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Editorial Team - PCB Directory

Sep 11, 2020

Solder Paste is a form of solder than can be easily applied on a Printed Circuit Board. It has a viscous state and is grey in color. The paste consists of a combination of tiny balls of solder and flux mixed together to form a paste. It is applied to the pads on a PCB where electronic components need to be placed. When heated this paste melts to form a connection between the pads and the leads of ...read more

What is Solder Beading?

Soldering

Editorial Team - PCB Directory

Aug 17, 2020

Solder Beads are balls of solder that are created when soldering components on a PCB. They are created due to the use of excessive solder paste when soldering components on a board. Solder beads can cause a short circuit between the component terminals which can result in failure of the circuit. Also, in case there are vibrations, the solder ball can break loose and cause a short circuit somewhere...read more

What is Backdrilling in PCB Fabrication?

Editorial Team - PCB Directory

Aug 17, 2020

Back drilling or Controlled depth drilling is a process used to remove the unwanted portion of a PCB Via Stub. Plated Through Hole (PTH) Vias are used to connect two or more layers of a Printed Circuit Board to each other. However often, a via does not need to run the entire thickness of the board to connect each layer. For example, if we have a 10 layer PCB and need to connect layer 1 to layer 3 ...read more

What is Conformal Coating on a PCB?

Editorial Team - PCB Directory

Aug 17, 2020

A conformal coating is a polymeric thin film applied over a PCB surface to protect the board and its components from corrosion and environmental contaminants. The performance of a PCB can be impacted by many external or environmental factors like moisture, extreme temperature, salt sprays, and chemicals. A conformal coating ensures the protection against PCB against these types of environmental co...read more

What are PCB Stiffeners?

PCB Fabrication

Editorial Team - PCB Directory

Aug 17, 2020

When working with flexible PCBs there are times when we need certain parts of the flexible printed circuit board to be rigid. We do so by adding mechanical support to parts of the PCB. This mechanical support is called a PCB Stiffener.Flexible PCBs have many advantages like the capability to bend, twist, and fold. However, it is challenging to add/solder components and interconnects to these board...read more

What is PCB Tombstoning?

PCB Assembly

Editorial Team - PCB Directory

Apr 24, 2020

PCB Tombstoning occurs due to a mismatch in the solder solidification time during the PCB assembly process. The term solder solidification or ‘Wetting’ comes in to the picture when surface mount components are soldered to their respective pads. To do so, solder is applied on the PCB board, after which the component is placed on the board and then passed through a reflow oven, where it ...read more

What is the Coefficient of Thermal Expansion (CTE) in a PCB?

PCB Basics

Editorial Team - PCB Directory

Apr 24, 2020

The Coefficient of Thermal Expansion (CTE) specifies how much a printed circuit board will expand/contract when it is heated or cooled. The unit of CTE is PPM/°C i.e parts per million per Celsius degree. So lets assume a PCB is made out of FR4 which has a CTE of 17 (usually it is 14 to 17 ppm/°C). If the PCB is 1 Million inches long then it will expand by 17 inches for every 1 °C incre...read more

What is BGA Reballing?

PCB Repair

Editorial Team - PCB Directory

Apr 24, 2020

The process of replacing all soldered balls on the chip ball grid array is called BGA Reballing. BGA or Ball Grid Array is a surface mount package that has an array/grid of metal alloy balls (Tin/ Silver/ Lead/ Copper) at the bottom of a package which is soldered on to a printed circuit board to provide an electrical connection. This package type requires less space than other package types as all...read more

What is a PCB Test Coupon?

Editorial Team - PCB Directory

Apr 24, 2020

During the PCB Manufacturing process, it is important to evaluate the quality of the boards being fabricated. A good way to do this is to fabricate a few extra boards called PCB Test Coupons which can be tested to evaluate the performance of the boards. PCB Test Coupons are designed to have the same spec (trace width, copper weight, via structure, etc.) as the original PCB board and are tested to ...read more

What is ENIG Plating?

Editorial Team - PCB Directory

Apr 13, 2020

ENIG (Electroless Nickel Immersion Gold) is a surface plating that is applied over the copper pads on a Printed Circuit Board to protect them from corrosion and other abnormalities. Initially, the copper pad is covered by a Nickel (Ni) layer followed by a thin immersion Gold (Au) layer. ENIG provides good oxidation resistance, excellent surface planarity and allows for easy soldering which results...read more

What is HASL - Hot Air Solder Leveling?

Editorial Team - PCB Directory

Jan 15, 2020

HASL (Hot Air Solder Leveling) is a metallic surface finishing technique, which is performed on the outermost layer of the PCB board to protect the exposed copper surfaces like tracks until the component placement and soldering is completed.The HASL coating is composed of Solder with 63% Tin and 37% Lead, and during the assembly process, this coating gets dissolved with the soldering material.The ...read more

What are PCB Gold Fingers?

PCB Basics

Editorial Team - PCB Directory

Jan 15, 2020

Gold Fingers are the gold plated narrow connectors found on the edge of printed circuit boards to enable connections between multiple boards. They are made from flesh gold, the hardest form of gold available and work for a long time with superior conductivity. The thickness of gold fingers usually ranges from 3 to 50 microns.Gold is chosen for these fingers as it has the highest corrosion resistan...read more

What are Fiducial Marks on a PCB?

PCB Basics

Editorial Team - PCB Directory

Jan 15, 2020

Fiducial marks are recognition marks, created in the form of small pads on the PCB board to act as reference points for PCB Stencil alignment and for automated component placement by Pick and Place machines. During the PCB Assembly process these points are used by automated machines to ensure correct positioning of the board. These points are also measurable and act as a frame of reference during ...read more

What is PCB V-Scoring?

PCB Basics

Editorial Team - PCB Directory

Jan 15, 2020

PCB V-Scoring is a process of cutting a ‘V’ shaped groove at the top and bottom of a printed circuit board leaving a thin layer between the Vees. Once this is done, the PCB Board can easily be separated at the V by applying minimal pressure.A single PCB board can be divided in to multiple sections by V-Scoring. This is must useful during the PCB assembly process, as all sections of the...read more

Polyester PCB Boards

PCB Substrates

Editorial Team - PCB Directory

Sep 15, 2019

Polyesters, also called Polyethylene Terephthalate (PET), are the most commonly used material to manufacture flexible PCBs. They are best-known for their flexibility, good electrical properties, and high chemical and moisture resistance.Key Characteristics:They have a melting point of 250ºC and a glass transition temperature of 80ºC.They have lower heat resistance that inhibits their use...read more

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