le 30 Juin 2020 à 10:55
Tags : SMT
Surface mount assembly (SMT) carries a crucial role to learn in the Cool product Introduction (NPI) process for electronics manufacturing.
The top a higher level automation from the SMT methodology provides 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 might be separated into four key stages:
Solder Paste Printing
Pick and Place
Automated Optical Inspection (AOI)
With respect to the complexity with the design, maybe own outsourcing strategy, your product could move through these processes consequently, or you might discover which you omit a step or two.
You want to highlight the specific attributes, and the vital importance, from the solder paste printing process to your NPI.
Working to your specifications
Step one to your EMS provider may be to analyse the pcb (PCB) data that's specific to your order, to ensure that they select the required stencil thickness and also the most suitable material.
Solder paste printing is easily the most common approach to applying solder paste to a PCB. Accurate solder paste application is hugely crucial in avoiding assembly defects which could use a knock on effect further down the production process. So it is vital that this key stage is correctly managed and controlled because of your EMS partner.
Solder paste it's essentially powdered solder which was suspended inside a thick medium called flux. The flux provides for a sort of temporary adhesive, holding the components set up until the soldering process begins. Solder paste is used to the PCB by using a stencil (generally metal, but occasionally nickel,) then after the solder is melted it forms an electrical/mechanical connection.
The thickness with the stencil is what determines the volume of solder applied. For many projects it may be also important to have a lot of thicknesses in several areas within the one stencil (also known as a multi-level stencil).
Another important element to take into consideration inside the solder printing process is paste release. The proper kind of solder paste should be selected in relation to the dimensions of the apertures (or holes) within the stencil. If the apertures are extremely small, by way of example, then a 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 managed, either by looking into making changes for the form of the aperture or by reduction of the thickness in the stencil.
The type of solder paste that is utilized could also effect on the ultimate top printing quality, therefore it is imperative that you pick the appropriate blend of solder sphere size and alloy for that project, and make sure it is mixed towards the correct consistency before use.
When the stencil may be designed and your EMS partner is getting ready to produce the first PCB, they're going to next want to consider machine settings.
Quite simply, the flatter you can maintain the PCB through the printing process, the higher the end result will be. So by fully supporting the PCB through the printing stage,either using automated tooling pins or using a dedicated support plate, your EMS provider can remove the potential for any defects for example poor paste deposit or smudging.
It's also important to consider the speed and pressure with the squeegees through the printing process. One solution is to have one speed for your solder paste but to possess varying degrees of pressure, based on the unique specifications of the PCB as well as the whole squeegee.
Cleansing the stencils, both just before and throughout production, will also be crucial in ensuring quality control. Many automatic printing machines possess a system which can be set to scrub the stencil from a fixed quantity of prints which will help to avoid smudging, and prevents any blockages in the apertures.
Finally too, the printers needs to have a built-in inspection system (for example Hawk-Eye optical inspection) that may be preset to evaluate the existence of paste throughout the whole PCB after printing.
The solder paste printing process is often a precise and detailed one which will have a significant part to play in the ultimate success of your new product. And, since this short article highlights, a huge amount of detailed jobs are likely to occur under the surface before your EMS partner solders the very first electronic ingredient of a board.