The Critical Function Of Solder Paste Printing In New Product Introduction
Surface mount assembly (SMT) includes a crucial role to learn in the Cool product Introduction (NPI) process for electronics manufacturing.
The top a higher level automation inside the SMT methodology offers a number 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 categorised into four key stages:
Solder Paste Printing
Pick and set
Oven Profiling
Automated Optical Inspection (AOI)
Based on the complexity in the design, or maybe your own outsourcing strategy, your product could move across these processes subsequently, or perhaps you could find that you just omit a measure or two.
We should highlight the specific attributes, as well as the vital importance, of the solder paste printing process for your NPI.
Fitting in with your specifications
Step one for your EMS provider may be to analyse the pcb (PCB) data that’s specific in your order, to ensure that they choose the required stencil thickness and the most suitable material.
Solder paste printing is regarded as the common way of applying solder paste to some PCB. Accurate solder paste application is hugely important in avoiding assembly defects which may possess a knock on effect further along the production process. Therefore it is vital that this key stage is correctly managed and controlled from your EMS partner.
Solder paste is essentially powdered solder that is suspended in the thick medium called flux. The flux acts as a type of temporary adhesive, holding the constituents in position prior to the soldering process begins. Solder paste is applied for the PCB using a stencil (generally stainless, but occasionally nickel,) then as soon as the solder is melted it forms an electrical/mechanical connection.
The thickness with the stencil is exactly what determines the total number of solder applied. For a few projects it may also be important to have several thicknesses in several areas from the one stencil (often referred to as a multi-level stencil).
Another important element to consider within the solder printing process is paste release. The best sort of solder paste needs to be selected based upon the dimensions of the apertures (or holes) inside the stencil. In the event the apertures have become small, as an example, then this solder paste might be very likely to staying with the stencil and never adhering correctly towards the PCB.
Manipulating the rate of paste release however can be easily managed, either start by making changes towards the kind of the aperture or by reduction of the thickness with the stencil.
The type of solder paste that is utilized may also affect the ultimate top printing quality, so it will be imperative that you select the appropriate combination of solder sphere size and alloy to the project, and also to ensure it is mixed to the correct consistency before use.
Ensuring quality
After the stencil has become designed plus your EMS partner is ready to create the first PCB, they will next be considering machine settings.
Put simply, the flatter you can the PCB through the printing process, the greater the outcome is going to be. So by fully supporting the PCB in the printing stage,either by the use of automated tooling pins or with a dedicated support plate, your EMS provider can get rid of the potential for any defects including poor paste deposit or smudging.
It’s also important to take into account the speed and pressure of the squeegees during the printing process. One solution is to get one speed for the solder paste but to own varying levels of pressure, in line with the unique specifications with the PCB and also the whole squeegee.
Cleansing the stencils, both before and throughout production, can also be crucial in ensuring quality control. Many automatic printing machines use a system that could be set to wash the stencil after a fixed quantity of prints which will help to stop smudging, and prevents any blockages of the apertures.
Finally too, the printers needs to have a built-in inspection system (for example Hawk-Eye optical inspection) which can be preset to monitor a good paste throughout the whole PCB after printing.
The solder paste printing process can be a precise and detailed the one which have a significant part to try out within the ultimate success of your respective new product. And, because this blog post highlights, a lot of detailed effort is more likely to occur under the surface before your EMS partner solders the very first electronic aspect of a board.