Surface mount assembly (SMT) carries a crucial role to try out within the Cool product Introduction (NPI) process for electronics manufacturing.
Our prime degree of automation inside SMT methodology comes with 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 categorised into four key stages:
Solder Paste Printing
Automated Optical Inspection (AOI)
With respect to the complexity from the design, maybe own outsourcing strategy, your product or service could move across these processes therefore, or you could find that you omit a measure or two.
We want to highlight the particular attributes, as well as the vital importance, of the solder paste printing process on your NPI.
Fitting in with your specifications
The first step for your EMS provider is to analyse the printed circuit board (PCB) data which is specific for your order, to make sure that they select the required stencil thickness and the the most suitable material.
Solder paste printing is among the most common approach to applying solder paste into a PCB. Accurate solder paste application is hugely critical in avoiding assembly defects that may have a knock on effect further down the production process. So it is vital until 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 behaves as a kind of temporary adhesive, holding the parts in position before the soldering process begins. Solder paste is used towards the PCB utilizing a stencil (generally stainless-steel, but occasionally nickel,) then after the solder is melted it forms an electrical/mechanical connection.
The thickness with the stencil is the thing that determines the total number of solder applied. For a lot of projects it could be also necessary to have several thicknesses in different areas inside the one stencil (known as a multi-level stencil).
Another key factor to take into account within the solder printing process is paste release. The proper type of solder paste ought to be selected based on how big is the apertures (or holes) from the stencil. If your apertures are incredibly small, as an example, then the solder paste could possibly be very likely to adhering to the stencil instead of adhering correctly for the PCB.
Manipulating the rate of paste release however can easily be managed, either start by making changes to the kind of the aperture or by lessening the thickness from the stencil.
The kind of solder paste which is used may also effect on the ultimate print quality, so it is vital that you select the appropriate blend of solder sphere size and alloy to the project, also to ensure it is mixed to the correct consistency before use.
Once the stencil has been designed plus your EMS partner is ready to produce the first PCB, they're going to next want to think about machine settings.
To put it differently, the flatter you can preserve the PCB through the printing process, better the outcome will be. So by fully supporting the PCB through the printing stage,either using automated tooling pins or with a dedicated support plate, your EMS provider can eliminate the chance for any defects for example poor paste deposit or smudging.
You'll want to consider the speed and pressure with the squeegees through the printing process. One solution is to get one speed for that solder paste but to have varying examples of pressure, in line with the unique specifications with the PCB and the entire squeegee.
Washing the stencils, both just before and throughout production, will also be essential in ensuring qc. Many automatic printing machines have a system which can be set to scrub the stencil following a fixed quantity of prints that helps to stop smudging, and prevents any blockages in the apertures.
Finally too, the printers needs to have a built-in inspection system (like Hawk-Eye optical inspection) which may be preset to evaluate the presence of paste through the whole PCB after printing.
The solder paste printing process is a precise and detailed one that have a significant part to try out in the ultimate success of one's new product. And, because this short article highlights, a huge amount of detailed tasks are planning to take place under the surface before your EMS partner solders the 1st electronic component to a board.