PCB: Materials Used in Manufacturing

Need of a perfect material
The properties of the manufactured PCB depends to a great extent (electrically, mechanically and chemically) on the application and the environment it has to be used. The materials employed in the manufacturing process play a key role in determining the properties of the resultant PCB. Therefore, selection of suitable materials for manufacturing of PCB is quite important as they are responsible both to the expected performance of the PCB as well as the equipment made.

A common PCB needs generally a conductive ink and a substrate on which the ink has to be deposited to design conductive paths on the substrate on which components can be placed as per will and need suitable for the application. Broadly, they can be laminates, copper clad laminates, or resin impregnated materials.

Conductive ink
The popular approaches use additive method of depositing a conductive ink onto the substrate to minimize material wastage and achieve greater resolution.

These inks are classified as fired high solid systems or PTF polymer thick film systems. These inks allow print circuit designs on a variety of substrate materials ranging from teflon to paper. The conductive flakes generally consist of conductive materials like powdered silver or carbon.

Silver inks have seen multiple uses in technologies like (Radio-frequency identification) RFID, keyboards and windshield defrosters.

Laminate materials
Laminate materials are particularly the substrates used for depositing the ink and binding different layers of the PCB in case of multilayer PCB.
The materials prominently used as laminates are:

1. BT-Epoxy: It is a group of thermosetting resins. It is obtained by mixing the epoxy and BT (Bismaleimide-Triazine) resins. This material has high glass transition temperature up to 300 degrees C and and  has a very low dielectric constant.

2. Composite Epoxy Material (CEM) : This is a class of materials where woven glass fabric structures with non woven glass core is combined with epoxy resin. There are different types of CEMs :

1. CEM1 : Single layered woven glass fabric with cellulose paper based laminate. It is of low cost and is flame retardant.
2. CEM2 : Woven glass fabric and cellulose paper core.
3. CEM3 : It's similar to FR4; flame retardant and white colored.
4. CEM4 : It's similar to CEM3 but not flame retardant.
5. CEM5 : Polyester woven glass core.

3.  Cyanate esters : They are bisphenol and novolac based chemical substances. They have the property of getting treated many times in a varied range of high to low temperatures. They have a high glass transition temperature up to 400 degrees C  and posses a very low dielectric constant. They are smoke, fire and toxicity resistant and their toughness gives them an edge over epoxies in space applications.

4. Flame Resistant-2(FR-2) : Basically, it is a synthetic resin bonded paper made by impregnating paper with a plasticized phenol formaldehyde resin. It's used in low end consumer electronics.

5. Flame Resistant-4 (FR-4) : These are glass reinforced epoxy laminate sheets made by combining glass fibers with a fire resistant epoxy resin. It's a widely used laminate material. When a thin layer of copper is deposited on both sides of the laminate, it's known as copper-clad laminate.

6. Polyimide : It is made by polymerizing imide monomers. They are flexible, high heat resistant and thermally stable. Used in producing flexible PCBs.

7. PTFE (Teflon) : Polytetrafluoroethylene (PTFE ) is commonly known as Teflon and is a polymer of tetrafluoroethane. It is water resistant and has a high temperature bearing capacity, which makes them ideal for the use in equipments like microwaves and furnaces.

Need for advanced materials
With the structures getting smaller with the time and the utilities and circuits getting more complex, electromagnetic interference problems arise. They obstruct the development of 3D printing. This is due to the difference in fabrication material used for different components and parts of the PCB.

This problem can be overcome by looking for anisotropic materials and materials with spatially variant lattices.

Material used for the purpose of PCB fabrication still has a long way to go in order to improvise their structure to suit the diverse applications.

Responsibilities of a Criminal Defense Lawyer

Criminal defense lawyers specialize in defense cases involving individuals. They are also called as defense attorneys, public defenders, defend individuals etc. Some criminal defense lawyers are privately retained and others are under the employment of various jurisdictions. These lawyers researches, argues and prepare for their clients. Criminal defense lawyers mostly work on the criminal cases as they are expertize in that field. So, these lawyers will have more grip to handle the cases easily. There are several roles and responsibilities of a criminal defense lawyer and some of them are explained below.   

Responsibilities of a Criminal Defense Lawyer:
There are several responsibilities and the duties that are to be performed by a lawyer to win their clients case in the court of law and also to become a good lawyer.

• He should be capable in competent defense. Competent defense is nothing but cross examining the witness, preparing the statements and also to present the documents relevant to the case. He will represent the client vigorously.

• They will investigate the case thoroughly and perform the legal actions.

• Acquires some evidences related to the case and to prove them in the court of law.

• They examine the crime sense and collect the proves from there.

• Attorney gives advices the client and tells them about  there rights and also ask them whether they have any witness to prove the case.

• Some clients will hesitate to ask their wishes to their attorney so, here the criminal defense lawyer will help you  to solve this issue. He/she will take the wishes of you and gives importance to them.

• Mainly he give confidentiality about you are your case. He will keep all the information confidential regarding your case and will not reveal it to anyone.

• They will help the people who are really innocent guides them all the way.

• Lawyer will have discussion with the prospector for asking them to reduces the charges.

• Attorney also tells the client about the case updates from time to time.

For performing all this duties criminal lawyer must have the qualifications required to become a lawyer and along with this he/she must have a license to represent the case.
Thus, the criminal lawyer helps his or her clients and performs their responsibilities. Apart from that they must also ensure that the are being loyal towards their client and make them feel comfort.

Safe Driving Tips

Safety is of prime importance for all - drivers and the passengers of  the car as well those on the road. You need to take the necessary precautions while driving. Following these tips while driving, which is likely to keep you in safe mode. Here are a few tips for safe driving.

• Don't drink and drive

This is first and foremost tip that every driver should keep in mind. Driving in unconscious state when you are drunk is a big crime in many countries like USA. This may lead to unknowing accidents that may not do intentionally. For this the law will give some serious punishments to the driver of the vehicle. So, better avoid it when you are going for a drive.

• Use seat belts:

Seat belts protects you from many dangerous situations. It reduces the impact of getting injured when your car slips or when it is crashed and also from sudden brakes. Many people are dying because of not using seat belts while driving and there is a law in many countries for the people to use seat belts when they are in car if not followed leads to some punishments by law.

• Deflect distractions:

The main cause for distractions is using the mobile phones for texting and making calls. It is the one of the main reasons for death of many people. Some other reasons like using electronic devices and other things may also cause distractions. So, avoid them while driving.

• Don't Drive Beyond the Speed Limit:

There are some rules and laws to be followed while driving in a car or else for the driver of the car. One among them is following the speed limit. Every state or car will have the speed limit based on there road conditions in that areas. So, driver of the car should follow those rules deflecting them many not only lead to penalization by law but some time may lead to serious accidents. Speed is one of the major factor for the youth because these are the people who while have the drives with great speed.

• Be Attentive When Your are Driving Bad Weather:

When you are driving in bad weather conditions like heavy rain, snow. It is necessary to take safety measures or precautions. Driving in snow and rain may lead to slipping of the cars with no control over it. So, your car must have some systems like Anti-lock braking system (ABS), Electronic Stability Control (EBS), Auto Emergency Braking etc which can reduce the accidents or impact of it.

• Don't Drive if you are Drowsy or Stressed:

It is batter to handle the driving position to some one else if you are drowsy or stressed because in that situation you will not have control over driving and you may some times get in to accidents unknowingly.
These tips are very important for any car driver or the owner to keep them and their family safe when they are in car.

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