Filler metal forming apparatus for ceramic substrate

Abstract

The present invention relates to a filler metal forming apparatus for a ceramic substrate, which can be manufactured at once with a desired material and can improve bonding force. To this end, the present invention provides a filler metal forming apparatus for a ceramic substrate, comprising: a vacuum chamber in which an inert gas inlet is formed; a plurality of filler metal raw material parts provided inside the vacuum chamber; a ceramic substrate moving part for moving the ceramic substrate; a voltage applying part for glow-discharging the inert gas by applying a voltage between the ceramic substrate and the filler metal raw material part; and a control part for controlling the ceramic substrate moving part and the voltage applying part. According to the present invention, a filler metal forming apparatus can be provided in which a customized filler metal is formed using a desired material and bonding force is strengthened.

Description

Filler material forming device for ceramic substrates

[0001] The present invention relates to a filler material forming device for a ceramic substrate, and more specifically, to a filler material forming device for a ceramic substrate capable of manufacturing a desired material at once and improving bonding strength.

[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, cost is reduced by removing Ag from the active metal paste and forming Ag in the form of a thin film, 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 provide a filler material forming device that forms a customized filler material using a desired material and enhances adhesive strength.

[0008] In addition, the purpose is to provide a method for manufacturing a ceramic printed circuit board by simplifying the process and forming a filler layer and a metal layer on a ceramic substrate through a continuous process.

[0009] In order to achieve the above object, the present invention provides a filler material forming apparatus for a ceramic substrate, comprising: a vacuum chamber in which an inert gas injection port is formed; a plurality of filler material portions provided inside the vacuum chamber; a ceramic substrate moving portion for moving a ceramic substrate; a voltage applying portion for applying voltage between the ceramic substrate and the filler material portion to cause a glow discharge of the inert gas; and a control portion for controlling the ceramic substrate moving portion and the voltage applying portion.

[0010] It is preferable that the above ceramic substrate moving part is provided with a position sensor that detects the position of the ceramic substrate, and that the control part controls the voltage application part according to the signal of the position sensor.

[0011] The above control unit can apply different voltages to the voltage application unit depending on the material of the filler material.

[0012] It is preferable that the above-mentioned filler material forming device for a ceramic substrate has an input unit for receiving a ratio of the filler material raw material, and that the control unit controls the voltage application unit according to the ratio of the filler material raw material received from the input unit.

[0013] According to the present invention, a filler metal forming device can be provided that forms a customized filler metal using a desired material and enhances adhesive strength. Since the filler metal layer is formed directly on the substrate surface, interface defects are minimized and bonding strength is significantly enhanced.

[0014] In addition, a method for manufacturing a ceramic printed circuit board can be provided by simplifying the process and forming a filler layer and a metal layer on a ceramic substrate in a continuous process.

[0015] Since the process is performed continuously within a single vacuum chamber, the number of process steps is reduced, increasing productivity and reducing manufacturing costs. The control unit synchronizes substrate movement and voltage application in real time, enabling precise control of deposition thickness and composition, reducing quality variation.

[0016] Because the raw material is ionized and deposited using a glow discharge method, high-purity thin films can be formed and a uniform filler metal layer 3-5 micrometers thick can be achieved. Furthermore, metal layers can be deposited within the same device, enabling the batch production of ceramic printed circuit boards without the need for separate equipment or subsequent processes.

[0017] By varying the voltage level and application time as needed, the ratio of various metals, such as titanium, silver, and copper, can be freely adjusted. This allows for optimization of thermal expansion coefficients and electrical characteristics to suit product requirements. Consequently, ceramic PCBs with superior heat dissipation and reliability can be economically and reliably provided for mounting high-power and high-frequency components.

[0018] Figure 1 is a configuration diagram of a ceramic substrate forming device according to the present invention;

[0019] Figure 2 is a configuration diagram of the inside of a ceramic printed circuit board manufacturing device for manufacturing a ceramic printed circuit board using the present invention.

[0020] The configuration and operation of a specific embodiment of the present invention will be described in detail with reference to the drawings.

[0021] Referring to FIG. 1, a ceramic substrate filler material forming device according to the present invention is configured to include a vacuum chamber (200), a ceramic substrate moving unit (400), a filler material raw material unit (500), a voltage applying unit (701, 702, 703), and a control unit (600).

[0022] The above vacuum chamber (200) is a device that can form a vacuum state inside, and can be connected to a vacuum pump that sucks in the air inside and decompresses it to form a vacuum state while maintaining airtightness. The vacuum chamber wall is made of stainless steel as a basic material to minimize contamination or damage caused by internal plasma, and an insulating coating layer can be formed on the inner surface to prevent current leakage when high voltage is applied.

[0023] An inlet (210) through which an inert gas such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), or nitrogen (N2) is injected and an outlet (230) through which the inert gas is discharged may be formed on one side of the vacuum chamber, and the inlet (210) and outlet (230) may be automatically opened and closed by a valve.

[0024] The inert gas inlet consists of a modular port flanged to the upper sidewall of the vacuum chamber. The inlet body is constructed of SUS stainless steel, preventing gas leakage and ensuring corrosion resistance even in high-vacuum environments. Inside the inlet, a high-vacuum vacuum valve for primary shutoff and a mass flow controller (MFC) for secondary flow control are arranged in series, ensuring that only the precise flow requested by the control unit is supplied to the chamber.

[0025] A multi-channel manifold is provided to support a full range of inert gases, including helium, argon, neon, and nitrogen. Each gas line is designed with a double-safety design, including a backflow prevention check valve and a microfilter, to prevent metal debris or powder that may be generated during filler metal deposition from contaminating the line.

[0026] Pressure and temperature sensors are integrated into the chamber wall immediately below the inlet, monitoring internal pressure increases and thermal changes in real time as gas is injected. Sensor signals are transmitted to the control unit, which automatically shuts down the MFC when the target pressure is reached. Chamber pressure is then feedback-controlled to ensure stable glow discharge at the voltage application unit.

[0027] To prevent the plasma generated during the voltage application phase from back-diffusion toward the inlet, a plasma shutter is installed inside the inlet, which swirls the gas flow. Made of silica-alumina ceramic, the plasma shutter suppresses chemical reactions with the high-temperature plasma and, when necessary, is completely closed by a control signal to cut off the gas supply.

[0028] To reduce the phenomenon of the ionization area expanding toward the inlet when the magnetic field generator is in operation, the control unit synchronizes the magnetic field strength and gas flow rate to ensure uniform particle straightness. This allows the metal ions released from the filler material unit to accurately reach the ceramic substrate surface.

[0029] This inlet module is a detachable structure, allowing for easy removal during routine maintenance by closing the blind flange behind the vacuum valve. This simplifies adding gas types or cleaning the lines. Furthermore, in emergency situations, the inlet can be replaced without affecting the internal vacuum of the chamber.

[0030] Additionally, a pressure sensor is provided inside the vacuum chamber to detect the internal pressure in real time.

[0031] Inside the vacuum chamber, a ceramic substrate moving part (400) is provided to support and move a ceramic substrate (300). The ceramic substrate may be made of a ceramic material including Al2O3, AlN, BN, BeO, sapphire, etc.

[0032] For example, the ceramic substrate moving unit (400) may be formed of a conveyor belt so as to allow the ceramic substrate to move horizontally and reciprocally, and the ceramic substrate moving unit is driven to move the ceramic substrate to an accurate position under the control of the control unit. The driving motor is located outside the vacuum chamber, and a magnetically coupled rotary feedthrough hermetically connects the inside and outside of the chamber. It is preferable that a vacuum chuck is provided on the upper part of the ceramic substrate moving unit for the convenience of substrate attachment and detachment, so that the substrate flatness is stably maintained even during the process.

[0033] As another example, the ceramic substrate moving unit (400) may be configured with a linear guide rail formed long along the bottom surface inside the vacuum chamber and a carriage structure that reciprocates on the rail. A quartz glass support panel is attached to the top of the carriage to support the ceramic substrate flatly, thereby minimizing particle contamination that may occur during the process. The carriage is connected to an externally mounted servo motor and timing belt through a vacuum rotation feedthrough, and is controlled in a closed loop to enable acceleration and deceleration according to commands from the control unit.

[0034] When voltage is applied, the ceramic substrate is grounded through a conductive jig embedded in the carriage, or a predetermined bias voltage can be applied as needed. This jig is made of high-temperature stainless steel and is electrically insulated from the carriage, ensuring a stable plasma current loop.

[0035] The substrate transport unit's travel speed can be varied in 1 mm / s increments based on a database-based process recipe. The control unit calculates the number of round trips and the position dwell time based on the target filler metal layer thickness set in the input unit. It also performs real-time feedback control during movement to ensure uniformity in raw material discharge. Furthermore, micro-vibration damping pads are attached to the carriage base to minimize powder scattering and film thickness variations caused by pulse movements.

[0036] To address the lubrication issues of moving parts in the high-vacuum environment of the chamber, the carriage shaft system incorporates lubrication-free magnetic levitation bearings coupled with a dry pump. This design fundamentally eliminates oil vapor contamination while supporting long-stroke, precision reciprocating motion.

[0037] With the carriage stationary, the voltage application unit collaborates with the magnetic field generator to focus the ionized filler particles toward the substrate surface. Therefore, the ceramic substrate transport unit performs a multi-functional role beyond simple transport, serving as the lower electrode of the plasma voltage circuit, an alignment reference, and a thermal heat dissipation path.

[0038] The above ceramic substrate moving part (400) is equipped with a position sensor, and the position sensor detects the position of the ceramic substrate provided on the upper portion. The position sensor may be formed of, for example, an ultrasonic or optical sensor.

[0039] The above position sensor detects the position of the ceramic substrate in real time when it enters under each filler material section. The signal from the position sensor is transmitted to the control unit, which synchronizes the operation of the ceramic substrate moving unit and voltage application unit based on the signal.

[0040] When the ceramic substrate moving unit moves the substrate to the next process position, the control unit verifies each position sensor feedback to perform inter-process interlock, so that the continuous deposition, mixing, and metal deposition steps proceed without process interference.

[0041] The back of the ceramic substrate may be provided with a conductive pad for a grounding or bias electrode. Setting the substrate to a cathodic or floating potential ensures a sufficient potential difference at the voltage application point, effectively guiding metal ions within the plasma formed by the ionized inert gas, thereby improving surface density. Furthermore, it is desirable to employ low-friction rollers or a magnetic levitation holder for the ceramic substrate moving section to suppress particle scattering during substrate movement and ensure repeatable positioning accuracy.

[0042] A plurality of filler material parts (500) are provided on the upper part of the vacuum chamber facing the conveyor belt (400).

[0043] The above-described filler material portion (500) may include a plurality of filler material portions (501, 502, 503), each of which is a raw material for forming a filler material layer desired by the manufacturer. A focusing shutter that limits the spraying angle is attached to the front of the filler material portion to increase the deposition efficiency onto the ceramic substrate. It is preferable that each filler material portion be cooled through a water jacket structure to suppress thermal deformation, and be electrically separated from a voltage application portion and an insulating support.

[0044] For example, the filler material portion (500) may include titanium (Ti), silver (Ag), and copper (Cu).

[0045] The filler material unit (500) may be formed of a plurality of cartridge-type modules arranged in a row or matrix format on the upper portion of the vacuum chamber (200). Each module includes a target for storing and releasing a predetermined filler material (e.g., Ti, Ag, Cu), a holder for supporting the target, and an individual shutter for exposing and shielding the target surface. The shutter may be electrically opened and closed according to a control signal from the control unit, so that only the selected filler material may be released toward the ceramic substrate.

[0046] The modular structure of the filler material section facilitates simple target replacement. Targets can be removed and inserted through a service port at the top of the chamber without opening the chamber. A holder with integrated cooling channels and a thermal resistance sensor suppresses component deviations due to rising target temperatures. The control unit uses target temperature data to correct for errors in voltage application conditions.

[0047] The filler material module is positioned perpendicular to the ceramic substrate moving section's path. When the ceramic substrate reaches a designated position, a position sensor detects this, and the control unit simultaneously opens the shutter of the corresponding filler material module and applies voltage to the voltage application unit. Even for the same filler material, two or more targets can be positioned to operate under different areas or voltage conditions, allowing for fine-tuning of the mixing ratio.

[0048] At the rear of each of the above-mentioned filler material parts, a voltage application part (701, 702, 703) is provided to control each filler material.

[0049] The voltage applying unit may include a magnet that can apply voltage between each filler material and the ceramic substrate and guides the direction in which a specific filler material moves to the ceramic substrate by forming a magnetic field.

[0050] Specifically, the voltage application unit applies a voltage between each filler material and the ceramic substrate to ionize the inert gas by causing a glow discharge. At this time, the amount of the inert gas to be ionized varies depending on the magnitude of the applied voltage, so the control unit can vary the voltage magnitude depending on the filler material to be deposited.

[0051] The above voltage application unit is composed of a discharge electrode, an insulating housing, a magnetic field generator, and a power module. The discharge electrode is divided into a cathode (target) and an anode (substrate bias plate). The anode is positioned parallel to the substrate surface when the ceramic substrate moves, and the control unit selectively applies ground potential or bias potential according to a signal transmitted from a position sensor.

[0052] The insulating housing is a metal cylinder coated with alumina ceramic, shielding high-voltage discharges from the outer wall and minimizing arc generation. Cooling channels are formed internally to maintain a stable cathode surface temperature even during extended operation.

[0053] The magnetic field generator can be configured as a hybrid structure combining a permanent magnet ring and an electromagnet coil. The permanent magnet provides a fixed magnetic field to confine the inert gas plasma to the electrode surface, while the electromagnet coil fine-tunes the magnetic flux according to a control signal to focus the ion trajectory toward the substrate. This ensures that the emitted filler metal particles are uniformly deposited at the center of the ceramic substrate, rather than being dispersed widely.

[0054] The power module is a multi-functional power supply capable of outputting pulsed DC, RF, or medium frequency (MF). The control unit reads the filler metal composition data set in the input section and transmits the optimal parameters (voltage level, pulse width, duty cycle) to each voltage application section. For example, it automatically applies optimal conditions for each metal, such as selecting RF for silver deposition and pulsed DC for copper deposition to suppress arcing.

[0055] A switching circuit is included between the power module and the filler material, allowing for selective supply of RF or DC bias, allowing independent control of different voltage levels for each material. Additionally, a pulse drive function is provided to stabilize the plasma and suppress arc generation.

[0056] The magnetic field generator is integrated with the voltage application unit. Using a solenoid coil or permanent magnet assembly, a transverse magnetic field is created across the target surface, concentrating the trajectories of ionized inert gas and deposition particles toward the center of the ceramic substrate. This contributes to improved sputtering efficiency and film thickness uniformity.

[0057] Since the magnetic field is adjusted in real time in conjunction with the voltage application level, the diffusion angle of the deposition plume can be maintained constant even when the filler material mixing ratio is changed.

[0058] 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.

[0059] The control unit (600) is a logic unit that centrally manages and controls the entire system. The operator inputs process parameters such as filler metal composition, target content of each metal, filler metal layer thickness, and metal layer material and thickness into the input unit. The control unit generates an operating schedule based on the input data and interlocks and controls the applied voltage, voltage application time, and ceramic substrate movement path and number of times for each filler metal raw material unit.

[0060] The input unit is a touchscreen interface installed on the chamber's front panel, allowing operators to easily input parameters such as the wt% ratio of each raw material, the target film thickness, and the number of substrate cycles. These input values ​​are immediately recorded in the control unit database and used to replicate the same process in the future.

[0061] When the operator sets the target wt% values ​​of Ti, Ag, and Cu, respectively, through the input unit (107), the control unit calculates the applied voltage, pulse width, shutter opening time, and the number of reciprocations of the ceramic substrate for the corresponding modules. The calculated results are sequentially executed according to the set process order, and while the substrate reciprocates, multiple filler metal ions are simultaneously and continuously mixed on the substrate surface to form a uniform filler metal layer.

[0062] If necessary, a nitrogen-argon mixed gas nozzle is provided at the outermost portion of the filler material section (102) to adjust the local gas atmosphere directly in front of the target, thereby stabilizing the ionization efficiency and target etching rate. This local control technology is effective in reducing the difference in sputtering rates of multiple materials.

[0063] Next, a method for driving a ceramic substrate forming device according to the present invention will be described.

[0064] The operator can input the name of the filler material, the ratio, the thickness of the filler layer, etc. through the input unit. The input unit may be equipped with a keyboard or a touch screen, and inputs data required for the process.

[0065] The control unit generates a driving schedule based on data input by the input unit. The driving schedule may include the movement order of the ceramic substrate, the number of round-trip movements, and the voltage application method.

[0066] For example, if a mixing ratio of 60 wt% to 80 wt% of silver (Ag), 19 wt% to 30 wt% of copper (Cu), and 1 wt% to 10 wt% of titanium (Ti) and a thickness of 4 μm are input by the input unit, the control unit calculates the driving voltage and voltage application time applied between the silver and the ceramic substrate, the driving voltage and voltage application time applied between the copper and the ceramic substrate, and the driving voltage and voltage application time applied between the titanium and the ceramic substrate, respectively, according to the mixing ratio, and determines the number of reciprocating movements of the ceramic substrate to correspond to a thickness of 4 μm of the filler metal layer.

[0067] To generate a driving schedule, the control unit can search a database to detect a driving method corresponding to input data or derive a result value from a relational expression.

[0068] 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. At this time, the internal pressure is measured by a pressure sensor installed inside the vacuum chamber, and when the measured internal pressure reaches the driving pressure, the control unit blocks the injection of the inert gas.

[0069] That is, the control unit determines the driving pressure of the inert gas based on input data, such as the thickness of the filler metal layer, input through the input unit, and controls the pressure inside the vacuum chamber by the inert gas to be maintained at the driving pressure. At this time, the control unit can search the database to detect the driving pressure corresponding to the thickness of the filler metal layer.

[0070] 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.

[0071] At this time, the control unit drives the conveyor belt so that the ceramic substrate is positioned under the filler material to which voltage is applied. That is, the conveyor belt is equipped with a position sensor, and when the ceramic substrate is positioned under a specific filler material, a detection signal from the position sensor is transmitted to the control unit, and the control unit stops the operation of the conveyor belt upon receiving the detection signal.

[0072] Then, the control unit applies a voltage set according to the driving schedule to move the corresponding filler material to the ceramic layer.

[0073] That is, the control unit applies the driving voltage for a preset voltage application time, and when the voltage application time has elapsed, the power is cut off, the conveyor belt is driven according to the driving schedule to move the ceramic substrate to a position facing the next filler material, and then the driving voltage corresponding to the filler material is applied again.

[0074] When a driving voltage is applied, specific filler material particles are released due to collision with the inert gas and move to the opposing ceramic substrate.

[0075] By repeating this process, the control unit can sequentially apply voltage to each filler material, and the ceramic substrate moves accordingly, mixing multiple filler materials.

[0076] 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.

[0077] As the above 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 filler material layer. The filler material formed in this way has a very high purity, so that it is possible to form a thin film of 3 to 5 μm.

[0078] When a filler layer is formed on a ceramic substrate, a metal layer can be formed on the filler layer to form a conductive layer, thereby manufacturing a ceramic printed circuit board.

[0079] Referring to FIG. 2, the metal layer can also be deposited on the ceramic substrate by applying voltage between the metal raw material portion (800) and the ceramic substrate in a vacuum chamber to ionize an inert gas.

[0080] That is, the metal raw material portion (800) 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 (800) to deposit the metal layer, thereby enabling a continuous process.

[0081] The above metal layer is formed in a predetermined pattern and can be an electrical conductor, a high-voltage node, or a low-voltage node. 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 0.2 mm to 0.8 mm.

[0082] The above metal layer may be formed of multiple metal layers taking into account mechanical stress or thermal expansion coefficient.

[0083] From a thermal management perspective, the ceramic substrate transfer unit can include built-in heaters or cooling channels. During filler metal layer deposition, the temperature is increased to promote metal diffusion, while during the metal layer deposition stage, the temperature is lowered to control thermal stress. This temperature control is automatically performed by the control unit according to the process profile set in the input unit.

[0084] 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 following claims.

Claims

1. A vacuum chamber in which an inert gas inlet is formed; A plurality of filler material parts provided inside the vacuum chamber; A ceramic substrate moving unit that moves a ceramic substrate; A voltage application unit that applies voltage between the ceramic substrate and the filler material unit to cause a glow discharge of the inert gas; and A ceramic substrate forming device comprising a control unit that controls the ceramic substrate moving unit and voltage applying unit.

2. In paragraph 1, A ceramic substrate forming device characterized in that the ceramic substrate moving unit is provided with a position sensor for detecting the position of the ceramic substrate, and the control unit controls the voltage application unit according to the signal of the position sensor.

3. In paragraph 1, A ceramic substrate filler material forming device characterized in that the control unit applies different voltages to the voltage application unit according to the filler material raw material unit.

4. In paragraph 3, The above ceramic substrate filler material forming device has an input unit for receiving the ratio of the above filler material raw material, A ceramic substrate filler forming device, characterized in that the control unit controls the voltage application unit according to the ratio of the filler material input from the input unit.

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