From the used to be pagers or beepers, to radios and radars, to the modern cell phones and laptops, all of such computer systems are composed of one common basic component: PCBs. Printed circuit boards or printed wiring boards or cards – however you may call it, it is one of the fundamentals of electronics and let’s take time to understand how it is made and used.
A printed circuit board, or PCB, is a self-contained module of interconnected electronic components. Simply speaking, it is a board consisting of lines and pads that connect various points together. It can perform a single specific function or even up to multiple ones.
Like what was said earlier, a printer circuit board is composed of lines and pads, but going into more detail, let’s break down the components that make up this board’s composition (as determined through PCB fabrication). Imagine it like a layered cake, or a lasagna, wherein different layers are laid up and are laminated together through heat and adhesive materials.
First off, is the base material, substrate, usually fiberglass. This is the main component of a printed circuit board. This gives the board a thick and rigid solid core. In some cases though, a printed circuit board can be built on flexible high-temperature plastic, Kapton, for example, or any equivalent.
Printed circuit boards come in different thicknesses; though, commonly, they come in 1.6mm or 0.063”. There are also cheaper printed circuit boards and they come in made from other less expensive materials such as epoxies or phenolics. You need to take note though, that should you be opting for this alternative that they come in less durable.
You will notice this when you solder to it during PCB fabrication, they will emit a relatively distinct bad odor. They should be handled or used with extra care as they can have a low thermal decomposition temperature, causing them to delaminate, smoke up, and even char. Low-end consumer electronics are usually built on these types of printed circuit boards.
The next layer, would be a thin copper foil, laminated to the board with head and adhesive materials. On double sided printed circuit boards, the more common ones, this is applied to both sides of the substrate. However, in lower end electronic gadgets, copper could only come in one side of the board. When talking about double sided printed circuit boards, it just means that it is referring to the number of copper layers the board has, which is 2 in this matter. It can come in as few as one layer, or can grow as many as twenty or even more.
The thickness of this copper layer can also vary between PCB fabrication processes, but it is, and should be, specified by weight, in ounces per square foot. Majority, well vast majority, of printed circuit boards have one ounce per square foot but should they need to handle very high power, they can have up to 2 or 3 ounces per square foot. Each ounce per square foot translates to about 35 micrometers or 1.4 thousandths of an inch of thickness of copper.
The solder mask would be the next layer laid on top of the copper foil. This is what makes the printed circuit board green in color, though some rare varieties can come in red too so any color is possible. It is laid on top of the copper foil layer to insulate it and prevent contact to other metal components. This can help the user to solder to the proper places and prevent what they call, accidental jumpers.
A white silkscreen layer is what’s overlaid onto the solder mask layer. This adds letters, or numbers, or any symbols to the printed circuit board and makes easier assembly for users. This way, humans can see indicators and better understand the board. The silkscreen labels are used in indicating what the function of each pin or LED is. Normally, the silkscreen labels are white in color but any color can be just used, such as gray, red, black, or yellow. But never a case that multiple ones are used as it will be difficult to embed.
As you can see a printed circuit board is made up of dedicated materials and can be quite a challenge to build. However, to make our lives easier, and not to mention, safer, there are some services out there that can provide you ready made circuit boards. Or should you have a more detailed and specific design or build in mind, they can do the PCB fabrication process for you. Some services, such as from Imagineering, Inc., come in online. Ordering and obtaining your printed circuit boards are less hassle and come in a very timely manner, and not to mention, with highest of quality.
Pcbnet are provide an important part of a wide range of machineries, computing devices, automobiles, appliances, and other electronic gadgets. PCB fabrication are ready and able to produce the finest quality products that our customers have come to expect.
Military coins have many uses. They are used as a reward and identification in various military units. They are also used as collectibles by many enthusiasts. In fact, some old coins can be traded for a huge price.
1. USN Navy Alaska SSBN-732 CPO Chief’s Mess
This challenge coin is expensive and it has a unique coin design and shape. It features an image of a strong man in a lotus or cross-legged position. This coin is expensive and it’s a bit difficult to find.
2. USS Constitution Old Iron sides Navy Frigate Challenge Coin
This coin is made of bronze and it has the shape and the image of a ship. This coin is also expensive and it is one of the most sought after challenge coins.
3. Command Master Chief Fleet JMSDF Coin
This was made for the officers of the marines. This coin is made of high quality materials and it contains an illustration of a gold shell. This coin is one of the most expensive coins in the market today.
4. Jolly Roger Submarine Commemorative Coin
This coin was created to commemorate the Jolly Roger submarine challenge. This coin contains the portrait of a mermaid and an anchor. This is a special edition coin so it is a bit difficult to find.
5. Navy Seal Team 5 Challenge Coin
This coin was only distributed to certain marine officers. This coin is colorful and it is made of high quality materials.
6. US Secret Service Intelligence and Assessment Division Coin
This challenge coin was given to the few men and women working in the US Secret Service. This coin is extremely rare and too expensive, too. So, if you want to add something valuable and uncommon to your collection, you should definitely add this.
7. Commanding General Special Forces Airborne Challenge Coin
This coin is only given to the commander general of the Special Forces Airborne of the United States Army. This is the reason why this coin is expensive and hard to find. It is every coin collector’s dream.
8. 82nd Airborne Coin Workhorse Special Forces
This coin is not only rare, it is unique, too. It has a workhorse design and it is made of high quality materials.
9. USS Norfolk SSN-714
This challenge coin contains the words “pride runs deep”. This coin is made with precision and passion. It has a glossy blue base and it contains the image of the American flag.
10. USS PONCE AFSB 15 Lion Navy Chief Copper
This coin is shaped after a fighting lion. It is made of bronze and copper and it is one of the most in demand military coins today.
11. Japanese Pinup Coin
This is a limited edition coin produced by the US navy. It contains an image of an anchor and a beautiful Japanese woman. This coin has a unique shape and design and it would be a good addition to your collection.
12. US Air Force MQ 9 Reaper Coin
This is a polished die cast coin that looks like a tiny airplane. It is one of the most in demand coins in the market right now and it is one of the collector’s favorites.
13. US Embassy Ecuador Coin
This is a vintage so it is extremely expensive. It is made of copper and bronze and it contains the seal of the US Department of State.
14. CIA Embossed Eagle Coin
This coin is made especially for CIA agents. This was produced in 1942 so it is one of the rare collectible items.
15. 57th Presidential Inauguration
This expensive coin was produced to commemorate the 57th inauguration of the president and the vice president of the United States.
16. Canadian Secret Intelligence Service Commemorative Coin
This coin is given to the members of the Canadian Secret Intelligence Service. This coin is made of high quality materials.
17. USN Navy Seals Bone Frog
This coin has a unique shape and it is really expensive. This coin resembles the skeleton of a frog. It is made of high quality raw materials.
18. 17th SMMC Barrett Challenge Coin
This coin is almost $200 and it was given only to high ranking marine corps officials.
19. Interpol Police Logo Coin
This coin resembles a badge. It contains the logo of the international police logo.
If you’re a serious challenge coin collector, you must try to get these military coins – to know more, just head on to ChallengeCoins4Less.com.Continue to read