Surface mount assembly (SMT) has a crucial role to try out in the New service Introduction (NPI) process for electronics manufacturing.
Our prime amount of automation inside the SMT methodology provides a various 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 for an electronics manufacturing services (EMS) provider might be separated into four key stages:
Solder Paste Printing
Automated Optical Inspection (AOI)
With regards to the complexity of the design, or perhaps your own outsourcing strategy, your products could move across each one of these processes therefore, or you may find which you omit a measure or two.
We should highlight the actual attributes, along with the vital importance, with the solder paste printing process to your NPI.
Working to your specifications
The first task on your EMS provider is to analyse the pcb (PCB) data that is specific for your order, in order that they find the required stencil thickness and also the the most appropriate material.
Solder paste printing is the most common technique of applying solder paste with a PCB. Accurate solder paste application is hugely essential in avoiding assembly defects which can have a knock on effect further around the production process. So it will be vital that this key stage is correctly managed and controlled by your EMS partner.
Solder paste it’s essentially powdered solder that has been suspended in a thick medium called flux. The flux provides a type of temporary adhesive, holding the components in place before soldering process begins. Solder paste is used to the PCB by using a stencil (generally stainless steel, but occasionally nickel,) then as soon as the solder is melted it forms an electrical/mechanical connection.
The thickness in the stencil ‘s what determines the level of solder applied. For a few projects it could also be required to have a lot of thicknesses in various areas inside the one stencil (sometimes called a multi-level stencil).
Another key factor to take into account within the solder printing process is paste release. The best kind of solder paste ought to be selected in relation to how big is the apertures (or holes) from the stencil. When the apertures are extremely small, as an example, then this solder paste could be quite likely going to staying with the stencil and never adhering correctly on the PCB.
Manipulating the rate of paste release however can be managed, either start by making changes towards the style of the aperture or by lessening the thickness of the stencil.
The sort of solder paste that is utilized may also influence on the ultimate print quality, so it’s vital that you pick the appropriate mixture of solder sphere size and alloy for the project, and help it become mixed to the correct consistency before use.
Once the stencil may be designed as well as your EMS partner is preparing to create the first PCB, they will next want to consider machine settings.
Basically, the flatter you can the PCB over the printing process, the greater the outcome will be. So by fully supporting the PCB through the printing stage,either by way of automated tooling pins or with a dedicated support plate, your EMS provider can remove the chance for any defects including poor paste deposit or smudging.
You’ll want to take into account the speed and pressure with the squeegees throughout the printing process. One solution is going to be have one speed for the solder paste but to have varying examples of pressure, using the unique specifications from the PCB as well as the length of the squeegee.
Cleaning the stencils, both before and throughout production, can also be crucial in ensuring quality control. Many automatic printing machines have a very system that could be set to scrub the stencil following a fixed quantity of prints that helps in order to avoid smudging, and prevents any blockages in the apertures.
Finally too, the printers should have a built-in inspection system (for example Hawk-Eye optical inspection) that may be preset to evaluate the use of paste across the whole PCB after printing.
The solder paste printing process can be a precise and detailed one that will have a significant part to play from the ultimate success of one’s cool product. And, because this short article highlights, a lot of detailed work is planning to happen behind the curtain before your EMS partner solders the first electronic ingredient of a board.