What is BGA Chip?

What is BGA Chip?

BGA Chip is the technology used for surface mounting ICs using the small balls located on the chip package’s underside instead of pins. The BGA is also called CSP. The term BGA chip is commonly used for packages that are 4-8 balls in diameter.

Features Of BGA Chips

The following are the features of the BGA:

• Very small in size, about ½th of the area of the pin-based package.
• Every contact is located at the bottom of the chip’s surface.
• Every contact is made with a solder ball.

The solder balls are usually reflowed to make reliable connections to the substrates. The solder balls are then melted with the help of hot gas at a temperature exceeding 700 degrees Fahrenheit. The BGA packages usually use larger balls than the CSP packages. The large size of the balls makes the gas distribution easy and allows it to reach the bottom of the package. The solder balls don’t need to be round, similar to CSP packages. They can be made from any shape and are primarily seen in triangular and rectangular shapes since they are more reliable.

The BGA packages are robust, and the balls are generally attached to the chip with the least amount of adhesive instead of solder. It will allow for misalignment between the contact pads and the balls on the BGA board without causing damage. Excessive misalignment can result in poor electrical contact and solder fatigue.  BGA packages are not as reliable as CSP packages. They usually have large pads. The small package makes it challenging to maintain an even temperature distribution during the soldering and perform reliable visual inspection post-assembly. BGA chip is a device classification since the tool has many variations, such as the flip-chip BGAs and multi-chip BGAs.

Disadvantages

BGA packages come with some disadvantages when compared to pin-based packages.

• Every ball must be soldered to the PCB. It needs the reflowing process at a temperature over 400 degrees Celsius. With this, the solder can potentially damage the substrate material. Due to this, the BGAs are not used much in applications where small size is not necessary, and large packages can be used. 
• BGA packages are also not ideal for applications where reliability is crucial and small size is not a problem.
• A high level of heat is needed for soldering the balls onto the substrate, and it can potentially damage the BGA Chip. In this, the balls are generally attached to the chip with a small amount of adhesive and are not soldered in the same place as the CSPs.
• The bad quality of the thermal contact between the ball and the substrate can result in large temperature differentials across the balls, which causes solder fatigue that can cause severe temperature differentials across the ball, resulting in unreliable operation or damage to the IC.
• The substrate may not withstand the temperature produced during the soldering process. in this. The BGA chip should be attached to the heat sink with the best thermal conductivity material to dissipate the heat. It is not always possible. For instance, the BGA Chip should be used where there is not enough room for the heat sink.

Solutions To The Issues When Using BGA

The BGA chipset has many applications with more benefits than disadvantages. Following are some of the solutions.

The whole PCB can layer with the solder, and then the rework will be completed with the help of the hot air or solder bath. It allows using BGA chips in applications that may not be feasible otherwise.

However, BGA packages are used in low-reliability applications only if the surface mounting technology is managed by a skilled operator who can perform a visual inspection. The operator must recognize whether the ball came off the package, which is not always easy since the balls are generally small.

Importance of BGA Sockets in BGA Chips

The BGA sockets are utilized to surface-mount the BGAs on the PCBs. These sockets help to mount the BGA chips on the PCB without any issues. The primary issue with mounting IC on the PCB is that it can be a challenge to locate the pins of the IC on the PCB, and you may have to solder them separately.

Moreover, the mounting process for the BGA chips can take a lot of time if not done appropriately. With the help of BGA sockets, all of these issues can be resolved. The BGA sockets are made up of plastic and are shaped like a rectangle with spaces on the underside that accommodate every BGA chipset solder ball.

There are two types of BGA sockets, such as passive and active. The active BGA socket has many electrical contacts on the underside to the area where the BGA chipset’s solder balls are connected. The passive BGA does not come with any contact pads on the underside. Rather, the passive BGA is connected to the PCB with the help of the surface mount technology components. 

The BGA sockets for the BGA chips are accessible in different sizes based on the size of the chips. Some BGA sockets are also made to accommodate only one BGA Chip, whereas others accommodate two or four chips. The BGA socket size is generally specified in the number of columns and rows on the underside. For instance, if the BGA socket is made to accommodate a 4×4 ball BGA Chip, then it will have about 16 contact pads arranged in four columns and four rows.

BGA Chips are accessible in different sizes of balls. The x1 size is the smallest ball size and has a diameter of about 0.4mm. The ball size x4 is the biggest size available, and the balls have a diameter of about 1.0mm. The larger ball size provides a larger footprint of the BGA chip on the printed circuit board.

Why manufacturing companies must consider BGAs?

There are many reasons for manufacturing to consider using the BGA chips instead of the CSP packages.

The BGA package is smaller than the CSP counterpart. And these BGA Chips can have greater packing density than other surface-mount packages

These BGA packages are usually cheaper due to their smaller size, fewer added features, and fewer balls. Additionally, the BGA chips are made with lead-free solder. The soldering balls are then placed on the BGA chip with the robotic equipment’s help; it is more efficient than placing the hand on the CSP packages.

BGA packages offer a wider variety of shapes than CSP packages. It allows for packaging, which benefits several mounting geometries and decreases the PCB’s height. The small size of the BGA Chips makes them best for limited spaces such as smartphone devices.

The BGA packages are not more prone to misalignment than the CSP packages since they use a small number of adhesives to secure the balls onto the chip. It provides a larger error margin during the mounting process.

Conclusion

The BGA chips are widely used in different applications, from high-power radio frequency amplifiers to the lowest-power sensors. The BGA provides the smallest packages available that are small enough to accommodate large pins number on the chip.