Do you have a need for SMT production? Are you in the food, electronics, or medical industry? Then, we can custom-design a production line to best suit your needs. Have you witnessed the dynamic changes in the synthesis of PCBs? Why are some PCBs quite different in design and dimensions? Nowadays, SMT has proven to be an efficient mounting style that minimizes the manufacturing cost. In the 1960s, assemblers developed this method, which later spread in the 1980s. Finally, in the 1990s, they used it in the leading assembly companies. SMT production has several advantages over the popular through-hole assembly technique, but at the same time, it has some demerits.
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What is SMT?
Surface mount technology (SMT) is a style we use while producing PCBs. It involves mounting electrical components on a bare board. SMT is a directly opposite process to through-hole mounting format. Assemblers developed it from the hybrid integrated circuit technology. SMT production is the process of synthesizing electronic circuits using plates or boards. In engineering literature, we refer to SMT as an SMT production line. We refer to electronic components prepared using SMT as surface-mounted devices (SMDs).
What are the steps in SMT production?
SMT is a lengthy process that requires a certain level of organization to achieve it. The following are the iterations that we follow in this production:
I. Component Preparation
Before proceeding to any other activity, we must prepare all the components and check for faults. For example, the bare board must have flat solder pads and no holes.
II. Stencil setting
We position the stencil according to the intended solder pad’s position on the PCB.
III. Printing of the solder paste
Solder paste, a mixture of tin and flux, works best in connecting the solder pads and SMC on the PCB.
IV. Placement of the components
The PCB moves on a conveyor belt to the pick-and-place machine, which places all the electronic components in their intended positions.
V. Reflow soldering
This process takes place in five consecutive zones. These are:
- Soldering oven – Having applied SMC, the boards continue to the reflow of the soldering oven.
- Pre-heat zone – This is a high-temperature zone with a temperature rising at one to two degrees Celsius per second until it is between 140ºC and 160ºC.
- Soak zone – the temperature in this zone is between140ºC and 160ºC. The boards spend between 60 and 90 seconds in this zone before proceeding to the reflow zone.
- Reflow zone – In this zone, the temperature rise rate is 1 – 2 degrees Celsius per second to a temperature between 210 ºC and 230 ºC. The tin in the paste melts, attaching the lead components to the pads. The surface tension of the molten solder aids in maintaining the position of the components.
- Cooling zone – As the board leaves the heating zone, they enter this zone which prevents abrupt cooling of the solder, hence eliminating connection problems.
VI. Cleaning and scanning of the board
Having soldered the board, we now clean them, checking them for any faults. We achieve this with the aid of flying probe testers, magnifying lenses, X-ray machines, and Automated Optical Inspection (AOI).
What factors do we consider when choosing the best SMT production machine?
The nature of the machine determines the quality and quantity of the products. It is therefore important that whenever you go for an SMT production machine, you consider the following factors:
- Speed
The operating speed of the pick-and-place machine determines how many boards you can assemble within a given period. A machine with a higher speed will pick, inspect, and place more components within a short period. Therefore, it proves to be more effective in the mass production of PCBs.
- Accuracy
A more accurate machine will perform numerous tasks without making many errors. Therefore, we are sure of high-quality products and maximum product outputs. In addition, the power consumption by the machine will be lesser if it has higher accuracy.
- Size of the components you intend to handle
If you purchase a surface mount technology machine, the size of the components you wish to mount using the machine is very important. Getting a machine that suits your components will save much of your time, as you do not need to go back to the dealer for machine exchange.
What are the advantages of surface mount technology (SMT) production?
- PCBs assembled using SMT are more compact and hence have higher circuit speeds.
- Using SMT, you can place many components closer together on one board. Eventually, you will have a smaller and more compact PCB with lesser weight.
- We can utilize both sides of the circuit board by applying SMT, allowing for more connections per component and a higher component density.
- SMT production process is, therefore, faster compared to the through-hole assembly since we do not require drilling holes on the bare board before the placement process. Thus, the preparation cost of the PCB will be lower.
- PCBs prepared using surface mount technology have lower inductance and resistance. Therefore, they will have higher frequency performance than those prepared with the through-hole assembly technique.
- Due to low lead inductance and compact package, the PCB will have an easily achievable Electromagnetic Compatibility (EMC).
What are the disadvantages of SMT production?
- The solder connections may get damaged as the PCB moves through different thermal cycles.
- Due to the less solder used in this process, the solder joints may not be reliable.
- Due to the small sizes, you will require expensive tools and a skilled operator to repair faulty PCBs.
- According to the design of the SMT-produced PCBs, we cannot install sockets that would facilitate the easy replacement of faulty components.
- SMDs are smaller in size than through-hole components, and therefore, there is no space for labeling the parts and stating component values.
- Subjecting components to mechanical strain may interfere with their functioning. Therefore, since SMT production involves stressing components to occupy smaller space, we cannot solely use it to manufacture PCBs.
Conclusion
SMT Production can help you take your business to the next level. Although SMT production is a highly specialized job and the demand for skilled SMT technicians will only increase, it is crucial to be on top of your game and have life skills you can use in any job.
We cannot perform SMT production successfully without an SMT production machine. If you want to purchase such a machine, the most suitable machine will depend on three factors. These are the speed, accuracy of the machine, and the size of components you wish to handle with this machine.
