Surface mount assembly (SMT) has a crucial role to try out in the Awesome Introduction (NPI) process for electronics manufacturing.
The prime amount of automation from the 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 on an electronics manufacturing services (EMS) provider could be separated into four key stages:
Solder Paste Printing
Pick and put
Automated Optical Inspection (AOI)
With regards to the complexity in the design, maybe own outsourcing strategy, your product could pass through all these processes in turn, otherwise you might find which you omit a stride or two.
We should highlight the actual attributes, as well as the vital importance, of the solder paste printing process for your NPI.
Trying to your specifications
Step one to your EMS provider may be to analyse the printed circuit board (PCB) data that is certainly specific to your order, in order that they pick the required stencil thickness along with the the best option material.
Solder paste printing is easily the most common method of applying solder paste with a PCB. Accurate solder paste application is hugely essential in avoiding assembly defects which can possess a knock on effect further down the production process. Therefore it is vital until 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 behaves as a form of temporary adhesive, holding the parts in place before the soldering process begins. Solder paste is used to the PCB by using a stencil (generally stainless-steel, but occasionally nickel,) then after the solder is melted it forms an electrical/mechanical connection.
The thickness of the stencil is the thing that determines the level of solder applied. For a lot of projects it might be also essential to have several thicknesses in various areas inside one stencil (often referred to as a multi-level stencil).
Another important element to take into account within the solder printing process is paste release. The correct form of solder paste ought to be selected in relation to the size of the apertures (or holes) within the stencil. If your apertures have become small, as an example, then a solder paste may be quite likely going to adhering to the stencil rather than adhering correctly on the PCB.
Governing the rate of paste release however can be managed, either by making changes on the form of the aperture or by reducing the thickness with the stencil.
The type of solder paste utilized could also affect the ultimate top printing quality, so it’s vital that you find the appropriate combination of solder sphere size and alloy for the project, and make sure it is mixed on the correct consistency before use.
As soon as the stencil continues to be designed along with your EMS partner is getting ready to make the first PCB, they are going to next want to think about machine settings.
To put it differently, the flatter you can keep the PCB with the printing process, the higher final results is going to be. So by fully supporting the PCB in the printing stage,either through automated tooling pins or having a dedicated support plate, your EMS provider can eliminate the chance of any defects like poor paste deposit or smudging.
You’ll want to think about the speed and pressure of the squeegees throughout the printing process. One solution is going to be have one speed for that solder paste but to own varying degrees of pressure, in line with the unique specifications of the PCB and the entire squeegee.
Cleansing the stencils, both prior to and throughout production, can also be crucial in ensuring quality control. Many automatic printing machines use a system that could be set to scrub the stencil from a fixed variety of prints that helps to prevent smudging, and prevents any blockages in the apertures.
Finally too, the printers really should have a built-in inspection system (for example Hawk-Eye optical inspection) that may be preset to evaluate a good paste through the whole PCB after printing.
The solder paste printing process can be a precise and detailed one which have a significant part to play inside the ultimate success of the cool product. And, simply because this post highlights, a lot of detailed effort is planning to occur behind the curtain before your EMS partner solders the first electronic element of a board.