Surface mount assembly (SMT) carries a crucial role to experience within the Awesome Introduction (NPI) process for electronics manufacturing.
The high amount of automation inside 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 for an electronics manufacturing services (EMS) provider can be divided into four key stages:
Solder Paste Printing
Automated Optical Inspection (AOI)
With respect to the complexity in the design, or maybe your own outsourcing strategy, your products could move through each one of these processes in turn, otherwise you may find which you omit a measure or two.
You want to highlight the specific attributes, as well as the vital importance, in the solder paste printing process on your NPI.
Working to your specifications
The first step on your EMS provider can be to analyse the printed circuit board (PCB) data that is specific to your order, in order that they select the required stencil thickness as well as the most suitable material.
Solder paste printing is among the most common technique 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 will be vital that key stage is correctly managed and controlled by your EMS partner.
Solder paste is basically powdered solder that has been suspended inside a thick medium called flux. The flux behaves as a form of temporary adhesive, holding the parts set up before soldering process begins. Solder paste is used towards the PCB employing a stencil (generally stainless, but occasionally nickel,) then once the solder is melted it forms an electrical/mechanical connection.
The thickness in the stencil ‘s what determines the volume of solder applied. For a lot of projects it may also be essential to have several thicknesses in various areas inside one stencil (also known as a multi-level stencil).
Another primary factor to take into consideration in the solder printing process is paste release. The proper form of solder paste must be selected dependant on the dimensions of the apertures (or holes) within the stencil. If the apertures are very small, by way of example, then a solder paste may be quite likely going to staying with the stencil and not adhering correctly on the PCB.
Controlling the rate of paste release however can be easily managed, either by looking into making changes for the form of the aperture or by reducing the thickness from the stencil.
The kind of solder paste that is utilized also can affect the last top printing quality, so it will be imperative that you choose the appropriate blend of solder sphere size and alloy for the project, and also to make sure it is mixed for the correct consistency before use.
Once the stencil continues to be designed as well as your EMS partner is able to make the first PCB, they will next be thinking about machine settings.
Put simply, the flatter you can keep the PCB over the printing process, better the end result will be. So by fully supporting the PCB throughout 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 take into account the speed and pressure with the squeegees in the printing process. One solution is usually to have one speed for that solder paste but to get varying numbers of pressure, using the unique specifications of the PCB and also the length of the squeegee.
Cleaning the stencils, both just before and throughout production, is likewise crucial in ensuring quality control. Many automatic printing machines use a system that could be set to scrub the stencil following a fixed number of prints which assists in order to avoid smudging, and prevents any blockages with the apertures.
Finally too, the printers really should have a built-in inspection system (including Hawk-Eye optical inspection) which may be preset to monitor the use of paste over the whole PCB after printing.
The solder paste printing process can be a precise and detailed one that may significant part to play inside the ultimate success of your awesome. And, simply because this post highlights, so much detailed jobs are likely to take place behind the scenes before your EMS partner solders the very first electronic component to a board.