Surface mount assembly (SMT) has a crucial role to experience in the Cool product Introduction (NPI) process for electronics manufacturing.
The prime amount of automation from the SMT methodology supplies 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 on an electronics manufacturing services (EMS) provider may be divided into four key stages:
Solder Paste Printing
Automated Optical Inspection (AOI)
With regards to the complexity from the design, maybe own outsourcing strategy, your products could move across these processes subsequently, or you might discover which you omit a step or two.
We should highlight the actual attributes, along with the vital importance, from the solder paste printing process on your NPI.
Fitting in with your specifications
Step one for your EMS provider may be to analyse the printed circuit board (PCB) data that’s specific on your order, to ensure that they select the required stencil thickness and the the most appropriate material.
Solder paste printing is among the most common approach to applying solder paste to some PCB. Accurate solder paste application is hugely essential in avoiding assembly defects which may have a knock on effect further on the production process. So it’s vital that key stage is correctly managed and controlled by your EMS partner.
Solder paste is actually powdered solder which was suspended within a thick medium called flux. The flux provides a form of temporary adhesive, holding the constituents available before soldering process begins. Solder paste is applied for the PCB employing a stencil (generally stainless steel, but occasionally nickel,) then after the solder is melted it forms an electrical/mechanical connection.
The thickness in the stencil is what determines the total number of solder applied. For a few projects it may well be important to have several thicknesses in different areas inside one stencil (known as a multi-level stencil).
Another important element to consider within the solder printing process is paste release. The right form of solder paste should be selected in relation to the dimensions of the apertures (or holes) within the stencil. When the apertures are extremely small, as an example, then this solder paste might be more prone to sticking with the stencil instead of adhering correctly towards the PCB.
Governing the rate of paste release however can be easily managed, either by making changes for the form of the aperture or by reducing the thickness in the stencil.
The kind of solder paste that is utilized can also effect on the ultimate top printing quality, so it is vital that you pick the appropriate mixture of solder sphere size and alloy for your project, and to make sure it is mixed to the correct consistency before use.
After the stencil has become designed along with your EMS partner is getting ready to generate the first PCB, they are going to next want to consider machine settings.
To put it differently, the flatter you can preserve the PCB from the printing process, the better the outcome will probably be. So by fully supporting the PCB throughout the printing stage,either through automated tooling pins or using a dedicated support plate, your EMS provider can get rid of the chance of any defects like poor paste deposit or smudging.
It’s also important to think about the speed and pressure with the squeegees during the printing process. One solution is going to be have one speed for that solder paste but to get varying levels of pressure, using the unique specifications in the PCB along with the length of the squeegee.
Cleaning the stencils, both ahead of and throughout production, is likewise crucial in ensuring qc. Many automatic printing machines have a system that can be set to clean the stencil from a fixed variety of prints that helps in order to avoid smudging, and prevents any blockages from the apertures.
Finally too, the printers needs to have a built-in inspection system (including Hawk-Eye optical inspection) which may be preset to monitor the use of paste through the whole PCB after printing.
The solder paste printing process can be a precise and detailed the one which may significant part to try out within the ultimate success of one’s cool product. And, as this short article highlights, plenty of detailed jobs are prone to happen c = continual reporting before your EMS partner solders the very first electronic ingredient of a board.