What is Package on Package Technology and How Does It Work

Package on package technology lets you stack package on package circuit packages on top of each other. You often see package on package in devices where a CPU or system on a chip is at the bottom, with RAM placed on top. This package on package setup saves space and allows you to put strong logic and fast memory in a small area. With package on package, you get better integration and more space for other parts in your device.

Key Takeaways

# Package on package technology puts chips like processors and memory on top of each other. This saves space and makes devices smaller and lighter.

# The stacked chips use tiny solder balls to connect. This helps signals move fast and makes it easy to test or change parts.

# PoP makes devices work faster and use less power. It also helps control heat by keeping chips close together.

# This technology lets designers pick different chips to use together. It makes upgrades and repairs easier and more flexible.

# PoP is used in smartphones, wearables, and gaming consoles. Many industries use it to make devices smaller, faster, and more reliable.

What is Package on Package

Definition

Package on package technology stacks two or more chip packages. This lets you put different chips together in one small unit. For example, a processor goes on the bottom and memory sits on top. Each chip gets checked before stacking. If one chip is bad, you can swap it out. This design saves space. Devices become smaller and lighter.

Package on package technology is flexible. You can use chips from different companies. The product still works well. This stacking helps with modular design. You can change parts if you need to fix or upgrade your device.

Core Function

The main job of package on package is stacking chips up and down. This makes your device take up less space. You connect the chips with tiny solder balls or microbumps. These carry signals between the chips. The top chip fits inside the bottom chip’s outline. No space is wasted.

Here is a simple table that shows how package on package works:

Layer	Typical Component	Function
Top Package	Memory (RAM)	Stores data
Bottom Package	Processor (CPU)	Runs instructions

Chips work better because they are close together. Signals move a short distance. This means less signal loss and faster speed. Repairs are easier. You can test and change each chip by itself. This technology is best for mobile devices. Space and speed are very important there.

How It Works

Stacking Process

You can think of package on package technology like stacking blocks. Each step is important to make sure the layers fit and work well. Here is how the stacking process usually happens:

1. PCB Preparation: First, you clean the printed circuit board (PCB). Machines use sound waves or air to remove dust. Next, you put solder paste on the right spots with a stencil.
2. Bottom Package Placement: Then, you place the bottom chip on the PCB. This chip is often a processor. Special machines help put the chip in the exact spot.
3. Top Package Placement: After that, you add the top chip above the bottom chip. This chip is usually memory. Machines make sure the chips line up just right. The top chip has tiny solder balls underneath to connect it.
4. Reflow Soldering: Both chips go into an oven. The oven heats up and melts the solder paste and solder balls. This step sticks the chips together safely.
5. Inspection and Testing: Last, you check the stacked chips for problems. X-ray machines look for hidden issues. Other machines check the surface. Electrical tests make sure everything works.

Tip: Each chip gets tested before and after stacking. This helps find problems early and lets you change any bad parts.

Interconnection

The way the chips connect is what makes package on package technology special. Ball Grid Array (BGA) solder balls link the chips together. These balls sit under the top chip and match up with pads on the bottom chip. When you heat the stack, the solder balls melt and make strong connections.

Here is a table with details about these solder balls and interfaces:

Aspect	Details
Solder Ball Sizes	0.060mm to 0.760mm (sometimes up to 0.9mm)
Common Alloys	Lead-free SAC alloys (SAC305, SAC405), Tin-Lead, Bismuth/Tin, Pure Tin, Pure Indium
Placement Methods	Dispensing machines, laser solder ball jetting, stencil-based machines
Interface Characteristics	High-density connections, better electrical performance, strong mechanical reliability
Importance Factors	Size, alloy type, placement accuracy, surface finish, thermal and mechanical reliability

Small solder balls and careful placement give strong and reliable connections. Signals move quickly between the logic and memory chips. The BGA interface helps keep the package strong.

Some advanced package on package designs use interposers. An interposer is like a bridge between chips. It helps send signals, spread power, and control heat. Interposers are made from silicon. They let you stack or place chips side by side. Interposers support different chip types and keep signals clear and fast.

Note: Interposers let you use chips made with different technologies. This helps build powerful and small devices.

Components

A package on package setup has several main parts. You usually find:

• Bottom Package: This is the logic chip, like a CPU. It runs instructions and controls the device.
• Top Package: This is the memory chip, such as DRAM or flash memory. It stores data for the logic chip.
• Solder Balls (BGA): These tiny balls connect the two packages. They carry signals and power between the chips.
• Interposer (in advanced designs): This layer sits between chips. It helps with signals, power, and heat.

The logic and memory chips work together in a stack. The logic chip goes at the bottom. The memory chip sits on top. Solder balls or special vias connect them. This lets them talk to each other fast. You can test and change each chip alone. This makes repairs and upgrades easier. The design helps you build smaller, faster, and more reliable devices.

Benefits

Space Efficiency

Package on package technology helps save space. Chips are stacked instead of placed side by side. This means devices need less room on the circuit board. You can add more features in a smaller device. Chip scale packages used in PoP are much smaller than older packages. Sometimes, these packages are only about 20% bigger than the chip. Older methods can be up to five times larger. This big change lets you make thinner phones, tablets, and wearables.

Stacking chips gives you more choices for memory size and suppliers. You can decide late in the design process. This makes it easier to meet new needs without changing your whole device.

Performance

Package on package technology makes devices work better in many ways. Stacked chips shorten the distance signals travel. Signals move faster and stay strong. Data is more reliable and there is less delay. Devices use less power because connections are shorter. Heat leaves the chips more easily, so everything works well.

Performance Benefit	How PoP Helps Your Device
Faster Data Transmission	Shorter signal paths reduce delay
Lower Power Consumption	Less resistance means better energy efficiency
Improved Signal Quality	Less crosstalk and signal loss
Better Heat Management	Stacked design helps spread heat
Higher Integration Density	More features in a smaller space

Modularity

Package on package technology gives you more flexibility. You can mix different chips, even from other suppliers. This modular way lets you upgrade or change parts easily. You do not need to redesign the whole system. You can pick the best chip for each job. This helps you get better performance and lower costs. If you need more power, you can add more chiplets or change memory sizes.

• You can use chiplets from other projects.
• You can quickly use new technology.
• You can make each chip work best for its job.

Cost

Package on package technology may cost more at first. You need special tools and research. Over time, you save money. You put several chips into one module. This lowers assembly and circuit board costs. As more companies use PoP, prices drop because of bigger production runs. You also spend less on repairs and upgrades. You can replace one chip instead of the whole package.

Cost Factor	Impact on Your Project
Upfront Investment	Higher at the start
Assembly Costs	Lower due to fewer steps and smaller boards
Long-term Savings	More efficient repairs and upgrades
Market Growth	Larger scale brings down costs over time

Package on package technology gives you a small, strong, and affordable solution. This is great as people want smaller devices.

Applications

Devices

Package on package technology is used in many devices. Smartphones use PoP to fit strong chips and fast memory inside thin cases. Tablets use PoP to stay small but work quickly. Wearable devices, like smartwatches and fitness trackers, need tiny chips. This saves space and helps batteries last longer. PoP helps these gadgets work well and run for more time.

Tip: Devices that are light and fast often use PoP technology.

Gaming consoles use PoP too. These systems need fast memory for good graphics and smooth play. PoP lets designers put memory right above the processor. This makes games load faster. Digital cameras use PoP to process pictures quickly and save them without waiting. You get better photos and videos because the chips work together in a small space.

Here is a short list of devices that use package on package technology:

• Smartphones
• Tablets
• Smartwatches
• Fitness trackers
• Gaming consoles
• Digital cameras

Industries

Many industries use package on package technology. Consumer electronics use PoP to make devices smaller, faster, and save energy. Car companies use PoP in screens and safety systems. These chips help with maps, music, and safety alerts.

Healthcare uses PoP for small medical devices. Wearable health monitors and handheld tools need tiny, strong chips. PoP lets these devices check your health and give results quickly. Phone companies use PoP in base stations, routers, and mobile devices. As networks move to 5G, PoP helps handle more data and faster speeds.

Here is a table that shows how different industries use package on package technology:

Industry	How PoP Technology Helps
Consumer Electronics	Makes devices smaller, more powerful, and energy-efficient (smartphones, tablets, wearables)
Automotive	Supports infotainment, ADAS, and electric vehicle components for connected and autonomous vehicles
Healthcare	Enables portable, feature-rich medical devices like wearable monitors and diagnostic tools
Telecommunications	Powers advanced base stations, routers, and mobile devices for faster networks like 5G

Note: Every time you use a modern device, PoP technology helps. It keeps your electronics small, quick, and dependable.

Advancements

Variations

There are many new types of package on package technology today. These updates help devices work better and faster. Here are some of the newest PoP types:

• 2.5D and 3D Packaging: Chips can be stacked up or placed next to each other. Interposers and through-silicon vias (TSVs) connect the chips. This makes data move quicker and reduces waiting time.
• Interposer Materials: Interposers can be made from silicon, organic, or glass. Glass interposers have thin wires and control heat well. They also work for big panels.
• Hybrid Bonding: This way uses copper-to-copper (Cu-Cu) links. It creates tiny and strong connections between chips. You get more bandwidth and save energy.
• Panel-Level Packaging: This method builds many packages at once. It helps lower costs. Bigger interposers can be used, but you must watch for bending.
• Co-Packaged Optics (CPO): This puts optical parts with chips. Data moves faster and uses less power. It is great for large data centers.

Big companies like TSMC, Intel, Samsung, and Amkor lead these changes. They call their PoP solutions names like CoWoS, FOVEROS, and I-Cube.

Recent Developments

3D integration is making package on package technology better. Chips are stacked using TSVs and wafer bonding. Devices get smaller and work faster. Shorter paths help signals move quickly and use less power. Bandwidth goes up and performance improves in less space.

Interposer technology is also getting better. Silicon interposers now have lots of tiny wires. This helps chips send data fast and mix different chip types. Companies use chiplets, which are small chip pieces, on interposers for flexible systems. New materials like graphene and silicon photonics help control heat and make building easier.

Smaller pitch connections have changed PoP stacks. Solder ball pitches can be as tiny as 0.4 mm now. This lets you stack more chips in a small space. Micro Pin Interconnect Layer (µPILR) uses solid copper pins for strong and steady links. These updates give you smaller, quicker, and tougher devices for today’s electronics.

Thanks to these changes, devices are now smaller, faster, and use less energy than before.

Package on package technology lets you put chips on top of each other. This helps save space and makes devices work better. You can find this in things like smartphones, wearables, and IoT devices. With this way, you get:

• Devices that are smaller and lighter but have more features
• Data moves faster and uses less power
• Designs that are easy to change or upgrade

Package on package helps make today’s electronics small, strong, and dependable.

FAQ

What is the main advantage of using package on package technology?

You save space in your device. PoP lets you stack chips, so you can fit more features into a smaller area. This helps you build thinner phones, tablets, and wearables.

Can you replace or upgrade one chip in a PoP stack?

Yes, you can swap out a single chip. You test each chip before stacking. If one chip fails, you change only that part, not the whole stack.

Does package on package technology affect device speed?

PoP makes your device faster. Chips sit close together, so signals travel quickly. You get better data speed and less delay.

Where do you see package on package technology most often?

You find PoP in smartphones, tablets, smartwatches, and gaming consoles. Many small and fast devices use this technology.

Is package on package technology expensive?

You pay more at first for PoP. Over time, you save money because repairs and upgrades cost less. Large production also lowers the price.

Tip: PoP helps you build devices that are small, fast, and easy to fix.