Surface mount assembly (SMT) has a crucial role to play inside the New Product Introduction (NPI) process for electronics manufacturing.

The high a higher level automation within the SMT methodology offers 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 to have an electronics manufacturing services (EMS) provider can be divided into four key stages:

Solder Paste Printing
Pick and set
Oven Profiling
Automated Optical Inspection (AOI)
Based on the complexity with the design, maybe own outsourcing strategy, your products could move through each of these processes in turn, or else you might discover that you omit a measure or two.

We want to highlight the particular attributes, and also the vital importance, with the solder paste printing process to your NPI.

Trying to your specifications
The initial step on your EMS provider is to analyse the pcb (PCB) data that is certainly specific on your order, in order that they find the required stencil thickness and the the best option material.

Solder paste printing is regarded as the common technique of applying solder paste with a PCB. Accurate solder paste application is hugely crucial in avoiding assembly defects that may use a knock on effect further around the production process. Therefore it is vital that this key stage is correctly managed and controlled from your EMS partner.

Solder paste is actually powdered solder which was suspended in a thick medium called flux. The flux provides for a kind of temporary adhesive, holding the parts set up prior to the soldering process begins. Solder paste is used to the PCB utilizing a stencil (generally stainless-steel, but occasionally nickel,) then when the solder is melted it forms an electrical/mechanical connection.

The thickness in the stencil is exactly what determines the level of solder applied. For some projects it may well even be important to have several thicknesses in numerous areas inside one stencil (known as a multi-level stencil).

Another important element to think about inside the solder printing process is paste release. The correct kind of solder paste should be selected in relation to the size of the apertures (or holes) inside the stencil. If the apertures have become small, for example, then the solder paste may be prone to sticking with the stencil and not adhering correctly for the PCB.

Controlling the rate of paste release however can be simply managed, either by causing changes on the design of the aperture or by lessening the thickness in the stencil.

The type of solder paste that is utilized could also affect the ultimate print quality, so it’s vital that you select the appropriate combination of solder sphere size and alloy for that project, and makes it mixed to the correct consistency before use.

Ensuring quality
When the stencil may be designed plus your EMS partner is getting ready to create the first PCB, they are going to next want to think about machine settings.

Put simply, the flatter you can preserve the PCB from the printing process, the higher the end result will be. So by fully supporting the PCB in the printing stage,either through automated tooling pins or which has a dedicated support plate, your EMS provider can eliminate the chance of any defects such as poor paste deposit or smudging.

You’ll want to consider the speed and pressure with the squeegees during the printing process. One solution can be to have one speed for the solder paste but to have varying levels of pressure, in line with the unique specifications from the PCB and the entire squeegee.

Cleaning the stencils, both just before and throughout production, may 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 amount of prints that helps to prevent smudging, and prevents any blockages with the apertures.

Finally too, the printers really should have a built-in inspection system (such as Hawk-Eye optical inspection) that may be preset to observe the existence of paste through the whole PCB after printing.

The solder paste printing process is often a precise and detailed one which have a significant part to play from the ultimate success of the awesome. And, since this post highlights, a lot of detailed work is likely to occur c = continual reporting before your EMS partner solders the initial electronic component to a board.