Surface mount assembly (SMT) has a crucial role to try out within the Cool product Introduction (NPI) process for electronics manufacturing.
The top amount of automation from the SMT methodology comes with 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 separated into four key stages:
Solder Paste Printing
Pick and put
Oven Profiling
Automated Optical Inspection (AOI)
With regards to the complexity with the design, or perhaps your own outsourcing strategy, your product or service could go through all these processes subsequently, or you may find that you just omit a stride or two.
We should highlight the specific attributes, along with the vital importance, with the solder paste printing process for your NPI.
Trying to your specifications
Step one for your EMS provider can be to analyse the printed circuit board (PCB) data that’s specific in your order, to make sure that they pick the required stencil thickness and also the the best option material.
Solder paste printing is among the most common way of applying solder paste to some PCB. Accurate solder paste application is hugely crucial in avoiding assembly defects which may use a knock on effect further on the production process. So it is vital that key stage is correctly managed and controlled by your EMS partner.
Solder paste is essentially powdered solder which was suspended in the thick medium called flux. The flux behaves as a kind of temporary adhesive, holding the parts in position before soldering process begins. Solder paste is used to the PCB by using a stencil (generally stainless-steel, but occasionally nickel,) then when the solder is melted it forms an electrical/mechanical connection.
The thickness from the stencil ‘s what determines the volume of solder applied. For some projects it might even be essential to have a lot of thicknesses in different areas inside one stencil (known as a multi-level stencil).
Another key factor to take into consideration in the solder printing process is paste release. The right sort of solder paste ought to be selected in relation to how big is the apertures (or holes) from the stencil. If the apertures have become small, for instance, then the solder paste could be quite likely going to sticking to the stencil and not adhering correctly for the PCB.
Manipulating the rate of paste release however can be simply managed, either start by making changes on the style of the aperture or by reducing the thickness in the stencil.
The sort of solder paste utilized could also influence on a final print quality, so it will be crucial that you choose the appropriate mixture of solder sphere size and alloy for your project, and help it become mixed on the correct consistency before use.
Ensuring quality
As soon as the stencil may be designed along with your EMS partner is able to produce the first PCB, they are going to next want to consider machine settings.
Put simply, the flatter you can maintain the PCB over the printing process, better the outcome 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 potential for any defects including poor paste deposit or smudging.
You’ll want to think about the speed and pressure in the squeegees in the printing process. One solution is usually to have one speed for your solder paste but to get varying examples of pressure, in line with the unique specifications from the PCB along with the length of the squeegee.
Washing the stencils, both ahead of and throughout production, is likewise crucial in ensuring qc. Many automatic printing machines possess a system that could be set to wash the stencil following a fixed variety of prints which helps to prevent smudging, and prevents any blockages with the apertures.
Finally too, the printers should have a built-in inspection system (for example Hawk-Eye optical inspection) which is often preset to watch the existence of paste throughout the whole PCB after printing.
The solder paste printing process is a precise and detailed the one that may significant part to experience in the ultimate success of your respective new service. And, since this blog post highlights, plenty of detailed jobs are more likely to come about behind the curtain before your EMS partner solders the 1st electronic ingredient of a board.