
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.

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A Printed Circuit Board (PCB) design for Mel Bartels' Alt/Az drive system
NOTE 1:
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.
NOTE 2:
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.
NOTE 3:
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 and myself.

Also see my CompuDob page that displays my 6" Computerized Dobsonian telescope

? WebRing Inc. scope drive
<< Prev | Ring Hub | Join | Rate| Next >>



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Preface
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
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Mydata M100 Series Sr.Tech 09/02/08 5 464
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soldering ROHS boards with sn/pb components

 
 
 
 
 
   
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electronic PCB design,circuit PCB design,PCB layout,shenzhen, China,Low cost