PCB BGA

With the continuous enhancement of electronic device functionalities, their sizes have been continuously shrinking. In order to meet the functional requirements of these smaller devices, component packaging technologies have also been advancing. Since the late 1980s, Ball Grid Array (BGA) has emerged as one of the most popular packaging technologies, making significant contributions to meet this demand. They provide higher interconnect density compared to through-hole PGA and surface-mount QFP, with comparable costs and without the manufacturing issues associated with these packaging types. Since then, their popularity has been continuously increasing, and they have become the default packaging for high pin-count integrated circuits such as microprocessors and storage devices.

What is BGA?

BGA, short for Ball Grid Array, is a type of surface-mount packaging (chip carrier) used for integrated circuits. Traditionally, conventional surface-mount packages use side connections to achieve limited pin connection area. In contrast, BGA packages utilize bottom connections, offering larger connection space, enabling high-density PCBs and high-performance electronic products.

BGA packages come in various pin pitch specifications such as 1.27mm, 1.0mm, 0.8mm, 0.75mm, 0.65mm, 0.5mm, 0.4mm, and more.

Let's now explore the BGA package through the video below!

Advantages of BGA Package

• Efficient utilization of PCB space: Using BGA packages means fewer components involved and a smaller footprint, which helps save space on custom PCBs and greatly improves PCB space efficiency.

• Enhanced thermal and electrical performance: Due to the smaller size of PCBs with BGA packaging, heat dissipation becomes easier. When the silicon chip is mounted on the top, most of the heat can transfer downward through the ball grid array. When the silicon chip is mounted on the bottom, the backside of the die is connected to the top of the package, which is considered one of the best cooling methods. BGA packages have no bendable or breakable pins, making them stable enough to ensure electrical performance on a large scale.

• Improved soldering process and increased production yield: Most BGA package solder balls are relatively large, making large-area soldering easier and more convenient, thereby increasing PCB manufacturing speed and yield. The larger solder balls also facilitate rework.

• Minimal damage to leads: BGA leads consist of solid solder balls, which are less prone to damage during use.

• Cost reduction: All of the above advantages contribute to cost reduction. Efficient utilization of PCB space provides opportunities for material savings, while improved thermal and electrical performance helps ensure the quality of electronic components and reduces the chances of defects.

Commonly Used BGA PackageTypes

Based on the substrate and other materials used, Ball Grid Array (BGA) packaging comes in various subtypes. All these subtypes use solder balls to connect the package to the circuit board. Let's introduce some common types of BGA packages.

• Plastic BGA (PBGA): PBGA typically uses BT resin/glass laminate as the substrate and plastic as the packaging material. Solder balls can be either leaded or lead-free. No additional solder is required to connect the solder balls to the package.

• Ceramic BGA (CBGA): CBGA is a long-standing BGA packaging type, different from PBGA and TBGA. It uses a multilayer ceramic substrate as the base material. The metal lid is soldered to the substrate with packaging solder to protect the chip, leads, and solder balls. Eutectic solder material is used for the solder balls.

• Tape BGA (TBGA): TBGA is a structure with cavities. There are two interconnection methods between the chip and the substrate: reverse bonding and wire bonding.

• Micro BGA (uBGA): uBGA is a BGA chip packaging technology developed by Tessera, primarily used for high-frequency operation in RDRAM. This technology allows for smaller chip sizes, improved heat dissipation, and increased data density in memory modules.

• Fine-Pitch BGA (FBGA): Also known as Chip Scale Package (CSP), FBGA is a pin grid array structure with solder balls on the bottom, making the required installation area close to the chip size. This high-density, compact, and flat package technology is well-suited for designing compact handheld consumer electronic devices such as personal digital assistants, mobile phones, camcorders, and digital cameras.

The reason why ENIG surface treatment is recommended for BGA is as follows

• The solder pads of small BGA are too small, and lead-free HASL can easily peel off. Generally, it is not recommended to use lead-free HASL on PCBs with BGA as it can lead to poor soldering.

• The solder pads of BGA are too small, and the thickness of lead-free HASL can range between 2-40um, resulting in significant height variations, which is not conducive to soldering. On the other hand, ENIG typically has a thickness between 0.025-0.05um, creating flat and even solder pads, which is advantageous for soldering.

PCBWay BGA Capability

Our prototype factory's production capability:

• The minimum diameter of BGA solder pads (denoted as 'a' in the diagram) is 0.25mm.

• The minimum distance from the copper trace edge to the edge of BGA solder pad is 0.15mm.

• The minimum distance from the BGA solder pad edge to solder pads edge of other components is 0.15mm (with 1 oz complete copper thickness).

• The minimum distance from the center of one BGA solder pad to the center of another BGA solder pad(denoted as 'b' in the diagram) is 0.35mm.

  
  

Our advanced PCB factory's production capability:

• The minimum diameter of BGA pad is 0.2MM (the sample limit can be 0.15MM).

• The minimum BGA to line is 3MIL (the prototype limit can be 2.5MIL).

• The BGA spacing limit is 0.4mm, and the conventional 0.5mm.

Challenges to the limit are not easy to produce, because the scrap rate is too high, resulting in increased costs.

If you need higher requirements, please make a note.

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