Chip package core extraction needle holding device and method

Abstract

The application relates to the field of semiconductor plastic packaging, in particular to a chip packaging core-pulling needle pressing device and method. The pressing device is arranged on a core-pulling press of a semiconductor plastic packaging mold. The pressing device comprises an upper mold base, a driving plate and core-pulling rods. The core-pulling rods are distributed below the driving plate, the upper ends of the core-pulling rods are connected with the lower side of the driving plate, and the lower ends of the core-pulling rods are connected with a core-pulling plate provided with core-pulling needles, so that the core-pulling plate moves with the up-down movement of the driving plate to make the core-pulling needles abut against or separate from a chip substrate or a base island. Each core-pulling rod is connected with the core-pulling plate through an elastic connection group, so that the core-pulling plate can elastically move in the axial direction of the core-pulling rod and / or elastically tilt relative to the plane where the driving plate is located. The elastic floating of the core-pulling plate realizes passive balanced pressure, can cope with different mold flatness and small tolerance differences, solves the problem of uneven pressing of the core-pulling needle, and reduces the problems of substrate warping, cracking or packaging failure caused by uneven pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor plastic packaging, in particular to a chip packaging core extraction needle holding device and method. BACKGROUND

[0002] The core extraction press is an extended function of the basic plastic packaging press. The function of the plastic packaging press is to encapsulate the fixed chip frame with heated resin during the chip packaging process. In some specific chip products, the internal ceramic substrate of the chip will displace during the injection molding process, resulting in product high voltage breakdown (short circuit) or ceramic back overflow.

[0003] The function of the core extraction needle is to drive the fixed core extraction needle in the mold using the upper core extraction mechanism during injection molding. The position of the substrate is fixed before injection molding to ensure that the back of the ceramic sheet can be attached to the surface of the cavity, and the position of the base island is in the center of the plastic package. After injection molding, the mechanism drives the core extraction needle to separate, and the mold continues to complete the curing process of the plastic package.

[0004] However, during the chip packaging process, the core extraction needle needs to apply pressure to the chip substrate accurately. If the core extraction plate is not flat or the pressure distribution is uneven, it may cause the chip substrate to warp, break or package poorly. In addition, according to different chip products, the corresponding mold tolerances and deformations are also diverse. The traditional core extraction plate may not be able to adapt to the small tolerance changes of the mold. In order to meet the requirement of lower scrap rate, a higher yield chip packaging core extraction needle holding structure or equipment is needed. SUMMARY

[0005] In view of the above technical problems, the present application provides a chip packaging core extraction needle holding device and method. By using the elastic floating of the core extraction plate, the passive pressure balancing mode is achieved, so that the core extraction plate can cope with the uneven pressure holding problem of the core extraction needle caused by the small and difficult to detect differences of different mold flatness tolerances, thereby reducing the substrate warping, breaking or packaging poor conditions caused by uneven core extraction needle holding.

[0006] The chip packaging core pulling needle pressing device is arranged on a core pulling press of a semiconductor plastic packaging mold, and an upper mold assembly and a lower mold assembly of the core pulling press realize clamping and opening actions under the driving of a core pulling power device controlled by a central control unit.

[0007] The chip packaging core pulling needle pressing device is arranged on a core pulling press of a semiconductor plastic packaging mold, and an upper mold assembly and a lower mold assembly of the core pulling press realize clamping and opening actions under the driving of a core pulling power device controlled by a central control unit.

[0008] In some possible embodiments, the elastic connection group comprises a connecting seat, a connecting rod and a first spring. One side of the connecting seat is detachably connected with the core pulling plate. The connecting rod is movably arranged on the connecting seat, and the upper end of the connecting rod is detachably connected with the lower end of the core pulling rod. The relative position of the connecting rod and the core pulling rod in the axial direction is adjustable. The first spring is sleeved on the connecting rod and distributed on the upper and lower sides of the connecting seat, so that the connecting seat can extrude the first spring when moving up and down.

[0009] The present application realizes elastic connection between the core pulling plate and the core pulling rod by combining the connecting seat, the connecting rod and the first spring, and provides more flexible and accurate pressure adjustment. The connecting seat and the core pulling plate are detachably connected, allowing adjustment or replacement, and the connecting rod and the core pulling rod are detachably connected, enhancing the maintainability of the device. The elastic reaction force of the first spring controls the floating range of the core pulling plate, avoiding uneven pressure caused by excessive floating or deformation, thereby ensuring that the chip substrate is subjected to uniform and adjustable pressure. Compared with the traditional rigid core pulling plate, the present application can adapt to the slight deformation of the chip substrate and the mold, flexibly adjust the pressure distribution, improve the packaging precision and stability, increase the yield, and avoid the instability problem caused by mechanical rigidity control in the traditional scheme.

[0010] In some feasible embodiments, at least four core pulling rods are distributed at the four corners of the core pulling plate; wherein two sides of the core pulling plate are each provided with one connecting seat; two connecting rods are arranged on one connecting seat to enable the two sides of the core pulling plate to perform coordinated elastic swinging action; or two connecting seats are arranged on each side of the core pulling plate; one connecting rod is arranged on each connecting seat to enable the four corners of the core pulling plate to perform coordinated elastic swinging action.

[0011] The present application distributes at least four core pulling rods at the four corners of the core pulling plate, and realizes coordinated elastic swinging through the connecting seat and the connecting rod, thereby optimizing the pressure distribution and self-adaptive adjustment. This design avoids the problem of local uneven pressure caused by single-point pressure or single-direction elasticity, and ensures that the four corners of the core pulling plate are adjusted in coordination through multiple connecting seats and connecting rods, so that the core pulling needle can apply pressure more flexibly and uniformly, and adapt to the unevenness of the chip substrate.

[0012] In some feasible embodiments, the driving plate is movably connected with the upper end of each core pulling rod in the axial direction of the core pulling rod, and an online pressure adjustment unit is arranged at the movable connection position; the online pressure adjustment unit comprises a cover plate, an upper sliding sleeve and a fine adjustment unit; the cover plate is detachably fixed to the upper end opening of the through slot formed in the driving plate; the upper end of the upper sliding sleeve is connected with the cover plate, and the upper sliding sleeve is arranged in the through slot; the fine adjustment unit is arranged in the upper sliding sleeve and located between the core pulling rod and the cover plate, and is used for adjusting the distance between the core pulling rod and the cover plate online; the fine adjustment unit is a gas spring or a gas cylinder; a pressure sensor is further arranged between the fine adjustment unit and the cover plate, or between the fine adjustment unit and the upper end of the core pulling rod; the pressure sensor is used for obtaining pressure information generated by the pressure sensor due to the deformation or displacement of the core pulling plate in the axial direction of the core pulling rod; and the fine adjustment unit is used for controlling the distance between the core pulling rod and the driving plate according to the pressure information obtained by the pressure sensor.

[0013] The gas spring or the air cylinder is arranged at the upper end of the core pulling rod, so that the fine adjustment unit directly acts on the driving end of the core pulling rod, the axial displacement of the core pulling rod can be adjusted in real time, the pressing force of the core pulling needle on the substrate can be better controlled, the uniformity of the pressure distribution is realized, and the installation and disassembly are more convenient. Moreover, the temperature of the chip packaging process is high, vibration and dynamic load exist, the gas spring or the air cylinder is directly arranged at the end of the core pulling rod, the pressure change can be quickly responded, external disturbance can be buffered, and the influence of temperature change on the gas in the gas spring or the air cylinder is reduced. Here, the gas spring / air cylinder is adopted, which has a short stroke, high responsiveness, can provide fine adjustment in a limited space, and is easy to form a closed loop control with the sensor.

[0014] The fine adjustment unit (such as a gas spring or an air cylinder) is arranged in the upper sliding sleeve, the distance between the core pulling rod and the cover plate is accurately adjusted according to the pressure requirement, dynamic pressure control is realized, and uniformity is ensured. The gas spring has a short stroke, is suitable for fine adjustment, and realizes accurate adjustment through a proportional valve and an electromagnetic valve. A pressure sensor monitors in real time.

[0015] In some possible embodiments, the core pulling plate is provided with a plurality of core pulling needles, and at least part of the core pulling needles are adjustable core pulling needles with adjustable pressing function; the adjustable core pulling needle comprises a base, a needle rod and an elastic adjustment unit; the base is arranged on the core pulling plate; the needle rod is movably arranged on the base and can slide along the axis relative to the base; and the elastic adjustment unit is arranged between the base and the needle rod and used for adjusting and controlling the pressing force of the needle rod and / or the distance from the end of the needle rod to the base.

[0016] After the floating core pulling plate is arranged, although the risk of uneven pressure can be alleviated, the passive adjustment characteristic cannot accurately adjust the pressure in the key area. Therefore, the adjustable core pulling needle is designed, the elastic adjustment unit is arranged in the core pulling needle, the core pulling needle can automatically adapt to the slight unevenness of the substrate, the uniform distribution of the pressure is ensured, and local overpressure or insufficient pressure is avoided. Different from the traditional rigid core pulling needle, the design can automatically adjust the pressure when the shape of the substrate changes through the passive adjustment mechanism, the operation complexity is reduced, and the adaptability of the device and the packaging quality are improved.

[0017] In some possible embodiments, the elastic adjustment unit comprises a spring barrel and a second spring; the upper end of the spring barrel is threadedly connected with a downwardly extending screw rod of the base, the screw rod can partially extend into the spring barrel, the lower end of the spring barrel is slidably connected with the outer circle of the needle rod, the upper segment of the needle rod extends into the spring barrel and is sleeved with and slidably connected with the screw rod; and the second spring is sleeved on the upper segment of the needle rod, the upper end of the second spring is connected with the lower end of the screw rod, and the lower end of the second spring is connected with the upper side of the bottom plate of the spring barrel, so that the second spring can be squeezed when the screw rod is rotated.

[0018] The present application realizes the pre-tightening force adjustment of the pressure by designing the combination of the spring barrel and the second spring in the elastic adjusting unit of the core pulling needle, and the screw rod is matched with the thread of the spring barrel, the rotation of the screw rod can adjust the pressure holding force of the needle rod or the distance between the needle rod and the base, so as to realize the control of the pressure of the adjustable core pulling needle. The cooperation design of the screw rod and the spring barrel in the structure makes the adjustment process simple and easy to operate, and the fine pressure control can be realized by rotating the screw rod, and the operability of the partial core pulling needle pressure of the core pulling plate in the plate surface is improved.

[0019] In this way, through the synergistic effect of the elastic floating core pulling plate, the adjustable core pulling needle and the active adjustment of the core pulling rod pressure, a highly adaptive and precisely controllable packaging pressure adjustment mechanism is formed. The elastic floating core pulling plate provides overall pressure distribution balance, which can automatically adjust according to the slight deformation of the chip substrate and the mold tolerance, and ensures that the substrate remains stable during packaging; at the same time, the partial adjustable core pulling needle can finely adjust the pressure of the adjustable core pulling needle in the key area through the built-in elastic adjusting unit, and locally compensates for the key area, avoiding the problem of uneven pressure caused by local unevenness or deformation after setting the floating core pulling plate. At the same time, the pressure of the active adjustment core pulling rod is adjusted to ensure that each link in the entire packaging process can be completed under the control of the multi-point adjustable pressure. The synergistic effect of the three makes the entire system adaptively adjust under different molds, chip substrates and packaging conditions, realizes the uniform distribution of pressure, improves the packaging quality and increases the yield, and effectively overcomes the packaging problems caused by the inability of the rigid structure to adapt to deformation in the traditional scheme.

[0020] In another aspect, the present application provides a chip packaging core pulling needle holding method using the chip packaging core pulling needle holding device described above, which includes the following operations:

[0021] A target pressure range and a maximum pressure deviation threshold value allowed for each core pulling rod are preset as a pressure adjustment reference;

[0022] The actual pressure values of each core pulling rod are collected in real time by the pressure sensor arranged on each core pulling rod;

[0023] The pressure deviation between the actual pressure and the target pressure of each core pulling rod is calculated, and the overall imbalance is obtained to represent the degree of pressure difference between the core pulling rods;

[0024] When the pressure deviation of any core pulling rod exceeds the maximum pressure deviation threshold value, or the overall imbalance value exceeds the imbalance threshold value, the online pressure adjusting unit is started to adjust the pressure applied to each core pulling rod by the online pressure adjusting unit to reduce the pressure deviation and the overall imbalance.

[0025] In some feasible embodiments, a chip packaging pin holding method specifically includes the following operations:

[0026] S0. Pre-set the target pressure range ΔP for each core-pulling rod. t (P) min ≤P≤P max Set the target pressure P of the core-pulling rod. t The adjustment range ΔF (F) of the gas spring min ≤F≤F max ), Maximum adjustment amount ΔF in a single instance max The overall maximum imbalance threshold δP global Linear fitting residual threshold ε fit and the noise allowable threshold ε noise This serves as the basis for determining subsequent voltage regulation.

[0027] S1. Obtain the actual pressure value of each core-pulling rod through a pressure sensor, sample the same position n times consecutively and take the average value to obtain the actual pressure P. i The standard deviation of the core-pulling rod pressure sampling is calculated as the noise magnitude σ. i If σ i ≤ε noise If so, the noise is determined to be within the allowable range;

[0028] S2. Perform disturbance identification, including applying a disturbance ΔF to a single gas spring (ΔF≤ΔF). max The pressure change ΔP of each core-pulling rod was measured. i This forms an influence matrix M; if the condition number cond(M) of the matrix is ​​less than or equal to the condition number threshold ε, then... cond And the fitting residual is ≤ the linear fitting residual threshold ε fit If the linear relationship is found to be reliable, it can serve as the basis for selecting subsequent adjustment methods.

[0029] S3. The actual pressure P of each core-pulling rod i With target pressure P t By comparison, the pressure deviation value ΔP is obtained. i =Actual pressure P i -Target pressure P t The overall imbalance is determined based on the pressure deviation value of each core-pulling rod, which is used to characterize the degree of pressure difference between multiple core-pulling rods, so as to obtain the degree of tilt of the core-pulling plate.

[0030] If the calculated maximum pressure deviation value is max|ΔP i |≥ Deviation allowable threshold δP ind Or pressure standard deviation σ i Noise tolerance threshold ε noise Or the condition number cond(M) of the matrix is ​​greater than the condition number threshold ε. condIf the maximum pressure deviation max|ΔP

[0031] If the maximum pressure deviation max|ΔP i | is greater than the deviation allowance threshold δP ind , and the pressure standard deviation σ i is less than the noise allowance threshold ε noise , and the condition number cond(M) of the matrix is less than the condition number threshold ε cond , and the fitting residual is less than the linear fitting residual threshold ε fit , then the weighted least squares method is used to calculate the joint adjustment amount ΔF j based on the matrix M, and the adjustment is performed on each gas spring (the weight is determined by the inverse of the noise size of each channel, and the smaller the noise, the higher the weight).

[0032] S4. Re-measure the pressure after adjustment.

[0033] If all the core-pulling rods satisfy the condition that the actual pressure is within the target pressure range, i.e., P min ≤ P i ≤ P max , and the adjustment amount ΔF j of the last two cycles is less than the minimum adjustment threshold ΔF min , then it is determined that the convergence is achieved and the pressure maintenance operation phase is entered.

[0034] If the pressure of a core-pulling rod exceeds the allowed maximum target pressure P max , or the overall imbalance is greater than the overall maximum imbalance threshold δP ind , and the continuous adjustment is invalid, then the last safe setting is reverted and the single maximum adjustment step ΔF max is reduced, and the sampling and adjustment are re-executed with the learning rate.

[0035] When the product is replaced or the mold temperature fluctuation exceeds the set threshold ΔT or the condition number cond(M) of the matrix exceeds the condition number threshold ε cond , the disturbance identification is re-executed to update the influence matrix M.

[0036] In some feasible embodiments, when the coarse adjustment condition and the fine adjustment condition are both satisfied, the following priority order is followed:

[0037] Determine whether the maximum pressure deviation max|ΔP i | is greater than the deviation allowance threshold δP ind , if so, the gradient descent method is prioritized for coarse adjustment until the pressure deviation of all core-pulling rods is less than the deviation allowance threshold δP ind ; after completing the coarse adjustment and satisfying the condition that the maximum pressure deviation max|ΔP i | < deviation allowance threshold δP ind , the weighted least squares method is used to calculate the joint adjustment amount ΔF j based on the matrix M.After that, the weighted least square method is performed for fine adjustment, so that the pressure of all the core rods is finally stabilized in the target pressure range [P min ,P max ].

[0038] In some possible embodiments, a mapping model of the pressure value measured by the sensor and the actual pressure of the core rod applied to the connecting seat on the side of the core plate is established, which includes:

[0039] M0. During the installation and debugging of the device, a known standard load L k (k=1…n, n is the number of core rods) is applied to each core rod, and the corresponding gas spring pressure sensor output value S k is recorded, which is used to establish a calibration reference;

[0040] M1. According to the known load L k and the sensor output S k , a linear or segmented linear fitting relationship is established:

[0041] P i =α i ·S i +β i ;

[0042] P i is the actual pressure of the i-th core rod on the core plate; S i is the measured value of the corresponding sensor of the i-th core rod;

[0043] α i is a proportional coefficient (obtained by fitting, used to correct the proportional difference between the sensor output and the actual pressure);

[0044] β i is an offset correction (obtained by fitting, used to correct the zero point error).

[0045] M2. Real-time calculation of the actual pressure, including real-time acquisition of the sensor output value during operation, and substitution into the mapping formula: =α i · +β i

[0046] to obtain the real-time actual pressure of the core rod.

[0047] M3. The calculated is taken as the actual pressure value.

[0048] In some feasible embodiments, when acquiring the core rod pressure signals, the noise standard deviations of the core rod pressure signals are calculated respectively; then the inverse of the noise standard deviations is taken as the weight value of the corresponding core rod, so as to obtain the weight coefficient of each core rod; the core rod with smaller noise has larger weight value, and has higher proportion in the calculation of the joint adjustment amount, so as to improve the overall fitting precision.

[0049] Another aspect of the present application also provides an electronic device connected with the fine adjustment unit and the pressure sensor as a controller, for controlling the fine adjustment unit, the electronic device comprising a processor and a memory, the memory being used for storing processor executable instructions; wherein the processor is configured to call the instructions stored in the memory, so as to execute the chip package core needle holding method.

[0050] Another aspect of the present application also provides a computer readable storage medium, which stores computer program instructions, the computer program instructions being executed by a processor to implement the chip package core needle holding method. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 It is a schematic diagram for explaining the chip package core needle holding device in the embodiment, which is arranged on the upper core pulling press;

[0052] Figure 2 It is a side view schematic diagram for explaining the chip package core needle holding device in the embodiment, which is arranged on the upper core pulling press;

[0053] Figure 3 It is a sectional view schematic diagram for explaining the chip package core needle holding device in the embodiment;

[0054] Figure 4 It is a partial enlarged view for explaining the elastic connection group part in the embodiment; Figure 3

[0055] Figure 5 It is a partial enlarged view for explaining the online pressure regulating unit part in the embodiment; Figure 3

[0056] Figure 6 It is a schematic diagram for explaining the adjustable core needle in the embodiment;

[0057] Figure 7 It is a sectional view for explaining the adjustable core needle in the embodiment;

[0058] Figure 8 It is a flow chart for explaining the chip package core needle holding method in the embodiment;

[0059] ​​1 - upper mold base; 2 - driving plate; 3 - core pulling rod; 100 - core pulling plate; 200 - adjustable core pulling needle; 210 - base; 220 - needle rod; 230 - elastic adjusting unit; 231 - spring cylinder; 232 - second spring; 300 - elastic connecting group; 310 - connecting seat; 320 - connecting rod; 330 - first spring; 400 - online pressure regulating unit; 410 - cover plate; 420 - upper sliding sleeve; 430 - fine adjustment unit; 440 - pressure sensor. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. In the embodiments of the present application, the words such as "exemplarily" or "for example" are used to represent an example, an illustration or an explanation.

[0061] Embodiment 1

[0062] Reference Figures 1 to 7 A chip package core pulling needle pressing device is arranged on a core pulling press of a semiconductor plastic package mold. An upper mold assembly and a lower mold assembly of the core pulling press realize clamping and opening actions under the driving of a core pulling power device controlled by a central control unit. The chip package core pulling needle pressing device comprises an upper mold base 1, a driving plate 2 and a core pulling rod 3. The core pulling power device is arranged on the upper mold base 1. The driving plate 2 is connected with the core pulling power device and is used for moving up and down through the core pulling power device. The core pulling rod 3 is distributed below the driving plate 2. The upper end of the core pulling rod 3 is connected with the lower side of the driving plate 2. The lower end of the core pulling rod 3 is connected with a core pulling plate 100 arranged for abutting against a core pulling needle. The core pulling plate 100 is used for moving with the up and down movement of the driving plate 2 to make the core pulling needle abut against or separate from a chip substrate or a base island. Each core pulling rod 3 is connected with the core pulling plate 100 through an elastic connecting group 300. The elastic connecting group 300 is used for enabling the core pulling plate 100 to be elastically movable in the axial direction of the core pulling rod 3 and to make elastic tilting action relative to the plane where the driving plate 2 is located. In use, the core pulling power device such as a motor driven screw is adopted. The driving plate 2 and the screw form a screw lifting transmission mechanism to drive the driving plate 2 to move up and down with the core pulling plate 100.

[0063] The chip packaging core pulling needle pressure holding device designed by the application adopts the elastic connection group 300 between the core pulling rod 3 and the core pulling plate 100, so that the core pulling plate 100 can elastically move in the axial direction and can be elastically inclined relative to the plane where the driving plate 2 is located. This innovative design significantly improves the adaptability of the device to the small tolerance of the mold and the unevenness of the substrate, ensuring that the core pulling needle can uniformly apply pressure to the chip substrate, thereby effectively avoiding problems such as substrate warping, cracking or poor packaging caused by uneven pressure distribution. Compared with the traditional scheme, the traditional core pulling plate 100 usually relies on rigid fixing structure and cannot adapt to the small tolerance change of the mold or the small deformation of the chip substrate, often leading to excessive or insufficient pressure, thereby affecting the packaging quality. The application introduces an elastic floating mechanism, which enables the core pulling plate 100 to adaptively adjust the pressure according to the actual situation, ensuring uniform distribution of pressure and avoiding the problem of local overpressure or insufficient pressure, thereby significantly improving the yield and packaging stability.

[0064] On the basis of the above-mentioned scheme, the elastic connection group 300 can be further optimized, which includes a connecting seat 310, a connecting rod 320, and a first spring 330. The connecting seat 310 is detachably connected to one side of the core pulling plate 100. The connecting rod 320 can move up and down and is arranged in the connecting seat 310. The upper end of the connecting rod 320 is detachably connected to the lower end of the core pulling rod 3, and the relative position of the connecting rod 320 and the core pulling rod 3 in the axial direction is adjustable. The first spring 330 is sleeved on the connecting rod 320 and is distributed on the upper and lower sides of the connecting seat 310, so that the connecting seat 310 can extrude the first spring 330 when moving up and down. The connecting seat 310 can be a component with slots on the upper and lower sides and the side facing the core pulling plate 100. The core pulling plate 100 extends outwardly on the side and is clamped in the side slot of the connecting seat 310. The lower end of the core pulling rod 3 can extend into the slot on the upper side of the connecting seat 310, and the lower end of the connecting rod 320 can also be accommodated in the slot on the lower side of the connecting seat 310. The first spring 330 is arranged in the slots on the upper and lower sides of the connecting seat 310. In this embodiment, the connecting rod 320 can be in the form of a screw, for example, a screw with a threaded hole at the lower end of the core pulling rod 3 is connected by screwing. This realizes the detachable connection mentioned above. Of course, other forms of connection such as clamping and latch can also be used.

[0065] In this way, the elastic connection group 300 realizes the elastic connection between the core pulling plate 100 and the core pulling rod 3 by combining the connecting seat 310, the connecting rod 320 and the first spring 330 together, and provides a more flexible and accurate pressure adjustment mode. Specifically, the connecting seat 310 is detachably connected with the core pulling plate 100, allowing the core pulling plate 100 to be replaced or adjusted as needed; and the connecting rod 320 is detachably connected with the lower end of the core pulling rod 3, further improving the maintainability and flexibility of the device. In this structure, the sleeve setting and the distribution of the upper and lower sides of the first spring 330 enable the connecting seat 310 to squeeze the spring when moving up and down, thereby providing a certain elastic reaction force. In this way, it can be ensured that the floating range of the core pulling plate 100 during the core pulling process is controlled by the spring, avoiding uneven pressure distribution caused by unnecessary excessive floating or deformation, and ensuring that the chip substrate is subjected to uniform and adjustable pressure. Compared with the traditional core pulling plate 100, which cannot adapt to the small deformation and tolerance changes in the chip substrate or mold, resulting in uneven pressure or inability to compensate for the differences in small tolerances of the mold in time. The present application cooperates the elastic connection and the detachable structure, and adjusts the relative position of the connecting rod 320 and the core pulling rod 3 to adjust the pressure of the first spring 330, so as to adaptively and flexibly adjust the pressure distribution while ensuring stability, improve the accuracy, stability and product yield of the packaging process. In addition, the elastic control of the first spring 330 ensures that the pressure regulation of the system is more flexible and flexible, and can exhibit higher adaptability, avoiding the problems caused by the mechanical rigid control in the traditional scheme.

[0066] Specifically, the four core pulling rods 3 are distributed at the four corners of the core pulling plate 100; wherein, the two sides of the core pulling plate 100 are respectively provided with one connecting seat 310; two connecting rods 320 are arranged on one connecting seat 310, for enabling the two sides of the core pulling plate 100 to make a coordinated elastic swinging action; or, the two sides of the core pulling plate 100 are respectively provided with two connecting seats 310; one connecting rod 320 is arranged on one connecting seat 310, for enabling the four corners of the core pulling plate 100 to make a coordinated elastic swinging action.

[0067] The four corners of the core pulling plate 100 of the present scheme are distributed with at least four core pulling rods 3, and the connecting seats 310 are arranged on the two sides of the core pulling plate 100, and each connecting seat 310 is designed to realize a coordinated elastic swinging action through the connecting rod 320, aiming to optimize the pressure distribution and self-adaptive adjustment capability of the core pulling plate 100.

[0068] The cooperation between the connecting seat 310 and the connecting rod 320 enables the four corners of the core pulling plate 100 to be elastically swung and finely adjusted in coordination. The structure can effectively avoid the problem of excessive or insufficient local pressure caused by the core pulling plate 100 relying on single-point pressure or single-direction elasticity. When the surface of the chip substrate is uneven, the overall core pulling plate 100 cannot be elastically floated as a whole to achieve multi-point and uniform pressure compensation. The present application ensures that the four corners of the core pulling plate 100 can be finely adjusted and adaptively adjusted in coordination by configuring multiple connecting seats 310 and connecting rods 320, so that the core pulling needle can more flexibly exert pressure on the chip substrate.

[0069] Here, the above-mentioned coordination refers to the cooperation and joint action of the multiple connecting seats 310 and connecting rods 320 during work. When the core pulling plate 100 is subjected to pressure during the core pulling process, the connecting seats 310 and connecting rods 320 will jointly adjust the angles or positions of the four corners of the core pulling plate 100 through elastic action, so that the core pulling plate 100 can uniformly adapt to the deformation of the substrate or the slight tolerance change of the mold. This mechanism ensures that the four corners or two sides of the core pulling plate 100 can be finely adjusted in synchronization or coordination, rather than adjusting a single angle, thereby avoiding the problem of excessive or insufficient local pressure.

[0070] Embodiment 2

[0071] Reference Figures 1 to 7 On the basis of the above-mentioned embodiment 1, the driving plate 2 is movably connected with the upper end of each core pulling rod 3 in the axial direction of the core pulling rod 3, and an online pressure adjusting unit 400 is arranged at the movable connection position. The online pressure adjusting unit 400 comprises a cover plate 410, an upper sliding sleeve 420, and a fine adjustment unit 430. The cover plate 410 is detachably fixed to the upper end opening of the through slot of the driving plate 2. The upper end of the upper sliding sleeve 420 is connected with the cover plate 410, and the upper sliding sleeve 420 is arranged in the through slot. The fine adjustment unit 430 is arranged in the upper sliding sleeve 420 and located between the core pulling rod 3 and the cover plate 410, and is used for online adjusting the distance between the core pulling rod 3 and the cover plate 410. The fine adjustment unit 430 is a gas spring or a gas cylinder. A pressure sensor 440 is further arranged between the fine adjustment unit 430 and the cover plate 410, or between the fine adjustment unit 430 and the upper end of the core pulling rod 3. The pressure sensor 440 is used for obtaining the pressure information generated by the pressure sensor 440 due to the downward or upward deformation or displacement of the core pulling plate 100 in the axial direction of the core pulling rod. The fine adjustment unit 430 is used for controlling the distance between the core pulling rod 3 and the driving plate 2 according to the pressure information obtained by the pressure sensor 440.

[0072] The gas spring or the air cylinder is arranged at the upper end of the core pulling rod 3, so that the fine adjustment unit 430 directly acts on the driving end of the core pulling rod 3, the axial displacement of the core pulling rod 3 can be adjusted in real time, the pressure holding force of the core pulling needle on the substrate is better controlled, the uniformity of the pressure distribution is realized, and the installation and disassembly are more convenient. And the chip packaging process has high temperature, vibration and dynamic load, the gas spring or the air cylinder is directly installed at the end of the core pulling rod 3, which can quickly respond to pressure changes, buffer external disturbances, and reduce the influence of temperature changes on the gas in the gas spring or the air cylinder. Here, the gas spring / air cylinder is used, which has a short stroke, high responsiveness, and can provide fine adjustment in a limited space, and is easy to form a closed loop control with the sensor.

[0073] The fine adjustment unit 430 (such as a gas spring or an air cylinder) is arranged in the upper sliding sleeve 420, which can accurately adjust the distance between the core pulling rod 3 and the cover plate 410 according to the pressure demand in the core pulling process, realize dynamic pressure control, and ensure the uniformity of the pressure in the packaging process. The detachable design of the cover plate 410 facilitates maintenance, makes the equipment more flexible and reliable in actual production, reduces downtime and production cost. Here, the gas spring is used, which usually has a short stroke (for example, 2-6 mm). The gas spring has a relatively small compression stroke, can provide a relatively low continuous pressure and a relatively small force variation range, is more suitable for fine adjustment, and can realize accurate pressure adjustment through a proportional valve and an electromagnetic valve. The pressure sensor 440 monitors the adjustment result in real time.

[0074] Embodiment 3

[0075] Reference Figures 1 to 7 On the basis of any scheme of the above embodiment, a plurality of core pulling needles are distributed on the core pulling plate 100, and at least part of the core pulling needles are adjustable core pulling needles 200 with adjustable pressure holding function; the adjustable core pulling needle 200 comprises a base 210, a needle rod 220, and an elastic adjustment unit 230; the base 210 is arranged on the core pulling plate 100; the needle rod 220 is movably arranged on the base 210 and can slide along the axial direction relative to the base 210; the elastic adjustment unit 230 is arranged between the base 210 and the needle rod 220, and is used for adjusting and controlling the pressure holding force of the needle rod 220 and / or the distance from the end of the needle rod 220 to the base 210.

[0076] After the floating core plate 100 is set, the risk of uneven pressure relief can be alleviated, but its elastic floating characteristics cannot provide accurate pressure self-regulation in critical areas because the floating structure itself is passive and can only be adjusted within the overall range. To solve this problem, the present scheme designs an adjustable core pulling needle. The adjustable core pulling needle can automatically adjust the pressure of the core pulling needle during the core pulling process according to the slight unevenness of the substrate through the built-in elastic adjustment unit 230. In this way, when the core pulling plate 100 floats, the adjustable core pulling needle can make fine pressure self-adjustment as needed in critical areas, ensuring that the pressure distribution in different areas is more uniform, and avoiding packaging defects caused by local overpressure or insufficient pressure.

[0077] The present application provides a passive self-regulation mechanism for the core pulling needle by setting multiple adjustable core pulling needles 200 with adjustable pressure holding function on the core pulling plate 100, adopting the design of base 210, needle rod 220 and elastic adjustment unit 230, so that the traditional core pulling needle may not accurately adapt to the morphological changes under the slight deformation of the mold or substrate, resulting in pressure concentration or insufficient pressure, thereby affecting the packaging quality. By adding an elastic adjustment unit 230 (such as a spring) inside the core pulling needle, the needle rod 220 can automatically adjust its length and the pressure exerted under the action of the spring according to the actual morphology and unevenness of the substrate, so that some core pulling needles can passively adapt to the deformation of the chip substrate in critical areas, ensuring that the core pulling needle uniformly exerts pressure. This design can automatically compensate for the pressure difference caused by the slight deformation of the chip substrate during the core pulling process on the surface of the core pulling plate 100, avoiding the problem of local overpressure or insufficient pressure in traditional rigid structures. Compared with traditional core pulling needles, this design does not require manual intervention or active adjustment of pressure, but achieves automatic and passive pressure adjustment through the elastic adjustment unit 230, reducing the complexity of operation and improving the adaptability of the device.

[0078] Specifically, the elastic adjustment unit 230 includes a spring barrel 231 and a second spring 232. The upper end of the spring barrel 231 is threadedly connected with the downwardly extending screw rod of the base 210, and the screw rod can partially extend into the spring barrel 231. The lower end of the spring barrel 231 is slidingly connected with the outer circle of the needle rod 220. The portion of the needle rod 220 inside the spring barrel 231 can be provided with a limiting table,

[0079] The limiting platform is slightly larger than the hole below the spring cylinder 231 for the needle rod 220 to pass through, limiting the stroke of the needle rod 220 in the spring cylinder 231, the upper section of the needle rod 220 extending into the spring cylinder 231 and sleeving and sliding with the screw rod; the second spring 232 is sleeved on the upper section of the needle rod 220, the upper end of the second spring 232 being connected with the lower end of the screw rod, and the lower end of the second spring 232 being connected with the upper side of the bottom plate of the spring cylinder 231, for extruding the spring when the screw rod is rotated. The above-mentioned adjustment of the pressing force refers to the adjustment of the distance between the needle rod 220 and the base 210, and the pre-tightening force of the second spring 232 can also be pre-adjusted. The above-mentioned needle rod 220 extending into the spring cylinder 231 and sleeving and sliding with the screw rod can be a hole in the screw rod, and the upper section of the needle rod 220 is inserted into the hole and can slide.

[0080] The present application realizes the pre-tightening force adjustment of the pressure by designing the combination of the spring cylinder 231 and the second spring 232 in the elastic adjustment unit 230 of the core-pulling needle, and by the threaded cooperation of the screw rod and the spring cylinder 231, the rotation of the screw rod can adjust the pressing force of the needle rod 220 or the distance between the needle rod 220 and the base 210, thereby realizing the control of the pressure of the adjustable core-pulling needle. The cooperation design of the screw rod and the spring cylinder 231 in the structure makes the adjustment process simple and easy to operate, and fine pressure control can be realized by rotating the screw rod, improving the operability of the partial core-pulling needle pressure of the core-pulling plate 100 on the plate surface.

[0081] Compared with the core-pulling plate 100 which is fixed and can only move up and down, the core-pulling plate 100 which can elastically float and slightly elastically tilt can adapt to the slight unevenness and deformation of the mold and the chip substrate, thereby providing certain pressure balance and avoiding local overpressure or insufficient pressure. However, although the elastic floating and tilting design improves the adaptability, such passive adjustment cannot provide precise pressure control in the local area of the chip substrate, especially when the morphology of the substrate changes slightly, the overall floating cannot ensure the uniform pressure of each area. The floating and tilting of the core-pulling plate 100 can ensure the preliminary distribution of the overall pressure, but for the key areas (such as the base island or the uneven part of the substrate surface), there may still be pressure differences, leading to poor packaging.

[0082] At this time, the adjustable core-pulling needle plays an important role. The adjustable core-pulling needle can accurately adjust the pressure when the substrate locally deforms through the built-in elastic adjustment unit 230 (such as a spring), ensuring that the pressure in different areas is carefully and evenly distributed. When the core-pulling plate 100 floats, the adjustable core-pulling needle adaptively adjusts its pressure at key positions, making up for the local pressure difference caused by the floating structure. Therefore, only by using the adjustable core-pulling needle in combination with the elastically floating and slightly elastically inclined core-pulling plate 100, can the local area pressure be accurately adjusted while ensuring uniform overall pressure, ensuring the stability and high quality of the entire packaging process. This synergy can fully utilize the advantages of each design, thereby improving packaging accuracy and avoiding the pressure imbalance problem in traditional solutions.

[0083] For a non-elastic floating core-pulling plate 100 that can only move up and down, there is a lack of sufficient adaptive ability to automatically adjust its pressure distribution when facing the slight deformation of the chip substrate or mold. When the substrate is uneven or deformed, the rigid structure of the core-pulling plate 100 can cause pressure concentration or deficiency, especially in local areas. Even if the adjustable core-pulling needle is provided locally or partially on the core-pulling plate 100, these needles are difficult to function optimally because they cannot adjust to the pressure difference when the overall float is not adjusted. The core-pulling needle can only adjust the pressure within a local range, but the non-elastic floating core-pulling plate 100 cannot flexibly compensate or adaptively adjust the overall pressure during the entire packaging process, resulting in uneven pressure. Therefore, simply relying on local adjustable core-pulling needles cannot effectively overcome the pressure imbalance problem caused by the rigid structure of the core-pulling plate 100, and cannot optimize the overall packaging quality.

[0084] However, the present solution forms a highly adaptive and precisely controllable packaging pressure adjustment mechanism through the synergistic effect of the elastically floating core-pulling plate 100, the adjustable core-pulling needle, and the actively adjusted core-pulling rod 3. The elastically floating core-pulling plate 100 provides overall pressure distribution balance, allowing it to automatically adjust according to the slight deformation of the chip substrate and the mold tolerance, ensuring that the substrate remains stable during the packaging process; at the same time, the adjustable core-pulling needle can finely adjust the pressure of the adjustable core-pulling needle in key areas through the built-in elastic adjustment unit 230, making local compensation for key areas, thereby further solving the problem of uneven pressure caused by local unevenness or deformation on the plate surface after the floating core-pulling plate 100 is set. At the same time, the pressure of the actively adjusted core-pulling rod 3 is adjusted to ensure that each link in the entire packaging process can be completed under the control of multi-point adjustable pressure. The synergistic effect of the three makes the entire system adaptively adjust under different molds, chip substrates, and packaging conditions, achieving uniform pressure distribution, improved packaging quality, and increased yield, effectively overcoming the packaging problems caused by the inability of rigid structures to adapt to deformation in traditional solutions.

[0085] Example 5

[0086] like Figure 8 A chip packaging core-pulling pin holding method, employing the aforementioned chip packaging core-pulling pin holding device, includes the following operations:

[0087] A target pressure range and a maximum allowable pressure deviation threshold are preset for each core-pulling rod, serving as a benchmark for pressure adjustment. The actual pressure value of each core-pulling rod is collected in real time using pressure sensors installed on each rod. The pressure deviation between the actual pressure and the target pressure of each rod is calculated, and the overall imbalance is obtained to characterize the degree of pressure difference between the rods. When the pressure deviation of any core-pulling rod exceeds the maximum pressure deviation threshold, or the overall imbalance exceeds the imbalance threshold, the online pressure adjustment unit is activated to adjust the pressure applied to each rod, thereby reducing the pressure deviation and overall imbalance. This online pressure adjustment unit can be adjusted using a gas spring. The gas spring connects sequentially upwards from the pressure sensor's central hole and the cover plate's through-hole to a proportional valve controlled by the controller. Alternatively, it can be connected to a solenoid valve controlled by the controller. In one embodiment, the proportional valve can dynamically change the internal pressure of the gas spring based on the feedback signal from the pressure sensor, thus controlling the force and displacement of the core-pulling rod. The pressure control based on the pressure feedback signal can be implemented using the following scheme. (In one embodiment, the gas spring extension and retraction can also be controlled by a quick-switching solenoid valve, which is suitable for coarse adjustment or action triggering.)

[0088] Specifically, the following operations are included:

[0089] S0. Pre-set the target pressure range ΔP for each core-pulling rod. t (P) min ≤P≤P max Set the target pressure P of the core-pulling rod. t The adjustment range ΔF (F) of the gas spring min ≤F≤F max ), Maximum adjustment amount ΔF in a single instance max The overall maximum imbalance threshold δP global , linear fitting residual threshold ε fit and the noise allowable threshold ε noise This serves as the basis for determining subsequent voltage regulation.

[0090] S1. Obtain the actual pressure value of each core-pulling rod through a pressure sensor, sample the same position n times consecutively and take the average value to obtain the actual pressure P. i The standard deviation of the core-pulling rod pressure sampling is calculated as the noise magnitude σ. i If σ i ≤ε noise If so, the noise is determined to be within the allowable range;

[0091] S2. Perform disturbance identification, including applying disturbance ΔF (ΔF≤ΔF max ) to each single air spring and measuring the pressure change of each core rod ΔP i , forming the influence matrix M; if the condition number cond(M) of the matrix is ≤ the condition number threshold ε cond and the fitting residual is ≤ the linear fitting residual threshold ε fit , it is determined that the linear relationship is reliable; as the basis for selecting the subsequent adjustment method;

[0092] S3. Compare the actual pressure P i of each core rod with the target pressure P t , and obtain the pressure deviation value ΔP i = actual pressure P i -target pressure P t , and determine the overall imbalance according to the pressure deviation value of each core rod, which is used to represent the degree of pressure difference between multiple core rods, so as to obtain the inclination degree of the core plate;

[0093] If the maximum pressure deviation value max|ΔP i | calculated is ≥ the deviation allowed threshold δP ind or the pressure standard deviation σ i > the noise allowed threshold ε noise or the condition number cond(M) of the matrix is > the condition number threshold ε cond , the gradient descent method is used for coarse adjustment, and the air springs are adjusted one by one or simultaneously;

[0094] If the maximum pressure deviation value max|ΔP i | calculated is < the deviation allowed threshold δP ind and the pressure standard deviation σ i ≤ the noise allowed threshold ε noise and the condition number cond(M) of the matrix is ≤ the condition number threshold ε cond and the fitting residual is ≤ the linear fitting residual threshold ε fit , the weighted least squares method is used to calculate the joint adjustment amount ΔF j based on the matrix M, and each air spring is adjusted (the weight is determined by the inverse of the noise size of each channel, and the smaller the noise, the higher the weight);

[0095] S4. Recalculate the pressure after adjustment;

[0096] If all core rods satisfy that the actual pressure is within the target pressure range, i.e., P min ≤P i ≤P max and the adjustment amount ΔF j of two consecutive cycles is ≤ the minimum adjustment threshold ΔF min , the method ends.If the core pulling rod pressure exceeds the allowable target pressure maximum value P

[0097] If the core pulling rod pressure exceeds the allowable target pressure maximum value P max , or the overall imbalance is greater than the overall maximum imbalance threshold δP ind and the continuous two adjustments are invalid, then the last safe setting is rolled back and the single maximum adjustment step ΔF max is reduced, and the sampling and adjustment are re-executed.

[0098] When the product is replaced or the mold temperature fluctuation exceeds the set threshold ΔT or the condition number cond(M) of the matrix exceeds the condition number threshold ε cond , the disturbance identification is re-executed to update the influence matrix M.

[0099] For a core pulling press system or an up-core pulling press, the packaging product and mold form are multiple, and the line replacement is frequent. Without considering the cost and installation and assembly difficulty, the adjustable core pulling needle can be used to resist the chip substrate or base island. However, the number of fully adjustable needles is huge, the cost of a single needle is high, the installation and adjustment or calibration workload is explosive, and the long-term reliability and maintenance cost in a high-temperature resin environment are also uncontrollable. Therefore, under the premise of not sacrificing yield and consistency, the applicant expects to use limited active components to achieve global uniform pressure holding and rapid adaptation.

[0100] Therefore, the scheme adopts a floating core pulling plate through invention and creation, which can compensate for the relative parallelism deviation of the upper die or the core pulling plate, the micro-uncommon surface of the mold cavity surface that is not easy to detect, the thickness or warpage tolerance of the ceramic substrate, that is, the core pulling plate allows small pitch / float up and down, so that the contact changes from rigid dead to soft fit, reducing the micro-cracking / local stress concentration of the substrate caused by single-point first contact. In this way, it can also be aimed at the thermal expansion difference and thermal warping under the injection molding condition, and the compliance part of the floating mechanism can follow, reducing the process drift.

[0101] The scheme mixes the floating mode core pulling plate designed by the scheme and the locally adjustable core pulling needle and the fixed core pulling needle. Specifically, a small number of adjustable elastic needles (adjustable core pulling needles) can be arranged in the key area of the base island / large electrode, used to passivate the contact sequence difference, share the peak load, and reduce the eccentricity / fracture caused by first contact. In this way, only the adjustable elastic needle in the key stress area, and the vast majority still uses the fixed needle, retains local flexibility, controls cost and assembly burden, and also makes the key area templated (based on historical data / template library) so that only the key needle is fine-tuned when changing type, and the debugging time is significantly shortened.

[0102] But with four core-pulling rods through the elastic clamping assembly and a piece of floating plate (core-pulling plate and connecting seat) constitute parallel elastic system as an example, its adjustment angle will pull other corners (so as to form a typical multi-input multi-output MIMO coupling), the increase of floating degree of freedom, the distribution of four corners pressure is no longer predictable, only by pre-tightening is difficult to ensure uniform, and temperature drift, spring aging, resin pressure fluctuation will change the force distribution, after starting or each batch consistency is difficult to maintain only by passive way.

[0103] Based on the above situation, the core-pulling needle pressure holding method uses disturbance identification (preferably, uses minimal disturbance) to establish the influence matrix of the gas spring adjustment amount to the response of each core-pulling rod pressure, and to transform the essentially coupled system into a calculable linear approximation model (MIMO), and through two-stage control, namely gradient descent method coarse adjustment (when the deviation is large / noise is large / model credibility is not enough, any one of them is satisfied), quickly pull the system from the "out-of-range area" back to the controllable area; weighted least squares fine adjustment (when linear is credible and noise is small and residual error is small), the joint adjustment amount is calculated once by weighted least squares, and the four corners can be balanced at the same time when coupling exists; The weight can be set during adjustment, and the weight is determined by the reciprocal of the noise, and the influence of good channels is greater. And for temperature drift, batch difference or model degradation, the scheme automatically triggers re-identification; When the safety condition is not met, it reverts to the safety setting, which can ensure process safety.

[0104] The above-mentioned minimal can be, for example, the target pressure range of each core-pulling rod is P target , the maximum allowable pressure deviation threshold is δP max , the disturbance amount ΔF disturb may be 1% to 5% of δP max , or 0.5% to 2% of P target , and at the same time ensure that the core-pulling rod pressure change ΔP i caused by the disturbance is 3 to 5 times the sensor noise level ε noise . In this way, it can be ensured that the disturbance is small enough and will not deviate from the process requirements, and at the same time, it can be ensured that the detection result is not drowned by noise.

[0105] The method can be solved by four-channel pressure and influence matrix regardless of the implementation scheme of one connecting seat on each side of the core-pulling plate, two rods per seat, or the implementation scheme of four seats on each corner, one rod per seat. The design algorithm level is also naturally compatible. In this scheme, the pressure distribution of the four corners and the key area is more uniform, which can significantly reduce the risk of ceramic substrate warping, micro-cracking or breakdown. For assembly deviation, thermal drift, material batch difference, it also has online self-correction ability, which helps batch consistency. Compared with the ideal "fully adjustable needle" mentioned above, this scheme forms a passive adjustment mode through floating core-pulling plate and partially adjustable core-pulling needle (which can be arranged in a small amount locally), and then actively adjusts the gas spring to achieve the same or better effect, reduce cost, assembly and maintenance, and shorten the replacement and debugging time.

[0106] If some special conditions occur, for example, when the coarse adjustment condition and the fine adjustment condition are met at the same time, the following priority order can be executed in this embodiment:

[0107] Determine the maximum pressure deviation max | ΔP i whether it is greater than the deviation allowed threshold δP ind , if so, the gradient descent method is executed for coarse adjustment until all core-pulling rod pressure deviations are less than the deviation allowed threshold δP ind ; after completing the coarse adjustment and meeting the maximum pressure deviation max | ΔP i | < deviation allowed threshold δP ind , the weighted least squares method is executed for fine adjustment to make all core-pulling rod pressures finally stable within the target pressure range [P min , P max ].

[0108] The pressure sensor is not directly placed at the contact between the core-pulling plate and the core-pulling rod, but is set in the cold area, i.e. between the gas spring and the cover plate. In order to avoid the interference of the hot area on the pressure sensor, it also brings the case that the actual value measured by it is not the reverse pressure exerted by the core-pulling rod on the core-pulling plate, but the force of the gas spring acting on the driving plate (the cover plate and the driving plate are fixed and can be screwed).

[0109] Since the core-pulling plate is floating, and the gas spring is coupled with the first spring and the core-pulling rod, there is a proportion, coupling or offset between the value measured by the sensor and the actual core-pulling rod-core-pulling plate action pressure. Therefore, a mapping relationship is designed here to correct it, to establish a mapping model of the pressure value measured by the sensor and the pressure exerted by the core-pulling rod on the connecting seat on the side of the core-pulling plate, including:

[0110] M0. During the installation and debugging of the device, a known standard load L k is applied to each core-pulling rod (k=1…n, n is the number of core-pulling rods), while the corresponding gas spring pressure sensor output value Sk , for establishing calibration reference;

[0111] M1. According to known load L k and sensor output S k , establish linear or segmented linear fitting relationship:

[0112] P i = α i · S i + β i ;

[0113] P i is the actual pressure of the i-th core rod on the core plate; S i is the measured value of the sensor corresponding to the i-th core rod;

[0114] α i is the proportional coefficient (obtained by fitting, used to correct the proportional difference between sensor output and true pressure);

[0115] β i is the offset correction (obtained by fitting, used to correct zero error).

[0116] M2. Real-time calculation of actual pressure, including real-time acquisition of sensor output value during operation , substitute into the mapping formula: = α i · + β i

[0117] Get the real-time actual pressure of the core rod.

[0118] M3. Take the calculated as the actual pressure value.

[0119] The core needle pressure holding method of the chip package arranges the sensor at the air spring-cover plate, and measures the reaction force of each core rod channel; through the mapping relationship (proportion / zero offset obtained by calibration), it is converted into the actual pressure on the core plate, filling the "invisible" gap.

[0120] When obtaining the pressure signal of each core rod, calculate the noise standard deviation of each core rod respectively; then take the reciprocal of the noise standard deviation as the weight value of the corresponding core rod, and get the weight coefficient of each core rod; the smaller the noise of the core rod, the greater the corresponding weight value, and the higher the proportion in calculating the joint adjustment amount, thereby improving the overall fitting accuracy. Specifically includes:

[0121] Statistically analyze the pressure sampling value of each core rod i, and calculate its noise standard deviation σ i , wherein σ iσi represents the size of the pressure fluctuation of the ith core rod under multiple sampling; the reciprocal square of each σi is taken as the weight:

[0122]

[0123] where w i represents the weight coefficient of the ith core rod;

[0124] The weight matrix W = diag(w1, w2, …, w n ) is constructed, where n is the total number of core rods;

[0125] When performing weighted least squares calculation of the joint adjustment amount ΔF, the following form is adopted:

[0126] ΔF = (M T WM) −1 M T WΔP

[0127] ΔF = [ΔF1, ΔF2, …, ΔFn] n ] T , ΔF is the adjustment amount vector of each gas spring;

[0128] M is the influence matrix of the gas spring adjustment amount and the core rod pressure change;

[0129] ΔP = [ΔP1, ΔP2, …, ΔPn] n ] T , ΔP is the pressure deviation vector of each core rod.

[0130] In specific implementation, the following execution steps can be performed:

[0131] Step 0. Parameter pre-setting:

[0132] The target pressure range [P i,min , P i,max ] of each core rod; the maximum pressure deviation threshold δP max allowed; the noise allowed threshold ε noise ; the condition number threshold ε cond ; the linear fitting residual threshold ε fit ;

[0133] Step 1. Actual pressure measurement and estimation

[0134] Through the pressure sensor, multiple pressure data of each core rod i are collected, the mean value is calculated as the actual pressure estimation value P i , and the standard deviation σ i is calculated as the noise index. Formula:

[0135]

[0136]

[0137] P i,j Pi,j is the pressure value of the ith core rod for the jth sampling;

[0138] P i Pi is the pressure estimate value (average) of the ith core rod;

[0139] σ i σi is the standard deviation of the pressure sampling of the ith core rod (noise size);

[0140] k is the number of samplings;

[0141] Step 2. Establish disturbance identification and influence matrix

[0142] Apply small perturbations to a single gas spring, record all core rod pressure changes, and obtain the influence matrix M of the gas spring adjustment and pressure response. Formula:

[0143] ΔP=M·ΔF

[0144] ΔP=[ΔP1,ΔP2,…,ΔP n ] T , ΔP is the pressure change vector of each core rod.

[0145] ΔF=[ΔF1,ΔF2,…,ΔF n ] T , ΔF is the adjustment amount vector of each gas spring;

[0146] M is the influence matrix, element M ij represents the unit influence of the jth gas spring adjustment on the ith core rod pressure.

[0147] At the same time, calculate the matrix condition number cond(M) to determine whether the linear relationship is stable.

[0148] The matrix condition number cond(M) is used to measure the numerical stability of a matrix, and is calculated by singular value decomposition or norm. The larger the value, the more ill-conditioned the matrix. In this embodiment, it is used to determine whether the linear mapping from the core rod to the gas spring is stable and reliable. When cond(M) is small, the difference between the maximum and minimum singular values of the matrix is not large, and the effects of each gas spring on the core rod pressure can be distinguished relatively independently. The numerical solution is stable and reliable. When cond(M) is too large, there is strong coupling or redundancy in the system, and small measurement noise or disturbance will be amplified, resulting in large fluctuations or even distortion of the calculated adjustment amount, which cannot be used for accurate control. Here, cond(M) is used as one of the judgment criteria, which provides a quantitative and calculable index, so that the reliability of linear approximation and the stability of solution can be objectively judged, thereby realizing automatic and standardized switching logic in the adjustment method, providing an algorithm basis for software program implementation, and ensuring accurate and safe adjustment process.

[0149] Step 3. Deviation calculation, including calculating the pressure deviation of each core rod:

[0150] ΔP i =P target,i −P i

[0151] ΔP i is the pressure deviation of the ith core rod;

[0152] P target,i is the target pressure value of the ith core rod;

[0153] P i is the actual pressure value of the ith core rod.

[0154] And statistics:

[0155] The maximum deviation value max | ΔP i | is calculated.

[0156] The overall standard deviation

[0157] Step 4. When max | ΔP i | > δP max or σ i > ε noise or cond(M) > ε cond , execute Step 5.1, select gradient descent method (gradient descent method) coarse adjustment.

[0158] When max | ΔP i | ≤ δP max , and σ i ≤ ε noiseand cond(M) < ε cond and linear fitting residual < ε fit Step 5.2 is performed, and the weighted least square method is selected for fine tuning.

[0159] Step 5.1. Coarse tuning (gradient descent method)

[0160] When the gradient descent method is used, the adjustment rule is:

[0161]

[0162] is the adjustment amount of the jth gas spring at the tth iteration;

[0163] is the learning rate (adjustment step size);

[0164] Objective function (sum of squares of pressure deviation):

[0165]

[0166] Step 5.2. Fine tuning (weighted least square method)

[0167] When the weighted least square method is used, first calculate the weight according to the noise:

[0168]

[0169] w i is the weight coefficient of the ith core rod;

[0170] σ i is the standard deviation of the noise of the ith core rod.

[0171] Construct the weight matrix:

[0172] W = diag(w1, w2, …, wn) n , where n is the total number of core rods;

[0173] Then solve the weighted least square:

[0174] ΔF = (M T WM) −1 M T WΔP

[0175] ΔF is the joint adjustment amount of each gas spring;

[0176] M T is the transpose of matrix M;

[0177] W is the weight matrix;

[0178] ΔP is the pressure deviation vector;

[0179] Step6. Convergence and backoff

[0180] If max |ΔP i | ≤ δP max and the adjustment amount is less than the preset step size for two consecutive times, it is determined that the pressure regulation is completed.

[0181] If the pressure of a certain core pulling rod exceeds the set upper limit P max , or the overall standard deviation σ sys > δP max , and the adjustment is ineffective for two consecutive times, the last safe set value is returned to and the step size and learning rate are reduced.

[0182] Since the cost and assembly of the above-mentioned "fully adjustable needle" are unbearable in semiconductor plastic packaging, the present scheme adopts a hybrid structure of floating core pulling plate and locally adjustable core pulling needle to obtain the necessary flexibility and controllable cost; and in order to overcome the multi-point coupling and uncertain posture brought by floating, an online joint adjustment method based on sensing-mapping-disturbance identification-gradient descent / weighted least squares is adopted, so that the pressure of the four corners of the core pulling plate and the overall imbalance can still quickly converge to the target interval under the working condition fluctuation, thereby realizing high consistency and high yield of the pressure holding control without significantly increasing the hardware complexity.

[0183] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A chip package core pulling needle holding device arranged on a core pulling press of a semiconductor plastic package mold, an upper mold assembly and a lower mold assembly of the core pulling press being driven to realize a mold closing and opening action by a core pulling power device under the control of a central control unit, characterized in that the chip package core pulling needle holding device comprises: an upper mold base on which the core pulling power device is arranged; a driving plate connected with the core pulling power device, the driving plate being used to move up and down by the core pulling power device; and core pulling rods distributed below the driving plate, upper ends of the core pulling rods being connected with the lower side of the driving plate, lower ends of the core pulling rods being connected with a core pulling plate arranged to abut against a core substrate, the core pulling plate being used to move with the driving plate to make the core pulling plate abut against or separate from the core substrate or an island. 2.A chip package core pulling needle holding device according to claim 1, characterized in that the elastic connection group comprises: a connecting seat, one side of the connecting seat being detachably connected with the core pulling plate; a connecting rod, the connecting rod being movably arranged on the connecting seat, an upper end of the connecting rod being detachably connected with the lower end of the core pulling rod, and the relative position of the connecting rod and the core pulling rod in the axial direction being adjustable; and a first spring, the first spring being sleeved on the connecting rod and being distributed on the upper and lower sides of the connecting seat, so that the connecting seat can extrude the first spring when moving up and down. 3.A chip package core pulling needle holding device according to claim 2, characterized in that at least four core pulling rods are distributed at four corners of the core pulling plate, wherein two connecting seats are arranged on the two sides of the core pulling plate respectively, two connecting rods are arranged on one connecting seat to make the two sides of the core pulling plate swing elastically in cooperation, or two connecting seats are arranged on the two sides of the core pulling plate respectively, and one connecting rod is arranged on one connecting seat to make the four corners of the core pulling plate swing elastically in cooperation. 4.A chip package core pulling needle holding device according to claim 1, characterized in that the driving plate and the upper ends of the core pulling rods are movably connected in the axial direction of the core pulling rods, an online pressure regulating unit being arranged at the movable connection position. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The core pulling plate is provided with a plurality of core pulling needles, at least part of which are adjustable core pulling needles with adjustable pressure holding function; The adjustable core pulling needle comprises: a base provided on the core pulling plate; a needle rod movably provided on the base and capable of sliding along the axial direction relative to the base; an elastic adjusting unit provided between the base and the needle rod for adjustable control of the pressure holding force of the needle rod and / or the distance between the end of the needle rod and the base.

5. The core pulling needle pressure holding device for chip packaging according to claim 4, wherein the elastic adjusting unit comprises: a spring barrel, the upper end of which is threadedly connected with the downwardly extending screw rod of the base, the screw rod being partially inserted into the spring barrel, the lower end of the spring barrel being slidingly connected with the outer circle of the needle rod, the upper segment of the needle rod being inserted into the spring barrel and being sleeved with and slidingly connected with the screw rod; a second spring, the upper segment of the needle rod being sleeved with the second spring, the upper end of the second spring being connected with the lower end of the screw rod, and the lower end of the second spring being connected with the upper side of the bottom plate of the spring barrel, for extruding the spring when the screw rod is rotated.

6. A method of holding a core of a chip package with a core extraction needle, characterized by The core pulling needle pressure holding method for chip packaging comprises the following operations by using the core pulling needle pressure holding device for chip packaging according to any one of claims 1-5: presetting the target pressure range and the maximum pressure deviation threshold value of each core pulling rod as the pressure adjustment reference; collecting the actual pressure values of the core pulling rods in real time through the pressure sensors arranged on the core pulling rods; calculating the pressure deviation between the actual pressure and the target pressure of each core pulling rod and obtaining the overall imbalance value for representing the degree of pressure difference between the core pulling rods; when the pressure deviation of any core pulling rod exceeds the maximum pressure deviation threshold value or the overall imbalance value exceeds the imbalance threshold value, starting the online pressure adjusting unit to adjust the pressure applied to each core pulling rod by the online pressure adjusting unit to reduce the pressure deviation and the overall imbalance value.

7. The method of claim 6, wherein the core pin is pressed by a core pin presser. Specifically comprising the following operations: S0. presetting the target pressure range of each core pulling rod, setting the target pressure of the core pulling rod, the adjusting range of the gas spring, the maximum adjustment amount, the overall maximum imbalance threshold value, the linear fitting residual threshold value and the noise allowance threshold value; S1. obtaining the actual pressure values of the core pulling rods through the pressure sensors, sampling multiple times at the same position and taking the average to obtain the actual pressure, and calculating the standard deviation of the core pulling rod pressure sampling as the noise size, if the noise size is less than or equal to the noise allowance threshold value, it is determined that the noise is within the allowable range; S2. disturbance identification, including applying disturbance to a single gas spring and measuring the pressure change of each core pulling rod to form an influence matrix; if the condition number of the matrix is less than or equal to the condition number threshold value and the fitting residual is less than or equal to the linear fitting residual threshold value, it is determined that the linear relationship is reliable; S3. comparing the actual pressure and the target pressure of each core pulling rod to obtain the pressure deviation value, and determining the overall imbalance value according to the pressure deviation value of each core pulling rod for representing the degree of pressure difference between the core pulling rods. If the calculated maximum pressure deviation value is greater than or equal to the deviation allowed threshold value, or the noise size is greater than the noise allowed threshold value, or the condition number of the matrix is greater than the condition number threshold value, the gradient descent method is used for coarse adjustment, and the gas springs are adjusted one by one or simultaneously; If the calculated maximum pressure deviation value is less than the deviation allowed threshold value, and the noise size is less than or equal to the noise allowed threshold value, and the condition number of the matrix is less than or equal to the condition number threshold value, and the fitting residual is less than or equal to the linear fitting residual threshold value, the weighted least squares method is used to calculate the joint adjustment amount based on the matrix, and each gas spring is adjusted; S4. Recalculating the pressure after adjustment; If all the core-pulling rods meet the condition that the actual pressure is within the target pressure range, and the adjustment amount of two consecutive cycles is less than or equal to the minimum adjustment threshold value, it is determined that the convergence is reached and the pressure holding operation stage is entered; If the pressure of a core-pulling rod exceeds the allowed maximum target pressure value, or the overall imbalance is greater than the overall maximum imbalance threshold value and the continuous two adjustments are invalid, the last safe setting is rolled back and the single maximum adjustment step and the learning rate are reduced, and the sampling and adjustment are re-executed. When the product is replaced or the mold temperature fluctuation exceeds the set threshold value or the condition number of the matrix exceeds the condition number threshold value, the disturbance identification is re-executed to update the influence matrix.

8. The core-pulling needle pressure holding method of claim 7, wherein, When the coarse adjustment condition and the fine adjustment condition are met at the same time, the following priority order is executed: Determine whether the maximum pressure deviation is greater than the deviation allowed threshold value, if so, the gradient descent method is preferentially executed for coarse adjustment until the pressure deviation of all core-pulling rods is less than the deviation allowed threshold value; After completing the coarse adjustment and meeting the condition that the maximum pressure deviation is less than the deviation allowed threshold value, the weighted least squares method is executed for fine adjustment to finally stabilize the pressure of all core-pulling rods within the target pressure range.

9. The core-pulling needle pressure holding method of claim 8, wherein, A pressure mapping model of the sensor measured pressure value and the actual pressure of the core-pulling rod acting on the connecting seat on the side of the core-pulling plate is established, including: M0. In the device installation and debugging phase, the known standard load L is applied to the core-pulling rod one by one k , k = 1…n, n is the number of core-pulling rods, and the corresponding gas spring pressure sensor output value S is recorded at the same time k , for establishing calibration reference; M1. According to the known load L k With the sensor output S k A linear or piecewise linear fitting relationship is established: P i =α i ·S i +β i ; P i is the actual acting pressure of the i-th core rod on the core plate; S i is the measured value of the i-th core rod corresponding sensor; a i is a proportionality factor; β i is the offset correction amount; M2. Real-time calculation of actual pressure, including in the running process, real-time acquisition of sensor output value , into the mapping formula: =α i · +β i ； Obtaining the real-time actual pressure of the core-pulling rod; M3. The calculated as the actual pressure value.

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