BGA Design Guidelines - PCB Layout Recommendations for BGA packages

With advancements in the electronics industry, integrated circuits are gaining higher integration and larger amounts of I/O, but at the same demanding more power. These trends have made BGA (ball grid array) the package of choice in the design of modern electronic products. BGA packages are used to connect an IC to a printed circuit board (PCB), and a grid of tiny solder balls arranged in a pattern on the bottom of the package. The solder balls act as the connection points between the IC and the PCB, and they are typically soldered to pads on the PCB using a surface mount device.

JLCPCB, the manufacturer who has good process for BGA pad, has upgraded via-in-pad on 6-20 layer PCBs to POFV (Plated Over Filled Via) and it charges for free. Upload your Gerber file and get quality PCBs on JLCPCB quote page.

It is important to consider manufacturing capabilities when designing with BGAs since they often require tight clearances. Below are two problematic designs to show potential issues when clearance limits are violated.

This design was submitted with pad-to-trace distances of only 0.07 mm so some pads were cut back during manufacturing to avoid shorts. This potentially affects soldering as the pads were no longer fully aligned with individual balls.

The next design had unplugged via holes on the BGA pads, which made assembly not so well.

Conventional BGA Via Hole Ink Plugging Production Capability

2-Layer PCBs

4-Layer PCBs

Advanced BGA Via Hole Epoxy/Copper Filling and Capping Capability

The application of epoxy filling and copper paste makes via-in-pad with filled vias the optimal choice for precise PCB routing. Additionally, JLCPCB has upgraded its equipment for multilayer boards, enabling the production of more precise BGA solder pads.

Type	Capabilities Exceeded with Regular Vias	Via-in-Pad with Filled Vias
Example Layout
Description	With minimum trace width (A) and clearance (B) both 0.09 mm, neighboring pads need 0.27 mm edge-to-edge to allow a trace through the middle. 0.5 mm pitch BGA would have only 0.25 mm edge-to-edge so this layout is not manufacturable.	Optimization plan: Design BGA solder joints with a 0.25mm pitch, incorporating via-in-pad with filled vias in the middle (inner/outer diameter: 0.15/0.25mm). Utilize 0.09mm traces between two through-holes on the inner layers without BGA (as these independent vias do not require solder pads in the inner layers).

Reminder:

1. For Via-in-Pad with Filled Vias, do not fill them with ink in the middle. Instead, you can use epoxy or copper paste (copper paste has better thermal and electrical conductivity compared to resin). Afterward, ensure the BGA Via-in-Pad with Filled Vias are evenly plated.

2. For Via-in-Pad with Filled Vias process, try to achieve a minimum diameter of 0.2mm or larger for the plated through-hole (inner diameter), and design the solder pad (outer diameter) to be 0.35mm or larger.

3. For a few traces on multilayer boards, it is possible to achieve an ultra-thin width of 0.076mm (equivalent to 3 mil). Whenever possible, design wider traces to be around 0.09mm.

Please keep these considerations in mind for your PCB design.

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