SMT PCB Assembly

SMT PCB Assembly

In surface mount SMT assembly, components are mounted directly on the PCB surface. This technique has contributed to the rising demand for miniature assemblies. We, at Sierra Assembly Technology, Inc.  

In surface mount SMT assembly, components are mounted directly on the PCB surface. This technique has contributed to the rising demand for miniature assemblies. We, at Sierra Assembly Technology, Inc. offer high quality Surface Mount SMT PCB assembly services at cost-effective prices in faster turnarounds. With automated assembly processes, we are capable of assembling double-sided/ multilevel printed circuit boards that ensure optimum performance when used in demanding applications. We ensure consistent high quality and accurate placement of components with the use of the latest SMT technology. Our surface mount SMT PCB assemblies are known for their high mechanical strength, making them a reliable choice for high-speed circuit and de-coupling applications.

Sierra SMT PCB Assembly Capabilities

We are equipped with the state-of-the-art manufacturing facility and sophisticated machinery to support the fabrication. We also have highly trained and experienced personnel to make sure your job is done faster with high quality. Our capabilities in high quality SMT pcb assembly services include, but not limited to:

  • Cutting-edge prototype SMT assembly line ensuring fast and flexible production.
  • Vast inventory of production- ready components for ensuring faster production.
  • Advanced machines providing unrivalled technical capability and product quality.
  • BGA removal and replacement station, SMT IR rework station, and thru-hole rework station.
  • Clean, well-organised and secure environment for the final assembly.
  • Inspection and testing using X-ray analysis, AOI, Microscope to 20X.
  • Expertise in assembling single and double sided SMT boards in the following types:
    • Ball Grid Array (BGA)
    • Ultra-Fine Ball Grid Array (uBGA)
    • Quad Flat Pack No-Lead (QFN)
    • Quad Flat Package (QFP)
    • Small Outline Integrated Circuit (SOIC)
  • Plastic Leaded Chip Carrier (PLCC)
  • Package-On-Package (PoP)
  • Small Chip Packages (pitch of 0.2 mm)
  • SMT PCB Assembly in conformance to AS9100 REV-D+ISO-9001-2015 Certification

With these capabilities, we achieve a high level of placement accuracy, solder joint integrity, and high-end quality in all the surface mount SMT PCB assembly. We have the capacity, experience and capability to supply our customers with a wide range of SMT PCB assemblies as per the design specifications in the quickest possible lead time. Working to the highest standards, you can be assured with optimum quality in all printed circuit board assembly from prototypes to high volume production runs. With consistent quality, extremely precise control system, and excellent services, Sierra Assembly has gained popularity as a leading SMT pcb assembly service provider in the market. Do you have a specific requirement? Get a Free Instant quotation on PCB surface mount SMT pcb assembly services.


  • What is Surface Mount Technology?
Surface Mount Technology (SMT) in PCB involves mounting components to the surface of the PCB by soldering. The components that are mounted are known as Surface Mount Device (SMD) components. The biggest advantage of surface mount technology is the ability to incorporate even smaller-sized components. This technology has enabled manufacturers to achieve complex electronic circuits with small footprints. 
  • How is the SMT PCB Assembly Process Performed?
The SMT PCB assembly process involves the following steps:
  1. Designing: In this process, the PCB layout and components are finalized. The data for manufacturing is prepared and the process kicks off in the next step.
  2. Programming: In this step, the machines are set for manufacturing. The program is generated for the machine that will populate components on the bare board. This program is generated using any reliable CAD software. In this step, the program is also generated for the Automated Optical Inspection (AOI).
  3. Solder Paste Printing: In this step, the solder paste printer is prepared to apply solder paste on the pads of the bare boards. The paste is applied through stencils, which are prepared carefully to avoid printing defects. The solder paste printer is also programmed to apply the paste in accurate amounts. The paste volume per pad is inspected by in-built automated inspection machines.
  4. Components: All components are placed on marked areas of the PCB using a programmed components placement machine. The AOI is performed immediately after this step to ensure the components are positioned in the right place. The AOI machine also checks the component value and polarity during the process.
  5. Reflow Soldering: In this process, the PCB assembly is heated to sufficient temperatures to form strong solder joints.
  • What are the Benefits of SMT PCB Assembly?
SMT assembly provides many benefits and some of them are as follows:
  • It can be used to incorporate small components.
  • In SMT, the components can be placed on both sides of the board.
  • It assures high component densities.
  • Fewer holes need to be drilled for surface mounting than through-hole.
  • It require low initial costs and time for setting up the mass production.
  • SMT is the simpler and faster-automated assembly when compared to through-hole.
  • Errors regarding the component placement can be easily rectified. 
  • Surface mount PCBs feature strong joints, which can easily withstand vibrations. 
  • What are the techniques used in Surface Mount Technology?
There are several techniques for the reflow process. After applying the solder paste or a flux mixture on the board and after placing the components, the boards are conveyed to a reflow soldering oven. The techniques used for reflowing soldering include infrared lamps, hot gas convection, fluorocarbon liquids with a high boiling point, and so on.
  • What are the different testing methods used in SMT PCB Assembly?
At Sierra Assembly, we perform the following testing and inspection to ensure the quality of surface mount PCBs.
  1. Automated Optical Inspection (AOI): This is performed before and after the soldering to identify the component placement, presence, and solder quality.
  2. X-ray Testing: In this type of testing, the operator relies on the X-ray images of the PCB to check the solder joints and lead-less components such as Quad Flat Packs and ball grid arrays, which are generally not visible to naked eyes.
  3. In-Circuit Testing (ICT): This method is used to detect manufacturing defects by testing the electrical properties in the SMT Assembly.
  • What are the different types of Surface Mount Device Packages (SMD) provided by Sierra Assembly?
We provide the following types of SMD Packages.
  1. Ball Grid Array (BGA): A BGA is a type of surface-mount packaging used for integrated circuits. In this type of package, the solder balls replace pins on the underside of the chip package.
  2. Ultra-Fine Ball Grid Array (uBGA): It is the finest form of BGA, which is used to permanently fix devices such as microprocessors.
  3. Quad Flat Pack No-Lead (QFN): It is a leadless package, which is compact sized, and possesses excellent heat dissipation capabilities. 
  4. Quad Flat Package (QFP): A quad flat package (QFP) features "gull wing" leads on all its four sides.
  5. Small Outline Integrated Circuit (SOIC): A small outline integrated circuit (SOIC) is a surface-mounted integrated circuit (IC) package which is almost 30–50% smaller and 70% thinner than a dual in-line package (DIP). 
  6. Plastic Leaded Chip Carrier (PLCC): The Plastic Leaded Chip Carrier(PLCC)is a type of SMD integrated circuit package, which allows IC to be socket mounted or soldered to the board directly.
  7. Package-On-Package (PoP)Package-On-Package(PoP) combines ball grid array packages, and discrete logic vertically.
  • Do you provide turnkey SMT PCB Assembly?
Yes, we provide turnkey SMT PCB assembly.

  • What type of files or documents should I send for SMT PCB Assembly? 
  1. Gerber Files: The file contains all details of physical board layers including solder masks, copper layers, drill data, legends, and so on.  
  2. Bill of Materials (BOM): This contains information on the list of items needed for the PCB manufacturing and the instructions of manufacturing. 
  3. Pick and Place File: This file contains information on all components to be used in the PCB design and their rotation and X-Y coordinates.

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