BGA Assembly (Ball Grid Array Assembly) plays a vital role in the production of modern electronic devices. It is used to mount advanced electronic components on printed circuit boards. With the advent of smaller, faster, and more advanced electronic devices, BGA Assembly has found acceptance as one of the most popular packaging styles in the design of high-performance electronic circuits.
Unlike other electronic components with leads, BGA components consist of an array of solder balls at the underside of the component to provide connectivity with the printed circuit board.
What is BGA Assembly?
BGA assembly is the Surface Mount Technology (SMT) procedure for mounting Ball Grid Array packages on PCBs through controlled soldering. In reflow soldering, the melted solder balls create strong bonds between the integrated circuit and the PCB pads. There are different types of BGA packages to suit different electrical, thermal, and economic specifications:
Plastic Ball Grid Array (PBGA)
Plastic Ball Grid Array (PBGA)
Wire-Bonded BGA
Flip-Chip BGA (FC-BGA)
Advanced and Fine-Pitch BGAs
Since the solder joints are not visible and are covered by the component package, BGA assembly involves more complex process control and inspection systems than in conventional SMT assembly.
BGA Assembly Process Flow
The BGA assembly process uses a sophisticated SMT assembly process flow:
Process Flow for BGA Assembly
The assembly process involves a highly advanced SMT assembly process flow. The steps are as follows:
Solder Paste Printing
Solder paste is printed on the PCB pads using a stencil printer.
BGA Component Placement
BGA components are placed on the solder paste using highly advanced pick-and-place machines. This is because the solder joints are hidden.
Reflow Soldering
The PCB is then passed through a reflow oven. In this process, the solder balls melt and align themselves due to surface tension.
Inspection and Verification
As the solder joints are hidden, X-ray inspection is carried out to verify the quality of the solder joints.
Cleaning and Functional Testing
Cleaning is done to verify the reliability of the solder joints.
Benefits of BGA Assembly
High Interconnection Density
The BGA type of packaging provides connections over the entire underside of the device, thus allowing for more I/O connections and space-saving PCB designs.
Improved Electrical Performance
Reduced signal path lengths result in less parasitic inductance and resistance, allowing for faster signal transmission and operation at higher frequencies.
Superior Thermal Performance
Solder ball array provides improved dissipation, thus ensuring stability in operation.
Enhanced Reliability
Self-alignment during the reflow process, larger joint spacings, and coplanar soldering provide improved yield and reliability.
Space and Size Efficiency
BGA technology is capable of delivering powerful electronics in compact packages.
Key Points & Control in BGA Assembly at PCBCart
For successful BGA assembly processes, strict control is required in the design and raw material processes as well as in SMT assembly processes.
Design and Raw Material Control
PCB Design Optimization
Design for Manufacturability (DFM) analysis is a key factor in successful BGA assembly. Engineers must analyze pad design, layout, and material carefully to avoid assembly errors. The preferred use of Non-Solder Mask Defined (NSMD) pads enhances solder wetting properties and joint strength. Correct pad size, ranging from 0.8 to 1.2 mm depending on package requirements, is essential for robust solder formation.
Other design factors include managing the copper residual rate for thermal equilibrium, optimizing component placement to avoid conflicts, using high-Tg PCB materials for thermal performance, and using compatible surface finishes. Design checks include IPC specification checks, Gerber file reviews, polarity checks, and layout checks to reduce production hazards.
Raw Material and Component Control
Incoming raw materials have to adhere to very stringent requirements in handling and storage. Components have to be subjected to baking and vacuum packaging if they are moisture-sensitive. The moisture absorbed by the component has to be expelled before it is subjected to the reflow process. The components have to be protected from electrostatic discharge. A barcode-based tracing system helps track the components. The verification of BOM and component specifications is crucial.
Production Process Control in BGA Manufacturing
Stencil Printing Control
The design and printing of the stencils have a significant impact on the solder joints. The thickness of the stencils and the geometry of the apertures have to be optimized. The width-to-thickness ratios also have to be optimized. The solder paste used has to be stored properly. The stability of the solder paste is crucial. The 3D SPI inspection system helps track the quality of the printing. First-article inspection helps verify the accuracy before mass production.
Component Placement Control
During SMT placement operations, highly accurate mounting machines are used to ensure component alignment. The setup of the feeders, choice of nozzles, and material verification procedures are carried out in a manner that prevents component placement errors. The Manufacturing Execution System helps in maintaining consistency in operations, while ESD precautions are also taken to protect sensitive components. The component alignment can also be verified using X-ray technology if needed.
Reflow Soldering Control
The reflow soldering operation is considered the most critical operation in BGA assembly. To ensure that the temperature is appropriate for the PCB, measurement boards are used in this operation. The temperature is also maintained in a controlled manner using multi-zone reflow ovens with controlled oxygen concentration. The temperature peaks need to be appropriate so that the components are not damaged due to excessive heat. The timing between the printing operation and the reflow operation also needs to be carefully controlled so that the solder paste does not get degraded.
Cleaning and Post Processing Control
Cleaning is carried out after the soldering process to remove flux residues that can compromise electrical reliability in the long term. The flux residues can be removed by carefully controlling the solvent concentration and the cleaning time. Surface ion contamination test is conducted to verify the cleanliness levels. Baking is carried out after cleaning to remove all the moisture.
Inspection and Quality Assurance
As the BGA joints are not visible under the component body, sophisticated inspection equipment is required for quality assurance. The inspection strategies include all aspects of AOI inspection, analysis of solder joints by X-ray inspection, and quality inspection. Traceability is carried out throughout the manufacturing process.
Packaging and Final Protection
The final packaging protects the assembled product against mechanical damage and environmental exposure during transportation and storage. The use of anti-static packaging materials with desiccants prevents damage due to moisture and static electricity. Stress-controlled depaneling helps reduce stress on the solder connections, while barcode tracking helps in tracing the product through the logistics process.
PCBCart BGA Assembly Capabilities and Services
To fulfill complex electronic manufacturing needs, PCBCart provides complete BGA assembly services that include diverse BGA packages, precise assembly techniques, and quality assurance processes that are suitable for mission-critical applications.
Supported BGA Package Types
We provide a variety of BGA packages like PBGA, TBGA, CBGA, FCBGA, EBGA, Micro BGA, PoP, CSP, and WLCSP packages. The extensive range of supported BGA packages enables diverse electronic manufacturing services for customer segments like consumer electronics, industrial automation, communication infrastructure, high-performance computing, and many more.
BGA & CSP Assembly Capability
Our BGA assembly services include precise BGA and CSP assembly techniques with high precision in terms of manufacturing capabilities. The range of supported BGA sizes includes 5 mm x 5 mm to 45 mm x 45 mm, with minimum solder ball pitch capability down to 0.3 mm and minimum solder ball diameter down to 0.15 mm. The range of supported BGA packages includes BGA, LGA, HDA, PoP, uBGA, WLCSP, CSP, etc.
Quality Assurance and Inspection
To ensure the quality of products, PCBCart adopts diverse methods of inspection and verification, including Automated Optical Inspection, X-ray inspection for hidden solder joints, and functional performance testing. These inspection methods can effectively achieve product yield while maintaining electrical and mechanical performance.
BGA Rework and Repair Services
Besides conventional PCB assembly services, PCBCart also provides professional BGA rework services including PCB reballing, BGA site modification, repairing damaged or absent pads, component removal and replacement, etc. These services can effectively satisfy engineering verification, prototype optimization, and maintenance of complex electronic products.
As an indispensable component in PCB assembly services, BGA technology plays an irreplaceable role in the development of modern PCB technology. As electronic products continue to evolve in terms of integration and miniaturization, BGA technology remains an elementary component in the development of advanced electronic products.
With strict control over PCB design, precise SMT manufacturing techniques, advanced inspection technologies, and comprehensive engineering services, reliable product yield and product reliability can be achieved in PCB assembly services. As a professional BGA assembly service supplier with rich experience in BGA assembly services, PCBCart can offer you reliable services in BGA PCB assembly.
