Solder Flux is a chemical cleaning agent used when soldering electronic components onto printed circuit boards. It is used in both manual hand-soldering as well as the different automated soldering processes used by PCB contract manufacturers.Printed Circuit boards usually have copper traces which can oxidize when exposed to air or get contaminated while handling the board. This can prevent the fo...read more

Water-Soluble Solder Paste as the name suggests is solder paste whose flux residue left after the solder reflow process can be dissolved or removed with water.The PCB assembly world now mostly uses no-clean solder, where flux residues can also be safely left on the board, without creating leakage current or corrosion issues. However, though the flux residue of no-clean solder paste is not conducti...read more

A Cold Solder Joint occurs when solder fails to melt entirely to form a proper joint. A cold solder joint or an improperly formed joint can be the trigger for reliability problems of an electronic assembly. Cold solder joints increase the electrical resistance of the solder joints, and hence reduce the reliability of the solder joints.There are a number of factors that can cause cold solder joints...read more

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

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

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

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

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

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

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

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

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

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

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

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