An unoriented laser sintering interconnection process

Abstract

The application discloses a kind of non-directional laser sintering interconnection processes, comprising the following steps: step one, select appropriate substrate and chip, and after the substrate and the chip are cleaned, it is pretreated;Step two, interconnection material is placed in chip and substrate as interconnection layer, so that it forms the interconnection structure of chip, interconnection material and substrate;Step three, protective gas is passed, appropriate laser parameters are selected using laser welding machine, and the irradiation direction of laser beam is set, while pressure and ultrasonic are applied and welding time is controlled to weld the interconnection structure;Step four, after cooling at room temperature, the interconnection structure is obtained.Non-directional laser sintering interconnection process, including fine-pitch interconnection and chip die bonding, can reduce the occurrence of substrate warping phenomenon, meet the requirements of advanced packaging, and solve the above technical problems.

Description

Technical Field

[0001] The present invention relates to a component packaging interconnection technology, in particular to a non-directional laser sintering interconnection process. Background Art

[0002] In today's advanced semiconductor and microelectronics packaging fields, the integration of various electronic components into a single package is becoming increasingly important. Traditional reflow soldering and hot-press soldering methods expose the entire "interconnect sandwich" to prolonged high-temperature heat-affected zones (HAZs), causing substrate warping and impacting normal operation. Severe substrate warping can even lead to cracking and package failure.

[0003] Currently, one approach to addressing substrate warpage is to thicken the substrate. However, this approach reduces the substrate's heat dissipation performance. This reduced heat dissipation can cause the chip to be exposed to high temperatures for extended periods, damaging it and severely impacting its lifespan. Therefore, addressing the substrate warpage issue is urgent. Summary of the Invention

[0004] In response to the above-mentioned defects, the purpose of the present invention is to propose a non-directional laser sintering interconnection process, including fine-pitch interconnection and chip bonding, which can reduce the occurrence of substrate warping, meet advanced packaging requirements, and solve the above-mentioned technical problems.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A non-directional laser sintering interconnection process includes the following steps:

[0007] Step 1: Select an appropriate substrate and chip, clean the substrate and chip, and then perform pretreatment;

[0008] Step 2: placing an interconnection material between the chip and the substrate as an interconnection layer to form an interconnection structure of the chip, the interconnection material and the substrate;

[0009] Step 3: introducing a protective gas, using a laser welding machine to select appropriate laser parameters, set the irradiation direction of the laser beam, apply pressure and ultrasound, and control the welding time to weld the interconnected structure;

[0010] Step 4: Cooling at room temperature to obtain the interconnected structure.

[0011] Preferably, in step 1, the size of the chip and substrate is 1 μm-500 mm; and the pretreatment includes one or more of acid treatment, plasma treatment and SAM.

[0012] Preferably, the interconnection material in step 2 includes nano-metal pastes such as gold, silver, copper, tin, and various alloy nano-materials such as silver / copper, gold / tin, tin / silver, and one or more of solder paste, die-bonding glue, and conductive glue.

[0013] Preferably, the interconnect material placement method in step 2 includes one of direct deposition, screen printing, and dipping.

[0014] Furthermore, the protective gas in step three includes one or more of air, helium, argon, and nitrogen.

[0015] Furthermore, the laser light source of the laser welding machine in step three includes one of a CO2 laser, a fiber laser, a semiconductor laser, and a Nd:YAG laser.

[0016] Furthermore, the laser parameters in step three include a laser power of 1-1000W and a laser wavelength of 0.1-13 μm.

[0017] Furthermore, the irradiation direction of the laser beam in step three is any direction around the interconnection structure.

[0018] Furthermore, in step three, the pressure is 0-60 MPa, the ultrasonic driving frequency is 0-200 kHz, and the welding time is 1-7200 s.

[0019] Furthermore, the process uses a rotary welding platform and a six-degree-of-freedom manipulator, the laser of the laser welding machine is installed at the execution end of the six-degree-of-freedom manipulator, and the rotary welding platform is used to place the substrate;

[0020] The rotary welding platform is located within the working range of the six-degree-of-freedom manipulator.

[0021] One of the above technical solutions includes the following beneficial effects: the present invention completes the interconnection process between the chip and the substrate by laser welding, selects a substrate and a chip of a certain specification, and cleans and pre-treats the substrate and the chip; places the interconnection material on the chip and the substrate as an interconnection layer to form an interconnection structure of chip-interconnection material-substrate; introduces a protective gas, uses a laser welding machine to select appropriate laser parameters and laser irradiation direction, and applies pressure, ultrasound and controls the welding time to weld the interconnection structure; and cools at room temperature to obtain the interconnection structure. The present invention uses the thermal radiation of a non-directional laser beam for sintering to optimize the welding process and reduce the high thermo-mechanical stress during the welding process, thereby significantly reducing the warping of the substrate, enhancing the stability and reliability of the chip interconnection, and achieving the effect of reducing the use cost and increasing the service life of the substrate and chip. The present invention designs a new chip interconnection process that can achieve more stable chip interconnection and meet the requirements of advanced packaging interconnection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Fig. 1 This is a method flow chart of a non-directional laser sintering interconnection process of the present invention;

[0023] Fig. 2 This is a schematic diagram of the application of non-directional laser sintering in the flip chip interconnection process;

[0024] Fig. 3 Schematic diagram of the application of non-directional laser sintering in chip bonding process. DETAILED DESCRIPTION

[0025] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0026] like Figs. 1-3 As shown, a non-directional laser sintering interconnection process includes the following steps:

[0027] Step 1: Select an appropriate substrate and chip, clean the substrate and chip, and then perform pretreatment;

[0028] Step 2: placing an interconnection material between the chip and the substrate as an interconnection layer to form an interconnection structure of the chip, the interconnection material and the substrate;

[0029] Step 3: introducing a protective gas, using a laser welding machine to select appropriate laser parameters, set the irradiation direction of the laser beam, apply pressure and ultrasound, and control the welding time to weld the interconnected structure;

[0030] Step 4: Cooling at room temperature to obtain the interconnected structure.

[0031] The present invention completes the interconnection process between the chip and the substrate by laser welding, selects substrates and chips of certain specifications, and cleans the substrate and the chip and performs pretreatment; places the interconnection material on the chip and the substrate as an interconnection layer to form an interconnection structure of chip-interconnection material-substrate; introduces protective gas, uses a laser welding machine to select appropriate laser parameters and laser irradiation direction, and applies pressure, ultrasound and controls the welding time to weld the interconnection structure; and cools to room temperature to obtain the interconnection structure. The present invention uses the thermal radiation of a non-directional laser beam for sintering to optimize the welding process and reduce the high thermo-mechanical stress during the welding process, thereby significantly reducing the warping of the substrate, enhancing the stability and reliability of the chip interconnection, and achieving the effect of reducing the use cost and increasing the service life of the substrate and chip. The present invention designs a new chip interconnection process that can achieve more stable chip interconnection and meet the requirements of advanced packaging interconnection.

[0032] Wherein, in step 1, the size of the chip and substrate is 1 μm-500 mm; the pretreatment includes one or more of acid treatment, plasma treatment and SAM.

[0033] This method can be used on chips and substrates in a larger size range and has a wide range of applications; and the pretreatment can clean the surface of the chip and substrate to remove impurities.

[0034] Among them, the interconnection materials in step 2 include nano-metal pastes such as gold, silver, copper, tin, and various alloy nano-materials such as silver / copper, gold / tin, tin / silver, as well as one or more of solder paste, die-bonding glue, and conductive glue.

[0035] It has a wide range of material applications and can meet the use of a variety of materials.

[0036] Wherein, the interconnection material placement method in step 2 includes one of direct deposition, screen printing, and dipping.

[0037] It can meet the use of various interconnect material placement methods and expand the scope of application.

[0038] In addition, the protective gas in step three includes one or more of air, helium, argon, and nitrogen.

[0039] It can be used in air atmosphere, which reduces the use of protective gas, expands the scope of application and reduces costs; it also meets the requirements of normal use under protective gas.

[0040] In addition, the laser light source of the laser welding machine in step three includes one of a CO2 laser, a fiber laser, a semiconductor laser, and a Nd:YAG laser.

[0041] This method can be used under a variety of laser light sources, allowing different materials to select more suitable laser light sources, forming a more adaptive effect and thus obtaining better performance.

[0042] In addition, the laser parameters in step three include a laser power of 1-1000W and a laser wavelength of 0.1-13 μm.

[0043] This method can be used in a larger laser power range and a wider laser wavelength range, and can better meet the requirements of different materials for laser power and wavelength, thereby expanding the application range of the method.

[0044] In addition, the irradiation direction of the laser beam in step three is any direction around the interconnection structure.

[0045] The non-directional irradiation of laser beams can better meet the needs of multiple application scenarios. When traditional methods make it difficult to achieve laser beam irradiation in a certain direction or on a certain surface, the method of using non-directional irradiation of laser beams in all directions will be more advantageous.

[0046] In addition, the pressure in step three is 0-60 MPa, the ultrasonic driving frequency is 0-200 kHz, and the welding time is 1-7200 s.

[0047] This method can be used under pressure and ultrasonic drive, and can also be used under pressureless and non-ultrasonic drive, and has a wider range of applications; this method can complete sintering in a very short time, achieving the effect of saving time and cost.

[0048] In addition, the process uses a rotary welding stage and a six-degree-of-freedom manipulator. The laser of the laser welding machine is installed at the execution end of the six-degree-of-freedom manipulator, and the rotary welding stage is used to place the substrate.

[0049] The rotary welding platform is located within the working range of the six-degree-of-freedom manipulator.

[0050] Example 1

[0051] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0052] Step 1: Select a chip and a substrate with a copper pillar diameter of 50 μm, a copper pillar spacing of 50 μm, and 10 copper pillar bumps, and clean the substrate and the chip and then perform pretreatment with ultrasonic cleaning using dilute sulfuric acid;

[0053] Step 2: Copper nano-paste is placed between the chip and the substrate as an interconnection layer by dipping, so as to form an interconnection structure of chip-copper nano-paste-substrate;

[0054] Step 3: nitrogen is introduced, and a laser welding machine with an Nd:YAG laser is used, and the laser power is set to 15 W, the laser wavelength is set to 1.06 μm, a pressure of 3 MPa, an ultrasonic drive of 0 kHz, and a welding time of 8 seconds, and then the interconnection structure is welded;

[0055] In step 4, after cooling at room temperature, a flip-chip interconnection structure is obtained. The overall shear strength is 34.6 MPa obtained by shearing with a push-pull testing machine, and the resistivity is 7.3 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0056] Example 2

[0057] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0058] Step 1: Select a chip and a substrate with a copper pillar diameter of 50 μm, a copper pillar spacing of 50 μm, and 10 copper pillar bumps, and clean the substrate and the chip and then perform pretreatment with ultrasonic cleaning using dilute sulfuric acid;

[0059] Step 2: Copper nano-paste is placed between the chip and the substrate as an interconnection layer by dipping, so as to form an interconnection structure of chip-copper nano-paste-substrate;

[0060] Step 3: nitrogen is introduced, and a laser welding machine with a fiber laser is used, and the laser power is set to 18W, the laser wavelength is set to 0.97μm, 3MPa pressure and 0kHz ultrasonic drive are applied, and the welding time is controlled to 6s to weld the interconnection structure;

[0061] In step 4, after cooling at room temperature, a flip-chip interconnection structure is obtained. The overall shear strength is 36.3 MPa obtained by shearing with a push-pull test machine, and the resistivity is 8.4 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0062] Example 3

[0063] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0064] Step 1: Select a 5mm chip and an 8mm substrate, clean the substrate and the chip, and then perform plasma cleaning for pretreatment;

[0065] Step 2: Solder paste is placed between the chip and the substrate by screen printing as an interconnection layer to form a chip-solder paste-substrate interconnection structure;

[0066] Step 3: Using a laser welding machine with an Nd:YAG laser, setting the laser power to 12 W, the laser wavelength to 1.06 μm, applying a pressure of 2 MPa, a 20 kHz ultrasonic drive, and controlling the welding time to 4 seconds, the interconnection structure is welded;

[0067] In step 4, after cooling at room temperature, a chip die-bonding structure with solder paste as the interconnection material is obtained. The overall shear strength is 38.4 MPa obtained by shearing with a push-pull test machine, and the resistivity is 13.4 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0068] Example 4

[0069] The present invention provides a non-directional laser sintering interconnection process, comprising the following steps:

[0070] Step 1: Select a 5mm chip and an 8mm substrate, clean the substrate and the chip, and then perform plasma cleaning for pretreatment;

[0071] Step 2: Solder paste is placed between the chip and the substrate by screen printing as an interconnection layer to form a chip-solder paste-substrate interconnection structure;

[0072] Step 3: Use a laser welding machine with a fiber laser, set the laser power to 10W, the laser wavelength to 0.97μm, apply a pressure of 2MPa, a 20kHz ultrasonic drive, and control the welding time to 6s to weld the interconnection structure;

[0073] In step 4, after cooling at room temperature, a chip die-bonding structure with solder paste as the interconnection material is obtained. The overall shear strength is 40.3 MPa obtained by shearing with a push-pull test machine, and the resistivity is 12.1 μΩ·cm measured by a four-point probe method. At the same time, there is no warping of the substrate.

[0074] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A non-directional laser sintering interconnection process, characterized in that: The following steps are involved: Step 1: Select an appropriate substrate and chip, clean the substrate and chip, and then perform pretreatment; Step 2: placing an interconnection material between the chip and the substrate as an interconnection layer to form an interconnection structure of the chip, the interconnection material and the substrate; Step 3: introducing a protective gas, using a laser welding machine to select appropriate laser parameters, set the irradiation direction of the laser beam, apply pressure and ultrasound, and control the welding time to weld the interconnected structure; Step 4, cooling at room temperature to obtain the interconnected structure; The laser parameters in step 3 include laser power of 1-1000W, laser wavelength of 0.1-13 ; The irradiation direction of the laser beam in step 3 is any direction around the interconnection structure; In step 3, the pressure is 0-60 MPa, the ultrasonic driving frequency is 0-200 kHz, and the welding time is 1-7200 s; The process uses a rotary welding platform and a six-degree-of-freedom manipulator. The laser of the laser welding machine is installed at the execution end of the six-degree-of-freedom manipulator, and the rotary welding platform is used to place the substrate. The rotary welding platform is located within the working range of the six-degree-of-freedom manipulator.

2. The non-directional laser sintering interconnection process according to claim 1, characterized in that: In step 1, the size of the chip and substrate is 1 -500mm; the pretreatment includes one or more of acid treatment and plasma treatment.

3. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The interconnection material in step 2 includes nano-metal paste containing gold, silver, copper, and tin, and various alloy nano-materials containing silver / copper, gold / tin, and tin / silver, as well as one or more of solder paste, die-bonding glue, and conductive glue.

4. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The interconnect material placement method in step 2 includes one of direct deposition, screen printing, and dipping.

5. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The protective gas in step 3 includes one or more of air, helium, argon, and nitrogen.

6. The non-directional laser sintering interconnection process according to claim 1, characterized in that: The laser light source of the laser welding machine in step 3 includes one of a CO2 laser, a fiber laser, a semiconductor laser, and a Nd:YAG laser.

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