package substrate

Introduction and application fields of package substrates

A complete chip is composed of a bare chip (wafer) and a package (package substrate, solid sealing material, leads, etc.). As the core material of chip packaging, the package substrate can protect, fix and support the chip on the one hand, enhance the thermal and heat dissipation performance of the chip, and ensure that the chip is not physically damaged. On the other hand, the upper layer of the package substrate is connected to the chip, and the lower layer is connected to the printed circuit board. In order to achieve electrical and physical connections, power distribution, signal distribution, and communication between the internal and external circuits of the chip and other functions.

The semiconductor packaging process from wafer to product can be divided into three levels (L0, L1, L2, L3), and the packaging substrate is mainly used in the first-level packaging process. According to the current electronic installation level, it can be divided into:

1) Zero-level packaging (chip process) (L0): refers to the circuit design and manufacturing of wafers;

2) First-level packaging (encapsulation process) (L1): refers to packaging the chip in a lead frame or packaging substrate, and completing the process of sealing and protecting the mechanism, circuit wiring, and thermal conductive wire;

3) Second-level packaging (module or SMT process) (L2): refers to the process of combining the components completed by the first-level packaging on the circuit board;

4) Three-level packaging (product manufacturing process) (L3): the manufacturing process of combining several circuit boards on a motherboard or combining several sub-systems into a complete electronic product.

From the classification of materials, packaging substrates can be divided into three categories: organic substrates, inorganic substrates and composite substrates (respectively corresponding to the types of raw materials). Various types of substrates have their own advantages and disadvantages in different packaging applications. The organic substrate is made of organic materials such as organic resin and epoxy resin. It has a low dielectric constant and is easy to process. It is suitable for high-frequency signal transmission with low thermal conductivity. Inorganic substrates are made of various inorganic ceramics, which have good heat resistance, easy wiring and stable dimensions, but their production costs and material toxicity have certain limitations. The composite substrate is based on the characteristics of different needs to composite different organic and inorganic materials. With the development of technology, the requirements for environmental protection and other aspects are gradually increasing, and inorganic substrates (ceramic substrates) will gradually be replaced by organic substrates and composite substrates due to factors such as material toxicity.

Organic packaging substrates are mainly used in the field of consumer electronics. They are currently the mainstream product of packaging substrates. According to statistics, the output value of organic packaging substrates accounts for more than 80% of the total output value of IC packaging substrates, and rigid substrates are mainly used. Among them, organic packaging substrates are mostly used in the consumer electronics field, and inorganic packaging substrates (ceramic substrates) are mainly used in fields that require higher reliability, such as the military industry. Organic packaging substrates can be divided into rigid and flexible due to different materials used. Rigid packaging substrates use rigid materials such as BT resin substrate materials and epoxy resins. Flexible packaging substrates use flexible materials. Rigid packaging substrates are mainly used for baseband chips. , Application processor chips, power amplifier chips, digital module chips and other fields. Flexible packaging substrates are mainly used in fields such as transistor liquid crystal display chips.

Technical threshold

The packaging substrate has certain similarities with PCB in the manufacturing process, but due to the smaller size of the packaging substrate and more complex electrical structure, the manufacturing technology is much more difficult than PCB. Similar to the PCB manufacturing process, the packaging substrate can be roughly divided into three different production processes: subtractive, additive, and semi-additive. At present, semi-additive and subtractive methods are the mainstream production. Craft. The production process includes multiple processes such as drilling, sinking, electroplating, pattern transfer, etching, solder mask, and coating. Due to the smaller size of the package substrate and higher precision, the technical difficulty in core board manufacturing (including coreless board technology) and via hole production is significantly higher than that of PCB.

1) Additive method: After the circuit is printed on the rubber plate without copper foil, the copper circuit pattern is plated on the rubber plate by the method of electroless copper plating to form a printed circuit board with the electroless copper layer as the circuit . The additive method has strict requirements on the bonding force of electroless copper plating and copper plating with the substrate. However, due to the simple process, no copper clad plate (lower material cost) is required, and there is no need to worry about the problem of electroplating dispersion ability (completely using electroless copper plating), so Mainly used to manufacture cheap double-sided panels.

2) Semi-additive method: The printed circuit board is made by using copper clad laminate, in which the circuit is formed by the subtractive method, that is, the circuit is protected by a normal phase pattern, and the copper layer of the non-circuit part is subtracted. Then use the additive method to form a copper connection layer in the through hole to connect the lines between the double-layer or multi-layer boards. This is the main manufacturing method for most circuit boards. Because only the hole metallization uses an additive method.

3) Subtractive method: After the pattern is printed on the copper clad board, the pattern is protected, and then the excess copper layer printed with the resist film is etched away to form a printed circuit by subtracting the copper layer. The earliest single-sided printed circuit boards were manufactured using this method. Nowadays, when using semi-additive methods for double-sided and multi-layer boards, subtractive methods are also used.

Market size

Packaging substrates have become the raw material with the largest sales share in the packaging material segment, accounting for more than 50% of packaging materials, and the global market size is close to tens of billions of dollars. According to SEMI statistics, the total market size of organic substrates and ceramic packages in 2016 reached 10.45 billion U.S. dollars, accounting for 53.3% of the total. In addition, the market size of lead frames is 3.46 billion U.S. dollars, accounting for 17.6%, and the total market size of package carrier materials (including package substrates and lead frames) is approximately 14 billion U.S. dollars, accounting for 70% of packaging materials. However, the traditional lead frame, due to its own performance and volume limitations, and the trend of various new high-end technology development and substitution, fluctuates around 17%, and as the density requirements increase, it is expected to gradually decrease in the future.

With the upgrading of the domestic packaging substrate industry and domestic substitution, the demand for local packaging substrates will increase rapidly. According to IC Mtia's statistics, the domestic packaging substrate (including machine substrate and ceramic substrate) market in 2016 reached 8 billion yuan, accounting for nearly 30% of packaging materials, far below the global 50%. Apart from the difference in the statistical caliber of different research institutions, our main reason is that the domestic chip design and package caliber are still focused on the low-end and the low-end, and the lead frame package accounts for a relatively high proportion. With the continuous development of the domestic integrated circuit industry, substrates in packaging applications will gradually replace lead frames. At the same time, with the continuous increase in the demand for domestic substrates from downstream industries, it is expected that the demand for local packaging substrates will maintain a compound growth of more than 20%.

Global industrial structure and major companies

The major global packaging substrate manufacturers are concentrated in Taiwan, South Korea and Japan. In the "emergent stage" of the development of organic packaging substrates, Japan is at the forefront of the development and application of IC packaging substrates in the world. In 1999, there were 28 manufacturers of rigid organic packaging substrates (BGA and other substrates) in Japan, of which 19 were large enterprises. Around 2003, the turning point in the development of flip chip packaging was ushered in. Japanese companies quickly turned to higher-end FC BGA packaging substrates. By 2004, 40% of the world's FC-PPGA package substrate market was under Japanese corporate strategy. Around 2000, packaging and testing plants and PCB factories in South Korea and Taiwan quickly entered the packaging substrate industry by introducing technology from the United States and Japan. Currently, Taiwan, South Korea, and Japan account for nearly 90% of the global packaging substrate industry.

China's industrial structure and major companies

With the gradual expansion and stability of my country's downstream packaging and testing industry, since 2009, companies have begun to enter the packaging substrate industry, and the industry participants are mainly PCB factories. Generally speaking, although the domestic packaging substrate share is still at a relatively low level in the world, the upward trend is obvious. At present, the mainstream domestic substrate manufacturers include Shennan Circuit, Zhuhai Yueya, Xingsen Technology and HOREXS, and the larger ones include Shennan Circuit and Zhuhai Yueya. From the perspective of product structure, both Shennan Circuit and Yueya Technology are mainly engaged in the development of FCBGA package substrate business. Xingsen Technology and HOREXS are focusing on the development of rigid packaging substrates and other high-end substrate businesses.