Overview of BGA Assembly
The new world has dictated the kind of electronic components it needs. It has called for flexible, portable, compact, and miniature devices. This is why industries are moving in speed to develop better technologies to assemble electronic components such as printed circuit boards. Implementation of small-sized, extremely complex chips in electronic printed circuit boards has become necessary for us to meet the technological improvements shaping within us. Such electronic chips have increased component packaging density. Therefore, it is necessary to make use of low-cost and high-density packaging methods to meet this design requirement. Among such methods is PCB BGA assembly.
BGA is an abbreviation of Ball Grid Arrays. BGA assembly is one of the PCBA assembly processes involved in the fabrication of printed circuit boards where ball grid arrays are mounted onto the PCB by employing the solder reflow technique of fabrication. In circuit board BGA assembly, the surface mount devices utilize the solder ball arrays to make interconnections between them. The solder balls are then melted to make the interconnection when the PCB is passed via the reflow oven.
BGA Assembly Capabilities
FS Technology is a well-known Chinese PCB assembly manufacturer, our BGA assembly service is one of the many types of services we provide. As one of the most successful BGA assembly service providers, our customers can get anything they want from FS Technology, from micro BGA to large BGA (0.2mm-45mm), from PBGA to CBGA full-service.
- PBGA (Plastic Ball Grid Array)
- TBGA (Tape Ball Grid Array)
- CBGA (ceramic ball grid array)
- µBGA (Micro Ball Grid Array)
- CTBGA (Thin Chip Array Ball Grid Array)
- CABGA (Chip Array Ball Grid Array)
- CVBGA (Very Thin Chip Array Ball Grid Array)
- VFBGA (Very Fine Pitch Ball Grid Array)
- LGA (Large Grid Array)
- CSP (Chip Scale Package)
- WLCSP (Wafer Level Chip Scale Package)
Types of BGA Assembly
There exist three types of BGAs and we are going to have a wider look at them below.
PBGA
PBGA is the abbreviation of Plastic Ball Grid Array, this type of BGA involves the use of lamination since the board is built of a substrate and plastic-made packaging. Also, there is a visible distribution of the placed solder balls located on the lead solder and lead-free.
TBGA
TBGA is the abbreviation of Tape Ball Grid Array. This is where there is a cavity in the structure. There exist two major categories between the substrate and the chip. Solder bonding comes first followed by lead bonding.
CBGA
CBGA is the abbreviation of ceramic ball grid array. This is the oldest method as compared to PBGA and TBGA. This has a substrate material that involves multilayer ceramic. It has a metallic coating placed on the substrate using the packaging solder method so that it can offer mechanical protection to PCB leads, pads, and the board itself.
How does FS Technology control the quality of BGA soldering?
- Make sure that adequate heat is used to melt all the balls in the grid so that a strong joint can be realized for all the BGA joints to be soldered.
- Ensure that the used surface tension of the balls being molten locks the BGA package in a steady intended position until when the solder solidifies. It is advisable to use a temperature-controlled technique of soldering for the achievement of a high-quality soldered joint. The practice is good in that it can also make the solder joint avoid short-circuiting against each other.
- Make sure that you choose the configuration of the soldering temperature and solder alloy precisely and accurately to prevent the solder from melting completely but staying in the semi-liquid form.
BGA Defect Inspection
After the process of soldering the BGA components can end up being detective. The defects might originate from the components, soldering process, equipment, and environment-related defects. Some of such defects are cold soldering, open circuits, bridging, short circuits, misalignment, and loose soldering. We cannot forget to mention that sometimes the solder balls for the BGA have defective issues such as uneven sizes and missing balls.
Regarding the inspection of the BGA, it is very difficult to judge the quality of the end product. This is attributed to the fact that the solder balls are located underneath the chip and the visual inspection, which is the most used method cannot reveal the cavities that are present in the soldered joints. This calls for use of sophisticated and professional inspection equipment which will make you end up with a quality joint inspection. Such methods are the use of the boundary scan, electrical tests, and X-ray inspection.
Traditional electrical tests are good for detecting open and short circuits. Boundary scanning helps to access solder joints where they connect that is boundary connectors. This makes sure that you can inspect short circuits on the SMD components connected. Although the boundary scan method will allow you to have tests on the invisible joints as compared to the electrical tests, the two, methods are good for checking the electrical performance of the board. They cannot test the quality of the solder. Therefore, it is well advised that you involve other methods to carry out the quality of the solder, and in this case the solder on the hidden joints.
X-ray machines are used to detect other defects that occur during BGA PCB assembly. Through inspection using the X-Ray method, soldering problems such as paste bridging and solder balls that occur on the board can be eliminated. Some X-Rays are software supported and can compute the size of the gap in the ball to ensure that it follows set standards. 2D X-rays can be used to render three-dimensional images to check for vias, bind vias’ inner layers, and cold solder joints on the BGA assembled joint.
BGA Assembly Benefits
In most cases, BCG assembly is perfectly achieved and it is very reliable. It is achieved without the addition of the reball paste simply because the soldering is successful by the use of the solder ball only. It is advisable that you do good site preparation and makes use of the right flux process. The rebelling paste is beneficial for areas and surfaces that suffer planarity challenges.
Let us now look at some of the benefits that accompany the use of the BGA method:
Heat Conduction
The assembly offers good heat conduction capability. With BGA, heat can be perfectly dissipated from microcircuits to the outward surface. This solves the challenges of overheating associated with PCB components.
Higher Density Circuits
Making use of the through-hole technology circuit makes printed circuit boards densely populated which makes soldering such circuits very difficult. The introduction of surface mount devices and the BGA assembly makes the process of generating densely populated circuits very easy and successful.
Leads that are less damaged
BGA leads are made up of solder balls. This type of lead does not subscribe to any form of damage be it mechanical or electrical during the fabrication operation.
Improved thermal and Electrical Performance
BGA assembly ensures that the result is miniature-printed circuit boards. This makes the process of heat dissipation very simplified. With the wafer mount build using silicon material available on the top, excessive heat is moved to the ball grids with ease. The BGA packaging has no connecting pins which can break or even bend easily and this makes them very stable ensuring much improved electrical conduction hence perfectly improved performance.
Summary
- BGA which stands for Ball Grid Array involves mounting the ball grid on the SMD and PCBA by employing the solder reflow method.
- There exist three types of BGA that is PBGA where lamination is used, TBGA which has a cavity in the structure, and CBGA which has a substrate method involving multilayer ceramic.
- BGA defect inspection can be done by use of traditional electrical tests, boundary scans, and X-ray inspection methods.
- For good soldering to happen in BGA, use adequate heat to melt the ball grid nicely, and use surface tensioners to hold the surfaces being soldered together until the solder cools down and solidifies, and choose the configuration of the soldering temperature and solder alloy precisely.
- The benefits of BGA assembly are; proper heat conduction, production of high-density circuits, utilization of less damaged leads, and improved thermal and electrical performances.
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