Surface mount assembly (SMT) includes a crucial role to experience from the New Product Introduction (NPI) process for electronics manufacturing.
The top amount of automation within the SMT methodology offers a selection of advantages, from automatic correction of errors, to simpler and faster assembly, better mechanical performance, increased production rates and reduced labour costs.
The SMT assembly process with an electronics manufacturing services (EMS) provider might be categorised into four key stages:
Solder Paste Printing
Pick make
Oven Profiling
Automated Optical Inspection (AOI)
With regards to the complexity of the design, or your own outsourcing strategy, your products could go through all these processes consequently, or you might find that you simply omit a measure or two.
We want to highlight the precise attributes, as well as the vital importance, from the solder paste printing process for the NPI.
Trying to your specifications
The initial step to your EMS provider will be to analyse the printed circuit board (PCB) data that’s specific in your order, to ensure they find the required stencil thickness and the the most suitable material.
Solder paste printing is regarded as the common way of applying solder paste with a PCB. Accurate solder paste application is hugely essential in avoiding assembly defects which can use a knock on effect further down the production process. So it is vital until this key stage is correctly managed and controlled from your EMS partner.
Solder paste is basically powdered solder that is suspended inside a thick medium called flux. The flux provides a type of temporary adhesive, holding the constituents in position before soldering process begins. Solder paste is used to the PCB utilizing a stencil (generally metal, but occasionally nickel,) then when the solder is melted it forms an electrical/mechanical connection.
The thickness of the stencil is exactly what determines the volume of solder applied. For a lot of projects it may well be required to have several thicknesses in various areas from the one stencil (sometimes called a multi-level stencil).
Another main factor to consider inside the solder printing process is paste release. The best kind of solder paste needs to be selected based on how big the apertures (or holes) inside stencil. If your apertures are very small, for example, then a solder paste may be prone to sticking to the stencil and not adhering correctly to the PCB.
Governing the rate of paste release however can easily be managed, either start by making changes on the kind of the aperture or by lessening the thickness of the stencil.
The solder paste that is utilized also can affect the final print quality, so it is important to pick the appropriate blend of solder sphere size and alloy to the project, and makes it mixed to the correct consistency before use.
Ensuring quality
When the stencil may be designed and your EMS partner is ready to create the first PCB, they’re going to next be thinking about machine settings.
Put simply, the flatter you can maintain the PCB from the printing process, the better the final results will probably be. So by fully supporting the PCB in the printing stage,either using automated tooling pins or having a dedicated support plate, your EMS provider can remove the potential for any defects such as poor paste deposit or smudging.
You’ll want to consider the speed and pressure from the squeegees in the printing process. One solution is usually to get one speed for the solder paste but to get varying numbers of pressure, using the unique specifications of the PCB along with the entire squeegee.
Cleaning the stencils, both just before and throughout production, can also be crucial in ensuring qc. Many automatic printing machines have a very system which can be set to completely clean the stencil following a fixed number of prints that helps to prevent smudging, and prevents any blockages with the apertures.
Finally too, the printers really should have a built-in inspection system (such as Hawk-Eye optical inspection) which can be preset to evaluate the existence of paste over the whole PCB after printing.
The solder paste printing process is often a precise and detailed the one which may significant part to try out in the ultimate success of your respective new product. And, simply because this short article highlights, a lot of detailed tasks are prone to occur behind the scenes before your EMS partner solders the 1st electronic ingredient of a board.