Surface mount assembly (SMT) has a crucial role to experience from the New service Introduction (NPI) process for electronics manufacturing.
The high a higher level automation from the SMT methodology supplies a number 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 to have an electronics manufacturing services (EMS) provider could be divided into four key stages:
Solder Paste Printing
Pick and put
Oven Profiling
Automated Optical Inspection (AOI)
With regards to the complexity from the design, maybe own outsourcing strategy, your product or service could go through each one of these processes therefore, or perhaps you might find which you omit one step or two.
You want to highlight the particular attributes, and also the vital importance, with the solder paste printing process to your NPI.
Attempting to your specifications
The first task to your EMS provider can be to analyse the pcb (PCB) data which is specific in your order, to make sure that they pick the required stencil thickness along with the the most suitable material.
Solder paste printing is among the most common method of applying solder paste with a PCB. Accurate solder paste application is hugely important in avoiding assembly defects that may have a knock on effect further around the production process. So it will be vital this key stage is correctly managed and controlled by your EMS partner.
Solder paste is essentially powdered solder which has been suspended inside a thick medium called flux. The flux provides a form of temporary adhesive, holding the components in position prior to the soldering process begins. Solder paste is used towards the PCB utilizing 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 is the thing that determines the level of solder applied. For some projects it may be also required to have a lot of thicknesses in different areas within the one stencil (sometimes called a multi-level stencil).
Another primary factor to consider inside the solder printing process is paste release. The best sort of solder paste ought to be selected dependant on the size of the apertures (or holes) from the stencil. If the apertures are very small, for instance, then your solder paste could possibly be more prone to sticking with the stencil and not adhering correctly to the PCB.
Manipulating the rate of paste release however can be simply managed, either by looking into making changes towards the design of the aperture or by reducing the thickness with the stencil.
The type of solder paste that is utilized could also affect the last top printing quality, therefore it is crucial that you find the appropriate mix of solder sphere size and alloy for that project, and make sure it is mixed to the correct consistency before use.
Ensuring quality
When the stencil may be designed and your EMS partner is preparing to produce the first PCB, they are going to next be thinking about machine settings.
Quite simply, the flatter you can preserve the PCB with the printing process, the better final results is going to be. So by fully supporting the PCB in the printing stage,either through automated tooling pins or with a dedicated support plate, your EMS provider can remove the possibility of any defects including poor paste deposit or smudging.
It’s also important to think about the speed and pressure from the squeegees through the printing process. One solution is going to be have one speed for that solder paste but to own varying numbers of pressure, using the unique specifications of the PCB along with the length of the squeegee.
Cleansing the stencils, both prior to and throughout production, may also be essential in ensuring qc. Many automatic printing machines possess a system that may be set to completely clean the stencil following a fixed quantity of prints that helps to stop smudging, and prevents any blockages from the apertures.
Finally too, the printers really should have a built-in inspection system (including Hawk-Eye optical inspection) which is often preset to evaluate the presence of paste throughout the whole PCB after printing.
The solder paste printing process is often a precise and detailed the one which may significant part to experience within the ultimate success of your respective awesome. And, as this short article highlights, plenty of detailed work is prone to take place c = continual reporting before your EMS partner solders the initial electronic aspect of a board.