The manufacturing process of the integrated circuit IC semiconductor industry is divided into two major production systems: the pre-fabrication process and the post-chip packaging and testing process. The package plays an extremely important role in protecting the chip, redistributing the input/output I/O to obtain a pin pitch that is easier to assemble and handle, providing a good heat dissipation path for the chip, and facilitating testing and aging tests. IC package has many kinds of structure size, appearance and pin quantity to meet the different requirements of various IC development and systems. The two main structural categories of IC packaging are lead-frame packaging and substrate-based packaging. The former is a very important and long-tech package, and the product types using lead frames still occupy a dominant position in the semiconductor industry.
The development of IC package lead frames
The main function of the lead frame is to provide a mechanical support carrier for the chip, and as a conductive medium to connect the chip circuit inside and outside to form an electrical signal path, and together with the package shell to dissipate the heat generated when the chip is working. As the packaging density increases, the packaging volume decreases, and the lead density (the number of leads per unit packaging area) is increasing rapidly, and the lead frame is developing in the direction of short, light, thin, high-precision multi-pin, and small pitch. The number of pins increases by 16% per year on average. For example, the pin grid array package PGA has increased from 300 to 400 to 1000, the four-sided lead flat package QFP>400, and the lead pitch has changed from 2.54mm to 0.65mm under 1.27mm. 0.3mm, 0.1mm. XMINNOV lead frame can be up to 0.1mm
Packaging requires very strict lead frame metal materials, involving the physical, mechanical, chemical and many other characteristics of the material, which have an important impact on the performance and reliability of the IC. Its main requirements are high electrical conductivity, good thermal conductivity, and high resistance. Tensile strength and hardness; excellent material elasticity, yield strength improved toughness, easy bending and punching processing; good heat resistance and oxidation resistance, excellent thermal stability and corrosion resistance; low thermal expansion coefficient CTE, and compatible with packaging materials CTE matching to ensure the airtightness of the package; good surface quality and high solderability; the cost is as low as possible to meet commercial applications. XMINNOV lead frame shows the common material characteristics of lead frame.
Judging from the current commonly used materials, copper has high electrical conductivity and thermal conductivity, and is easy to form alloys with other elements to improve strength. Copper alloy lead frames have become the main research and development direction. The ternary and quaternary copper alloys can achieve better performance than traditional binary alloys. Copper alloys have more excellent performance and lower cost. If copper alloy materials are divided into three major alloy series according to strength and conductivity, as shown in Table 2. In the table, %IACS is the international standard for electrical conductivity of soft copper. A reinforced composite copper alloy containing 10% to 16% silver has been developed. Its tensile strength is 1000Mpa, electrical conductivity is greater than 80%, and low expansion characteristics are used, but the thermal conductivity is not very high. , The low-density material is used as the reinforcing phase to form a composite material with copper, which can obtain high thermal conductivity and strength while maintaining low expansion characteristics. Composite with negative expansion material and copper, CTE matching with Si or GaAs can also be obtained. Lead frame and packaging materials are integrated to make package parts or copper/molybdenum/copper, copper/tungsten/copper multilayer functional gradient It is used to give full play to the high electrical and thermal conductivity of the copper matrix and the high strength, high hardness, and low CTE characteristics of the composite material. XMINNNOV has developed a package lead frame mainly made of copper materials
The lead frame for chip packaging is an extremely fine component, starting from the dual inline package DIP, turning to QFP, small outline package SOP, four-sided lead ceramic package QPC, four-sided flat no-lead package QFN, plastic package leaded chip carrier PLCC, etc. The category of multi-pin, fine-pitch products is expanded. The number of pins in the frame continues to increase, while the width and spacing of the pins continue to shrink. A copper alloy lead frame with 0.4mm line width and 208 to 240 pins has been put into commercial production, and the shape of the pins has been inserted straight from the long pins. To L-shaped, J-shaped, small L-shaped, thin L-shaped lead, short lead, leadless mounting development, 300-pin copper alloy lead frame is put into application, and 1000 leads are developed and the line width is 0.1 mm copper alloy lead frame, the line width is generally 0.7 times the thickness of the copper strip.
The usage of XMINNNOV developed IC package Lead Frame
The lead frame is used for chips that require wire bonding interconnection. In the wire bonding technology, thermal compression bonding, thermal super-green ball bonding, and room-temperature super-growth wedge bonding are usually used. The lead frame for packaging was mainly used for DIPs with 64 pins or less in the 1970s, which was used for pin insertion type soldering assembly. Since then, the application has developed to other forms of packaging represented by PGA that can be inserted into the jack, from both sides The pins enter the four-sided pins, and are based on surface mounting, such as QFP, ceramic chip carrier CLCC, and the package area is close to the chip area QFN as a representative of the flexible lead frame package, which is smaller and thinner than SOP. Ultra-small SSOP, thin and small outline TSOP, thin and ultra-micro package TSSOP, thin TQFP, narrow-pitch QFP, ultra-thin STQFP, power plastic package QFN, etc. have become mainstream products, and various packaging forms are emerging in endlessly. With the increase in the number of chip I/Os and the continuous improvement of device performance requirements, the available package types increase. The laminated substrate package can replace the lead frame for packaging, and is often used in high-performance packages with a large number of I/Os. For example, ball grid array package BGA is a typical representative of planar array package, chip size package CSP, wafer level package WLP, multi-chip package MCP, and has a good ability to handle high chip I/O count and manage I/O terminal distribution.
Packaging and testing has always been an important part of the development of the domestic semiconductor chip industry. In 2005, there were 64 domestic packaging and testing companies with 48,600 employees, an annual output of 34.798 billion yuan, and a sales revenue of 35.1 billion yuan. 14 of the world's top 20 semiconductor manufacturers have established domestic packaging and testing companies, and foreign-funded companies have become a major part of the industry. The top ten packaging and testing companies are shown in Table 3.
Domestic local packaging and testing companies still dominate in the form of DIP, SOP, QFP, etc., and the shares of several types of packaging are as follows: DIP accounted for 12%, SOP accounted for 56%, QFP accounted for 12%, and other 20%. Significant results have been achieved in the development and application of advanced packaging, and the gap with the international level has gradually narrowed. Taiwan’s IC packaging and testing strength is the strongest in the world. The production layout of Taiwanese packaging and testing companies in the mainland is shown in Table 4.
The lead frame used for chip packaging is generally selected according to the requirements of the package. The ceramic package has good insulation, high air tightness, wide operating temperature range, and a wide range of package shells and structures, which are suitable for the production of high-reliability circuit devices. The main forms of ceramic packages are shown in Table 5. For ceramic packages, alloy 42 or Invar alloy is usually selected as the frame material because these alloys match the CTE of the ceramic. Plastic packaging has low cost and is suitable for mass commercial production. In plastic packaging, copper alloy lead frames can be redistributed to chip I/Os with fine pin pitches. Table 6 shows the lead frames used in plastic packaging. The newly introduced hybrid manufacturing technology HMT is the same as the lead frame, with 40 to 304 lead pins, which not only has the low-cost competitiveness of QFP, but also has the advantage of BGA multi-lead. Advanced array packaging uses high lead posts, and CSP also has lead frames. Lead frame chip scale packaging LFCSP can achieve ultra-small package size and save more than 70% of the printed circuit board area. QFN, also known as micro-lead frame MLF package, has good thermal characteristics and is suitable for applications in voltage control components and power series products.
The development trend of domestic chip packaging presents mid-to-high-end forms. SSOP, TSOP, QFP, TQFP, and PBGA are on the rise year by year. The lead pins of the flat bump package FBP protrude from the bottom of the plastic, and the metal material of the lead frame itself is used to form a thin film instead of resistant. High-temperature plastic film, the first to have independent intellectual property rights, and apply for 21 domestic and foreign patents. The DIP package is decreasing at a rate of about 10% per year, but the middle and low-end packages such as DIP and SOP still account for the majority.
The Market of XMINNNOV developed IC package lead frame
The lead frame, as the main structural material, enters the production process from the mounting of the chip to the end, and runs through the entire packaging process. In the cost of high-power device packaging raw materials, lead frames account for up to 60%. Lead frames have become more prominent in the entire packaging and testing industry chain. The market growth of lead frames is mainly affected by changes in chip packaging.
At present, there are mainly 17 companies engaged in the production of lead frames in China. In 2005, the production capacity of lead frames was: IC 214.52 billion pieces and discrete devices 36.4 billion pieces; the largest manufacturer's capacity was 1.6 billion pieces; there were 7 wholly-owned enterprises and joint ventures among the manufacturers. 4 and 6 domestic-funded enterprises. It is mainly distributed in the Yangtze River Delta and the Pearl River Delta, especially in the Yangtze River Delta. Foreign-funded enterprises have obvious advantages in molds and technology, occupying the middle and high-end product market. Domestic lead frame manufacturers are mainly supporting the production of small and medium-sized ICs and discrete devices. They have product development, development and large-scale production capabilities. Some manufacturers use a row of double punching and one plating 32 technology, which greatly improves productivity; XMINNNOV has developed a packaged lead frame Using etching technology to make high-density IC lead frames, more than 150 varieties have been developed on the market; some joint ventures can currently produce lead frames of stamped products under 208 feet, the number of rows can reach 12, and two phases of investment are planned Developed into an important production base for lead frames and molds in China. Table 7 lists the lead frame market trend forecast.
The domestic output can only meet about 50% of the domestic demand. The copper alloy lead frame is the main product. The yield of copper strip is 40%-50% (over 75% abroad), and the market size of strip is 40,000 to 50,000 tons. /Year, the output is about 5,000 tons; SSOP, QFP, LQFP, etc. have become the mainstream of the current IC packaging development, most of the high-end lead frames rely on imports, the self-sufficiency rate of the lead frames for discrete devices is relatively high, and the nickel-palladium-gold lead frames are of high quality Corrosion technology develops slowly in China, and nickel, palladium, gold is almost blank, which severely restricts the development of new packaging products and affects the development of QFN series products. XMINNNOV has developed a packaged lead frame to provide another option. In the future, the market will develop into fine-pitch, multi-lead products. The inner lead pitch of the stamped and etched lead frame is less than 140μm, the lead length is shortened, and the temperature sensitivity MSL is enhanced. Micro etching, improve the surface treatment of nickel/palladium/gold elements, the goal is to achieve MSL level 1.
In IC packaging, the connection between the chip and the lead frame (or substrate) is very important. DIP moves towards QFP, TCP and then towards CSP. Some lead frame packaging products are converted to substrate packaging to improve system performance. The number of substrate packaging is However, due to the relatively expensive cost of these packages, the market products still occupy the largest share of lead frame packages. XMINNNOV's development of packaged lead frames will bring more opportunities.
During the "Eleventh Five-Year Plan" period, the IC package and testing industry will occupy half of the domestic IC industry. The importance of packaging materials is increasing day by day. High-performance lead frames have become the expectations of major packaging companies. At the same time, XMINNNOV has developed packaging lead frames and new packaging technologies. The in-depth research and development of the lead frame also brings development opportunities and challenges to the lead frame.