With the continuous development of advanced packaging technologies, packaging and testing equipment now accounts for an increasing share of the semiconductor equipment industry. Die bonding is a critical step in the backend (post-fabrication) semiconductor manufacturing process. This article explains what die bonding is, outlines key die bonding techniques, and highlights the importance of die bonder machines.
What Is Bonding?
In semiconductor manufacturing, bonding refers to the process of attaching a diced wafer chip (die) onto a substrate, lead frame, or package base. This step establishes the mechanical and thermal foundation required for subsequent interconnection and encapsulation processes.
Bonding technologies are generally divided into two main categories: traditional methods and advanced methods.
· Traditional Methods
Traditional packaging typically involves die bonding (die attach) followed by wire bonding. In this approach, the die is first attached to the substrate using adhesive or solder materials. Electrical connections are then created between the die and the package leads using fine bonding wires.
· Advanced Methods
Advanced packaging technologies, such as flip-chip bonding—originally developed by IBM in the late 1960s—integrate chip attachment and electrical interconnection into a single process. In flip-chip bonding, conductive bumps are formed on the chip pads, allowing the die to be flipped and directly connected to the packaging substrate. This method reduces signal path length, improves electrical performance, and enhances thermal management.
As semiconductor devices continue to scale down while increasing in performance and functionality, die bonding techniques—and the precision die bonder machines that perform them—have become more critical than ever in ensuring reliability, yield, and overall product quality.
What Are Die Bonding Techniques in Semiconductors?
Die bonding process is an important process for semiconductor chip manufacturing. It is the process of separating the chip from the carrier, and also the process of connecting the chip to the packaging substrate. In semiconductor chip manufacturing, the quality and efficiency of the die bonding process has an important impact on the performance and cost of the chip.
Die Bonding Process
The die bonding process is a very important process in semiconductor chip manufacturing. The quality and efficiency of the die bonding process have an important impact on the performance and cost of the chip. In order to ensure the quality and efficiency of the die bonding process, it is necessary to use high-precision die bonder machines and process control technology.
The main steps of the die bonding process include: chip positioning, glue coating, chip alignment, heat curing, carrier separation, and cleaning.
· Chip Positioning: The chips need to be positioned on the carrier, which requires the use of sophisticated positioning equipment.
· Glue Coating: Apply glue between the chip and the carrier to ensure the bond between them.
· Chip Alignment: Chips need to be aligned to the package substrate, which requires the use of high-precision alignment equipment.
· Heat Curing: Heat cures the glue to ensure a strong bond between the chip and package substrate.
· Carrier Separation and Cleaning: Separating the carrier from the chip and cleaning the chip and package substrate to ensure their surfaces are clean.
What Is the Difference Between Die Bonding and Wire Bonding?
Wire bonding is a method of connecting metal leads to pads, serving as a technology that links internal and external components of a chip. Structurally, the metal leads act as a bridge between the chip pads (primary bonding) and the carrier pads (secondary bonding). In the early days, lead frames were used as the carrier substrate, but with rapid technological development, printed circuit boards (PCBs) are increasingly used as substrates.
Wire bonding that connects two independent pads differs significantly in wire material, bonding conditions, and bonding position. In addition to connecting a chip to a substrate, wire bonding can also connect two chips or two substrates.
Die bonding, on the other hand, refers to fixing the chip onto the PCB, which can be an FR4 rigid board, FPC, or ceramic substrate. The equipment used to complete this process is called a die bonder machine. A typical die bonding process includes: feeding → dispensing → chip removal → bonding. Currently, there are four main die bonding methods: silver paste bonding, eutectic bonding, flip chip bonding, and thermosonic flip chip bonding.
What Is a Die Bonder Machine?
A die bonder, also called an SMT mounter, is the most critical device in the die attach stage of chip packaging and testing. It picks up chips from the diced wafer, places them onto the corresponding die flag on the substrate, and uses epoxy to bond the chip to the substrate.
Die bonders operate with high speed and high precision, performing key steps such as positioning, alignment, flip-chip placement, and continuous placement of multiple chips.
What Are the Types of Die Bonder Machines?
Die bonder machines can be classified based on package type and application:
By Package Type:
· FC Package Placement Machine
· FO Package Placement Machine
· 2.5D / 3D Placement Machine
By Application:
· IC Die Bonder – for integrated circuits
· Discrete Device Die Bonder – for individual components
· LED Die Bonder – includes SMT die bonder and COB die bonder
These machines are mainly used in packaging processes for semiconductor electric chips, optical chips, optical modules, silicon photonics devices, sensors, and other related components.
Die bonding is a critical step in subsequent packaging and testing. Higher requirements for accuracy and speed lead to faster units per hour (UPH) but can increase deviations. The quality of die bonding directly affects downstream wire bonding and other processes, impacting production capacity, chip packaging and testing yield, and overall cost.
Precision Categories of Die Bonders:
1. Ultra-High Precision Die Bonder: Accuracy within ±3–5 μm.
2. Medium and High Precision Die Bonder: Accuracy within ±25 μm; UPH approximately 15–20K.
3. Low Precision Die Bonder: For applications with less stringent accuracy requirements.
Applications of Die Bonder Machines
Die bonders are mainly used in the packaging processes of semiconductor electronic chips, optical chips, optical modules, silicon photonics devices, sensors, and similar components. Here, we focus on their applications in the semiconductor and electronics industries, taking China as an example.
1. Semiconductor Industry
In China, die bonder machines used in the semiconductor industry show significant variation in localization:
· LED Die Bonders: The localization rate is over 90%, the highest among all types.
· IC Die Bonders and Discrete Device Die Bonders: Localization rates are relatively low, both below 10%.
This reflects the gradual concentration of global semiconductor projects in China and the uneven development of domestic die bonder technologies across different chip types.
2. Electronics Industry
In the electronics industry, the localization rate of die bonders is generally low:
These figures indicate that, while China leads in certain high-volume applications like LED packaging, there remains significant reliance on imported machines for other semiconductor and electronics packaging processes.
Conclusion
With the popularization of advanced packaging technologies such as SiP (System-in-Package) and 3D packaging, the share of packaging and testing equipment in the semiconductor equipment industry has gradually increased.
These advanced packaging production lines place higher demands on the performance of die bonder machines, including SMT mounters. Key requirements such as placement accuracy, speed, yield, stable force control, temperature uniformity, and deformation control are becoming increasingly stringent.
FAQ
1. What is a die bonder?
Die bonder machines are mainly used for lead cabinet frame pressure plates of various gold wire ultrasonic welding equipment, and various suction nozzles, thimbles, dispensing heads, ceramic nozzles, through pins, motors, carbon brushes, encoders, transmission belts, and other spare parts of automation equipment, instruments, and meters in chip mounting equipment.
2. What is the die bonding process in semiconductor?
Die bonding process is an important process for semiconductor chip manufacturing.
The main steps of the die bonding process include: chip positioning, glue coating, chip alignment, heat curing, carrier separation, and cleaning.
3. How many types of die bonder machines are there?
Die bonder machines are divided into FC package placement machine, FO package placement machine, and 2.5D/3D placement machine.
According to the application type, they can be divided into IC die bonder, discrete device die bonder, LED die bonder (SMT die bonder and COB die bonder), mainly used in semiconductor electric chips, optical chips, optical modules, silicon photonics devices, sensors, and other packaging processes.
