TWI834227B - Probe preheating method for wafer-level probe card - Google Patents

Abstract

A probe card, a plurality of probes on the probe card, a wafer carrier that can move linearly, A test machine is electrically connected to the probe card. The tips of all probes together form a probe card tip. The wafer carrier carries a wafer. The surface of the wafer with circuits faces the probe card tip. . The test machine controls the wafer carrier to move in the direction of the probe card until a first needle tip of the probe card directly contacts the surface of the wafer, and then controls the wafer carrier to move in the direction of the probe card. Move a non-contact safety distance away from the probe card to a safe height, then stop for a safety preheating time, and then repeat the above actions until the wafer carrier moves a non-contact effective distance away from the probe card. After reaching an effective height, it remains stationary for an effective preheating time.

Description

Probe preheating method for wafer-level probe card

A probe preheating method, especially a probe preheating method for a wafer-level probe card.

When testing multiple integrated circuit (IC) products on a wafer (also known as wafer-level IC testing), depending on the characteristics and specification requirements of the IC products, they are usually tested at different temperatures, such as Conduct IC testing in normal, high or low temperature environments. When testing multiple IC products on a wafer, a test fixture is required to make signal connections (or electrical connections) between multiple pins of the multiple IC products and a test machine. Therefore, the test The fixture usually has many precision probes, so the test fixture is generally called a probe card. The needle tips of the multiple probes on the probe card must be in direct contact with multiple pins of the IC product to form signal connections (or electrical connections) between them. The needle tips of the multiple probes on the probe card must be in direct contact with multiple pins of the IC product. Consists of probe card tips. When the probe card tip is used for IC testing at different temperatures, due to the physical phenomenon of thermal expansion and contraction, the position of the probe card tip will change with different test temperatures, so there are many problems on the wafer. When an IC product is to be mass-produced and tested, if the temperature of the probe card is different from the temperature of the test to be carried out, the probe card needs to be preheated or pre-cooled first so that the overall temperature of the probe card is consistent with the temperature of the test to be carried out. The temperature of the test is the same to ensure that the tip position of the probe card reaches a stable state before mass production testing can be carried out to avoid damage to the tip of the probe card and the pins of the IC product caused by preheating or pre-cooling of the probe card. problem.

When the current probe card is preheating/precooling, a wafer chuck is used to fix the wafer to be tested, and the probe card is set on the wafer without contacting the wafer to be tested. The probe card tip is preheated/precooled at a fixed height from the wafer to be tested. However, if the material or structure of the probe card tip itself has a large change in temperature, then the The preheating/precooling method in which the probe card is set at a fixed height and does not contact the wafer to be tested will not be able to effectively stabilize the position of the probe card tip. However, if the probe card tip directly contacts the wafer to be tested, The probe card tip is preheated in a certain way, and due to the phenomenon of thermal expansion and cold contraction, the risk of damage to the probe card tip will be greatly increased. And if the test pin pressure is applied to the probe card tip to test the wafer to be tested before the position of the probe card tip reaches a stable state (that is, the probe temperature of the probe card is still changing significantly), then the wafer to be tested will be tested. During the wafer testing process, various problems may arise due to the continuous changes of the probe card tip after contacting the electrode bump/pad of the wafer to be tested. For example, during high temperature testing, the probe card tip will continue to change. The needle tip continues to expand when exposed to heat, resulting in poor needle position of the probe card needle tip, resulting in an excessive needle mark area. For example, during low-temperature testing, the probe card needle tip continues to shrink when exposed to cold, resulting in insufficient needle pressure, resulting in test failure. The problem of accidental slaughter.

In view of this, it is urgent to preheat/precool the probe card tip more effectively to reduce the above-mentioned risks of probe card tip damage, poor needle position, excessive needle mark area, and insufficient needle pressure. need.

In order to solve the above problems, the present invention discloses a probe preheating method for a wafer-level probe card, which includes the following technical contents: providing: a probe card, a plurality of probes fixed on the probe card, A wafer carrier that can move linearly, and a test machine electrically connected to the probe card, in which the tips of all probes fixed on the probe card jointly form a probe card tip, and the wafer The carrier plate is used to carry a wafer, and a surface of the wafer with an integrated circuit (IC) faces the tip of the probe card. The method includes the following steps: Step 1: The test machine controls the wafer The carrier plate moves in the direction of the probe card until a first needle tip of the probe card directly contacts the surface of the wafer. At this time, the height of the wafer carrier plate is a safe starting height. ; Step 2: The test machine controls the wafer carrier to move a non-contact safe distance away from the probe card to a safe height. At this time, the tip of the probe card is not in direct contact with the surface of the wafer. ; Step 3: The test machine controls the wafer carrier to stand still for a safe preheating time, in which the temperature of the wafer is transmitted to the tip of the probe card through thermal radiation and heat convection; Step 4: The test machine controls The wafer carrier moves toward the direction of the probe card until a first needle tip of the probe card directly contacts the surface of the wafer. At this time, the height of the wafer carrier is an effective Starting height; Step 5: The test machine controls the wafer carrier to move a non-contact effective distance away from the probe card to an effective height. At this time, the tip of the probe card is in contact with the surface of the wafer. There is no direct contact, and the non-contact effective distance is smaller than the non-contact safety distance; Step 6: The test machine controls the wafer carrier to be stationary for an effective preheating time, in which the temperature of the wafer is determined by thermal radiation and thermal convection. to the tip of the probe card.

Preferably, the method also includes the following steps: Step 7: The testing machine controls the wafer carrier to move in the direction of the probe card, so that a first tip of the probe card tip is in contact with the wafer. until the surface is in direct contact, at this time the height of the wafer carrier is a stable starting height; Step 8: The test machine controls the wafer carrier to move a stable contact distance in the direction of the probe card to a stable contact distance Stable height, at this time, the tip of the probe card is in direct contact with the surface of the wafer; Step 9: The test machine controls the wafer carrier to remain stationary for a stable preheating time, in which the temperature of the wafer is determined by thermal conduction to the tip of the probe card.

Preferably, the method also includes the following steps: Step 10: The testing machine assigns the value of the stable starting height to a previous stability judgment starting height; Step 11: The testing machine controls the wafer load The disk moves away from the probe card until the tip of the probe card is not in direct contact with the surface of the wafer, and then controls the wafer carrier disk to move toward the surface of the wafer. The direction of the probe card is moved until a first tip of the probe card tip is in direct contact with the surface of the wafer. At this time, the height of the wafer carrier is a stability judgment starting height; step 12 : The test machine controls the wafer carrier to move a stability judgment contact distance to a stability judgment height in the direction of the probe card. At this time, the tip of the probe card is in direct contact with the surface of the wafer; Step 13: The test machine controls the wafer carrier to remain stationary for a stability judgment time; Step 14: The test machine compares the starting height of the stability judgment with the starting height of the previous stability judgment. If The height difference between the two is less than a second contact threshold, and the process ends; Step 15: If the height difference between the two is greater than or equal to the second contact threshold, the testing machine determines the stability The value of the starting height is assigned to the starting height of the previous stability judgment and returns to step 11.

According to the probe preheating method of the wafer-level probe card disclosed in the present invention, it first goes through two non-contact preheating/precooling steps, then enters a contact preheating/precooling step, and finally Only then enters a contact stability judgment process, that is, the probe preheating method of the wafer level probe card disclosed in the present invention performs the probe preheating of the wafer level probe card in a progressive manner, so that It can not only make the probe card tip reach a stable state in a short time, but also avoid the problem of damage to the pins of the probe card tip and IC products due to thermal expansion and cold contraction when the probe card tip comes into contact with the wafer. achieve the purpose of the present invention.

1: Wafer-level integrated circuit test system

10: Probe card

11:Probe

12: needle tip

14: Probe card tip

20:wafer

30:Wafer carrier

50:Testing machine

51:Test space

d1: non-contact safety distance

d2: Non-contact effective distance

d3: Stable contact distance

d4: Stability judgment contact distance

t1: the first time

t2: second time

t3: The third time

Figure 1 is a schematic diagram of the safety preheating/precooling steps of a wafer-level integrated circuit testing system that implements the probe preheating method of the wafer-level probe card of the present invention.

Figure 2 is a schematic diagram of the effective preheating/precooling steps of a wafer-level integrated circuit testing system that implements the probe preheating method of the wafer-level probe card of the present invention.

FIG. 3 is a schematic diagram of the stable preheating/precooling steps of a wafer-level integrated circuit testing system that implements the probe preheating method of the wafer-level probe card of the present invention.

FIG. 4 is a schematic diagram of the stability judgment procedure of the wafer-level integrated circuit testing system that implements the probe preheating method of the wafer-level probe card of the present invention.

Figure 5 is a schematic diagram of the temperature characteristic curve of the tip of the probe card.

6A and 6B are flow charts of the probe preheating method of the wafer-level probe card of the present invention.

Please refer to FIG. 1 . FIG. 1 is a wafer-level integrated circuit testing system 1 that performs the probe preheating method of the wafer-level probe card of the present invention. The wafer level integrated circuit testing system 1 includes a fixed probe card 10, a plurality of probes 11 fixed on the probe card 10, and a wafer carrier that can move up and down along the z-axis direction. The disk 30 and a testing machine 50 are electrically connected to the probe card 10 . The testing machine 50 has a sealed testing space 51 , and the probe card 10 and the wafer carrier 30 are accommodated in the testing space 51 . The wafer carrier 30 has a temperature control device and a moving mechanism that moves up and down along the z-axis direction (neither shown); the test machine 50 has a computer, a monitor, a control interface, and a test interface. And an application program can be executed to control the hardware of the wafer-level integrated circuit testing system 1 and the process of the probe preheating method of the wafer-level probe card of the present invention. The test interface of the test machine 50 is electrically connected to the probe card 10 to perform wafer-level integrated circuit testing, and the control interface of the test machine 50 is connected to the moving mechanism of the wafer carrier 30 The temperature control device is electrically connected to control the height and temperature of the wafer carrier 30 .

Each of the plurality of probes 11 has a needle tip 12 , and the needle tips 12 of all the plurality of probes 11 fixed on the probe card 10 together form a probe card tip 14 . The probe card 10 is fixed at a fixed position by a supporting mechanism (not shown). The plurality of probes 11 fixed on the probe card 10 are located on the lower side of the probe card 10 and the The needle tips 12 of the plurality of probes 11 are all facing downward (that is, against the z-axis direction). The wafer carrier 30 is located directly under the probe card 10 and the plurality of probes 11 Square, an upper side of the wafer carrier 30 can be fixed and carried a wafer 20 by a fixing mechanism (such as a suction cup, not shown), and a surface of the wafer 20 with an integrated circuit (IC) faces toward On and facing the plurality of probes 11 , the surface of the wafer 20 having the integrated circuit (IC) also has a plurality of electrode bumps/pads (bumps/pads), so the wafer carrier 30 can be moved along the Move upward in the z-axis direction, so that the probe card tip 14 is in direct contact with the plurality of electrode bumps/pads on the surface of the wafer 20, so as to form the probe card tip 14 and the plurality of electrode bumps. electrical connection between the blocks/pads, so that the test machine 50 can generate the plurality of electrode bumps/pads on the surface of the wafer 20 through the probe card 10 and the probe card tip 14 Electrical connection, so that the test machine 50 can generate a signal connection with the integrated circuit (IC) on the surface of the wafer 20, and the test machine 50 can generate a signal connection with the integrated circuit (IC) on the surface of the wafer 20. Circuits (ICs) are tested, so wafer-level integrated circuit testing can be achieved. From the above, it can be seen that the probe card 10 , the wafer carrier 30 and the wafer 20 are accommodated in the sealed environment of the test space 51 .

The test machine 50 can control the temperature of the wafer 20 at the test temperature according to a test temperature of the integrated circuit on the wafer 20 through the temperature control device of the wafer carrier 30, so that the wafer Integrated circuits above 20 can be tested at this test temperature. However, since the temperature of the probe card 10 and the plurality of probes 11 is different from the temperature of the wafer 20, when the two come into contact, the position of the probe card tip 14 will change due to thermal expansion and contraction. Changes in temperature may cause damage between the probe card tip 14 and the multiple electrode bumps/pads on the surface of the wafer 20, thus affecting the probe card tip 14 and the multiple electrodes on the surface of the wafer 20. Electrical connection between bumps/pads. Therefore, before the probe card tip 14 directly contacts the multiple electrode bumps/pads on the surface of the wafer 20, a probe preheating process is necessary to make the probe card tip 14 contact the electrode bumps/pads on the surface of the wafer 20. The multiple electrode bumps/pads have very close temperatures before direct contact to reduce thermal expansion and contraction during contact and avoid damage to the two after direct contact.

In the probe preheating method of the wafer-level probe card of the present invention, when the wafer 20 and the probe card tip 14 are in direct contact, the temperature of the wafer 20 is mainly transmitted to the probe through thermal conduction. needle card needle tip 14 to achieve uniform temperature of the wafer 20 and the probe card needle tip 14; when the wafer 20 and the probe card needle tip 14 are very close but not in direct contact, the wafer The temperature 20 is mainly transmitted to the probe card tip 14 through thermal radiation and air heat convection to achieve uniform temperatures of the wafer 20 and the probe card tip 14 .

Please refer to Figure 5. Figure 5 shows a tip temperature characteristic curve measured through a temperature test of a probe card used in the present invention, in which the probe of the probe card is extended along the z-axis. It can be seen that from the beginning to the first time t1 (about 45 minutes), the displacement of the tip of the probe card in the z-axis direction changes the most, so the period from the beginning to the first time t1 is called a safe preheating time , and from the first time t1 to the second time t2 (about 135 minutes), the displacement of the tip of the probe card in the z-axis direction changes little, so it is said that from the first time t1 to the second time t2 The period of the second time t2 is an effective preheating time, and from the second time t2 to a third time t3 (about 150 minutes), the displacement of the tip of the probe card in the z-axis direction changes minimally. , so the period from the second time t2 to the third time t3 is called a stable preheating time, and starting from the third time t3, the displacement of the tip of the probe card in the z-axis direction is It is judged that a stable state has been reached.

Regarding the probe preheating method of the wafer-level probe card of the present invention, please refer to Figure 1. Figure 1 shows the wafer-level integrated circuit testing system of the present invention performing a safe preheating/precooling step. First, By executing the application program, the test machine 50 first moves the wafer carrier 30 upward along the z-axis direction, so that a first needle tip 12 of the probe card needle tips 14 is in contact with the wafer 20 Until an electrode bump/pad on the surface is in direct contact, for example, when the test machine 50 detects that the resistance between the probe card 10 and the wafer 20 drops sharply from a high impedance state, it can be determined that the A first needle tip 12 of the probe card needle tips 14 is in direct contact with an electrode bump/pad on the surface of the wafer 20. At this time, the height of the wafer carrier 30 is a safe starting height; then The application moves the wafer carrier 30 downward along the z-axis direction by a non-contact safety distance d1 to a safe height and then stops for a safety preheating time.

Following the above, when the wafer carrier 30 is stationary at the safe height after the safe preheating time, please refer to Figure 2. Figure 2 shows that the wafer level integrated circuit testing system of the present invention performs an effective preheating/ In the pre-cooling step, the application program again moves the wafer carrier 30 upward along the z-axis direction, so that a first tip 12 of the probe card tips 14 is in contact with a first tip 12 on the surface of the wafer 20 Until the electrode bumps/pads are in direct contact, the height of the wafer carrier 30 is an effective starting height, and then the application moves the wafer carrier 30 downward along the z-axis direction by a non-contact effective height. After reaching an effective height from d2, it remains stationary for an effective preheating time. In order to speed up the preheating/precooling time of the probe card tip 14, the non-contact effective distance d2 is smaller than the non-contact safety distance d1, and the effective preheating time is larger than the safe preheating time.

Following the above, when the wafer carrier 30 is stationary at the effective height after the effective preheating time, please refer to Figure 3. Figure 3 shows that the wafer level integrated circuit testing system of the present invention performs a stable preheating/ In the pre-cooling step, the application program again moves the wafer carrier 30 upward along the z-axis direction, so that a first tip 12 of the probe card tips 14 is in contact with a first tip 12 on the surface of the wafer 20 Until the electrode bumps/pads are in direct contact, the height of the wafer carrier 30 is a stable starting height, and then the application moves the wafer carrier 30 upward along the z-axis direction by a stable contact distance d3 After reaching a stable height, it rests for a stable preheating time. At this time, although there is direct contact between the electrode bumps/pads on the surface of the wafer 20 and the probe card tip 14, the probe card tip 14 is The pressure of the preelectrode bump/pad is adjusted in such a way that the stable contact distance d3 is less than a first contact threshold to reduce the pressure to avoid the aforementioned probe card tip 14 and the surface of the wafer 20 Issue with multiple electrode bumps/pads being damaged. In addition, in order to speed up the preheating/precooling time of the probe card tip 14, the stable preheating time is smaller than the safe preheating time.

Wherein, the sum of the safety preheating time, the effective preheating time and the stable preheating time is a total preheating time, the safety preheating time is equal to the total preheating time multiplied by a safety percentage P1%, the The effective preheating time is equal to the total preheating time multiplied by an effective percentage P2%. The stable preheating time The time is equal to the total preheating time multiplied by a stable percentage P3%, then P1%+P2%+P3%=100%, and because the effective preheating time is greater than the safe preheating time, the stable preheating time is less than The safe preheating time is as above, so P2%>P1%>P3%. Alternatively, a predetermined safety percentage P1%, an effective percentage P2%, a stable percentage P3% and a total preheating time can also be used to obtain the safe preheating time, the effective preheating time and the stable preheating time. Hot time three. It can be seen from Figure 5 that a tip temperature characteristic curve measured by a probe card through a temperature test can be used to set the safe preheating time, the effective preheating time and the stable preheating time, or by It can be seen from Figure 5 that the needle tip temperature characteristic curve can also be used to set the safety percentage P1%, the effective percentage P2%, the stable percentage P3% and the total preheating time.

Following the above, when the wafer carrier 30 is stationary at the stable height after the stable preheating time, please refer to FIG. 4 . FIG. 4 shows the wafer-level integrated circuit testing system of the present invention performing a stability judgment process. . At this time, the electrode bumps/pads on the surface of the wafer 20 and the probe card tip 14 are still in direct contact and continue to be preheated/precooled. At this time, the application program will stabilize the starting height. value is assigned to a previous stability determination starting height, and then the application moves the wafer carrier 30 downward along the z-axis direction until the probe card tip 14 is no longer in contact with the surface of the wafer 20 until the wafer carrier 30 is in direct contact, and then control the wafer carrier 30 to move upward so that a first tip of the probe card tip 14 is in direct contact with an electrode bump/pad on the surface of the wafer 20. At this time The height of the wafer carrier 30 is a stability judgment starting height, and then the application moves the wafer carrier 30 upward along the z-axis direction by a stability judgment contact distance d4 to a stability judgment height. , and then rest for a stability judgment time. At this time, there is direct contact between the electrode bumps/pads on the surface of the wafer 20 and the probe card tip 14; then the application starts the stability judgment. The height is compared with the starting height of the previous stability judgment. If the height difference between the two is less than a second contact threshold, it means that the probe card tip 14 has reached a stable state, and the application The program can automatically set the test pin pressure to start testing the wafer 20. If the height difference between the two is greater than or equal to the second contact threshold, the application program will The value of the stability judgment starting height is assigned to a previous stability judgment starting height, and then the application repeats the above process and re-compares the current stability judgment starting height with the previous stability judgment. The starting heights are both until the height difference between the two is less than the second contact threshold. In order to speed up the preheating time, the stability judgment time can be less than or equal to the stable preheating time, but the stability judgment contact distance d4 is equal to the stable contact distance d3.

Please refer to the flow chart of the probe preheating method of the wafer-level probe card of the present invention shown in FIGS. 6A and 6B. From the above, the probe preheating method of the wafer-level probe card of the present invention can be organized into the following steps: Step 1: The test machine controls the wafer carrier to move in the direction of the probe card, so that the probe Until a first needle tip among the card needles is in direct contact with the surface of the wafer, the height of the wafer carrier is a safe starting height; Step 2: The test machine controls the direction of the wafer carrier Move a non-contact safety distance away from the probe card to a safe height. At this time, the tip of the probe card is not in direct contact with the surface of the wafer; Step 3: The test machine controls the wafer carrier to remain stationary. A safe preheating time, during which the temperature of the wafer is transmitted to the tip of the probe card through heat radiation and heat convection; Step 4: The test machine controls the wafer carrier to move in the direction of the probe card, Until a first tip of the probe card tip is in direct contact with the surface of the wafer, the height of the wafer carrier is an effective starting height; Step 5: The test machine controls the wafer The circular carrier moves a non-contact effective distance away from the probe card to an effective height. At this time, the tip of the probe card is not in direct contact with the surface of the wafer, and the non-contact effective distance is smaller than the non-contact safety distance. ; Step 6: The test machine controls the wafer carrier to stand still for an effective preheating time, in which the temperature of the wafer is transmitted to the tip of the probe card through thermal radiation and thermal convection; Step 7: The test machine controls the wafer carrier to move in the direction of the probe card until a first needle tip of the probe card directly contacts the surface of the wafer. At this time, the wafer The height of the circular carrier is a stable starting height; Step 8: The test machine controls the wafer carrier to move in the direction of the probe card by a stable contact distance to a stable height. At this time, the tip of the probe card is in contact with the probe card. The surface of the wafer is in direct contact; Step 9: The test machine controls the wafer carrier to remain stationary for a stable preheating time; wherein the temperature of the wafer is transmitted to the tip of the probe card through thermal conduction; Step 10: The testing machine assigns the value of the stable starting height to a previous stability judgment starting height; Step 11: The testing machine controls the wafer carrier to move away from the probe card until Until the tip of the probe card is not in direct contact with the surface of the wafer, the wafer carrier is controlled to move in the direction of the probe card, so that a first tip of the probe card tip is in contact with the surface of the wafer. Until the surface is in direct contact, the height of the wafer carrier is a stability judgment starting height; Step 12: The test machine controls the wafer carrier to move in the direction of the probe card to a stability judgment At this time, the tip of the probe card is in direct contact with the surface of the wafer; Step 13: The test machine controls the wafer carrier to be stationary for a stability judgment time; Step 14: The test machine compares the The starting height of the stability judgment and the starting height of the previous stability judgment, if the height difference between the two is less than a second contact threshold, the process ends; Step 15: If the height difference between the two If the difference is greater than or equal to the second contact threshold, the testing machine assigns the value of the stability judgment starting height to a previous stability judgment starting height, and returns to step 11.

The probe preheating method of the wafer-level probe card disclosed in the present invention first goes through a non-contact safe preheating/precooling step and an effective preheating/precooling step to safely enter a contact type. Stable preheating/precooling steps, and finally enter a contact-type stability judgment process, which is the process disclosed by the present invention. The exposed probe preheating method of the wafer level probe card is to preheat the probe of the wafer level probe card in a gradual manner, so that the probe card tip can reach a stable state in a short time, and at the same time It also avoids the problem of damage to the pins of the probe card tip and the IC product due to thermal expansion and cold contraction when the probe card tip is in contact with the wafer, thereby achieving the purpose of the present invention.

1: Wafer-level integrated circuit test system

10: Probe card

11:Probe

12: needle tip

14: Probe card tip

20:wafer

30:Wafer carrier

50:Testing machine

51:Test space

d1: non-contact safety distance

Claims (8)

A probe preheating method for a wafer-level probe card, which provides: a probe card, a plurality of probes fixed on the probe card, a linearly movable wafer carrier, and the probe A test machine for card electrical connection, in which the tips of all probes fixed on the probe card jointly form a probe card tip. The wafer carrier is used to carry a wafer, and the wafer is A surface with an integrated circuit is facing the tip of the probe card. The method includes the following steps: Step 1: The test machine controls the wafer carrier to move in the direction of the probe card until a first needle tip of the probe card directly contacts the surface of the wafer. At this time, the wafer The height of the circular bearing plate is a safe starting height; Step 2: The test machine controls the wafer carrier to move a non-contact safe distance away from the probe card to a safe height. At this time, the tip of the probe card is not in direct contact with the surface of the wafer; Step 3: The testing machine controls the wafer carrier to remain stationary for a safe preheating time, in which the temperature of the wafer is transmitted to the tip of the probe card through thermal radiation and thermal convection; Step 4: The test machine controls the wafer carrier to move in the direction of the probe card until a first tip of the probe card is in direct contact with the surface of the wafer. At this time, the wafer The height of the circular bearing plate is an effective starting height; Step 5: The test machine controls the wafer carrier to move a non-contact effective distance away from the probe card to an effective height. At this time, the tip of the probe card is not in direct contact with the surface of the wafer. The non-contact effective distance is smaller than the non-contact safety distance; Step 6: The testing machine controls the wafer carrier to remain stationary for an effective preheating time, in which the temperature of the wafer is transmitted to the tip of the probe card through heat radiation and heat convection. The probe preheating method of the wafer-level probe card as described in claim 1, wherein, The effective preheating time is greater than the safe preheating time. The probe preheating method of the wafer-level probe card as described in claim 1, wherein, The safe preheating time is equal to a total preheating time multiplied by a safety percentage, the effective preheating time is equal to the total preheating time multiplied by an effective percentage, and the effective percentage is greater than the safety percentage. The probe preheating method of the wafer-level probe card as described in request item 1, the method also includes the following steps: Step 7: The test machine controls the wafer carrier to move in the direction of the probe card until a first needle tip of the probe card directly contacts the surface of the wafer. At this time, the wafer The height of the circular bearing plate is a stable starting height; Step 8: The test machine controls the wafer carrier to move a stable contact distance to a stable height in the direction of the probe card. At this time, the tip of the probe card is in direct contact with the surface of the wafer; Step 9: The testing machine controls the wafer carrier to remain stationary for a stable preheating time, in which the temperature of the wafer is transmitted to the tip of the probe card through thermal conduction. The probe preheating method of the wafer-level probe card as described in claim 4, wherein The stable preheating time is less than the safety preheating time, and the stable contact distance is less than a first contact threshold. The probe preheating method of the wafer-level probe card as described in claim 4, wherein, The stable preheating time is equal to a total preheating time multiplied by a stability percentage, the safe preheating time is equal to the total preheating time multiplied by a safety percentage, and the stability percentage is less than the safety percentage. The probe preheating method of the wafer-level probe card as described in request item 4 also includes the following steps: Step 10: The testing machine assigns the value of the stable starting height to a previous stability judgment starting height; Step 11: The test machine controls the wafer carrier to move away from the probe card until the tip of the probe card is not in direct contact with the surface of the wafer, and then controls the wafer carrier to move toward the probe card. The direction of the probe card is moved until a first needle tip of the probe card is in direct contact with the surface of the wafer. At this time, the height of the wafer carrier is a stability judgment starting height; Step 12: The test machine controls the wafer carrier to move in the direction of the probe card by a stability judgment contact distance to a stability judgment height. At this time, the tip of the probe card is directly connected to the surface of the wafer. get in touch with; Step 13: The testing machine controls the wafer carrier to remain stationary for a stability judgment time; Step 14: The testing machine compares the starting height of the stability judgment with the starting height of the previous stability judgment. If the height difference between the two is less than a second contact threshold, the process ends; Step 15: If the height difference between the two is greater than or equal to the second contact threshold, the testing machine assigns the value of the stability judgment starting height to a previous stability judgment starting height and returns to Step 11. The probe preheating method of the wafer-level probe card as described in claim 7, wherein The stability judgment contact distance is equal to the stable contact distance, and the stability judgment time is less than or equal to the stable preheating time.

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