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Solder Paste Printing

Solder paste printing is a key part in the SMT (Surface Mount Technology) process.The primary purpose is to apply adequate amount of solder onto the SMD pads of the bare PCBs. The most common way of carrying the process of Solder paste printing is by screen-print the solder paste through a SMD stencil and with the help of squeegee blade. SMT has a flexible requirement of viscosity but fortunately viscosity itself is a variable aspect of solder paste the solder paste's transfer efficiency from the stencil to the board during the printing process is determined by a number of variables- Squeegee Speed and pressure - The speed determine how much time is available for the solder paste to roll into aperaure cutt outs in a stencil.Inadequate pressure can cause excess solder paste sedement or low area coverage of solder pads both contributes majorly in issues like poor solder joints Squeeze Angle- the typical angle of the squeegees is set to 60° , any variation in the application angle can cause "scooping" of holder paste from the stencil apertures Stencil Separation Speed- This is the speed at which the stencil and pcb are seprated after a successful stroke of Squeegee on stencil. Print Stroke:This is the distance the squeegee travels across the stencil and is recommended to be a minimum of 20mm past the furthest aperture

Pick and Place

Pick and place systems, pick and place machines or pick and place robots as they can be known are part of the success of surface mount technology. In this way manual placement which is slow and relatively inaccurate is avoided, and the throughput is highly increased with high quality and accuracy. A pick and place (PNP) machine is a robotic assembly device that uses a vacuum to lift a component off of a piece of tape, rotate it to the right orientation, then place it on a circuit board. The nozzle which has vaccum in its nozzle picks up a component from the feeder section of the pick and place machine,the picked up compoenent is then putted under an inspection camera then the compnent is placed on the desired placed with right position and polarity.

Reflow Oven

A reflow oven is a machine used primarily for reflow soldering of surface mount electronic components to printed circuit boards (PCBs). Inline reflow ovens are configured with a number of heating zones followed by cooling sections. Depending on the length and throughput the reflow can have verying heating zones and cooling zones like 5,8,12 . During the reflow soldering process, the zones are programmed with a thermal set point. This set point corresponds to the temperature the circuit board should be exposed to as it passes through that zone. The loaded pcb travels through a conveyor belt under different zones heating or cooling,the pcb is slowly heated and finally is putted through the highest tempeature setted making the solder paste applied on the pcb flow and then solidified creating a strong joint with clean and good finish.