阅读说明：本技术 一种集成电路封装用bga锡球的材料配方及熔炼工艺 (Material formula and smelting process of BGA solder balls for packaging integrated circuit ) 是由 唐坤 王广欣 马庆 王要利 王钰森 于 2020-06-29 设计创作，主要内容包括：本发明公开了一种集成电路封装用BGA锡球的材料配方及熔炼工艺,包括材料配方中合金成分配比为：96～96.5％锡,3％Ag,0.5％Cu,0.1％～0.5Re。材料配方中添加的保护剂为KCl、LiCl混合保护剂；熔炼工艺具体步骤为：Step.1：一种集成电路封装用BGA锡球的熔炼工艺中合金成分配置；Step.2：一种集成电路封装用BGA锡球的熔炼工艺中称重及熔炼；Step.3：一种集成电路封装用BGA锡球的熔炼工艺添加保护剂；Step.4：熔炼工艺中融化合金及加入稀土；所述Step.4操作：为打开箱式电阻炉并设定温度260度,温度达到后260度后,将坩埚放入箱式电阻炉保温至坩埚内金属完全融化,将称量后的稀土快速加入熔融合金中并用搅拌均匀。Step.5：合金冷却及后处理。(The invention discloses a material formula and a smelting process of a BGA solder ball for packaging an integrated circuit, wherein the material formula comprises the following alloy components in proportion: 96-96.5% of tin, 3% of Ag, 0.5% of Cu and 0.1-0.5% of Re. The protective agent added in the material formula is a KCl and LiCl mixed protective agent; the smelting process comprises the following specific steps: step.1: an alloy component configuration in the smelting process of BGA solder balls for packaging integrated circuits; step.2: weighing and smelting in a smelting process of BGA solder balls for packaging an integrated circuit; step.3: a protective agent is added in the melting process of BGA solder balls for packaging integrated circuits; step.4: melting alloy and adding rare earth in the smelting process; step.4 operation: opening the box-type resistance furnace, setting the temperature to be 260 ℃, putting the crucible into the box-type resistance furnace after the temperature reaches 260 ℃, preserving the heat until the metal in the crucible is completely melted, quickly adding the weighed rare earth into the molten alloy, and uniformly stirring. Step.5: and (5) cooling and post-treating the alloy.)

1. A material formula of BGA solder balls for packaging integrated circuits is characterized by comprising

The alloy component proportion in the material formula is as follows: 96-96.5% of tin, 3% of Ag, 0.5% of Cu and 0.1-0.5% of Re.

The protective agent added in the material formula is a KCl and LiCl mixed protective agent.

2. The material formulation of BGA solder balls for integrated circuit package of claim 1, wherein: the purity of each material used in the material formula of the BGA solder ball for the integrated circuit packaging is more than 99.9 percent of analytical purity.

3. The material formulation of BGA solder balls for integrated circuit package of claim 1, wherein: KCl in a KCl and LiCl mixed protective agent added in the material formula of the BGA solder ball for integrated circuit packaging is as follows: the LiCl ratio was 3: 1.

4. A smelting process of BGA solder balls for packaging an integrated circuit comprises the following specific steps:

step.1: an alloy component configuration in the smelting process of BGA solder balls for packaging integrated circuits.

Step.2: weighing and smelting in a smelting process of BGA solder balls for packaging an integrated circuit; in step.2, an electronic balance with the accuracy of one ten thousandth gram is used for weighing and analyzing pure tin, pure silver and pure copper according to the proportion respectively, and the weighed materials are smelted into a button state by a non-consumable vacuum arc furnace.

Step.3: a protective agent is added in the smelting process of BGA solder balls for packaging integrated circuits.

Step.4: in the smelting process of the BGA tin ball for packaging the integrated circuit, alloy is melted and rare earth is added; step.4 operation: opening the box-type resistance furnace, setting the temperature to be 260 ℃, putting the crucible into the box-type resistance furnace after the temperature reaches 260 ℃, preserving the heat until the metal in the crucible is completely melted, quickly adding the weighed rare earth into the molten alloy, and uniformly stirring.

Step.5: alloy cooling and post-treatment in the smelting process of the BGA solder balls for packaging the integrated circuit; and in step.5, cooling the uniformly stirred liquid alloy along with the furnace, knocking off the protective agent from the cooled metal ingot, mechanically polishing the surface to metal color, cleaning the metal color by using ultrasonic waves, and placing the cleaned alloy in a dry environment.

5. The process of claim 4, wherein the melting of the BGA solder balls comprises: the three components in step.2 must be in the form of lumps or large particles and all the added materials must not be in powder form, mainly because the powder is blown away by the arc during the non-consumable vacuum arc melting process.

6. The process of claim 4, wherein the melting of the BGA solder balls comprises: remelting the button-shaped alloy in the step.4 by using a box-type resistance furnace; the stirring rod in step.4 is a glass rod; the rare earth adding method in step.4 is to wrap the rare earth by paper and stick the paper to the lower end of a glass rod, and quickly press the glass rod into the bottom of molten metal and stir the glass rod; the steps in step.4 ensure the uniformity of the distribution of the components in the alloy.

7. The process of claim 4, wherein the melting of the BGA solder balls comprises: and the ultrasonic cleaning liquid in step.5 is alcohol, and the cleaning time is 20-30 min.

8. The process of claim 4, wherein the melting of the BGA solder balls comprises: the non-consumable vacuum arc furnace in step.2 has short smelting time, the burning loss of each component is obviously reduced, and the components of the smelted alloy are guaranteed.

Technical Field

The invention belongs to the technical field of integrated circuit packaging material preparation, and relates to a material formula and a smelting process of a BGA solder ball for integrated circuit packaging.

Background

With the rapid development of microelectronic products such as notebook computers, mobile phones, mobile communication devices and the like, the chip demand is increasing day by day. The traditional quad flat and dual in-line chip packaging technology can not meet the technical development requirement. The BGA package has the advantages of large number of I/O pins, large pin spacing, small parasitic parameters and the like, and becomes the best choice for high-density, high-performance and multifunctional packaging of VLSI chips such as a CPU (central processing unit), a north-south bridge and the like. However, more than 90% of BGA balls are imported at present. The conventional BGA solder ball materials are commonly provided with SAC305 and SAC105, the materials have poor spreadability and creep resistance, and after packaging, the solder ball is often subjected to the phenomena of no welding, welding point deviation and poor joint mechanical property, so that the welding point is fallen and failed. The existing research shows that the rare earth can reduce the surface tension of the liquid solder and improve the wettability of the liquid solder, and simultaneously, the rare earth plays a role in dispersion strengthening along with the addition of RE, so that a coarse Sn-rich phase is refined, and the shear strength of a packaging interface is improved. Therefore, the development of a novel SnAgCuRe material for the BGA solder balls and a smelting process is very necessary.

Disclosure of Invention

In view of the problems in the prior art, the invention discloses a material formula of a BGA solder ball for packaging an integrated circuit, which adopts the technical scheme that the material formula comprises the following alloy components in proportion: 96-96.5% of tin, 3% of Ag, 0.5% of Cu and 0.1-0.5% of Re. The protective agent added in the material formula is a KCl and LiCl mixed protective agent.

In a preferred embodiment of the present invention, the purity of each material used in the material formulation of the BGA solder balls for packaging an integrated circuit is greater than 99.9%.

As a preferred scheme of the invention, the KCl and LiCl mixed protective agent added in the material formula of the BGA solder ball for integrated circuit packaging has the following components: the LiCl ratio was 3: 1.

A smelting process of BGA solder balls for packaging an integrated circuit comprises the following specific steps:

step.1: an alloy component configuration in the smelting process of BGA solder balls for packaging integrated circuits.

Step.2: weighing and smelting in a smelting process of BGA solder balls for packaging an integrated circuit; in step.2, an electronic balance with the accuracy of one ten thousandth gram is used for weighing and analyzing pure tin, pure silver and pure copper according to the proportion respectively, and the weighed materials are smelted into a button state by a non-consumable vacuum arc furnace.

Step.3: a protective agent is added in the smelting process of BGA solder balls for packaging integrated circuits.

Step.4: in the smelting process of the BGA tin ball for packaging the integrated circuit, alloy is melted and rare earth is added; step.4 operation: opening the box-type resistance furnace, setting the temperature to be 260 ℃, putting the crucible into the box-type resistance furnace after the temperature reaches 260 ℃, preserving the heat until the metal in the crucible is completely melted, quickly adding the weighed rare earth into the molten alloy, and uniformly stirring.

Step.5: alloy cooling and post-treatment in the smelting process of the BGA solder balls for packaging the integrated circuit; and in step.5, cooling the uniformly stirred liquid alloy along with the furnace, knocking off the protective agent from the cooled metal ingot, mechanically polishing the surface to metal color, cleaning the metal color by using ultrasonic waves, and placing the cleaned alloy in a dry environment.

In a preferred technical scheme of the invention, the three components in the step.2 are required to be in a block shape or a large particle shape, and all the added materials cannot be in a powder shape, mainly because the powder can be blown away by electric arc in a non-consumable vacuum electric arc melting process.

In the step.4, a box-type resistance furnace is adopted for remelting the button-shaped alloy; the stirring rod in step.4 is a glass rod; the rare earth adding method in step.4 is to wrap the rare earth by paper and stick the paper to the lower end of a glass rod, and quickly press the glass rod into the bottom of molten metal and stir the glass rod; the steps in step.4 ensure the uniformity of the distribution of the components in the alloy.

In a preferable technical scheme of the invention, the ultrasonic cleaning liquid in step.5 is alcohol, and the cleaning time is 20-30 min.

In a preferable technical scheme of the invention, the non-consumable vacuum arc furnace in step.2 has short smelting time, the burning loss of each component is obviously reduced, and the components of the smelted alloy are further guaranteed.

The invention has the beneficial effects that: the invention improves the ductility, tensile strength and shear strength of the material by changing the smelting process. Compared with the prior SAC305 and SAC105 materials and smelting process, the SnAgCuRe alloy has better wettability and spreadability and high shear strength. The non-consumable vacuum arc melting can reduce the burning loss of the material, reduce the introduction of impurities and ensure higher material purity. Meanwhile, the rare earth is added and smelted by adopting a press-in box type resistance furnace, so that the burning loss of the rare earth is reduced, and the material purity and the uniformity are higher. After the material is used for balling, the material tissue distribution is finer, the surface quality is high, the thickness of intermetallic compounds at the welding spot interface is more uniform after reflow soldering, and the reliability of the welding spot is good.

Drawings

FIG. 1 is a diagram of the material formulation and melting process steps of the present invention;

FIG. 2 is a graph of the alloy spread area in the example;

FIG. 3 is a graph of the shear strength of the alloys of the examples;

FIG. 4 is a graph of tensile strength of alloys in the examples;

Detailed Description