What is Ball Grid Array (BGA) of PCB board?

What is PCB BGA?

BGA is also known as Ball Grid Array, which is a type of surface-mount packaging used for integrated circuits. BGA uses a different approach to the connections and is used for permanently mount devices. Other packages such as the quad flat pack, QFP, used the sides of the package for the connections. This meant that there was limited space for the pins which had to be spaced very closely and made much smaller to provide the required level of connectivity. The Ball Grid Array, BGA, uses the underside of the package, where there is a considerable area for the connections, which means the whole bottom surface could be fully used. 

The pins are placed in a grid pattern (hence the name Ball Grid Array) on the bottom of the integrated circuits. Not only the pins could help connect, pads with balls of solder are also featured with the function of connection. There is a set of cooper pads fitted on the BGA printed circuit board that used for the conncection.

The Advantages of BGA PCB

Efficiently PCB Space Usage in BGA Package

By using BGA package, we could use fewer PCB components and smaller footprint in PCBs, and such package can also be used in custom PCBs which could make the PCB space more effective. 

The Improvement in Electrical and Thermal Performance

Because of the small size of BGA packages, most of the heat could be transferred directly to the ball grid whenever the silicon wafer is mounted over the top. So this is considered as best way for heat dissipation. And as there are no bendable or breakable pins in the BGA packages, which would enhance the durability of these PCBs and also keeps good electrical performance.

Manufacturing Profit Improvement Because of Welding Improvement

The larger the pads of the BGA packages, the easier the soldering work. Therefore, it would definitely increase the speed of manufacturing which lead to profit improvement. One more ting, the larger pads of such PCBs also makes it very easy and possible to re-work.

Less Damage Danger

The solid solder balls on BGA package is not that easy to be damaged during operation.

Reducing PCB Assembly Cost

Efficiently PCB space using, improved features, quick manufacturing speed and less damage danger, all of these would definitely help reduce the PCB assembly cost when we are using BGA package.

BGA Types Explained

Because there are lots of different requirements for different types of assembly and equipment, a lot of different but useful BGA variants are produced to meet those requirements.

MAPBGA (Moulded Array Process Ball Grid Array)

The MAPBGA package is used in low-performance to mid-performance devices that require packaging with low inductance, ease of surface mounting. It provides a low cost option with a small footprint and high level of reliability.

PBGA (Plastic Ball Grid Array)

The PBGA package is used in mid to high performance devices that require low inductance, ease of surface mounting, relatively low cost, but still retaining high levels of reliability. Such kind of PBGA package has some additional copper layers in the substrate that used for improving power dissipation ability.

TEPBGA (Thermally Enhanced Plastic Ball Grid Array)

The TEPBGA package is featured with much higher heat dissipation ability. It uses thick copper planes in the substrate to draw heat from the die to the customer board.

TBGA (Tape Ball Grid Array)

The TBGA package is used in middle and high-end solution for applications which need high thermal performance without an external heatsink.

PoP (Package on Package)

The PoP package is used in applications where space is at a real premium. It allows for stacking a memory package on top of a base device.

MicroBGA

The MicroBGA package is smaller than the standard BGA package. There are three pitches that are prevalent in the industry: 0.65, 0.75 and 0.8mm.

How to Test BGA Assembly Board? 

One of the problems with BGA devices is that it is not possible to view the soldered connections using optical methods. As a result, many manufactures suspect about the technology when it was first introduced, they were not sure whether they were able to solder the devices satisfied. The main problem with soldering Ball Grid Array devices, is that sufficient heat must be applied to ensure that all the balls in the grid melt sufficiently for every joint to be satisfactorily made.

The joints cannot be fully tested by checking the electrical performance. It is possible that the joint may not be adequately made and that over time it will fail. The only satisfactory means of testing BGA assembly board is to use X-ray, because it is able to look through the device at the soldered joint beneath. Once the heat profile for the solder machine is set up correctly, the BGA devices are soldered well, it could make BGA assembly possible for most applications.

Factors Affecting PCB BGA Assembly Quality

Feasibility of BGA Pad Design

Because of different pitches, the BGA pacakges are classified as different types. So their own different advantages and disadvantages and corresponding pad would definitely affect the PCB BGA assembly quality.

Solder Paste Printing

Solder paste printing is the accurate transformation of solder paste from stencil to pad with stencil, so it plays a very important role to decide the BGA quality.

Positioning Accuracy

Accurate positions of BGA components on printed circuit board is extremely helpful to improve the BGA soldering reliability.

Soldering Temperature Curve and Soldering Defects

Due to the particularity of BGA package, it's extremely difficult to generate a satisfying soldering temperature curve. While the soldering temperature curve setting determines the forming process of soldering joints, it has very close relationship with the reliability of soldering joints.

BGA Inspection and Rework Technologies

Because all BGA solder joints are below packages after soldering, and the traditional testing means is not suitable for it. So how the testing technologies would be used on BGA will also affect the quality a lot.

How to Clean BGA Package

1. Place the BGA package on a conductive pad and use a litter solder paste on the surface of it.

2. By using the solder wire and soldering iron, we need to carefully remove the ball from the BGA. Use the soldering iron to heat the absorbent wire and melt the tin ball before you swipe the wash line over the BGA surface. 

3. Clean the BGA surface immediately with industrial alcohol. Use friction motion to remove solder aid on BGA surface.

4. By using the microscope to examine the clean pads, damaged pads, and unremoved tin balls.

5. Using deionized water and brush to scrub the BGA surface carefully.

6. Let the BGA dry in the air and double-check the BGA surface.

The Future of BGA Package of PCB

Due to the reasons of cost effectiveness and durability, the BGA packages will be more and more popular in the electrical and electronic product markets in the future. Furthermore, there are a lot of different BGA package types were developed to meet different requirements in the PCB industy, and there are a lot of great advantages by using this technology, so we could really expect a bright future by using the BGA package, if you have the requirement, please feel free to contact us at PCBA Store.