A Brief Guide To Printed Circuit Boards by Katharine Gillespie

Paul Eisle invented the first PCB in 1936. However, it became popular only in the 1950s when the US military started using the technology in bomb detonators. Today, PCB Circuit Boards are an integral part of almost all equipment, like cars, mobile phones, computers and more.

How Is A Printed Circuit Board Manufactured?

To make a custom PCB, first the electronic diagram of the required circuit is prepared using Computer Aided Design (CAD) software. After that the PCB prototype is developed using Computer Aided Manufacturing Software technology.

The common materials used for manufacturing PCBs are: FR4, FR4 High Temperature, Polyimide, GeTek, Rogers, Arlon, Nelco, Alumina, Ceramic, Bakelite, FR1, CEM1, and CEM5. The size and thickness of the board depends upon the requirements of the circuit. The substrate is coated with a layer of copper. Then, using photosensitive coating, the circuit diagram is printed on the board. The undesired copper is etched out from the board to form copper "tracks", called traces. This process is known as Photoengraving. There are two other common methods used for developing connecting traces. PCB milling is a mechanical system where undesired copper is removed with CNC machines. Another process is Silk-Screen printing, where special ink that is etch-resistant is used to cover the areas where the copper traces have to be made.

Once the board is ready with copper traces, holes are drilled into the board to assemble leaded electrical and electronic components. For drilling, special Tungsten Carbide drill bits or laser is used. The holes made are filled with hollow rivets or coated through using an electroplating process, thus forming an electrical connection among the various layers. The next step is coating of the entire board, except holes and pads, with masking material. Materials commonly used for this purpose are: lead solder, lead free solder, OSP (Entek), deep/hard gold (electrolytic nickel gold), immersion gold (electroless nickel gold - ENIG), wire bondable gold (99.99% pure gold), immersion silver,
flash gold, immersion tin (white tin), carbon ink, and SN 100CL, an alloy of tin, copper, and nickel. The last step is screen-printing, where the legend and text are printed on the PCB.

Testing Of PCB

Before assembly of components or delivery of Printed Circuit Boards, the board should be tested to find any possible "shorts" and "opens" that could lead to a non-functioning board. A "short" indicates the existence of an undesired connection and an "open" indicates that two points that should have been connected are unconnected. All such errors should be fixed before PCB assembly. It is important to note that not all PCB Manufacturing shops test the boards before shipping, it is sometimes considered an added cost but a vital one to provide a fully functioning board before adding components.

PCB Assembly

Once the board is ready, components are assembled and added to the surface as per the circuit diagram. Some of the common assembly techniques used are surface-mount construction and through-hole construction. Sometimes, a combination of these two techniques is also used for assembly.

Types of Printed Circuit Boards

Single Sided Board

This is the least complex of the Printed Circuit Boards, since there is only a single layer of substrate. All electrical parts and components are fixed on one side and copper traces are on the other side.

Double Sided Board

This is the most common type of board, where parts and components are attached to both sides of the substrate. In such cases, double-sided PCBs that have connecting traces on both the sides are used. Double-sided Printed Circuit Boards usually use through-hole construction for assembly of components.

Multi Layered Board

Multi layered PCB consists of several layers of substrate separated by insulation. Most common multilayer boards are: four layers, six layers, eight layers, and 10 layers. However, the total number of layers that can be manufactured can exceed over 42 layers. These types of boards are used in extremely complex electronic circuits.

PCB Universe offers prototype and production printed circuit boards and Flex PCB circuits at reasonable prices. Get an instant online pcb quotes or browse the site for technical resources and capability questions.

Article Source: http://www.earticlesonline.com/Article/A-Brief-Guide-To-Printed-Circuit-Boards/763618

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Web Traffic With Keyword Research~Can You Increase Site Traffic With Keyword Research~Get More Web Traffic With This Unique Keyword Research Tip~Your Most Relevance Keyword Search Terms To Increase Web Traffic~More Web Traffic Starts With Decent Keyword Research}

Would you be interested in find out what keyword phrases Google think are the most related to your google search query?  Would you like results returned to be up to date all the time?  How about getting hold of the information for free?

And furthermore what about if I told you that you could access all this info using nothing but Firefox (or any other browser)  and a standard Google search?

Interested?  Then continue reading....

Firstly lets start with the basics and talk about relevance, as this term a very important part of Googles search engine results.

Google wants to give the searcher with extremely accurate and relevant results possible.  They know that if they are unable to provide this information, it’s probable that users will no longer use their services completely, and no searchers means no Adwords revenues which is their main source of income!

For a prime example of a search engine losing market share, spare a thought for AltaVista?  Back in the day it was the most used search engine, and almost overnight (not quite) lost the crown to Google because they dropped the ball with relevance.

I doubt there is such a thing as search engine loyalty (at least not for the non Internet Marketing search engine person).  If a better alternative comes along, the everyday people will just start using that service.

Trust me when I say The Powers To Be At Google are very conscious of this, and put enormous thought and manpower into ensuring that when you search for something, the results that come back are highly related to your search term.

Google need to keep the average user happy so that they return Google again and again.

Shred Internet Marketers have, of course found methods to "game" Google in previous years, so that their own web pages come up instead of what should be the most relevant pages, and such tricks are still used today.

Usually these black hat techniques are picked up by Google who is getting cleverer at locating these types of hacks.

Google seems to get it right most of the time, and certainly more than the other major search engines at this point in time.

Ok so given that Google is currently providing the most relevant information and has the biggest user base when compared to any other search engine, and that its obvious that their primary mission is info relevance to their searchers, does it not make sense to go to their search results and be using this information more when conducting keyword research?

For example lets say your searching for the keyword phrase web traffic

When I typed in search term into google, I got a list of current pages that Google believe are the most relevance to that search term (along with a host of ads).

But in additional to these results at the bottom of the page they also provide (and here is the key)....

Searches RELATED to: web traffic (Their words).

Hmm interesting a list of keywords that Google think are relevant to my search.

Google actually display to you the keywords that they deem to be the most relevant to your search.

If you do some research about this, there is some speculation on how google decide on what phrases are displayed, but in any event you think I think it's certainly worth investigating further, isn’t it?

In my testing I found the keywords it came up with seemed to be keywords heavily searched on.

In the case of web traffic, the keyword phrases I got back were

increase web traffic
free web traffic
buy web traffic
google web traffic
web traffic report
web traffic generator
web traffic monitoring
measure web traffic

They all seem pretty related to my original search.

And you can drill down by clicking on a search term to get relevant keywords to that phrase.  For example I could have selected increase web traffic and received a list of related keywords that relate to that term.

This is getting interesting.   Before you discount this method compared to using your favorite keyword tool, I would ask that you consider the following.

1)  The information from these searches are directly from Google, so the data has not been corrupted in any way.

Many keyword research tools do not use information from Google at all (Wordtracker) or combine data from many sources.  Here we have information direct from the source!

2) The information that comes back from Google is of course very up to date, unlike a lot of other keyword research data that can be months out of date.

I am not saying that you get rid of all other keyword tools in favor of this technique, but I do recommend you check it out.  With all the latest whiz bang all conquering, overly hyped software tools that seemingly gets released everyday, sometimes it pays to take a step back and go back to just using a very simple method like searching in Google!

In my case, I actually use this method in conjunction with other keyword tools, and get the best out of both worlds.  My two favorite keyword research tools currently are Nichebot and Market Samurai (google them).

I find the best use of this technique is when searching new niches, or when trying to establish the viability of entering a particular market.

One final thing to note is that unfortunately not all keywords are supported.  Sometimes no related searches come back for a given keyword, but given that it’s free I’m happy to overlook that oversight.

And occasionally I have to mention that the search terms returned seem a little weird.  But this seems to be in more unusual niches that perhaps Google have not collected enough information for (my speculation).

Get out there and have a look at the related search function in Google.  The keywords returned might end up being very useful.

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