The majority of the surface mount technology (SMT) parts on a PCB will be assembled with automated pick-and-place equipment. To prepare for that, the raw boards and the components must be prepared for production. This begins with both being validated by the CM’s inspection teams. Once that is complete, the boards will then be prepared for assembly using this process:

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And if you are going learn the knowledge of SMT PCB assembly, please check and read the content for more detailed information below.

1.     What are the preparations before SMT PCB assembly?

A few preparatory steps have to happen before real PCBA process even begins. This helps PCB manufacturers assess the functionality of a PCB design, and primarily includes a DFM check.

Most companies specializing in PCB assembly need the design file of the PCB to start out, along with any other design notes and specific requirements. This is so the PCB assembly company can check the PCB file for any issues that may affect the PCB's functionality or manufacturability. This is a design for manufacturability check, or DFM check, for short.

The DFM check looks at all the design specifications of a PCB. Specifically, this check looks for any missing, redundant or potentially problematic features. Any of these issues may severely and negatively influence the functionality of the final project. For example, one common PCB design flaw is leaving too little spacing between PCB components. This can result in shorts and other malfunctions.

2.     How to solder the paste for SMT PCB assembly?

Applying soldering paste is one of the first steps in the SMT assembly process. Soldering paste is "printed" on the boards using the silk-screen method. Depending on the design of the board, different stainless-steel stencils for "printing" the paste onto the board and various product-specific pastes are used. Using a laser cut stainless-steel stencil custom made for the project, the soldering paste to be applied only to the areas where components will be soldered. After the soldering paste is on the boards, a 2D-soldering paste inspection is performed to ensure that the paste is evenly and correctly applied. Once the accuracy of the soldering paste application has been confirmed, the boards are transferred to the SMT assembly line, where the components will be soldered.

3.     How to make DFM check for SMT PCB assembly?

Once a turnkey order is released to Bittele’s production team, their very first task is the validate the design through a thorough DFM / DFA Check process. These checks include verification of consistency across different design documents (i.e. BoM, Gerbers, Centroid, etc.), part spacing, footprint accuracy, and clear orientation markings. The main objective of this procedure is to minimize as much as possible the potential for design errors to affect the finished product, which acts to protect Bittele’s clients against the additional time and cost involved with board-level rework.

Clients should watch for emails from Bittele’s production team over course of the first one or two days after placing an order. If any issues or discrepancies are detected during this initial check, the production coordinator for the order in question will reach out to the client directly for resolution. Generally, an itemized report will be sent for response, and the order will be placed on hold pending full confirmation, so it is important to reply to these questions as soon as possible in order to avoid delays.

4.     What is the process of SMT?

Here we divided the complete SMT soldering process into 10 steps:

·  Printing

·  Adhesive Dispense

·  Component Placement

·  Pre-Reflow Automated Optical Inspection (AOI)

·  Reflow Soldering

·  Post-Reflow Automated Optical Inspection (AOI)

·  Conformal Coating

·  Final Inspection and Functional Test

·  Washing & Drying

·  Packaging & Shipping

5.     What are the uses of SMT?

SMT assembly was born as a way to create a better, more powerful electronic product.

One look around your office or living room will show you several common surface mount technology applications. Basically, turn to surface mount PCB assembly whenever you need a product that’s:

·  Smaller

·  Lighter

·  Faster

·  More powerful

While through-hole is still used in certain applications or even certain locations on a board, SMT assembly has largely taken over