Ball Grid Array is an electrical packaging technology used in manufacturing, and its abbreviation is BGA. We install an integrated circuit or other electronic components on a small substrate in a BGA package and connections between the package and the printed circuit board (PCB). Here, we mount it using a series of tiny solder balls attached to the substrate’s bottom.
BGA is superior to other packaging technologies in several ways. They include increased density, better electrical performance, and smaller and lighter dimensions. BGA packages are also ideal for portable electronic devices, where weight and space are constraints due to their compact size and high density.
Laptops, mobile phones, game consoles, and automotive electronics frequently use BGA packages. In addition, they are also helpful in many industrial applications where performance and dependability are crucial.
BGA package production is a multi-step process that includes substrate fabrication, ball placement, underfilling, and final testing. The process needs specialized equipment and trained technicians to create high-quality, dependable packages that match the required criteria.
Substrate Fabrication
Substrate fabrication is the initial stage of the BGA manufacturing process. The substrate, also known as FR4 substrate, is the foundation layer of a BGA package and is typically constructed of a thin layer of epoxy resin reinforced with fiberglass. The BGA package needs mechanical support provided by the non-conductive FR4 substrate. We laminate the copper layer with the FR4 material to create the substrate, which we etch with the desired design.
Die Attach
Die attach is the following stage in the production of BGAs. First, die-attach entails attaching the integrated circuit (IC) die to the substrate using a conductive adhesive. The average IC die is only a few millimeters in size, which is extremely small. Next, the substrate and the IC die are electrically connected using conductive glue. Often, conductive paste or silver-filled epoxy act as the glue.
There are several steps in the die attach process. First, we cleanse the substrate to eliminate any impurities hindering the adhesive’s adhesion. The glue is then applied to the substrate as a single dot or a continuous line depending on the IC design. After picking up the IC die and placing it on the adhesive, any alignment changes will ensure it is correctly centered. Finally, we harden the glue once we place the die correctly to fasten it to the substrate.
Wire Bonding
Wire bonding is the third stage of the BGA manufacturing process. First, thin gold or aluminum wires are attached using wire bonding between the IC die and substrate pads. Then, a wire bonding machine joins the tiny wires, typically only a few microns in diameter. There are multiple processes in the wire bonding process:
The wire bonding machine places the wire over the first pad before melting its tip and adhering it to the pad with a flame or laser.
The machine then places the other end of the wire over the appropriate pad on the substrate, melts the other end, and attaches it to the pad.
For every wire that needs to bond, we repeat this procedure. This is because the wires make the electrical connections between the IC die and the substrate possible. The wire bonding procedure is crucial to the BGA package’s overall performance. Any flaw or failure during the bonding process might result in subpar electrical performance or package failure.
Encapsulation
Encapsulation comes next in the BGA production process. To shield the IC die and wire bonds from physical harm, moisture, and other environmental variables, encapsulation entails coating them with an epoxy resin layer. Then, to generate the required shape, we pour the epoxy into a mold during the molding step of the encapsulation process.
The BGA package’s overall dependability depends on the encapsulation process. It guards against damage to the IC die and sensitive wire bonds during handling and use. In addition, the encapsulating material is often ideal for its mechanical, electrical, and environmental resistance qualities and capacity to survive temperature changes.
Solder ball attachment
We add little solder balls to the bottom of the BGA package as the last stage in the manufacturing process for BGAs (Ball Grid Arrays). After that, the BGA package and the printed circuit board (PCB) connect electrically and mechanically via solder balls.
While the performance and dependability of the BGA package are dependent on the caliber and consistency of the solder balls, solder ball attachment is a crucial stage in the BGA production process. Poor electrical connections caused by insufficient solder ball attachment might result in BGA package malfunctions or even total failure.
The solder ball attachment process typically involves several steps, including:
Solder Ball Preparation:
Preparing the solder balls is the first stage in the attachment procedure. Typically, the solder balls help to make a lead-free alloy suitable with the BGA package and the PCB. Depending on the unique needs of the BGA package, solder balls are often made in various diameters. They range from 0.2mm to 1.0mm in diameter.
Flux Application:
After producing the solder balls, we cover the BGA package’s surface in flux. Flux aids in the surface cleaning of the solder balls and BGA package and promotes a strong solder joint.
Solder Ball Placement:
Using a specialized instrument, such as a pick-and-place machine, the solder balls move onto the BGA package once we deposit the flux. Using a high-precision alignment mechanism, the solder balls are meticulously positioned on the pads at the bottom of the BGA package. As a result, they ensure each ball is in the right place.
Reflow:
A reflow technique is applied to the BGA package once we position the solder balls. Reflow is heating the BGA package to a range of 220-260°C, which causes the solder balls to melt and bond with the BGA package’s pads. To ensure that the solder balls melt and connect properly, we manage the reflow and let the process lasts a few minutes.
Inspection:
After the reflow process, we examine the BGA package to ensure the solder balls have properly joined and that the solder junction is free of flaws or voids. In addition, we examine the solder ball attachment’s quality using various inspection techniques. For example X-ray, optical microscopy, and automated optical inspection (AOI).
Cleaning:
We clean the BGA package to remove any flux leftovers or other pollutants that might have accumulated during the solder ball attachment procedure. A solvent- or water-based cleaning technique appropriate for the BGA package. Additionally, the solder balls are commonly helpful for the cleaning procedure.
Overall, the solder ball attachment procedure is a crucial stage in manufacturing BGAs and necessitates a high degree of control and precision. In addition, the BGA package’s overall performance and longevity depend heavily on the consistency and dependability of the solder junctions.
Final testing:
After creating the BGA package, it goes through several tests to ensure it satisfies the necessary requirements. We frequently perform Visual examination, electrical testing, and environmental testing as part of the tests.
Summary
In conclusion, there are multiple processes in producing a Ball Grid Array (BGA) package. They include substrate fabrication, ball placement, underfilling, and final testing. Electrical communication between the BGA package and the printed circuit board comes from the high-performance material known as substrate fabrication (PCB). A pick-and-place machine inserts the balls, and epoxy material is helpful for the underfill. The final testing process includes electrical testing and visual inspection to ensure the integrity of the solder joints and the underfill material. The BGA manufacturing process is a precise, sophisticated procedure. It calls for cutting-edge machinery and qualified personnel to generate dependable, high-quality packages.
