Surface mount assembly (SMT) features a crucial role to try out inside the Awesome Introduction (NPI) process for electronics manufacturing.
The top a higher level automation inside SMT methodology comes with a variety 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 to have an electronics manufacturing services (EMS) provider could be divided into four key stages:
Solder Paste Printing
Automated Optical Inspection (AOI)
With regards to the complexity in the design, or maybe your own outsourcing strategy, your products or services could move across all these processes therefore, otherwise you could find which you omit one step or two.
You want to highlight the particular attributes, as well as the vital importance, in the solder paste printing process on your NPI.
Attempting to your specifications
The first step to your EMS provider can be to analyse the pcb (PCB) data which is specific to your order, in order that they select the required stencil thickness and also the most suitable material.
Solder paste printing is the most common approach to applying solder paste to some PCB. Accurate solder paste application is hugely crucial in avoiding assembly defects which can have a knock on effect further around the production process. Therefore it is vital this key stage is correctly managed and controlled by your EMS partner.
Solder paste is essentially powdered solder which has been suspended inside a thick medium called flux. The flux acts as a form of temporary adhesive, holding the parts set up before soldering process begins. Solder paste is applied on the PCB utilizing a stencil (generally stainless steel, but occasionally nickel,) then once the solder is melted it forms an electrical/mechanical connection.
The thickness from the stencil ‘s what determines the level of solder applied. For a few projects it may be also required to have several thicknesses in different areas within the one stencil (also known as a multi-level stencil).
Another key factor to consider from the solder printing process is paste release. The best sort of solder paste ought to be selected based upon the dimensions of the apertures (or holes) inside stencil. In the event the apertures have become small, for example, then this solder paste could be very likely to sticking with the stencil and not adhering correctly towards the PCB.
Controlling the rate of paste release however can be managed, either by looking into making changes on the form of the aperture or by lessening the thickness from the stencil.
The kind of solder paste that is utilized could also impact on the ultimate top printing quality, so it will be important to choose the appropriate blend of solder sphere size and alloy to the project, also to ensure it is mixed towards the correct consistency before use.
When the stencil has become designed plus your EMS partner is preparing to create the first PCB, they will next want to think about machine settings.
Basically, the flatter you can the PCB through the printing process, better the outcome will likely be. So by fully supporting the PCB through the printing stage,either through automated tooling pins or which has 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 in the squeegees in the printing process. One solution can be to have one speed for your solder paste but to have varying levels of pressure, based on the unique specifications of the PCB along with the length of the squeegee.
Cleaning the stencils, both prior to and throughout production, can also be essential in ensuring qc. Many automatic printing machines have a system that could be set to clean the stencil from a fixed variety of prints which assists in order to avoid smudging, and prevents any blockages from the apertures.
Finally too, the printers must have a built-in inspection system (for example Hawk-Eye optical inspection) which may be preset to monitor the use of paste throughout the whole PCB after printing.
The solder paste printing process can be a precise and detailed one which have a significant part to try out in the ultimate success of your respective awesome. And, since this post highlights, a huge amount of detailed work is prone to occur behind the curtain before your EMS partner solders the 1st electronic component to a board.