Ceramic printed circuit board and manufacturing method therefor

Abstract

The present invention relates to: a ceramic printed circuit board capable of forming a filler metal layer at once by increasing a bonding force and using a desired material; and to a manufacturing method therefor. To this end, the present invention provides a method for manufacturing a ceramic printed circuit board, the method comprising: a step in which a ceramic substrate is supported to the interior of a vacuum chamber; a step in which a plurality of filler metal raw material parts are provided in the vacuum chamber; a step in which an inert gas is injected into the vacuum chamber; a step in which power is applied between the ceramic substrate and the filler metal raw material parts to glow-discharge the inert gas such that a plurality of filler metal raw materials are mixed together on the ceramic substrate, thereby forming a filler metal layer; and a step in which a metal layer is formed on the filler metal layer. Therefore, according to the present invention, a ceramic printed circuit board process is simplified to increase productivity, and at the same time, adhesion is strengthened to improve durability.

Description

Ceramic printed circuit board and manufacturing method thereof

[0001] The present invention relates to a ceramic printed circuit board and a method for manufacturing the same, and more particularly, to a ceramic ceramic printed circuit board and a method for manufacturing the same, which can increase bonding strength and form a filler layer at once using a desired material.

[0002] Ceramic PCBs have recently been attracting attention to improve heat dissipation and RF impedance characteristics when mounting high-power components.

[0003] In particular, ceramic PCBs have the advantage of being able to overcome the disadvantage of metal PCBs having a large coefficient of thermal expansion, which places a lot of mechanical stress on mounted components.

[0004] However, unlike metal PCBs, ceramic PCBs are difficult to bond to metal layers, so a separate adhesive layer must be formed.

[0005] According to prior art Korean Patent Publication No. KR10-2020-0137763, a ceramic printed circuit board for mounting electronic components is disclosed, which includes a ceramic substrate, a bonding layer, and a conductive layer formed in a circuit pattern on one or both sides of the ceramic substrate using an electrically conductive metal material. According to the patent, by removing Ag from the active metal paste and forming Ag in the form of a thin film, costs are reduced, and reliability is improved by inserting and forming a metal layer between the ceramic substrate and the copper foil.

[0006] However, according to the above conventional technology, there is a problem that the process becomes complicated and the thickness increases, weakening the adhesive strength, since multiple bonding layers must be formed.

[0007] The present invention is intended to solve the above-mentioned problems, and specifically, to simplify the ceramic printed circuit board process to increase productivity, and at the same time to enhance durability by strengthening adhesive strength.

[0008] Additionally, it is possible to manufacture printed circuit boards using desired materials depending on the situation, thereby lowering manufacturing costs and securing product competitiveness.

[0009] In order to achieve the above object, the present invention provides a method for manufacturing a ceramic printed circuit board, comprising: a step of supporting a ceramic substrate inside a vacuum chamber; a step of providing a plurality of filler material portions inside the vacuum chamber; a step of injecting an inert gas into the vacuum chamber; a step of applying voltage between the ceramic substrate and the filler material portions to cause a glow discharge of the inert gas, thereby mixing a plurality of filler material portions on the ceramic substrate to form a filler material layer; and a step of forming a metal layer on the filler material layer.

[0010] It is preferable that different voltages be applied to each of the above-mentioned plurality of filler material parts.

[0011] Voltage can be sequentially applied to the above plurality of filler material sections.

[0012] In addition, according to the present invention, a ceramic printed circuit board is provided, which is produced by performing the steps of: supporting a ceramic substrate inside a vacuum chamber; providing a plurality of filler material portions inside the vacuum chamber; injecting an inert gas into the vacuum chamber; applying voltage between the ceramic substrate and the filler material portions to cause a glow discharge of the inert gas, thereby mixing a plurality of filler material portions on the ceramic substrate to form a filler material layer; and forming a metal layer on the filler material layer.

[0013] According to the present invention, there is an advantage in that the ceramic printed circuit board process can be simplified to increase productivity, while at the same time, durability can be improved by strengthening adhesive strength.

[0014] Additionally, there is an advantage in that printed circuit boards can be manufactured using desired materials depending on the situation, thereby lowering manufacturing costs and securing product competitiveness.

[0015] By forming the filler metal layer with high purity in a single step, the bonding strength between the ceramic substrate and the metal layer is increased, and durability against thermal and mechanical shocks is improved.

[0016] Since the voltage and discharge rate can be independently controlled for each filler material, the composition of titanium, silver, copper, etc. can be freely adjusted, enabling customized substrate design tailored to electrical and thermal requirements.

[0017] Metal layer deposition can be performed continuously in the same chamber, making line integration easy and forming a uniform conductive layer even on a large-area substrate.

[0018] The low thermal resistance of the substrate interface improves the heat dissipation performance of high-power semiconductor packages, and the low thermal expansion characteristics reduce the stress applied to the chip, thereby increasing reliability.

[0019] Figure 1 is a configuration diagram of the inside of a vacuum chamber for manufacturing a ceramic printed circuit board according to the present invention;

[0020] Figure 2 is a flowchart showing a method for manufacturing a ceramic printed circuit board according to the present invention;

[0021] Figure 3 is a configuration diagram of the inside of a vacuum chamber for manufacturing a ceramic printed circuit board according to another embodiment.

[0022] The configuration and operation of a specific embodiment of the present invention will be described in detail with reference to the drawings.

[0023] The printed circuit board according to the present invention is a circuit board capable of mounting semiconductor elements such as power semiconductors, thermoelectric semiconductors, or LEDs.

[0024] Referring to FIGS. 1 and 2, in order to manufacture a ceramic printed circuit board according to the present invention, a ceramic substrate is supported inside a vacuum chamber (200).

[0025] A moving means such as a conveyor belt (400) is provided inside the vacuum chamber (200), and the ceramic substrate can be supported so as to be movable on the conveyor belt.

[0026] The above ceramic substrate is formed of a ceramic material with high thermal conductivity and low coefficient of thermal expansion, such as Al2O3, AlN, BN, BeO, or sapphire, and provides mechanical and thermal stability capable of accommodating high-heat generation devices such as power semiconductors or LEDs. The ceramic substrate is supported inside a vacuum chamber, and its surface may undergo a polishing or cleaning process to protect it from thermal shock or contaminants outside the chamber.

[0027] The vacuum chamber comprises a metal housing with a sealed structure and includes an exhaust port and a gas injection port for controlling internal pressure. A conveyor is positioned on the chamber floor, and a conveyor belt connected to the drive shaft of the conveyor extends along the length of the chamber. The conveyor belt reciprocates while supporting the ceramic substrate, performing positional alignment for each process.

[0028] A plurality of filler material parts (500) are provided on the upper part of the vacuum chamber facing the conveyor belt (400).

[0029] In this embodiment, a metal layer is formed on a ceramic substrate via a filler layer. In addition, the filler material raw material section (500) is provided with raw materials for manufacturing a filler material desired by the manufacturer.

[0030] The filler metal layer is formed by the adhesion and mutual diffusion of multi-element particles released from the filler metal material onto the substrate surface, mixing them, and can range in thickness from a thin film several micrometers to tens of micrometers, as needed. This layer absorbs interfacial stress between the ceramic and the subsequently deposited metal layer, enhancing electrical and thermal bonding strength.

[0031] Separate from the arrangement of the filler material section, a metal material section is arranged parallel to the chamber sidewall. Each metal material section, equipped with its own power supply and magnets, is configured to transport the substrate on which the filler material layer has been formed, allowing for continuous metal layer deposition to complete the circuit pattern. The control unit synchronizes the conveyor belt position and the timing of each power supply in real time, preventing interference between processes.

[0032] In this embodiment, the filler material portion (500) may include titanium (Ti), silver (Ag), and copper (Cu).

[0033] Additionally, a magnet and a power source are provided at the rear of each of the above-mentioned filler material sections to control each filler material.

[0034] The above power source can apply a specific voltage waveform or shape (amplitude, period, etc.) between each filler material and the ceramic substrate, and the magnet forms a magnetic field to guide the direction of movement of a specific filler material toward the ceramic substrate. As a result, different voltages can be applied between each filler material and the ceramic substrate, thereby causing different discharge rates of the filler material.

[0035] The vacuum chamber is equipped with an easily replaceable filler metal cartridge. A magnet located behind the filler material section generates a transverse magnetic field, confining the glow discharge plasma close to the front of the target and directing the ionized metal atoms toward the ceramic substrate. The power supply is configured to output various waveforms, including DC, pulse, and RF, enabling the realization of different voltage waveforms and shapes. The control unit sequentially or simultaneously switches this power supply to precisely control the discharge rate and mixing ratio.

[0036] Each filler material section features a retractable shutter at the bottom to prevent debris or gaseous particles from the previous cartridge from entering the next cartridge during operation. Furthermore, channels are provided on the outer wall of the vacuum chamber to circulate a fluid coolant, maintaining a stable filler material temperature even during high-power discharges.

[0037] The arrangement of the filler material section is linear, parallel to the conveyor belt's path. This allows the ceramic substrate to pass beneath each target through forward and reverse motions, forming a mixed layer. Depending on your needs, you can choose not only the sequential deposition method (target 1 → target 2 → target 3), but also the simultaneous deposition method, which simultaneously discharges all three targets at a specific location to produce a single mixed layer.

[0038] The control unit (600) controls the filler material unit (500) and the conveyor belt (400) to form a filler material layer.

[0039] The above control unit is a PLC or MCU-based electronic controller that comprehensively manages conveyor belt position, power supply sequence, gas pressure, discharge time, and other factors. Closed-loop control is performed based on a memory containing process recipes and real-time sensor data, maintaining a constant filler metal layer thickness and composition ratio.

[0040] When the process begins, inert gases such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and nitrogen (N2) are injected into the vacuum chamber. A pressure sensor is installed inside the vacuum chamber, and when a certain pressure is reached, the control unit blocks the injection of the inert gas.

[0041] That is, the inert gas supply unit injects a mixture of He, Ne, Ar, etc. into the chamber and maintains the pressure range required for glow discharge. The control unit linked to the pressure sensor blocks the supply when the target pressure is reached, preventing over-injection.

[0042] The inert gas supply section is additionally equipped with a gas switching manifold, allowing for the selection of different gases depending on the type of filler material section and process conditions. For example, the titanium deposition step can be configured to sequentially inject helium, which has high thermal conductivity, while the copper deposition step can sequentially inject argon, which has excellent ionization properties.

[0043] All piping utilizes corrosion-resistant stainless steel tubing and uses metal gaskets instead of rubber seals to minimize contamination. Furthermore, its detachable design allows for individual modules to be removed and replaced during maintenance.

[0044] The inert gas supply unit configured in this manner quickly forms a uniform and clean gas atmosphere inside the vacuum chamber, thereby increasing the reproducibility and bonding reliability of the filler layer and metal layer deposition process.

[0045] When the injection of the inert gas is completed, the control unit drives the conveyor belt to move the ceramic substrate, and at the same time, voltage is applied to a preset specific filler material to ionize the inert gas by causing a glow discharge.

[0046] At this time, the control unit drives the conveyor belt so that the ceramic substrate is positioned below the filler material to which voltage is applied.

[0047] The control unit applies a voltage of a specific size or waveform for a preset driving time, and when the driving time has elapsed, the power is cut off, the conveyor belt is driven to move the ceramic substrate to a position facing the next filler material, and then the voltage is applied.

[0048] When voltage is applied, specific filler material particles are released by collision with the inert gas and migrate to the opposing ceramic substrate.

[0049] By repeating this method, the control unit can sequentially apply voltage to each filler material, and the ceramic substrate moves accordingly, mixing multiple filler materials.

[0050] A filler metal layer formed on the upper surface of a ceramic substrate inside a vacuum chamber is formed by directly mixing and condensing various filler metal particles emitted from filler material raw materials on the surface of the ceramic substrate. At this time, voltages with different waveforms and amplitudes are sequentially applied from a power source to each filler material raw material section, and a magnetic field formed by a magnet collectively guides the movement trajectories of the emitted particles toward the ceramic substrate. The magnet need not be a fixed magnet, but may be formed of a coil or the like so as to be provided so as to be able to control the direction and strength of the magnetic field.

[0051] The control unit precisely manages the composition and thickness of the filler material layer by driving the conveyor belt to synchronously control the ceramic substrate to pass through the lower part of each filler material section.

[0052] By applying different voltage waveforms to each filler material section, the mixing ratio of Ti, Ag, Cu, etc. can be finely adjusted. For example, when Ag is mixed in the range of 60-80 wt%, Cu is 19-30 wt%, and Ti is 1-10 wt%, Ti secures chemical bonding with the ceramic substrate, and the Ag-Cu alloy strengthens the metallic bond with the metal layer, thereby improving both electrical and thermal properties.

[0053] In this embodiment, the filler materials may be arranged in the order of titanium, silver, and copper, and as the ceramic substrate moves horizontally back and forth, the titanium, silver, and copper particles are mixed on the surface of the ceramic substrate.

[0054] At this time, the mixing ratio of titanium, silver, and copper particles can be determined depending on the magnitude of the voltage applied to each filler material and the operating time. For example, the mixing ratio can be such that the silver (Ag) content is 60 wt% to 80 wt%, the copper (Cu) content is 19 wt% to 30 wt%, and the titanium (Ti) content is 1 wt% to 10 wt%.

[0055] In this way, a specific voltage is applied sequentially or in a preset order to a plurality of filler material sections to discharge the filler material, and the discharged filler material is mixed on the substrate to form a filler material layer.

[0056] In this embodiment, as the ceramic substrate moves back and forth at a rapid rate, each filler material is mixed on the surface of the ceramic substrate to form a single filler material layer, and the filler material formed in this way has a very high purity, so that a thin film of 1 to 50 μm can be formed.

[0057] When a filler layer is formed on a ceramic substrate, a metal layer is formed on the filler layer to form a conductive layer.

[0058] Referring to FIG. 3, the metal layer can also be deposited on the ceramic substrate by applying voltage between the metal raw material portion (700) and the ceramic substrate in a vacuum chamber to ionize an inert gas.

[0059] That is, the metal raw material portion (700) is provided in parallel to the side of the filler material portion, and when the filler material layer is formed, the ceramic substrate is moved to a position facing the metal raw material portion (700) to deposit the metal layer, thereby enabling a continuous process.

[0060] The above metal source portion is arranged longitudinally parallel to the filler material portion at the top of the vacuum chamber. The metal source portion is composed of a metal source target, a target holder, a magnet (107), a power source (106), and a cooling block for depositing a metal layer. The metal source target is modularized so that it can be replaced with the necessary metal, such as copper, aluminum, or nickel, and a cooling channel is formed inside the target holder to prevent target deterioration and particle contamination due to heat.

[0061] Magnets positioned behind the metal raw material section generate an asymmetric magnetic field in the plane, concentrating the plasma toward the front. The power source applies a voltage between the metal raw material section and the ceramic substrate, either via high-frequency RF or pulsed DC, ionizing argon injected from the inert gas supply section into a glow discharge state. The ionized gas ions strike the metal raw material, scattering metal atoms. These atoms then adhere to the surface of the substrate located on the conveyor belt, forming a metal layer.

[0062] A slit-type shutter is attached to the front of the metal material section to prevent metal particles from flying away while the conveyor belt is moving. The control unit synchronizes the shutter opening and closing, applied power, gas flow, and substrate speed to continuously deposit uniformly thick metal layers on the filler metal layer. Once a single metal layer is deposited, the shutter can be closed, the target replaced, or the power can be reset to sequentially form a multilayer structure.

[0063] Metal particles released from the metal source region are mechanically and metallurgically bonded directly to the filler layer without chemical reaction, minimizing interfacial diffusion between the two layers and enhancing thermal stress reliability. Furthermore, varying the power pulse waveform allows for control of grain size and internal stress, thereby enhancing patterning precision in subsequent processes.

[0064] The above metal layer is formed in a predetermined pattern, and can form an electrical conductor. The thickness of the metal layer forming the electrically conductive layer varies depending on the operating power of the mounted semiconductor device, and is preferably 0.1 mm to 1.0 mm.

[0065] The above metal layer may be formed of multiple metal layers taking into account mechanical stress or thermal expansion coefficient.

[0066] Examining the cross-sectional structure of the ceramic printed circuit board according to this embodiment, a filler metal layer is continuously interposed between the ceramic substrate and the metal layer. This layer buffers the difference in thermal expansion coefficient between the ceramic and the metal, absorbing thermal and mechanical stress that may occur at the bonding interface. Simultaneously, the excellent electrical conductivity provided by the Ag-Cu alloy minimizes circuit resistance.

[0067] The metal layer can be patterned in two ways. First, a shadow mask is combined with the metal material immediately after the filler metal layer is formed, without the need for photolithography, and the desired circuit shape is directly deposited. Second, a continuous planar deposition is followed by laser ablation to finely pattern the circuit pattern. Both methods require no additional dry film process, resulting in shorter manufacturing times and lower defect rates.

[0068] When a multilayer structure is required, a thick layer of low-resistivity copper can be deposited as the first sublayer, followed by a thin nickel film as a barrier layer to prevent oxidation and electrochemical diffusion. Selectively plating a gold (Au) film over the layer can ensure wire bonding reliability.

[0069] The final thickness of the metal layer is determined by the control unit based on the power consumption and thermal resistance requirements of the power semiconductor device to be mounted. If necessary, solder leveling or electroless nickel-gold (ENIG) treatment can be performed on the entire metal layer to improve solderability.

[0070] In this way, the metal layer simultaneously improves the electrical, thermal, and mechanical reliability of ceramic printed circuit boards by taking charge of not only simple conductive wiring but also heat dissipation, mechanical protection, and packaging interface.

[0071] Although the present invention has been described above with reference to embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. A step in which a ceramic substrate is supported inside a vacuum chamber; A step in which a plurality of filler material parts are provided within the vacuum chamber; A step in which an inert gas is injected into the vacuum chamber; A step of applying power between the ceramic substrate and the filler material portion to cause a glow discharge of an inert gas, thereby mixing a plurality of filler material materials on the ceramic substrate and forming a filler material layer; A method for manufacturing a ceramic printed circuit board, comprising a step of forming a metal layer on the above-mentioned filler layer.

2. In paragraph 1, A method for manufacturing a ceramic printed circuit board, characterized in that each of the plurality of filler material parts is applied with different voltage waveforms and shapes.

3. A step in which a ceramic substrate is supported inside a vacuum chamber; A step in which a plurality of filler material parts are provided within the vacuum chamber; A step in which an inert gas is injected into the vacuum chamber; A step of applying power between the ceramic substrate and the filler material portion to cause a glow discharge of an inert gas, thereby mixing a plurality of filler material materials on the ceramic substrate and forming a filler material layer; A ceramic printed circuit board produced by performing a step of forming a metal layer on the above-mentioned filler layer.

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