Warm-pressure integrated intracranial pressure sensor probe packaging structure based on gold wire bonding

Abstract

The invention discloses a gold wire bonding-based temperature and pressure integrated intracranial pressure sensor probe packaging structure, which relates to the technical field of sensors, and comprises a circuit board, a temperature and pressure integrated sensor chip mounted on the upper surface of the circuit board, and a titanium base for bearing the circuit board and the temperature and pressure integrated sensor chip, one end of the hose is inserted into the titanium base; and the glue injection window is formed in the outer wall of the titanium base. According to the invention, the temperature and pressure integrated sensor chip integrated with the Wheatstone full bridge is adopted to replace the traditional dual-chip discrete packaging, so that the chip does not need to be positioned and fixed for many times, the sealing process is simplified from the hardware level, the alignment error problem of multi-chip assembly is solved, and the temperature and pressure integrated sensor can be assembled through a step with a constant height. The height of the circuit board assembled in the titanium base is limited, so that under the assistance of the constant-height circuit board and the constant-height titanium base, the flexible glue injection range in the titanium base is constant, and then the flexible glue injection thickness is accurately controlled.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sensors, in particular to a temperature and pressure integrated intracranial pressure sensor probe packaging structure based on gold wire bonding. BACKGROUND

[0002] Intracranial pressure refers to the pressure generated by the contents in the cranial cavity on the cranial cavity wall, and is one of important physiological indexes for maintaining the normal function of the central nervous system; when the intracranial pressure is abnormally increased or decreased, serious nervous system damage will be caused, and even life will be endangered, therefore, accurate monitoring of the intracranial pressure is particularly crucial for the diagnosis and treatment of neurological critical patients. Intracranial temperature, i.e. the temperature of intracranial brain tissue, is a key physiological index reflecting the metabolic state and functional integrity of the central nervous system, directly affecting neuron activity, cerebral blood flow and neurotransmitter balance; intracranial temperature is closer to the real environment of brain function, and its abnormality (excessively high or low) will cause irreversible brain damage; when the intracranial condition of a patient deteriorates or postoperative infection occurs, the intracranial temperature and intracranial pressure will be simultaneously increased, therefore, the intracranial temperature and intracranial pressure need to be simultaneously monitored, so as to more completely monitor the real-time changes of the intracranial condition.

[0003] The existing temperature and pressure monitoring needs two kinds of chips, and when the two kinds of chips are installed on a circuit board, positioning and gluing need to be separately performed, so that the whole probe needs to be glued and solidified for multiple times, and the process flow is long. Secondly, in order to ensure the biocompatibility and thickness deviation in the gluing process, a thick enough glue needs to be coated, i.e. after the temperature and pressure chips are fixed on the base, a dam (such as an epoxy dam or a metal dam) needs to be made around the chips, the glue layer thickness is limited by the dam height, and then soft glue is filled to cover the chips, so as to store the chips, but in the operation, the glue thickness precision is limited by the dam, and when the dam position deviates, the uniformity of the gluing thickness will be affected, and the consistency of the glue layer thickness coating each time cannot be ensured. SUMMARY

[0004] The application aims to provide a temperature and pressure integrated intracranial pressure sensor probe packaging structure based on gold wire bonding, and solve the problems in the prior art that how to reduce the assembly difficulty of the two kinds of temperature and pressure monitoring chips on the circuit board, and how to accurately control the soft glue coating thickness when the chips are stored by the soft glue.

[0005] The application can be realized by the following technical scheme. A kind of based on gold wire bonding temperature-pressure integrated intracranial pressure sensor probe packaging structure, comprising: circuit board, the upper surface of the circuit board is fixed with temperature-pressure integrated sensor chip by die bonding glue, the upper surface of the circuit board is installed with gold wire by gold wire bonding equipment, the upper surface of the circuit board is welded with lead-out wire at one end;Titanium base, after combination the circuit board and temperature-pressure integrated sensor chip are fixed in the inside of titanium base by hard glue;Hose, the hose is fixed by biocompatible glue and inserted in the inside of titanium base, the lead-out wire is led out by hose at one end;Glue injection window, the glue injection window is opened in the outer wall of titanium base, and soft glue is filled in the inside of titanium base by glue injection window, and the glue thickness of soft glue is controlled by the cooperation of the circuit board and titanium base.

[0006] Preferably, the temperature-pressure integrated sensor chip type is a Wheatstone full bridge.

[0007] Preferably, the circuit board, titanium base and hose are configured by hard glue, soft glue and biocompatible glue.

[0008] Preferably, the inside of the titanium base is fixedly provided with a positioning step, and the positioning step is used for positioning the setting height of the circuit board in the titanium base.

[0009] Preferably, a group of through holes for hard glue injection are opened on the upper surface of the circuit board, and the lower surface of the circuit board is fixedly connected with the positioning step by hard glue.

[0010] Preferably, another group of through holes for observing the filling amount of hard glue are opened on the upper surface of the circuit board.

[0011] Preferably, a cylindrical hole is opened at one end of the titanium base, and the circuit board is installed in the inside of the titanium base through the cylindrical hole.

[0012] Preferably, one end of the hose coated with biocompatible glue is inserted into the inside of the titanium base through the cylindrical hole, and the other end of the hose extends to the outside of the titanium base.

[0013] The beneficial effects of the present application are: 1. In the present application, the temperature-pressure integrated sensor chip integrated with Wheatstone full bridge is used to replace the traditional double-chip discrete packaging, so that multiple positioning and fixing of the chip are not needed, the packaging process is simplified from the hardware level, the alignment error problem of multi-chip assembly is solved, the temperature-pressure integrated sensor chip is combined with the circuit board through gold wire bonding technology, the dependence on imported welding equipment is reduced, the lead connection difficulty is effectively reduced, and the manufacturing yield is improved to the industry conventional bonding process level.

[0014] 2. In the application, by setting a constant height step in the titanium base, the height of the circuit board assembled in the titanium base can be limited, and under the assistance of the constant height circuit board and the constant height titanium base, the range for soft glue injection in the titanium base is constant, thereby accurately controlling the soft glue injection thickness, solving the problem of unstable and inaccurate control of soft glue thickness by damming around the chip in the traditional scheme.

[0015] 3. In the application, through the systematic design of warm pressure integrated chip integration, circuit board accurate positioning, gold wire bonding interconnection, titanium base rigid bearing and soft and hard glue function partitioning, the three core problems of low integration, complex process and insufficient precision are solved, and the combination technology improves the overall generation yield, optimizes the measurement precision and reduces the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] The application will be further described below with reference to the accompanying drawings.

[0017] Figure 1 is a schematic diagram of the overall structure of the application; Figure 2 is a schematic diagram of the connection structure of the circuit board and the warm pressure integrated sensor chip in the application; Figure 3 is a schematic diagram of the titanium base and the cylindrical hole structure in the application; Figure 4 is a top view of the structure of the circuit board and the warm pressure integrated sensor chip in the application.

[0018] In the figure: 1, circuit board; 2, die bonding glue; 3, warm pressure integrated sensor chip; 4, gold wire; 5, lead wire; 6, titanium base; 7, hose; 8, biocompatible glue; 9, glue injection window; 10, cylindrical hole; 11, positioning step; 12, through hole. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0020] Please refer to Figures 1 to 4 shown, a warm pressure integrated intracranial pressure sensor probe packaging structure based on gold wire bonding, comprising: a circuit board 1, a warm pressure integrated sensor chip 3 installed on the upper surface of the circuit board 1, the circuit board 1 carrying the warm pressure integrated sensor chip 3 is installed inside a titanium base 6, and one end of the titanium base 6 is inserted with a hose 7.

[0021] The temperature and pressure integrated sensor chip 3 is fixed on the upper surface of the circuit board 1 by the die bonding glue 2, that is, the circuit board 1 is provided with a pad corresponding to the mounting position of the temperature and pressure integrated sensor chip 3, the temperature and pressure integrated sensor chip 3 is mounted on the pad by gold wire bonding technology, the temperature and pressure integrated sensor chip 3 is a Wheatstone full bridge, specifically a Wheatstone full bridge sensor integrated with a temperature sensor, a piezoresistive pressure sensor chip using the principle of Wheatstone bridge, the resistance on the chip changes with the change of pressure; The temperature and pressure integrated sensor chip 3 is a single-chip integration, which replaces the discrete chip, specifically, for the existing temperature and pressure double-chip discrete packaging scheme, the independent pressure chip and temperature chip are respectively provided and need to be interconnected by wire welding, and positioning and gluing are needed twice during packaging, while for the temperature and pressure integrated sensor chip 3, the single-chip integration and the upper surface of the circuit board 1 are installed with a gold wire 4 by a gold wire bonding device, and the lead wire 5 is welded at the specified pad on the upper surface of the circuit board 1, so that the process of single-chip integration and gold wire bonding is combined, the difficulty of sealing is simplified from the source, and the yield is improved; Please refer again to Figures 3 to 4 As shown in the figure, the circuit board 1 carrying the temperature and pressure integrated sensor chip 3 is fixed in the inside of the titanium base 6 by the hard glue, the inside of the titanium base 6 is fixedly provided with a positioning step 11, the positioning step 11 is used for positioning the setting height of the circuit board 1 in the titanium base 6, and the positioning step 11 is matched with the circuit board 1; The injection of the hard glue is through a group of through holes 12 opened on the upper surface of the circuit board 1, so that the hard glue is filled on the lower surface of the circuit board 1, and then the lower surface of the circuit board 1 is fixedly connected with the positioning step 11 through the hard glue, and another group of through holes 12 are opened on the upper surface of the circuit board 1 for observing the filling amount of the hard glue, so that the hard glue can be uniformly filled on the lower surface of the circuit board 1, and the stable adhesion between the circuit board 1 and the titanium base 6 is ensured; In particular, the circuit board 1 is of a known custom size, and its height is fixed. When the circuit board 1 is installed in the inside of the titanium base 6, the positioning step 11 at a constant height in the titanium base 6 assists the positioning, ensures that the circuit board 1 is at a constant height in the titanium base 6, places the circuit board 1 at the position of the positioning step 11, and then injects the glue between the circuit board 1 and the positioning step 11 through a group of through holes 12, so that the glue height of the hard glue can be controlled, and another group of through holes 12 can be used to observe the injection amount of the hard glue, so that the circuit board 1 is completely filled with glue, the circuit board 1 and the titanium base 6 are seamlessly bonded, and the adhesion is ensured.

[0022] Please refer again to Figure 1 and Figure 3As shown, the titanium base 6 has a cylindrical hole 10 at one end, the circuit board 1 is installed inside the titanium base 6 through the cylindrical hole 10, one end of the soft tube 7 coated with biocompatible glue 8 is inserted into the inside of the titanium base 6 through the cylindrical hole 10, the other end of the soft tube 7 extends to the outside of the titanium base 6, and one end of the lead wire 5 is led out through the soft tube 7. The soft tube 7 is made of medical-grade biocompatible material. The biocompatible glue 8 filled in the contact position of the soft tube 7 and the titanium base 6 forms a sealed structure between them, that is, the side of the circuit board 1 facing the soft tube 7 is sealed, so that it can avoid the leakage of intracranial body fluid through the gap between the connection position of the soft tube 7 and the titanium base 6 to the outside, and at the same time prevent external bacteria from entering the intracranial cavity through the gap between the soft tube 7 and the titanium base 6 to cause infection, so that the temperature and pressure integrated sensor chip 3 does not directly contact the brain tissue, avoiding the stimulation of intracranial tissue by single-chip integration, and at the same time, the pressure is transmitted to the single-chip integration without loss through the fluid in the soft tube 7, ensuring that the monitoring value is consistent with the actual intracranial pressure.

[0023] The glue injection window 9 is provided on the outer wall of the titanium base 6, and the soft glue is filled in the inside of the titanium base 6 through the glue injection window 9, and the glue thickness of the soft glue is controlled by the cooperation of the circuit board 1 and the titanium base 6. For glue thickness precision control, the titanium base 6 and the circuit board 1 are rigidly positioned, that is, the circuit board 1 is of a customized size, and its height is constant. The circuit board 1 is positioned at a constant height in the inside of the titanium base 6 by the positioning step 11, so that the range for soft glue filling between the circuit board 1 at a constant height and the titanium base 6 is constant in height. The soft glue filling range is the blank area in the titanium base 6 excluding the circuit board 1 and the soft tube 7. For details, please refer to the drawings. Figure 1 As shown; The hierarchical glue layer design of "hard glue (circuit board 1 fixed) + soft glue (signal transmission) + biocompatible glue 8 (interface sealing)" not only ensures the structural stability, but also does not affect the transmission of pressure and temperature signals, while meeting the biocompatibility requirements of intracranial implantation. The type of soft glue used is Liveo™ Medical Adhesive Type A; the type of hard glue used is LOCTITE® EAM-31CL™; and the biocompatible glue 6 can be Liveo™ Medical Adhesive Type A or LOCTITE® EAM-31CL™. All the glues used meet the biocompatibility standards. For biocompatibility, in blood compatibility, the material needs to avoid causing blood clotting, hemolysis, or damage to blood cells when it comes into contact with blood; in tissue compatibility, the material needs to avoid causing inflammation, allergy, rejection reaction, or damage to surrounding cells and tissues after being implanted into human tissues.

[0024] In particular, the controllable glue thickness can reduce signal loss and improve transmission stability, optimize the transmission effect of pressure and temperature signals, and avoid pressure conduction delay caused by excessive glue layer thickness or local pressure "blind area" caused by uneven glue layer, ensuring that the pressure signal is accurately and quickly transmitted to the sensor sensitive element. The soft glue is a medium for transmitting pressure, and the main pressure transmitted is intracranial pressure. After the glue layer is filled, the soft glue as the outer material directly contacts with the intracranial tissue fluid or brain tissue will first receive the change of intracranial pressure. After the soft glue receives the pressure, it will uniformly transmit the pressure to the temperature and pressure integrated sensor chip 3 on the circuit board 1 through its internal molecular structure. When the transmitted pressure acts on the temperature and pressure integrated sensor chip 3, the temperature and pressure integrated sensor chip 3 will convert the physical pressure signal into an electrical signal that can be detected.

[0025] The fixed glue thickness can reduce the uncertainty of the glue layer compression amount. For example, in the packaging of a pressure sensor, the deviation of the glue thickness will directly cause the error of the pressure-electric signal conversion. The controllable glue thickness can control the error within a small range, improving the measurement accuracy. The glue layer is an intermediate medium for temperature transmission. An excessively thick glue layer will increase the thermal resistance, causing the temperature signal transmission to lag. The controllable glue thickness can set the optimal thickness according to the requirements (such as a thin glue layer to reduce thermal resistance), allowing the temperature change to be quickly captured by the sensor. If the glue layer thickness is uneven, there will be local thermal resistance differences, causing the temperature signals received by different areas of the sensor to be inconsistent (such as local overheating or overcooling). Uniform glue thickness can ensure uniform conduction of temperature in the glue layer, ensuring that the temperature signal obtained by the sensor reflects the true environmental temperature.

[0026] In summary, the packaging specific steps are as follows: First, prepare the circuit board 1, use the die attach film to fix the temperature and pressure integrated sensor chip 3 on the upper surface of the circuit board 1 (in order to ensure the consistency of the chip volume, the glue between the chip and the base can be a thin film material, such as die attach film, to ensure micron-level precision), and use the necessary curing process to ensure the bonding strength of the chip and the circuit board 1 after the glue solidifies. Then, transfer the circuit board 1 to the gold wire bonding machine, complete the gold wire bonding, and weld the lead wire 5 to the specified pad of the circuit board 1 to complete the lead extension. Next, insert the circuit board 1 into the titanium base 6 from the cylindrical hole 10 on one side of the titanium base 6, and position the titanium base 6 on the positioning step 11. Then, inject hard glue into the lower surface of the circuit board 1 through a group of through holes 12. During this process, observe the hard glue injection amount through another group of through holes 12 to ensure that the bottom of the circuit board 1 is completely filled with glue, making the circuit board 1 and the titanium base 6 seamlessly bonded, and making the circuit board 1 fixed inside the titanium base 6. Then, one end of the hose 7 is inserted into the inside of the titanium base 6 through the cylindrical hole 10, and the hose 7 and the titanium base 6 are sealed and connected by the biocompatible glue 8, and then the lead wire 5 is inserted into the hose 7; Finally, soft glue is injected into the position where the circuit board 1 is installed on the titanium base 6 through the glue injection window 9 on the titanium base 6, at this time the surface of the temperature and pressure integrated sensor chip 3 is filled with soft glue as a whole for protection, and the thickness of the filled soft glue is controlled under the rigid cooperative positioning of the titanium base 6 and the circuit board 1, so as to fix them, and after the fixation, necessary curing process can be used to ensure the bonding strength of the glue and the titanium base 6.

[0027] Above, the temperature and pressure integrated sensor chip 3 integrated by single chip is used to replace the traditional temperature and pressure double-chip discrete packaging scheme, after the temperature and pressure integrated sensor chip 3 is assembled with the circuit board 1 by gold wire bonding technology, the circuit board 1 is inserted into the inside of the titanium base 6 together, and the positions of the two are fixed by hard glue; then, the hose 7 is fixed and inserted into the titanium base 6 by the biocompatible glue 8, so as to realize the sealing of the circuit board 1 towards one end of the hose 7; finally, the positioning is completed by the constant height of the circuit board 1 and the constant height of the titanium base 6, the glue layer with controllable thickness is injected into the titanium base 6 through the glue injection window 9, and the temperature and pressure integrated sensor chip 3 is packaged in the inside of the titanium base 6.

[0028] It should be noted that in this text, terms such as "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment.

[0029] Although the embodiments of the present application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application.

Claims

1. A gold wire bonding-based temperature and pressure integrated intracranial pressure sensor probe packaging structure, characterized in that, Include: Circuit board (1), the upper surface of the circuit board (1) is fixed with a temperature and pressure integrated sensor chip (3) through die bonding glue (2), the upper surface of the circuit board (1) is installed with gold wire (4) through gold wire bonding equipment, one end of the upper surface of the circuit board (1) is welded with lead-out wire (5); Titanium base (6), after combination, the circuit board (1) and the temperature and pressure integrated sensor chip (3) are fixed in the inside of the titanium base (6) through hard glue; Soft tube (7), the soft tube (7) is fixed and inserted into the inside of the titanium base (6) through biocompatible glue (8), one end of the lead-out wire (5) is led out through the soft tube (7); Glue injection window (9), the glue injection window (9) is opened in the outer wall of the titanium base (6), the soft glue is filled in the inside of the titanium base (6) through the glue injection window (9), and the glue thickness of the soft glue is controlled through the cooperation of the circuit board (1) and the titanium base (6).

2. The gold wire bonding based ICP sensor probe package structure of claim 1, wherein: The temperature and pressure integrated sensor chip (3) is of the type of Wheatstone full bridge.

3. The gold wire bonding based ICP sensor probe package structure of claim 1, wherein: The circuit board (1), the titanium base (6) and the soft tube (7) are configured by hard glue, soft glue and biocompatible glue (8) in stages.

4. The gold wire bonding based ICP sensor probe package structure of claim 1, wherein: The inside of the titanium base (6) is fixedly provided with a positioning step (11), and the positioning step (11) is used for positioning the setting height of the circuit board (1) in the titanium base (6).

5. The gold wire bonding based ICP sensor probe package structure of claim 4, wherein: A group of through holes (12) for hard glue injection are opened in the upper surface of the circuit board (1), and the lower surface of the circuit board (1) is fixedly connected with the positioning step (11) through hard glue.

6. The gold wire bonding based ICP sensor probe package structure of claim 1, wherein: Another group of through holes (12) for observing the filling amount of hard glue are opened in the upper surface of the circuit board (1).

7. The gold wire bonding based ICP sensor probe package structure of claim 6, wherein: One end of the titanium base (6) is provided with a cylindrical hole (10), and the circuit board (1) is installed in the inside of the titanium base (6) through the cylindrical hole (10).

8. The gold wire bonding based ICP sensor probe package structure of claim 1, wherein: One end of the soft tube (7) coated with biocompatible glue (8) is inserted into the inside of the titanium base (6) through the cylindrical hole (10), and the other end of the soft tube (7) extends to the outside of the titanium base (6). One end of the soft tube (7) coated with biocompatible glue (8) is inserted into the inside of the titanium base (6) through the cylindrical hole (10), and the other end of the soft tube (7) extends to the outside of the titanium base (6).

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