Surface mount assembly (SMT) includes a crucial role to try out inside the Awesome Introduction (NPI) process for electronics manufacturing.
Our prime a higher level automation within the SMT methodology offers 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 can be divided into four key stages:
Solder Paste Printing
Pick and Place
Automated Optical Inspection (AOI)
With respect to the complexity from the design, or maybe your own outsourcing strategy, your products or services could move through these processes consequently, otherwise you could find that you simply omit one step or two.
You want to highlight the particular attributes, along with the vital importance, from the solder paste printing process for your NPI.
Working to your specifications
The first task on your EMS provider may be to analyse the pcb (PCB) data that is specific on your order, to ensure that they pick the required stencil thickness and the most suitable material.
Solder paste printing is easily the most common approach to applying solder paste into a PCB. Accurate solder paste application is hugely essential in avoiding assembly defects which can possess a knock on effect further around the production process. So it is vital that key stage is correctly managed and controlled through your EMS partner.
Solder paste is actually powdered solder which was suspended in the thick medium called flux. The flux provides for a type of temporary adhesive, holding the components in position prior to the soldering process begins. Solder paste is applied on the PCB employing a stencil (generally stainless steel, but occasionally nickel,) then as soon as the solder is melted it forms an electrical/mechanical connection.
The thickness from the stencil is what determines the total number of solder applied. For some projects it may also be necessary to have a lot of thicknesses in numerous areas inside the one stencil (also known as a multi-level stencil).
Another key factor to think about in the solder printing process is paste release. The correct form of solder paste needs to be selected in relation to the dimensions of the apertures (or holes) inside stencil. If the apertures are very small, by way of example, then a solder paste could possibly be very likely to sticking with the stencil rather than adhering correctly for the PCB.
Manipulating the rate of paste release however can easily be managed, either by making changes to the kind of the aperture or by lessening the thickness of the stencil.
The sort of solder paste utilized could also effect on the final print quality, so it’s vital that you choose the appropriate combination of solder sphere size and alloy to the project, and to makes it mixed towards the correct consistency before use.
After the stencil has been designed as well as your EMS partner is able to produce the first PCB, they will next want to consider machine settings.
To put it differently, the flatter you can preserve the PCB through the printing process, better the outcome 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 get rid of the chance of any defects for example poor paste deposit or smudging.
You’ll want to think about the speed and pressure from the squeegees throughout the printing process. One solution is going to be have one speed for that solder paste but to have varying examples of pressure, in line with the unique specifications from the PCB along with the whole squeegee.
Cleansing the stencils, both before and throughout production, can also be essential in ensuring qc. Many automatic printing machines have a very system that could be set to clean the stencil after having a fixed quantity of prints which assists to stop smudging, and prevents any blockages of the apertures.
Finally too, the printers must have a built-in inspection system (such as Hawk-Eye optical inspection) which may be preset to monitor the existence of paste across the whole PCB after printing.
The solder paste printing process is often a precise and detailed the one that may significant part to play from the ultimate success of your new product. And, because this blog post highlights, plenty of detailed tasks are more likely to happen behind the curtain before your EMS partner solders the very first electronic component to a board.