Surface mount assembly (SMT) includes a crucial role to learn from the New Product Introduction (NPI) process for electronics manufacturing.
Our prime amount of automation inside the SMT methodology comes with a variety 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 on an electronics manufacturing services (EMS) provider might be broken down into four key stages:
Solder Paste Printing
Pick and set
Automated Optical Inspection (AOI)
With respect to the complexity in the design, or perhaps your own outsourcing strategy, your products or services could pass through each of these processes therefore, or you could find which you omit one step or two.
We would like to highlight the specific attributes, as well as the vital importance, of the solder paste printing process for your NPI.
Working to your specifications
The first task for the EMS provider can be to analyse the printed circuit board (PCB) data that is specific to your order, to ensure they select the required stencil thickness and the the best option material.
Solder paste printing is the most common way of applying solder paste with a PCB. Accurate solder paste application is hugely crucial in avoiding assembly defects that may use a knock on effect further around the production process. So it is vital until this key stage is correctly managed and controlled because of your EMS partner.
Solder paste it’s essentially powdered solder which was suspended in the thick medium called flux. The flux provides for a form of temporary adhesive, holding the constituents in position until the soldering process begins. Solder paste is used towards the PCB utilizing a stencil (generally stainless, but occasionally nickel,) then when the solder is melted it forms an electrical/mechanical connection.
The thickness with the stencil is exactly what determines the total number of solder applied. For some projects it may even be important to have several thicknesses in numerous areas inside one stencil (also known as a multi-level stencil).
Another key factor to take into consideration from the solder printing process is paste release. The right type of solder paste must be selected based on how big the apertures (or holes) inside stencil. If your apertures have become small, by way of example, then your solder paste could be more prone to sticking to the stencil instead of adhering correctly for the PCB.
Managing the rate of paste release however can be easily managed, either start by making changes to the design of the aperture or by reduction of the thickness in the stencil.
The sort of solder paste that is utilized also can impact on the last top printing quality, so it will be imperative that you find the appropriate combination of solder sphere size and alloy for your project, also to help it become mixed towards the correct consistency before use.
When the stencil may be designed and your EMS partner is getting ready to make the first PCB, they are going to next want to think about machine settings.
Quite simply, the flatter you can keep the PCB over the printing process, the greater the end result is going to be. So by fully supporting the PCB through the printing stage,either using automated tooling pins or having a dedicated support plate, your EMS provider can eliminate the chance for any defects such as poor paste deposit or smudging.
It’s also important to think about the speed and pressure from the squeegees in the printing process. One solution is to have one speed for that solder paste but to get varying levels of pressure, depending on the unique specifications with the PCB and the length of the squeegee.
Washing the stencils, both ahead of and throughout production, is likewise essential in ensuring qc. Many automatic printing machines have a system that can be set to wash the stencil after having a fixed variety of prints that helps to stop smudging, and prevents any blockages of the apertures.
Finally too, the printers really should have a built-in inspection system (for example Hawk-Eye optical inspection) which can be preset to watch the existence of paste throughout the whole PCB after printing.
The solder paste printing process is really a precise and detailed one that will have a significant part to learn in the ultimate success of your respective awesome. And, as this short article highlights, plenty of detailed work is likely to occur c = continual reporting before your EMS partner solders the first electronic element of a board.