Surface mount assembly (SMT) carries a crucial role to learn in the Cool product Introduction (NPI) process for electronics manufacturing.
Our prime a higher level automation inside SMT methodology supplies 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 with an electronics manufacturing services (EMS) provider can be broken down into four key stages:
Solder Paste Printing
Pick make
Oven Profiling
Automated Optical Inspection (AOI)
With regards to the complexity with the design, or perhaps your own outsourcing strategy, your products could move through all these processes subsequently, or you may find that you omit one step or two.
We want to highlight the actual attributes, along with the vital importance, in the solder paste printing process to your NPI.
Attempting to your specifications
The initial step for the EMS provider can be to analyse the printed circuit board (PCB) data that is certainly specific on your order, to ensure that they find the required stencil thickness along with the the most appropriate material.
Solder paste printing is easily the most common approach to applying solder paste to a PCB. Accurate solder paste application is hugely critical in avoiding assembly defects that may use a knock on effect further along 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 which has been suspended inside a thick medium called flux. The flux behaves as a type of temporary adhesive, holding the constituents in place prior to the soldering process begins. Solder paste is applied for the PCB utilizing a stencil (generally metal, but occasionally nickel,) then after the solder is melted it forms an electrical/mechanical connection.
The thickness from the stencil is the thing that determines the volume of solder applied. For some projects it may well be also important to have a lot of thicknesses in different areas inside the one stencil (known as a multi-level stencil).
Another primary factor to consider within the solder printing process is paste release. The best form of solder paste should be selected in relation to the dimensions of the apertures (or holes) from the stencil. When the apertures have become 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.
Governing the rate of paste release however can be easily managed, either by looking into making changes for the style of the aperture or by reduction of the thickness from the stencil.
The solder paste utilized could also impact on the final print quality, therefore it is crucial that you find the appropriate mix of solder sphere size and alloy to the project, also to ensure it is mixed on the correct consistency before use.
Ensuring quality
After the stencil continues to be designed as well as your EMS partner is ready to generate the first PCB, they’re going to next want to think about machine settings.
Basically, the flatter you can maintain the PCB over the printing process, better the final results will be. So by fully supporting the PCB through the printing stage,either by way of automated tooling pins or using a dedicated support plate, your EMS provider can eliminate the chance for any defects including poor paste deposit or smudging.
You’ll want to consider the speed and pressure with the squeegees throughout the printing process. One solution is to have one speed for your solder paste but to possess varying degrees of pressure, using the unique specifications in the PCB and the whole squeegee.
Washing the stencils, both ahead of and throughout production, will also be essential in ensuring qc. Many automatic printing machines possess a system that can be set to clean the stencil from a fixed amount of prints which helps in order to avoid smudging, and prevents any blockages of the apertures.
Finally too, the printers should have a built-in inspection system (for example Hawk-Eye optical inspection) which is often preset to watch the use of paste throughout the whole PCB after printing.
The solder paste printing process is really a precise and detailed the one which may significant part to learn from the ultimate success of one’s awesome. And, since this short article highlights, a huge amount of detailed jobs are likely to occur behind the scenes before your EMS partner solders the initial electronic element of a board.