Surface mount technology SMT is a method for constructing electronic circuits in which the components are mounted directly onto the surface of printed circuit boards PCBs.
In the electronics industry SMT has largely replaced the previous construction method of fitting components with wire leads into holes in the circuit board also called through-hole technology.
An SMT component is usually smaller than its leaded counterpart because it has either no leads or smaller leads. It can have short pins, flat contacts, a matrix of balls BGAs, terminations on the body of the component passives, or short leads in a gull-wing formation QFPs.
Whats SMT stencil
Surface mount stencils are far more than just sheet of metal, it plays a very important role in the PCB assembly process. The primary function of the stencil is helping to deposit the optimum amount of paste onto each individual pad of the PCB. They are the single most important tool whose design and optimisation influences the success of every surface mount assembly line.
PCBCORE offers stencil solutions in two technologies as follows:
Chemical etching- can be used for non-fine pitch printing applications
For component pitches down to 0.635mm
Good paste release
Cost effective process - all apertures created simultaneously
Durable stainless steel material
Chemical etching stencil using photo etching, is a subtractive process that selectively removes metal by chemical action. It is a cost-effective process, usually its appropriate for IC pitch larger than 60 mil, for finer pitch requirements laser cutting are recommended.
For component pitches down to 0.4m
Improved aperture accuracy
Enhanced paste release
Durable full hard stainless steel material
Laser technology is ideally suited for dense, highly compacted boards with fine pitch features even down to 16mil, the photographic steps are not needed and date file is used for production directly, Using speed Lasers offers a very good accuracy and smoothest aperture walls, Far superior to Chemically etched Stencils. The opening position tolerance could be controlled under 4m. Though laser cutting stencil is a bit more expensive, but it has superior accuracy for 16mil fine pitch apertures.
We strive for excellence in quality, our high quality materials stencils assure you lasting durability, strength, stability, no matter chemical etching stencil or laser cutting stencil with framed or frameless, all support high volume screen printing. So dont simply compare our price with the prototype stencil in the market and bargain with us for an impossible price, you will see our steel stencils price even at prototype stencil rate at your local supplier.
In case of missing any aperture cutting, kindly double check the check plot we send to you before production. The check plot will show you exactly what we are going to make.
To achieve proper paste release from the stencil, an apertures aspect ratio should be >1.5, and the area ratio should be >0.66. When the stencil separates from the board, paste release encounters a competing process; solder paste will either transfer to the pad on the board or stick to the aperture side walls. When the pad area is greater than 0.66 of the inside aperture wall area, a complete paste transfer should occur. Please see the below calculator which you can use to determine pad size for your aperture, and foil thickness of the stencil.