What is a BGA rework station?

Introduction

A BGA rework station is a specialized system used to replace or remove ball grid array (BGA) devices from printed circuit boards (PCBs). As BGAs have become widely used in electronics, reworking faulty or outdated BGA components is often necessary. However, their fine pitch and hidden solder balls underneath the package make BGA rework challenging.

Dedicated BGA rework stations provide the capabilities to professionally desolder, re-ball, and install BGA packages on PCBs. This article will explore what BGA rework stations are, how they work, key features, and best practices for BGA rework using these systems. We’ll also examine alternatives for facilities with lower BGA rework volumes.

What is a BGA Package?

First, let’s briefly review what defines a BGA component package:

• Input/output terminals – The input/output connections are small solder balls in a grid layout on the bottom of the package.
• Package types – BGA package types include plastic PBGA, ceramic CBGA, and tape BGA.
• Pitch – The distance between adjacent solder ball centers defines the pitch. Common pitches are 1.00mm, 0.8mm, 0.65mm, and down to 0.4mm.
• Sizes – Package dimensions range from around 5mm x 5mm up to around 50mm x 50mm, depending on the die and ball count.
• Materials – BGAs utilize various substrate materials such as FR-4, ceramic, and polyimide tape.
• Mounting – The underside balls align with matching pads on a PCB and solder during reflow attachment.

BGA packaging provides a dense, reliable connection method for integrated circuit dies. However, this construction presents challenges for reworkability.

Why BGA Rework is Difficult

While BGAs provide excellent circuit density and performance, their hidden solder balls and fine pitch make reworking faulty devices quite challenging:

• Solder inaccessibility – The solder joints are concealed underneath the package, preventing direct access.
• Small pads/balls – Narrow pitch between pads limits heating selectivity.
• Thermal mass – Large BGAs can act as heat sinks, slowing melting.
• Collapse during reflow – Parts can shift or collapse as solder liquefies.
• Warping stress – Differential thermal expansion can warp or crack boards/packages.
• Precision alignment – Sub-millimeter accuracy needed to position BGAs for assembly.
• Process complexity – Heat profiles must be carefully optimized for best results.

These factors mean properly reworking BGAs requires specialized equipment, materials, and process expertise.

BGA Rework Station Overview

A BGA rework station integrates the key elements needed for professional BGA removal and replacement:

• Microscope – High magnification optical scope allows viewing BGA balls underneath packages.
• Split optics – Provides a clear view of the hidden solder joints throughout the process.
• Precision XY table – Allows accurate alignment of BGAs over pads before assembly.
• Pick-and-place tools – For safely handling BGAs; some allow ball grid transfer.
• Heaters – Infrared lamp heaters, bottom preheaters, and top hot gas heaters reflow solder.
• Temperature sensors – Thermocouples, pyrometers, and profiling tools monitor PCB temperature.
• Cameras – Help position components and observe solder melting.
• Software – Controls heaters and automation based on optimized profiles.

These capabilities allow properly controlling the reflow process to remove or install BGA components. Let’s examine popular rework station configurations.

Key Types of BGA Rework Systems

There are several common setups and options for BGA rework stations:

Professional Stations

• High-end – Dedicated all-in-one systems with precision automation and extensive features. Prices from $20k to $100k+.
• Mid-range – Integrated stations with quality optics, heaters, and capability. $5k to $20k range.
• Economy – Lower cost basic systems. Under $5k.

Manual vs. Automated

• Manual – Require user manipulation for alignment and reflow steps.
• Semi-automated – Some movement automated but still need user input.
• Fully automated – Programmable autopositioning and reflow.

Modular Components

• Microscope – Standalone high-magnification inspection scope.
• Heating tools – Individual bottom preheaters, convective hot gas, IR lamps.
• Positioners – High-precision XY tables for alignment.

Configurations range from all-in-one professional stations to modular DIY systems mixing components.

Professional BGA Rework Station Examples

Leading manufacturers of professional BGA rework equipment include:

Pace Premier Series

• High-end automated rework stations
• IR bottom heating and precision top gas heating
• Automatic pick-and-place, alignment, and rework process
• High resolution split-optics camera system
• Thermal profiling for repeatable profiles

HAKKO 808 Series

• Powerful IR bottom preheating up to 430°C
• Convective heat and gas nozzles up to 450°C
• Programmable automated operation
• Precision microscope and optics
• Handling tools for safe BGA manipulation

METCAL MX-5200 Soldering/Rework System

• Advanced convection preheating and top heating
• Automated pick-and-place alignment
• High magnification 3D viewer
• Profiling and closed-loop temperature controls
• Semi-automated rework process

Jovy JRS Series

• Modular frames accepting different rework heads
• IR bottom and precision convection heating
• HD cameras for process monitoring
• Automatic component pick-and-place
• Software and touchscreen controls

High-end rework stations provide advanced capabilities but have higher costs.

DIY Modular BGA Rework Solutions

For lower volume rework needs, DIY stations assembled from modular components provide a lower cost option:

Microscope

• High magnification inspection scopes from Amscope, Celestron, Carson.

Heaters

• Bottom preheat plates like those from Manncorp, Puhui.
• Mini convection ovens, heat guns, infrared lamps.

Positioning

• High-precision XY tables – SMTLand, Signswise.

Handling

• SMT mini tweezers, picks and placement tools.

Software

• OpenBoardView for viewing PCBs under microscope.

While requiring more manual effort, DIY stations maximize customization and value for money.

Key Criteria for BGA Rework Stations

When selecting a BGA rework system, here are key factors to consider:

• Magnification – High zoom microscopy is essential for inspecting hidden joints. 50x to 200x is typical.
• Heating methods – Bottom preheating with top convection/IR allows reflow control.
• Temperature range – A wide range exceeding solder melting is ideal, around 150°C to 450°C+.
• Temperature sensors – Multiple sensors like thermocouples and pyrometers should monitor PCB temperature.
• Positioning accuracy – Precision XY tables should offer at least 0.001″ accuracy for alignment.
• Ease of use – Intuitive controls and programming reduce operator errors.
• Software – Allows automating, saving, and repeating optimal profiles.
• Manual vs. automated – Precision automation simplifies rework but costs more.

Select systems tailored to your needs – high-end for frequent complex BGAs or economical for modest volumes.

Typical BGA Rework Process Overview

A BGA rework cycle typically involves the following generalized process steps:

Removal Phase

1. Select optimal heat profile based on BGA size, pitch, PCB, etc.
2. Position PCB on bottom preheater and raise to soak temperature.
3. Apply localized heat above BGA with hot gas/IR to melt solder.
4. Carefully remove BGA package once solder reflows using pick tool.
5. Clean residual solder from PCB with wick braid and flux.

Installation Phase

1. Inspect site thoroughly and resolve any issues under microscope.
2. Apply solder paste to BGA footprint – stencil, syringe, or paste spheres.
3. Position new BGA using split optics and XY table.
4. Reflow solder paste using similar heat profile; allow slow cool down.
5. Clean package, inspect for defects, rework if needed.
6. Program completed; run next board.

BGA Rework Best Practices

For best results, operators should follow certain best practices when reworking BGAs on a rework station:

• Take time to properly optimize heat profiles – start conservative.
• Thoroughly clean pads of old solder before applying new paste.
• Use minimum needed paste volume – solder spheres often ideal.
• Carefully align BGA within 0.05mm accuracy before reflow.
• Minimize thermal cycles to avoid damage – use lowest viable temps.
• Allow gradual cooldown after reflow to minimize warping stress.
• Inspect under high magnification for defects like voids or bridging.
• Save profiles so optimal processes can be repeated.

Following careful, disciplined procedures will provide the most robust BGA rework outcomes.

BGA Rework Safety

As with all soldering operations, safety is paramount. Users should utilize:

• Fume extraction to remove harmful fumes
• ESD control measures – grounded wrist straps, ESD-safe clothing
• Heat resistant gloves, especially for handling hot PCBs
• Eye protection like safety glasses when working
• Care when handling boards to avoid touching hot surfaces
• Soldering station accessories like stands, holders, supports

Proper gear and awareness help create a safe rework environment.

Rework Challenges and Troubleshooting

Common challenges during BGA rework to be aware of include:

Bridging

• Adjacent solder joints or pads short together with solder
• Cause – Excess solder paste, misaligned component, shifted during reflow
• Solution – Carefully apply minimum paste needed, improve alignment accuracy, adjust reflow profile

Insufficient Heat

• Solder paste does not adequately melt and reflow
• Cause – Low heater output, large thermal mass, suboptimal heater position
• Solution – Boost heater output, preheat more, adjust heater location

Popcorning

• Package “pops” up from board as solder reflows
• Cause – Excess paste volume, temperature ramp too fast during reflow
• Solution – Reduce paste volume, slow temperature ramp rate

Voiding

• Air gaps and voids in solder joints under package
• Cause – Contaminated surfaces, uneven paste application, poor wetting
• Solution – Flux board and BGAs, improve paste deposition, adjust reflow profile

Diagnosing and correcting these potential issues takes experience but improves outcomes.

Alternatives to Dedicated Rework Stations

For lower BGA rework volumes, potential lower-cost alternatives exist:

• Soldering iron – Challenging but possible for large BGAs with right tip, flux, patience.
• Hot air station – Dual hot air nozzle capable of BGA removal. Limited re-install capability.
• Toaster oven – Reflow small BGAs using standard oven. Limited control and difficult.
• Spot heating – Small spot IR/air heaters. Again, re-balling is challenge.
• Skip rework – Sometimes defective BGAs can be bypassed or worked around instead of replaced.

While demanding, these lower-cost improvised solutions may suit hobbyists’ occasional BGA needs.

The Future of BGA Rework Technology

Advances in BGA rework station technology aim to improve several areas:

• Automation – More reliable automated pick-and-place, alignment, and heating.
• Miniaturization – Ability to rework ultra-fine pitch BGAs down to 0.4mm pitch.
• Advanced optics – Higher zoom 3D microscopy with multiple viewing angles.
• Sensors – More accurate temperature sensing and closed-loop process control.
• Heating – Faster, more versatile heaters using directed microwave and RF energy.
• Software analytics – Collect data to recommend process improvements over time.

The demands of smaller components and reduced pitch will push rework technology to new levels.

Conclusion

In summary, BGA rework stations provide specialized capabilities to professionally remove and replace difficult-to-access BGA components. Premier all-in-one systems offer the highest quality optics, automation, controls, and process repeatability for frequent BGA rework. For lower volumes, DIY stations assembled from modular tools provide a more affordable option. With practice and experience following sound procedures, BGA rework stations can reinstate defective boards to full functionality. As BGAs become only more ubiquitous in electronics, these systems will remain essential tools for PCB repair and rework.

Frequently Asked Questions

What kinds of defects or failures typically require BGA rework?

Typical problems include intermittent electrical connectivity, out-of-spec operation due to damage, overheating issues, broken solder balls, and general unreliability requiring component replacement.

What are some warning signs indicating a BGA device may need removal/replacement?

Clues include strange behavior, logic errors, thermal overheating, shorts/opens detected during testing, intermittent signal dropouts, code execution errors, and complete PCB failure localized to the BGA.

What precautions should be taken when handling BGAs?

Use specialized vacuum pickup tools. Avoid touching solder ball surfaces. Control ESD. Keep BGAs properly packaged before and after rework. Handle carefully to prevent mechanical or ESD damage.

Is it possible to salvage and reuse removed BGA components?

It’s generally not recommended to reuse removed BGAs due to potential hidden damage from stress or overheating. Some may be reused in less critical applications if thoroughly inspected.

What training or skills are recommended to rework BGAs?

Proper training in soldering plus experience with SMT assembly, thermal control, and inspection help operators master the BGA rework process. Mentoring from experts is also advised.