Surface mount assembly (SMT) features a crucial role to experience in the Cool product Introduction (NPI) process for electronics manufacturing.
The top a higher level automation from the SMT methodology comes with 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 can be separated into four key stages:
Solder Paste Printing
Pick and Place
Automated Optical Inspection (AOI)
Depending on the complexity with the design, maybe own outsourcing strategy, your products or services could go through these processes consequently, or else you could find which you omit a stride or two.
We should highlight the particular attributes, along with the vital importance, from the solder paste printing process for your NPI.
Fitting in with your specifications
The first task for the EMS provider will be to analyse the pcb (PCB) data that’s specific on your order, to ensure they find the required stencil thickness and the most suitable material.
Solder paste printing is among the most common way of applying solder paste into a PCB. Accurate solder paste application is hugely crucial in avoiding assembly defects which may possess a knock on effect further down the production process. So it is vital this key stage is correctly managed and controlled through your EMS partner.
Solder paste is essentially powdered solder which was suspended inside a thick medium called flux. The flux acts as a sort of temporary adhesive, holding the constituents available before soldering process begins. Solder paste is applied towards 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 from the stencil is what determines the volume of solder applied. For some projects it could also be required to have a lot of thicknesses in various areas inside the one stencil (known as a multi-level stencil).
Another key factor to consider from the solder printing process is paste release. The best form of solder paste must be selected dependant on how big is the apertures (or holes) inside the stencil. When the apertures are extremely small, by way of example, then this solder paste might be very likely to sticking to the stencil rather than adhering correctly to the PCB.
Controlling the rate of paste release however can be managed, either start by making changes to the style of the aperture or by lessening the thickness from the stencil.
The sort of solder paste that is used can also affect a final top printing quality, so it’s important to find the appropriate blend of solder sphere size and alloy for your project, and makes it mixed on the correct consistency before use.
When the stencil has become designed as well as your EMS partner is getting ready to create the first PCB, they’re going to next want to think about machine settings.
Basically, the flatter you can keep the PCB from the printing process, the higher the end result will probably be. So by fully supporting the PCB in the printing stage,either through automated tooling pins or which has a dedicated support plate, your EMS provider can take away the chance of any defects like poor paste deposit or smudging.
It’s also important to take into account the speed and pressure from the squeegees during the printing process. One solution is usually to have one speed for the solder paste but to have varying numbers of pressure, using the unique specifications in the PCB and the length of the squeegee.
Cleansing the stencils, both just before and throughout production, will also be essential in ensuring qc. Many automatic printing machines have a very system that can be set to clean the stencil after a fixed amount of prints which will help to stop smudging, and prevents any blockages with the apertures.
Finally too, the printers really should have a built-in inspection system (such as Hawk-Eye optical inspection) which is often preset to observe a good paste through the whole PCB after printing.
The solder paste printing process is often a precise and detailed one which will have a significant part to experience from the ultimate success of the cool product. And, since this article highlights, so much detailed tasks are planning to happen c = continual reporting before your EMS partner solders the first electronic aspect of a board.