PCB Assembly

BGA Assembly: A Beginner’s Guide to Ball Grid Array Assembly

BGA assembly (Ball Grid Array Assembly) plays a crucial role in chip design PCBs to place BGA (ball grid array) parts. BGA assembly was used in complex PCBs. It uses a fine-pitch assembly method to place BGA parts on the parts. BGA offers low assembly costs and excellent density to the customer.

Basically, BGA Assembly is one of the best methods to place ball grid parts on the PCB using automatic reflow soldering. BGAs are surface-mount components that have a number of ball arrays to provide connections to the PCB. LGA is a similar part of BGA. LGA is land gird arrays, which have square-type ball arrays on them to make connections on the PCB.

What is BGA?

BGA is a surface-mount component that is used in chip-design ICs. BGA’s full form is a ball grid array. So, it has a number of balls in array form. Normally, BGAs are used in chip-design PCBs like microprocessors and integrated ICs. So that’s why ICs and processors need a permanent solution to mount any PCBs. Because these chips and processors are used in computers, RAM, laptops, etc. So, BGAs are the best solution for the future due to their high density. BGA components are placed using only an automatic pick-and-place machine and also soldered using a reflow soldering machine. Because it’s very hard to rework them. That’s why sometimes customers need extra inspections on BGA parts.

BGA Package Types

  1. Plastic BGAs
  2. Ceramic BGAs
  3. Tape BGAs
  4. Enhanced BGAs
  5. Metal BGAs
  6. Mirco BGAs

BGA assembly process

Stencil creation and inspection: Firstly, a solder stencil was created and inspected by the solder paste inspection machine for solder joints and unwanted pastes.

BGA placement: After solder paste creation, these PCBs are going to be picked and placed by the machine to place the BGA components on the PCB.

Reflow soldering: BGA PCBAs were received at the reflow oven to heat the solder and place parts on solder pads properly.

Cleaning and inspection: After the reflow soldering process, PCBs need to cool down the solder. Normally, BGA  PCB assembly is preferred for no-clean assembly. Sometimes cleaning is required, then the BGA PCBA should be cleaned according to the requirements. Assembled boards are inspected using different inspection methods for proper solder joints.

 

Key factors for a successful BGA assembly

key factors in BGA assembly

  • Baking Procedures

BGA parts needed some baking procedures during production due to their packaging. Basically, BGAs are packaged in plastic bags and packaging. So, it absorbs humidity. That’s why it needs to be baked at low temperatures to remove humidity and air cavities.

  • Precautions in Solder Paste Printing

As we know, BGA has a number of balls in array form. Basically, that’s balls having some specific fine pitches like 0.05 mm, 1.27 mm, etc. So, it needs more precautions in the solder paste printing process. If proper solder paste was not applied, then it would have short-circuited issues and might be misaligned for placement.

  • Pressure in BGA Placement

BGA components are placed on the PCB using a pick-and-place machine. This pick-and-place machine has one outlet to mount them on the PCB. So, this outlet uses some pressure to place them on the PCB. Sometimes it might be high pressure to place BGAs on the PCB, and then BGAs are affected by some manufacturability.

  • Specific Reflow Temperature

BGAs are placed on the PCB using the reflow soldering process. Reflow soldering requires some temperature to melt solder to connect the balls with the PCBs. Sometimes, BGAs are affected by the reflow oven temperature. So, most customers provide a specific temperature for BGA, which is used in reflow ovens.

  • Inspection for Solder Joints and Performance

BGA parts are not used again on the PCBs due to their capabilities. And also, BGA components are very hard to rework. BGA rework needs more time due to its tiny solder balls. PCB assembly BGA needs more inspection methods for solder joints and their performance.

  • Via-in-pad Method for BGA Assembly

When you place a BGA assembly order, please use the via-in-pad method for ball grid array assembly since BGA has fine pitches. So, there would be benefits for PCB assembly BGA.

  • No-clean Solder Paste

BGA assembly was preferred to no-clean solder paste for solder cleaning.

Quality inspection methods for BGA Assembly

Quality Inspection in BGA Assembly

  • AOI and Manual Inspection

We can use AOI and manual inspection for BGA connections. AOI and manual inspection methods are used to catch poor solder joints, solder shorts, and other types of errors.

  • X-ray Inspection

The automatic X-ray inspection machine inspected whole BGA parts, solder joints, solder voids, solder bridges, misalignments of BGA parts, and shorts. These types of errors are normally visible on the PCB. So, it was easily caught by the X-ray inspection. Some customers want X-ray images for BGA assembly.

  • Electrical Testing

We can verify BGA assembly short circuit and open circuit errors using the electrical testing method.

 

Advantages of BGA Assembly

  • High Reliability

BGA parts have solder balls for electrical connections. We can easily solder BGA parts on the solder pads. So, BGA assemblies provide high reliability for placing BGA parts on the PCB.

  • Excellent Performance

BGA components have very close solder balls due to their fine pitches. We can get excellent performance due to the close solder balls that form a strong bond between them.

  • Thermal Management

BGA parts have thermal lines to remove overheating from the chip ICs. So, BGA assemblies are more efficient against overheating, which benefits the thermal resistance of the PCB.

  • High Compact

BGA parts have small sizes and they require less space on the PCB. So, The BGA assembly provides a high compact for the PCB.

 

Disadvantages of BGA assembly

Disadvantages of BGA assembly

  • More Inspection

BGA assemblies have BGA parts, which have tiny solder balls for soldering. So, are these solder balls properly done or not? That’s why assembly vendors are using more inspection methods to inspect various types of errors in BGA assemblies.

  • Cost

Many BGA parts are cheaper and some have a higher cost. Normally, chip-designed BGAs are more expensive in the electronics market. And also, these chip-based BGAs are more expensive for rework.

  • More precautions

BGAs are very sensitive parts. So, we need to take more precautions for BGA parts and their storage requirements. So, BGA assembly is quite tough for bulky orders.

Conclusion

After thoroughly reviewing everything about BGA assembly, I concluded that we need to review the BGA assembly instructions, cons, and pros before placing the BGA components on the PCB. It would be beneficial for us. If you are not aware of those requirements, then it is wasting time for all of us, like assembly vendors and manufacturers. As we know, BGA assembly is used in chip ICs and processors. So, please refer to the fine pitches for routing in PCB design. And also, creating stencils and mask patterns according to the BGA assembly.

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