An online monitoring method and device for temperature and strain in an electronic package

Abstract

The present invention provides an on-line monitoring method and device for temperature and strain in an electronic package. In the present invention, fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors are arranged on the surface of a selected semiconductor chip, on the side surface of the selected semiconductor chip after primary encapsulation, above each measuring point, in the filling space of the epoxy molding compound, and in the space between the side surface of the semiconductor chip and the side wall of the encapsulation mold. The fiber Bragg grating is used to monitor the real-time changes of temperature and strain during the electronic packaging process and / or the service process. It is possible to monitor the temperature and strain of the semiconductor chip, the epoxy molding compound, and the interface between the two in multiple points, simultaneously, in-situ, and in real-time on-line, improving the test accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic packaging testing, and relates to an on-line monitoring method and device for the temperature and strain in an electronic package body. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention, and do not necessarily constitute prior art.

[0003] With the progress of electronic technology and the rapid development of modern information technology, the functions of electronic systems are continuously enhanced, the installation and wiring density of components are getting higher and higher, and the requirements for the reliability of electronic packaging are getting higher and higher. However, the contradictions among the area, yield, complex process and cost of electronic systems are difficult to reconcile. To solve these problems, 2.5D / 3D packaging is imperative. 2.5D / 3D packaging is to arrange or stack multiple chips in the in-plane / vertical direction of the package body, change a large chip that originally needed to be fabricated in one go into several small-area chips, and then assemble these small-area chips into a package body through advanced packaging processes, so as to achieve the functions and performances of the original single large chip. However, while the advanced packaging technology brings advantages such as shortening interconnections, improving performance, and reducing power consumption, its complex production process and heterogeneous packaging structure also pose more challenges to the reliability of the package body during the manufacturing and service processes, such as thermo-mechanical reliability problems. A common problem is that the increase in the number of layers will lead to too high a temperature inside the package, inducing thermal stress problems. Therefore, the on-line detection of advanced packaging structures becomes increasingly important.

[0004] The plastic packaging process is generally divided into two parts: the process steps before plastic packaging (sealing) are called front-end operations, and the process steps of plastic packaging are called back-end operations. Most of the current electronic packaging materials used are epoxy molding compounds (EMC), which have balanced physical properties and many advantages, such as: high adhesion, low shrinkage, and high electrical insulation. However, during the packaging process, the coefficient of thermal expansion (CTE) between the epoxy molding compound and the semiconductor chip does not match. During the rapid cooling stage after the chemical reaction of the epoxy molding compound is basically completed, the EMC undergoes a greater cold shrinkage than the semiconductor chip. At this time, the interfacial stress between the EMC / semiconductor chip increases sharply, causing the semiconductor chip to be subjected to compressive stress in the in-plane direction, the EMC to be subjected to tensile stress in the in-plane direction and it is difficult to relax.

[0005] There are generally two forms of 3D packaging structures: one form is that the EMC around the semiconductor chip is thicker and the EMC on the top is thinner; the other form is that the semiconductor chip on the top is not covered with EMC, and the top of the semiconductor chip is exposed, in order to enhance heat dissipation. In the case where the EMC around the semiconductor chip is thicker and the EMC on the top is thinner or even non-existent, the thin semiconductor chip itself is prone to deformation or even instability and buckling due to in-plane pressure, which may cause interlayer shear damage and tensile damage to the functional materials in the semiconductor chip, tensile damage and compression damage caused by microbending in the brittle functional material layer, and in-plane shear damage or normal peeling damage at the semiconductor chip / substrate / solder point interface. If the magnitude of this part of the stress cannot be reliably controlled, it will affect the performance and reliability of the semiconductor chip, causing solder joint fatigue fracture, chip warping, interface cracking, etc., leading to chip failure. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes an online monitoring method and device for temperature and strain in an electronic package. The present invention uses fiber Bragg grating (FBG) to monitor the real-time changes of temperature and strain during the electronic packaging process and / or service process.

[0007] According to some embodiments, the present invention adopts the following technical solutions:

[0008] An online monitoring method for temperature and strain in an electronic package, comprising:

[0009] A fiber Bragg grating strain sensor and a fiber Bragg grating temperature sensor are fixed in parallel on the surface of a selected semiconductor chip, with a certain distance between the two sensors, to determine whether the surface of the semiconductor chip is damaged;

[0010] A fiber Bragg grating strain sensor and a fiber Bragg grating temperature sensor are fixed on the side surface of the selected semiconductor chip after the primary plastic packaging to determine whether the side surface of the semiconductor chip is damaged;

[0011] According to the design requirements of electronic packaging, a packaging substrate, a semiconductor chip without a fiber Bragg grating fixed thereto, and a semiconductor chip with a fiber Bragg grating fixed thereto are placed and fixed in a packaging mold cavity;

[0012] Above each measuring point of the semiconductor chip with a fiber Bragg grating sensor fixed on its surface, multiple groups of fiber Bragg grating sensors are arranged in the filling space of the epoxy molding compound. Each group includes a strain sensor and a temperature sensor. The temperature and strain measured at each measuring point of the semiconductor chip with a fiber Bragg grating sensor fixed on its surface are quantitatively compared, and the nominal average shear strain and temperature gradient between the upper and lower adjacent measuring points of these measuring points are calculated.

[0013] Fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors are arranged in the space between the side surface of the semiconductor chip and the side wall of the encapsulation mold. The strain and temperature of the epoxy molding compound in the space between the side surface of the semiconductor chip and the side wall of the encapsulation mold are measured. The strain and temperature of the epoxy molding compound in the same direction as the fiber grating on the measuring point of the side surface of the semiconductor chip are quantitatively compared, as well as the strain and temperature monitored at the measuring point of the side surface of the semiconductor chip. The nominal average shear strain and temperature gradient between the left and right adjacent measuring points of these measuring points are calculated.

[0014] As an alternative implementation, the grating regions of the fiber Bragg grating strain sensors and the fiber Bragg grating temperature sensors undergo a thinning process; the diameter of the grating region after the thinning process is 125μm - 10μm, preferably 35μm - 15μm; the thinning process includes, but is not limited to, hydrofluoric acid etching, preferably etching with 40wt% hydrofluoric acid.

[0015] The grating region length of the fiber Bragg grating strain sensors and the fiber Bragg grating temperature sensors is less than 5mm; the preferred grating region length is 2 - 4mm; the more preferred grating region length is 3mm.

[0016] As an alternative implementation, the specific process for determining whether damage occurs on the surface of the semiconductor chip includes: by detecting the strain along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located, calculating the tensile / compressive stress along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located according to the elastic modulus and Poisson's ratio of the semiconductor chip material.

[0017] If the tensile / compressive stress along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located reaches the tensile / compressive strength of the semiconductor chip material at that location, it indicates that mechanical damage has occurred on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located.

[0018] As an alternative implementation, the strain along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located is directly obtained through the compensation of the temperature sensor on the assumption that the thermal expansion coefficients of the materials used for the semiconductor chip and the fiber where the measuring point of the fiber grating sensor is located are the same.

[0019] When it is necessary to study the influence caused by the different coefficients of thermal expansion of the materials used for the optical fiber and the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located, the mechanical equilibrium formula is adopted and corrected based on the meso-elastic mechanics to improve the accuracy of the strain data along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located.

[0020] As an alternative implementation, the specific process of determining whether the side surface of the semiconductor chip is damaged includes: by detecting the strain along the grating axis on the side surface of the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located, calculating the tensile / compressive stress along the grating axis on the side surface of the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located according to the elastic modulus and Poisson's ratio of the semiconductor chip material;

[0021] If the tensile / compressive stress along the grating axis on the side surface of the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located reaches the tensile / compressive strength of the semiconductor chip material at that place, it indicates that the side surface of the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located has mechanical damage.

[0022] As an alternative implementation, the strain along the grating axis on the side surface of the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located is directly obtained through the compensation of the temperature sensor on the assumption that the coefficients of thermal expansion of the materials used for the semiconductor chip and the optical fiber where the measuring point of the fiber Bragg grating sensor is located are the same;

[0023] When it is necessary to study the influence caused by the different coefficients of thermal expansion of the materials used for the optical fiber and the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located, the mechanical equilibrium formula is adopted and corrected based on the meso-elastic mechanics to improve the accuracy of the strain data along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber Bragg grating sensor is located.

[0024] As an alternative implementation, the surface of the semiconductor chip includes the upper surface or / and the lower surface.

[0025] As an alternative implementation, the fiber Bragg grating temperature sensor needs to be encapsulated to be insensitive to environmental stress before being implanted into the electronic package;

[0026] The process of encapsulating to be insensitive to environmental stress is: select the length, outer diameter and inner diameter of a high-rigidity capillary suitable for the length of the grating area, place the grating area of the fiber Bragg grating sensor in the middle position of the high-rigidity capillary, and seal both ends of the capillary.

[0027] As an alternative implementation, multiple groups of the fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors are arranged as needed on the surface of the same semiconductor chip at different angles.

[0028] As an alternative embodiment, the distance between the fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor is 1 mm - 5 mm; when arranging the sensors on the surface of the selected semiconductor chip, the fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are closely attached to the surface of the semiconductor chip to avoid transmission losses of temperature and strain.

[0029] When arranging the sensors on the side surface of the selected semiconductor chip, the fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are closely attached to the side surface of the semiconductor chip to avoid transmission losses of temperature and strain.

[0030] As an alternative embodiment, the distances between each group of fiber Bragg grating sensors arranged in the filling space of the epoxy molding compound and the surface of the semiconductor chip are different, and the distances are determined according to the height of the filling space of the epoxy molding compound, the number of groups of fiber Bragg grating sensors, and the position of the detection area of key concern; and the distances left between the fiber Bragg grating temperature sensor and the fiber Bragg grating strain sensor in each group are the same as the corresponding distances of the other groups.

[0031] Preferably, the distance is the same as the distance between the fiber Bragg grating temperature sensor and the fiber Bragg grating strain sensor fixed to the surface of the semiconductor chip.

[0032] As an alternative embodiment, an optical fiber in a channel in the mold wall located between the top mold and the bottom mold of the encapsulation mold is used to connect the optical fiber in the mold cavity to the optical fiber grating demodulator outside the mold cavity; after the optical fiber is arranged, fixed, and connected, the channel of the optical fiber in the mold wall is filled with a sealant.

[0033] As an alternative embodiment, in the space between the semiconductor chip and the top wall of the mold, an optical fiber positioning support bonded to the top wall of the mold is used to position the optical fiber, thereby realizing the positioning of the grating grating area.

[0034] As an alternative embodiment, in the space between the semiconductor chip and the side wall of the mold, an optical fiber positioning support bonded to the side wall of the mold is used to position the optical fiber, thereby realizing the positioning of the grating grating area.

[0035] As an alternative embodiment, the juxtaposed fiber Bragg grating strain sensor and fiber Bragg grating temperature sensor fixed on the surface of the selected semiconductor chip are bonded and fixed with a polymer adhesive; the preferred polymer adhesive is epoxy adhesive; the further preferred polymer adhesive is room temperature curing epoxy adhesive.

[0036] As an alternative embodiment, the fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are fixedly bonded to the side surface of the selected semiconductor chip after the first encapsulation using a polymer adhesive; the preferred polymer adhesive is epoxy adhesive; the further preferred polymer adhesive is room temperature curing epoxy adhesive.

[0037] The semiconductor chip includes but is not limited to a bare semiconductor chip, a semiconductor chip encapsulated with epoxy molding compound for the first time, a semiconductor chip module encapsulated with epoxy molding compound, a chip substrate, and a chip connector.

[0038] An on-line monitoring device for temperature and strain in an electronic package body includes multiple groups of fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors arranged side by side, wherein several groups of fiber Bragg grating sensors are arranged on the surface of the selected semiconductor chip, several groups of fiber Bragg grating sensors are arranged on the side surface of the selected semiconductor chip after the first encapsulation, and several groups of fiber Bragg grating sensors are arranged in the epoxy molding compound between the corresponding positions of each sensor measurement point on the semiconductor chip and the wall of the encapsulation mold;

[0039] The fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are connected to a fiber grating demodulation system.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] (1) The present invention can monitor the temperature and strain of the semiconductor chip, the epoxy molding compound, and the interface between the two at multiple points, simultaneously, in-situ, and in real-time online, improving the test accuracy.

[0042] (2) The present invention can quantitatively compare the temperature and strain at multiple spatial positions, and calculate the nominal shear strain and temperature gradient between each adjacent measurement point of those comparable measurement points.

[0043] (3) The present invention performs high-precision online monitoring of the encapsulation process of the electronic package body by selecting gratings with short grating regions and gratings with reduced diameter.

[0044] (4) The present invention can continue to perform high-precision online monitoring during the service process after the encapsulation of the electronic package body, obtain the temperature and strain data of the epoxy molding compound and the semiconductor chip during the thermal-oxidative aging process, and further predict the life of the electronic package body under thermal-oxidative aging conditions. It can also be used for online monitoring of overheating, overload, impact, and drop problems during the service process. Description of the Drawings

[0045] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0046] Figure 1 This is a schematic diagram of the mold device for encapsulating semiconductor chips with EMC and the layout of FBG sensors in the embodiments of the present invention;

[0047] Figure 2 This is a schematic diagram of a layout method of FBG temperature sensors and strain sensors in Embodiment 1 of the present invention;

[0048] Figure 3 This is a schematic diagram of an FBG sensing system;

[0049] Figure 4 This is the temperature test result of Embodiment 1 of the present invention;

[0050] Figure 5 This is the strain test result of Embodiment 1 of the present invention;

[0051] Figure 6 This is a schematic diagram of a layout method for pasting and fixing FBG sensors on a semiconductor chip in the embodiments of the present invention;

[0052] Wherein: 1 - top mold; 2 - bottom mold; 3 - epoxy molding compound; 4 - processor chip; 5 - memory chip; 6 - optical fiber; 7 - optical fiber positioning support; 8 - grating grid area (for detecting the horizontal strain and temperature of EMC between the chip and the mold side wall); 9 - grating grid area (for detecting the strain and temperature on the chip surface); 10 - grating grid area (for detecting the horizontal strain and temperature of EMC between the chip and the mold top wall); 11 - grating grid area (for detecting the vertical strain and temperature of EMC between the chip and the mold side wall); 12 - sealant for the channel of the optical fiber in the mold wall; 13 - slider of the mold; 14 - broadband light source; 15 - optical fiber coupler; 16 - grating grid area of FBG; 17 - wavelength demodulation system; 18 - user interface and computing processing system; 19 - FBG1S; 20 - FBG1T; 21 - FBG2T; 22 - FBG2S; 23 - FBG strain sensor laid in the 0° direction; 24 - FBG temperature sensor laid in the 0° direction; 25 - FBG temperature sensor laid in the -45° direction; 26 - FBG strain sensor laid in the -45° direction; 27 - FBG strain sensor laid in the 90° direction; 28 - FBG temperature sensor laid in the 90° direction. Detailed implementation manners

[0053] The present invention will be further described below in conjunction with the drawings and embodiments.

[0054] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0055] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0056] Example 1

[0057] During the EMC curing shrinkage in the electronic packaging process, it is an important reason for excessive internal stress in the electronic package, poor chip performance and reliability. Based on this, this example provides an online real-time monitoring method and device for temperature and strain during the curing process of epoxy molding compound in a chip packaging process. Through the monitored data, the process parameters can be improved, the process flow can be optimized, and various reliability problems caused by thermal overload or force overload can be alleviated. This embodiment is divided into two parts: the fabrication and embedding of FBG sensors and the monitoring of the packaging process.

[0058] (1) Fabrication and embedding of FBG sensors: In this embodiment, it is necessary to monitor the temperature and strain on the upper surface of the uppermost semiconductor chip, and the strain and temperature of the EMC between the semiconductor chip and the mold wall. Select the commonly used FBG with a fiber diameter of 250 μm, a grating region diameter (after removing the surface polyimide protective layer) of 125 μm, and a grating region length of 3 mm. It can be used in the range of -200 to 2350 °C, and its accuracy and operating conditions are sufficient to support the molding of EMC at 175 °C for 120 s during the electronic packaging process in this embodiment. The outer diameter of the stainless steel capillary for the temperature-measuring fiber grating is 0.2 mm, and the inner diameter is 0.3 mm. The two ends of the stainless steel capillary are sealed with glue and placed at room temperature for 24 hours for later use. The molding process selected in this embodiment is the transfer molding process; as Figure 1 shown, a set of FBG sensors (each set of FBG sensors includes a temperature sensor marked as T and a strain sensor marked as S, and the two are 2 mm apart) are adhesively fixed at positions 5 mm from the left end and 5 mm from the right end of the upper surface of the uppermost semiconductor chip, respectively, so as to realize the positioning of the grating region 9; among them, as Figure 2As shown in the figure, the sensor located 5 mm to the left end of the upper surface of the uppermost semiconductor chip is marked as FBG1, and the sensor located 5 mm to the right end of the upper surface of the uppermost semiconductor chip is marked as FBG2. In the space between the uppermost semiconductor chip and the top wall of the mold, fiber Bragg grating strain sensors and temperature sensors are arranged along the horizontal direction, and the optical fibers are positioned by the optical fiber positioning supports adhered to the top wall of the mold, thereby realizing the positioning of the grating grid area 10. In the space between the semiconductor chip and the right side wall of the mold, fiber Bragg grating strain sensors and temperature sensors are arranged along the horizontal direction, and the optical fibers are positioned by the optical fiber positioning supports adhered to the right side wall of the mold, thereby realizing the positioning of the grating grid area 8. In the space between the semiconductor chip and the left side wall of the mold, fiber Bragg grating strain sensors and temperature sensors are arranged along the vertical direction, and the optical fibers are positioned by the optical fiber positioning supports adhered to the left side wall of the mold, thereby realizing the positioning of the grating grid area 11. The FBG sensors are connected to the fiber Bragg grating demodulator through the channels of the optical fibers in the mold wall between the top mold 1 and the bottom mold 2, and after the optical fibers are connected, the channels are filled with sealant 12.

[0059] (2) Process monitoring: After the FBG temperature sensors and strain sensors are laid, connect the fiber Bragg grating demodulator, as Figure 3 shown; after the mold is evacuated, the epoxy molding compound at 175 °C is injected into the mold cavity under pressure by the transfer molding process, and the electronic package is kept at a constant temperature and pressure for 120 s; the fiber Bragg grating demodulator converts the changes in the optical signals of temperature and strain monitored by the fiber Bragg grating sensors into digital signals, and realizes on-line monitoring and records the test results through the analysis software of the computer; Figure 3 The results measured by the FBG1T and FBG2T fiber Bragg grating temperature sensors shown in Figure 4 are as shown in Figure 5 shown, and the results measured by the FBG1S and FBG2S fiber Bragg grating strain sensors are as shown in

[0060] Example Two

[0061] In this example, in order to monitor the temperature and strain of the semiconductor chip as accurately as possible, FBG sensors with a grating area length of 2 mm and a grating area diameter of 30 μm are selected to monitor the semiconductor chip. In this example, the processed FBG strain sensors and FBG temperature sensors are pasted on the upper surface of the uppermost semiconductor chip with epoxy resin glue, and a distance of 2 mm is left between them; 3 groups of FBG sensors (each group includes an FBG strain sensor and an FBG temperature sensor) are laid on the upper surface of the semiconductor chip along the 0°, -45°, and 90° directions respectively. The specific laying positions are as Figure 6 shown, and the rest of the content is the same as the corresponding content of Example One.

[0062] It should be noted that for different embodiments, the selected chips may not be the same. In the same package, there may be semiconductor chips that have not undergone primary encapsulation, or there may be semiconductor chips that have undergone primary encapsulation. FBG strain sensors and FBG temperature sensors can be installed only on the selected semiconductor chips.

[0063] Similarly, even if primary encapsulation has occurred, sensors may not necessarily be installed on the side. The chips to be measured for installing FBG strain sensors and FBG temperature sensors can be comprehensively selected based on considerations such as cost, signal processing difficulty, and hardware implementation difficulty.

[0064] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0065] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0066] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that realizes the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0067] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide means for realizing the functions in the flow Figure 1Steps of the functions specified in one or more processes and / or boxes Figure 1 Steps of the functions specified in one or more boxes

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0069] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, they are not limitations on the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. An on-line monitoring method for temperature and strain in an electronic package, characterized in that, Including: Fixing parallel fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors on the surface of a selected semiconductor chip, with a certain distance between the two sensors, for judging whether damage occurs on the surface of the semiconductor chip; Fixing fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors on the side surface of a selected semiconductor chip after primary encapsulation, for judging whether damage occurs on the side surface of the semiconductor chip; Placing and fixing a packaging substrate, a semiconductor chip without fixed fiber Bragg gratings, and a semiconductor chip with fixed fiber Bragg gratings in a packaging cavity according to the design requirements of electronic packaging; Above each measuring point of the semiconductor chip with fiber Bragg grating sensors fixed on its surface, arranging multiple groups of fiber Bragg grating sensors in the filling space of the epoxy molding compound. Each group includes a strain sensor and a temperature sensor, and making a quantitative comparison with the temperature and strain measured at each measuring point of the semiconductor chip with fiber Bragg grating sensors fixed on its surface, and calculating the nominal average shear strain and temperature gradient between the upper and lower adjacent measuring points of each measuring point of the semiconductor chip with fiber Bragg grating sensors fixed on its surface; Arranging fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors in the space between the side surface of the semiconductor chip and the side wall of the packaging mold, measuring the strain and temperature of the epoxy molding compound in the space between the side surface of the semiconductor chip and the side wall of the packaging mold, making a quantitative comparison of the strain and temperature of the epoxy molding compound in the same direction as the fiber grating at the measuring points on the side surface of the semiconductor chip, and the strain and temperature monitored at the measuring points on the side surface of the semiconductor chip, and calculating the nominal average shear strain and temperature gradient between the left and right adjacent measuring points of the measuring points on the side surface of the semiconductor chip; 2. The on-line monitoring method for temperature and strain in an electronic package according to claim 1, characterized in that, The grating regions of the fiber Bragg grating strain sensors and the fiber Bragg grating temperature sensors undergo a thinning process; The diameter of the grating region after the thinning process is 125μm - 10μm; Or further, it is 35μm - 15μm; The thinning process method is etching with hydrofluoric acid; Or further, etching with 40wt% hydrofluoric acid; 3. The on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, The grating region length of the fiber Bragg grating strain sensors and the fiber Bragg grating temperature sensors is less than 5mm; Or further, the grating region length is 2 - 4mm; Or further, the grating region length is 3mm; 4. The on-line monitoring method for temperature and strain in an electronic package as claimed in claim 1, characterized in that, The specific process of judging whether damage occurs on the surface of the semiconductor chip includes: detecting the strain along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located, and calculating the tensile / compressive stress along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located according to the elastic modulus and Poisson's ratio of the semiconductor chip material; If the tensile / compressive stress along the grating axis on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located reaches the tensile / compressive strength of the semiconductor chip material at the measuring point of the fiber grating sensor, it indicates that mechanical damage occurs on the surface of the semiconductor chip where the measuring point of the fiber grating sensor is located.

5. The on-line monitoring method for temperature and strain in an electronic package according to claim 4, characterized in that, The strain along the grating axis on the surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located is directly obtained through the compensation of the temperature sensor on the assumption that the thermal expansion coefficients of the materials used for the semiconductor chip where the fiber Bragg grating sensor measurement point is located and the fiber are the same. When it is necessary to study the influence caused by different thermal expansion coefficients of the material used for the fiber and the material used for the semiconductor chip where the fiber Bragg grating sensor measurement point is located, the mechanical equilibrium formula is adopted and corrected based on meso-elastomechanics to improve the accuracy of the strain data of the surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located along the grating axis.

6. The on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, The specific process of judging whether the side surface of the semiconductor chip is damaged includes: by detecting the strain along the grating axis on the side surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located, calculating the tensile / compressive stress along the grating axis on the side surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located according to the elastic modulus and Poisson's ratio of the semiconductor chip material. If the tensile / compressive stress along the grating axis on the side surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located reaches the tensile / compressive strength of the semiconductor chip material at the fiber Bragg grating sensor measurement point, it indicates that the side surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located has mechanical damage.

7. The on-line monitoring method for temperature and strain in an electronic package as described in claim 6, characterized in that, The strain along the grating axis on the side surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located is directly obtained through the compensation of the temperature sensor on the assumption that the thermal expansion coefficients of the materials used for the semiconductor chip where the fiber Bragg grating sensor measurement point is located and the fiber are the same. When it is necessary to study the influence caused by different thermal expansion coefficients of the material used for the fiber and the material used for the semiconductor chip where the fiber Bragg grating sensor measurement point is located, the mechanical equilibrium formula is adopted and corrected based on meso-elastomechanics to improve the accuracy of the strain data of the side surface of the semiconductor chip where the fiber Bragg grating sensor measurement point is located along the grating axis.

8. The on-line monitoring method for temperature and strain in an electronic package as claimed in claim 1, characterized in that, The fiber Bragg grating temperature sensor needs to be packaged with environmental stress insensitivity before being implanted into the electronic package. The process of the environmental stress insensitive packaging is: select the length, outer diameter and inner diameter of a high-rigidity capillary suitable for the grating zone length, place the grating zone of the fiber Bragg grating sensor in the middle position of the high-rigidity capillary, and seal both ends of the capillary.

9. The on-line monitoring method for temperature and strain in an electronic package as claimed in claim 1, characterized in that, The fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors are in multiple groups and are arranged as needed on the surface of the same semiconductor chip at different angles.

10. The on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, The distance between the fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor is 1 mm - 5 mm; when arranging the sensors on the selected semiconductor chip surface, the fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are closely attached to the semiconductor chip surface to avoid the transmission loss of temperature and strain. When arranging the sensors on the selected side surface of the semiconductor chip, the fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are closely attached to the side surface of the semiconductor chip to avoid the transmission loss of temperature and strain.

11. The on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, in The distance between each group of fiber Bragg grating sensors arranged in the filling space of the epoxy molding compound and the surface of the semiconductor chip is different, and the distance is determined according to the height of the filling space of the epoxy molding compound, the number of groups of fiber Bragg grating sensors, and the position of the detection area of key concern; and the distance between the fiber Bragg grating temperature sensor and the fiber Bragg grating strain sensor in each group is the same as the corresponding distance of the other groups; Or further, the distance is the same as the distance between the fiber Bragg grating temperature sensor and the fiber Bragg grating strain sensor fixed on the surface of the semiconductor chip.

12. The on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, An optical fiber in the channel of the mold wall located between the top mold and the bottom mold of the encapsulation mold is used to connect the optical fiber in the mold cavity to the optical fiber grating demodulator outside the mold cavity; after the optical fiber is arranged, fixed and connected, the channel of the optical fiber in the mold wall is filled with sealant.

13. The on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, In the space between the semiconductor chip and the top wall of the mold, the optical fiber is positioned by an optical fiber positioning support bonded to the top wall of the mold, so as to realize the positioning of the grating grating area; In the space between the semiconductor chip and the side wall of the mold, the optical fiber is positioned by an optical fiber positioning support bonded to the side wall of the mold, so as to realize the positioning of the grating grating area.

14. An on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, The fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are bonded and fixed with polymer glue; Or further, the polymer glue is epoxy glue; Or further, the polymer glue is room temperature curing epoxy glue.

15. An on-line monitoring device for temperature and strain in an electronic package applying the on-line monitoring method for temperature and strain in an electronic package as described in claim 1, characterized in that, It includes multiple groups of fiber Bragg grating strain sensors and fiber Bragg grating temperature sensors arranged side by side, among which several groups of fiber Bragg grating sensors are arranged on the selected surface of the semiconductor chip, several groups of fiber Bragg grating sensors are arranged on the side surface of the semiconductor chip after the first plastic encapsulation, and several groups of fiber Bragg grating sensors are arranged in the epoxy molding compound between the corresponding positions of each sensor measurement point on the semiconductor chip and the encapsulation mold wall; The fiber Bragg grating strain sensor and the fiber Bragg grating temperature sensor are connected to the fiber grating demodulation system.

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