CN-122007525-A - High-efficiency high-reliability copper core solder ball implantation process method

CN122007525ACN 122007525 ACN122007525 ACN 122007525ACN-122007525-A

Abstract

The invention belongs to the technical field of integrated circuit manufacturing, and particularly relates to a high-efficiency and high-reliability copper core solder ball implantation process method. The method comprises the steps of coating soldering flux on a bonding pad of a ball-planting carrier, presetting copper core solder balls on the bonding pad, homogenizing by a high-energy laser beam to form a homogenized laser beam, and performing laser-assisted welding on the homogenized laser beam aiming at the copper core balls to enable a copper core solder ball solder coating to be molten and infiltrate with the bonding pad to form intermetallic compounds, so that the high-efficiency and high-reliability copper core ball-planting process is completed. Compared with the traditional reflow soldering process, the invention improves the process problems of copper ball position deviation in the copper core solder ball, uneven coating of an external solder coating and the like, reduces the soldering stress, increases the soldering strength, shortens the soldering time, and improves the yield and the production efficiency of the copper core solder ball soldering process.

Inventors

ZHU JIACHANG
YANG KUN
CHEN XUEQING
LI YANG
YAO XIN

Assignees

中国电子科技集团公司第五十八研究所

Dates

Publication Date: 20260512
Application Date: 20260331

Claims (10)

1. A high-efficiency and high-reliability copper core solder ball implanting process method is characterized by comprising the following steps of: coating soldering flux on the bonding pad of the ball-planting carrier; presetting copper core solder balls on the bonding pads; Homogenizing the high-energy laser beam to form a homogenized laser beam; And (3) aligning the homogeneous laser beam to the copper core solder ball for laser auxiliary welding, so that the copper core solder ball solder coating is melted and is infiltrated with the bonding pad to form an intermetallic compound, and thus, the ball implantation process is completed.
2. The method of claim 1, wherein the step of applying flux to the ball-attach carrier pads comprises: Placing a printing screen on one surface of the ball-planting carrier, which is provided with bonding pads, wherein the meshes of the placed printing screen correspond to the bonding pads one by one, and the diameters of the corresponding meshes are smaller than the diameters of the bonding pads; Brushing scaling powder with the area corresponding to the mesh openings into each mesh opening by using a scraper, and removing the printing screen plate; the area of the soldering flux is consistent with the area of the mesh, and the height of the soldering flux does not exceed the thickness of the screen plate.
3. The method for efficiently and reliably implanting copper core solder balls according to claim 1, wherein the pre-placing copper core solder balls on the bonding pads comprises: placing the ball-planting net plate on one surface of the ball-planting carrier provided with the bonding pads, wherein the placed ball-planting net plate corresponds to the bonding pads on the ball-planting carrier one by one, and the corresponding mesh diameter is larger than the diameter of the bonding pads on the ball-planting carrier; and filling copper core solder balls with diameters corresponding to the meshes into each mesh.
4. The method of claim 1, wherein the homogenizing the high-energy laser beam to form a homogenized laser beam comprises: Placing a diffraction optical element on one surface of a laser emitting a high-energy laser beam, and setting a certain working distance between the diffraction optical element and the high-energy laser beam, wherein the working distance is determined according to the spot energy and the spot size parameters of an actually-output homogeneous laser beam; The high-energy laser beam penetrates through the diffraction optical element, and the diffraction optical element controls the phase of the laser beam, so that the Gaussian distribution light spot is converted into a flat-top light spot, and a homogeneous laser beam is formed.
5. The method of claim 4, wherein the high-energy laser beam comprises a single transverse laser beam and a multi-mode laser beam, and the flat-top light spot comprises a square, a rectangle or a circle.
6. An efficient and effective device as defined in claim 1 a reliable copper core solder ball implantation process method, characterized in that the forming of the intermetallic compound comprises: Aligning the homogenized laser beam to one surface of the ball-planting carrier, which is preset with the copper core solder balls, and setting parameters of laser type, laser wavelength, laser power density and laser irradiation time of the homogenized laser beam; The external solder coating of the copper core solder ball is fully melted and fully infiltrated with the bonding pad on the ball-implanted carrier, so that the interface between the solder and the bonding pad forms intermetallic compound.
7. The method for implanting copper core solder balls, as claimed in claim 6, is characterized in that the laser-assisted welding comprises a preheating process and a welding process to achieve effective welding, wherein the laser type is near infrared laser, the laser wavelength is 700-1400 nm, the laser power is 50W/cm 2 ~100W/cm 2 in the preheating process, the laser irradiation time is 0.5-1 s, the laser power is 100W/cm 2 ~150W/cm 2 in the welding process, and the laser irradiation time is 1 s-2 s.
8. The method of any one of claims 1-7, wherein the copper core solder ball comprises an inner copper ball and an outer solder coating, and the outer solder coating is made of SnPb, snAg or SnAgCu.
9. The method of any one of claims 1-7, wherein the ball carrier comprises a wafer, a single chip, a ceramic substrate, an organic substrate, a silicon substrate, or a glass substrate.
10. The method of any one of claims 1-7, wherein the flux comprises rosin flux, water-soluble flux or no-clean flux, and the material of the diffractive optical element comprises fused quartz, sapphire or plastic.

Description

High-efficiency high-reliability copper core solder ball implantation process method Technical Field The invention belongs to the technical field of integrated circuit manufacturing, and particularly relates to a high-efficiency and high-reliability copper core solder ball implantation process method. Background Compared with the traditional surface mounting technology, the surface array type packaging technology represented by Ball Grid Array (BGA), chip Scale Package (CSP), flip Chip (FC) and the like has the advantages of supporting more input/output numbers, higher functional density, more complex electronic performance and the like, and has been widely applied to signal processing circuits such as SoC, FPGA, CPU, DSP and microsystem packages thereof. Typically, solder balls are implanted on BGA package assembly substrates and CSP package chips to provide signal connection and mechanical support. The traditional solder balls are solder balls processed by alloy materials such as SnPb, snAgCu and the like, as the circuit integration level and complexity are improved, the circuit package puts forward higher dimensional accuracy, lower resistivity and higher reliability requirements on the solder balls, and as the alloy solder balls such as SnPb, snAgCu and the like can be melted and collapsed in the reflow soldering process, the height of the solder points, coplanarity and intermetallic compound (IMC) control can not be adapted to the requirements of the next-generation face array type package. In recent years, a novel copper core solder ball is proposed, which consists of an inner solid copper ball and an outer solder coating. The inner layer solid copper ball is not melted in the welding process, has excellent collapse resistance and dimensional stability, the height and coplanarity of the solder ball array after ball implantation are controlled, and meanwhile, copper has more excellent electric and thermal properties, so that the inner layer solid copper ball has great application value in the packaging of new-generation electronic devices. However, the copper core solder ball implanting process based on the traditional reflow soldering technology is easy to cause problems of deviation of the position of the copper ball on the inner layer, uneven coating of the solder on the surface of the copper ball and the like in the long-time melting process of the outer layer solder, thereby affecting the ball implanting yield and the use reliability of the copper core solder ball and limiting the application of the copper core solder ball. Disclosure of Invention Compared with the traditional reflow soldering process, the invention improves the process problems of copper ball position deviation inside the copper core solder ball, uneven coating of an external solder coating and the like, reduces the soldering stress, increases the soldering strength, shortens the soldering time, and improves the yield and the production efficiency of the copper core solder ball soldering process. In order to solve the technical problems, the invention provides a high-efficiency and high-reliability copper core solder ball implanting process method, which comprises the following steps: coating soldering flux on the bonding pad of the ball-planting carrier; presetting copper core solder balls on the bonding pads; Homogenizing the high-energy laser beam to form a homogenized laser beam; And (3) aligning the homogeneous laser beam to the copper core solder ball for laser auxiliary welding, so that the copper core solder ball solder coating is melted and is infiltrated with the bonding pad to form an intermetallic compound, and thus, the ball implantation process is completed. Preferably, the coating the soldering flux on the ball-mounting carrier pad comprises: Placing a printing screen on one surface of the ball-planting carrier, which is provided with bonding pads, wherein the meshes of the placed printing screen correspond to the bonding pads one by one, and the diameters of the corresponding meshes are smaller than the diameters of the bonding pads; Brushing scaling powder with the area corresponding to the mesh openings into each mesh opening by using a scraper, and removing the printing screen plate; the area of the soldering flux is consistent with the area of the mesh, and the height of the soldering flux does not exceed the thickness of the screen plate. Preferably, the pre-setting copper core solder balls on the bonding pads includes: placing the ball-planting net plate on one surface of the ball-planting carrier provided with the bonding pads, wherein the placed ball-planting net plate corresponds to the bonding pads on the ball-planting carrier one by one, and the corresponding mesh diameter is larger than the diameter of the bonding pads on the ball-planting carrier; and filling copper core solder balls with diameters corresponding to the meshes into each mesh. Preferably, the homogenizing of the high energy laser beam f