What are the Steps in BGA Repairing? – Part I

Jan 03,2019 Ball Grid Array (BGA) packages have become very popular in the Printed Circuit Board (PCB) design and manufacturing industry. These packages not only help reduce the size of PCBs, but also improve their functionality. Though the BGA are capable of bearing the increasing pressure of decreasing sizes of the products, they seldom require maintenance and repair. How are BGA packages repaired? What are the steps involved in the BGA rework? This post is dedicated to answer these questions. Read on to know the entire process of BGA assembly.

Repairing BGA Assembly

There are several steps involved in the repair of a BGA assembly. Here is a systematic explanation of all these four steps in detail:

• Step 1 – Baking the PCB: This is the basic, and one of the most important steps of BGA rework process. It is very important for a BGA and the PCB to be moisture-free before the repair process starts. In this step, the PCB is baked by following the JEDEC (Joint Electron Devices Engineering Council) standards. Baking of PCB eliminates all the moisture content and saves it from ‘Popcorning’, which makes BGA irreparable. ‘Popcorn’ are small bumps that occur on a PCB during the rework process.
• Step 2 – BGA Removal: After the PCB is baked dry, the BGA is safe to remove. The removal is performed using advanced equipment. This process employs custom thermal profiles for every BGA and PCB location. It is done by trained personnel, who follow manufacture guidelines strictly.
• Step 3 – Baking BGA: This step is optional, meaning the decision to carry out this step depends on the condition. If the BGA is just removed from a baked PCB, then there is no need for this process. On the other hand, if the BGA is exposed to moisture greater than its moisture rating, then this step is necessary. BGAs are baked at 125° C for 24 hours.
• Step 4 – Site Dress BGA: This step is generally carried out under a microscope. The remnant solder is removed, and the BGA is cleaned. In this step, utmost care is taken for not damaging PCB or components on the board. In this step, the chip is brought back to its original condition as the one prior to the baking.
• Step 5 – Pasting High Temperature BGA: This step is mostly used in case of high temperature BGAs. This creates a fillet around the solder spheres, which are at high temperatures.

The repair process is not over yet. In the next post, we will discuss the further steps involved in the BGA assembly repair process.