TWI718770B - Micro-electromechanical structure of probe card of image sensor chip - Google Patents

Abstract

A micro-electromechanical structure of a probe card of an image sensing chip includes a circuit board fixed together from top to bottom, a spacer fixed plate, and a probe carrier. A plurality of probes are horizontally fixed on the probe slide. A plurality of elastic thimble pins are confined in the spaced fixing plate, and the upper and lower ends of each elastic thimble are respectively electrically connected to the circuit contacts of the circuit board and the corresponding probes. One end of the probe has a downward tip and the body has a plurality of downwardly facing first positioning pillars and second positioning pillars. The probe carrier has a positioning group composed of a plurality of positioning holes corresponding to each probe. The positioning pillar and the second positioning pillar are located in the opposite positioning holes, and the probe tip can contact the wafer to be tested. The probe is processed by the micro-electromechanical process and is carried by the probe carrier. It is suitable for the back focus distance less than Test operation of 3mm image sensor chip.

Description

Micro-electromechanical structure of probe card of image sensor chip

The present invention relates to the technical field of a probe card for an image sensor chip, and in particular refers to a probe using a microelectromechanical structure to make it suitable for testing image sensor chips with a back focal length of less than 3 mm.

Nowadays, digital imaging technology continues to innovate and change, especially in the development of miniaturization of digital camera carriers such as digital cameras and mobile phones, and the longitudinal size of the internal camera module can be less than 8mm. In order to meet this requirement, the image sensor chip of the optical system is nothing more than a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor Sensor (CMOS Sensor). The matched optical lens group uses a multi-element lens structure, such as 4 elements, 5 elements, or even up to 7 elements, thereby shortening the back focal length between the optical lens group and the image sensor chip, and further reducing the size.

"Back focal length" refers to the distance from the vertex of the last optical surface of the optical lens group to the rear focal point. The back focal length of the technology can reach under 3mm in recent days. Relatively speaking, the test operation of this kind of image sensor chip must be carried out within this distance. The current probe molding methods used for this type of probe card are mainly divided into two categories: 1. It is made by thin film deposition technology; 2. It is directly formed on the substrate by micro-electromechanical process; but the equipment investment cost required for the above two Higher. For this reason, the inventor designed a micro-electromechanical structure of the probe card of the image sensor chip.

The main purpose of the present invention is to provide a micro-electro-mechanical structure of the probe card of the image sensor chip, which is mainly to provide a multi-layer stacked combination structure to reduce the longitudinal size of the probe head, and in addition, it is equipped with the micro-electro-mechanical manufacturing process. The micro-probe is used to fix the probe in a horizontal manner, so that in an environment with a small back focus, the cantilevered tip of the probe still maintains elasticity and strength, ensuring that a good electrical connection is maintained during testing.

To achieve the above objective, the present invention provides a micro-electromechanical structure of a probe card of an image sensor chip, which includes a circuit board fixed together from top to bottom, a spacer plate, and a probe carrier. A plurality of probes are horizontally fixed on the probe slide. Multiple elastic thimble pins are confined in the spaced fixed plate, and the upper and lower ends of each elastic thimble are electrically connected to the circuit contacts of the circuit board and the corresponding probe; one end of the probe has a downwardly bent tip and a body There are a plurality of downwardly facing first positioning pillars and second positioning pillars. The probe slide has multiple positioning groups corresponding to multiple probes, each positioning group is composed of multiple positioning holes, and the first positioning pillar and the second positioning pillar of each probe are located in the corresponding positioning groups. In the positioning hole, the tip can be in contact with the wafer to be tested.

In a preferred embodiment of the present invention, the circuit board has at least one upper window, and the lower surface of the circuit board around the upper window has a plurality of circuit contacts; the spacer fixing plate has at least one middle window, and the spacer fixing plate is around the middle window A plurality of limiting holes are distributed; the probe carrier has at least a lower layer window, and at least one accommodating area is provided on the upper surface of the probe carrier around the lower window; a plurality of probes are fixed in the accommodating area, elastic The thimble is located in the corresponding limit hole, and the upper and lower ends of each elastic thimble are pressed on the circuit contact and the probe to form an electrical connection.

In a preferred embodiment of the present invention, the probe is fixed in the recessed accommodating area with a cement, and the composition of the cement includes resin or a mixture of resin and ceramic powder.

In a preferred embodiment of the present invention, the probe carrier sheet includes an upper layer sheet and a lower layer sheet which are stacked and glued. Radial positioning groups, each positioning group is composed of a plurality of positioning holes, the upper layer sheet is connected with a plurality of notches around the lower layer window, and the notches form a accommodating area after the upper layer sheet and the lower layer sheet are combined.

In a preferred embodiment of the present invention, the multiple positioning holes of each positioning group are not in the same linear position.

In a preferred embodiment of the present invention, the probe is flat, and the tip is curved and connected by a rib.

In the preferred implementation of the present invention, the spacer and the probe carrier are made of at least one of silicon nitride, silicon carbide, zirconia, and aluminum oxide.

In summary, the micro-electromechanical structure of the probe card of the image sensor chip of the present invention has the following specific functions: 1. The probe carrier of the present invention uses a high-hardness sheet to carry small-sized probes. The needle is a small-sized micro-probe processed by a micro-electromechanical process. The tip of the probe has ribs to increase the strength, so that the probe can maintain strength and flexibility on the one hand, and on the other hand, it can reduce the longitudinal size to achieve a short back focus space. 2. The probe slide of the present invention has multiple positioning groups, and each positioning group is composed of multiple positioning holes. The multiple positioning holes make it easier to fix the probe on the probe slide without using The aid of the jig speeds up the completion of the assembly work; 3. The present invention uses multiple positioning holes to fix the probe, and then guide the probe to bend, so that the distance between the ends of two adjacent probes can be increased, and the end of the probe can be adjusted Position, which helps design and adjust flexibility The contact position of the thimble with the probe and the circuit board is very helpful under the requirement of today's small-sized image sensor chip with hundreds of contacts that must be electrically contacted; 4. The probe carrier can be insulated The material is composed of, in the case of short back focus, it can block the high temperature heat transfer of the image sensor chip during testing, and reduce the impact of thermal expansion and contraction on the cement composed of resin. During subsequent testing, it will not There is a problem that the wafer probe mark (Wafer Probe Mark) is large and small due to thermal expansion and contraction, and the overall service life is prolonged.

The following describes the implementation of the present invention in more detail with the drawings and component symbols, so that those who are familiar with the art can implement it after studying this specification.

1: circuit board

11: Circuit contact

12: Upper window

2: Interval fixed plate

21: Middle window

22: Limit hole

23: Reinforcement area

3: Probe slide

31: Positioning group

311: positioning hole

32: Lower window

33: containment area

34: upper layer piece

341: Gap

35: lower layer

4: Cantilever probe

41: Tip

42: The first positioning column

43: second positioning column

44: rib

5: Elastic thimble

6: Cement

7: Test machine

71: light source

72: diffuser

73: Optical lens group

8: Image sensor chip

Figure 1 is a schematic cross-sectional view of the present invention; Figure 2 is a schematic cross-sectional view of the structure when the present invention is applied to an image sensor chip; Figure 3 is a partially enlarged perspective view of the present invention; Figure 4 is a probe carrier of the present invention with probes fixed Fig. 5 is a partial enlarged and exploded schematic view of the probe carrier of the present invention; Fig. 6 is an exploded view of the probe carrier of the present invention; Fig. 7 is a three-dimensional view of the spacer fixing plate and the probe carrier of the present invention after assembly Schematic.

As shown in FIG. 1 and FIG. 2, respectively, the cross-sectional view of the present invention and the schematic cross-sectional view of the structure when applied to the image sensor chip. The micro-electromechanical structure of the probe card of the image sensor chip of the present invention mainly refers to The structure of the probe head includes a circuit board 1, a spacer plate 2, a probe carrier 3, a plurality of probes 4, and a plurality of elastic thimbles 5. The circuit board 1, the spacer fixing plate 2, and the probe carrier 3 are stacked and fixed together from top to bottom. A plurality of probes 4 are partially fixed on the probe slide 3 in a horizontal manner. A plurality of elastic thimbles 5 are confined in the spacer plate 2, and the upper and lower ends of each elastic thimble 5 are electrically connected to the circuit contact 11 of the circuit board 1 and the corresponding probe 4. One end of the probe 4 has a downwardly curved tip 41 and the body has a plurality of downwardly facing first positioning posts 42 and at least one second positioning post 43. The probe carrier 3 has a plurality of positioning groups 31 corresponding to a plurality of probes 4, and each positioning group 31 is composed of a plurality of positioning holes 311, and the first positioning pillars 42 and the second positioning pillars 43 are located in the corresponding plurality of positioning In the hole 311, the position of the probe 4 is thereby fixed, so that the tip 41 can contact the wafer to be tested. The front end of the probe 4 extends in a cantilever shape and can be slightly bent upward to maintain elasticity and maintain pressure after contact. The present invention utilizes the probe 4 processed by the micro-electromechanical manufacturing process and reduces the longitudinal size of the probe carrier 3 so that the probe 4 can enter the working environment with a back focus distance of less than 3 mm to perform test operations on the image sensor wafer.

Next, a detailed description of the structure of each component is given: the circuit board 1 is responsible for combining with the testing machine to perform related testing of the image sensor chip. The bottom surface of the circuit board 1 has a plurality of circuit contacts 11, and the circuit contacts 11 are electrically connected to the corresponding probes 4 via the elastic thimble 5. Since the present invention is used for the test of image sensor chips, the circuit board 1 has at least one upper window 12 for installing an optical lens set. In addition, the test machine will also provide a light source to simulate the actual operating environment. To test whether the image sensor chip is a good product, the detailed operation method will be described later. An upper window 12 represents a test area of an image sensor chip, and only one is shown in the figure. In fact, there are many upper windows 12 on a circuit board 1. Each upper window 12 has a plurality of circuit contacts 11 corresponding to the number and position on the lower surface of the circuit board 1.

Please refer to FIG. 3 together. The spacer plate 2 is used to increase the strength of the probe carrier 3, and the elastic thimble 5 is arranged as an intermediate electrical connector (Interposer), so that the signal of the circuit board 1 can be elastic The thimble 5 is received by the probe 4, and the signal can also be smoothly transmitted back to the testing machine for interpretation. The spacing fixing plate 2 has at least one middle window 21 for the optical lens group to pass through. A plurality of limiting holes 22 are distributed around the middle window 21 in the spacer fixing plate 2. Each elastic thimble 5 is located in the corresponding limit hole 22. The elastic thimble 5 can choose POGO PIN commonly used in the semiconductor industry, such as pogo pins, spring pins, spring probes and other electrical connectors. The elasticity that can be compressed and restored in the vertical direction is used to make the upper and lower ends of each elastic thimble 5 They are respectively mounted on the circuit contact 11 and the probe 4 to form an electrical connection.

In this embodiment, the thickness of the spacer plate 2 is less than 5mm, actually only 3.5mm or less. Therefore, it must have high strength and low thermal expansion characteristics. It can be made of at least one of silicon nitride, silicon carbide, zirconia, and alumina. Made of materials. The spacing fixing plate 2 can be processed from a single plate body, or for processing convenience, it can also be processed by multiple thin plates and then pasted and fixed into a single structure. The spacer plate 2 has the function of increasing the strength of the probe carrier 3. In this embodiment, it includes a reinforcing area 23. The size and shape of the reinforcing area 23 are similar to those of the probe carrier 3, and the reinforcing area 23 can be extended to the optics during assembly. Below the lens group.

Please also refer to FIG. 5. In this embodiment, the probe 4 is a flat metal probe processed by a microelectromechanical manufacturing process. One end of the probe 4 has a downwardly curved tip 41 and the body has a plurality of downwardly facing first positioning posts 42 and at least one second positioning post 43. The tip 41 is connected to the body of the probe 4 with a rib 44 to increase the strength of the area where the tip 41 is located. The distribution position of the first positioning post 42 is close to the tip 41, and the number is at least two. In this embodiment, there are three. The first positioning post 42 is used to maintain the tip 41 in the correct position during fixation. At least one second fixing post 43 is provided, and in this embodiment, there are multiple and equally spaced. As shown in Fig. 5, the probe 4 is thin and can be bent. Using multiple second positioning posts 43 installed in the positioning holes 311 that are not in the same straight line, the position of the end of the probe 4 can be adjusted to increase adjacent positions. The distance between the ends of the two probes 4 makes it easier to design and adjust the contact position of the elastic thimble 5 and the probe 4.

The present invention adopts a probe carrier 3 to carry a plurality of probes 4, the longitudinal dimension of the probe 4 is less than or equal to 1mm, and in this embodiment is less than or equal to 0.5mm, so that the back focal length is less than 3mm and the size of the optical lens group is large. Under the conditions, the present invention can overcome the problem of poor strength of the probe 4 due to too long dangling distance, ensure the strength of the probe 4 and perform related electrical contacts and tests. Please also refer to FIG. 4, the probe carrier 3 has at least a lower layer window 32, where light can be projected to the chip under test, so the shape and size of the lower window 32 are larger than the chip under test. At least one recessed accommodating area 33 is formed on the probe carrier 3 around the lower window 32, and each accommodating area 33 is provided with multiple positioning groups 31 (as shown in FIGS. 5 and 6). A plurality of positioning holes 311 are provided in the group positioning group 31. The number of positioning groups 31 is the same as the number of probes 4 to be installed. When assembling, the tip 41 with the front end of the probe 4 bent downwards extends downward through the lower window 32, and the first positioning pillar 42 and the second positioning pillar 43 are located in the corresponding positioning holes 311, so that the plurality of probes 4 are fixed to In the accommodating area 33. The probe 4 after positioning is partially fixed by a cement 6 (as shown in FIG. 1 to FIG. 3), and the cement 6 may be composed of resin or a mixture of resin and ceramic powder. The fixed probe 4 is in the shape of a cantilever, and its front end can still slightly rise upwards, maintaining elasticity and maintaining pressure after contact.

As shown in FIG. 5, in this embodiment, the multiple positioning holes 311 are arranged non-linearly. The plurality of first positioning posts 42 of the probe 4 are located in the corresponding positioning holes 311, so that the two adjacent tips 41 are close to each other but not in contact, and correspond to the corresponding connections on the image sensor chip. point. However, the rear section of the probe 4 is sequentially offset by a plurality of second positioning posts 43, thereby increasing the interval between the ends of two adjacent probes 4, which facilitates the subsequent contact of the elastic thimble 5 with it.

In this embodiment, the thickness of the probe carrier 3 is less than 1mm, which is actually less than or equal to 0.5mm. Therefore, it must also have high strength and low thermal expansion characteristics. It can be made of silicon nitride, silicon carbide, and oxygen. It is composed of at least one of zirconium and alumina. In addition, for the convenience of processing in this embodiment, as shown in FIGS. 4 and 6, the probe carrier 3 includes an upper layer 34 and a lower layer 35 stacked and solidified. Although both the upper layer sheet 34 and the lower layer sheet 35 have the lower layer windows 32 located opposite to each other, the shapes are not the same. The upper layer piece 34 is further connected with a plurality of notches 341 around the lower layer window 32. The notches 341 form the accommodating area 33 after the upper layer piece 34 and the lower layer piece 35 are combined. The lower-layer sheet 35 is distributed around the lower window 32 with a plurality of radial positioning groups 31, and each positioning group 31 is composed of a plurality of positioning holes 311.

Next, the assembly method of the present invention will be explained. First, the processed upper layer sheet 34 and the lower layer sheet 35 are cemented to form the probe carrier sheet 3. The plurality of probes 4 are inserted into the corresponding positioning holes 311 of the probe carrier 3 with the first positioning posts 42 and the second positioning posts 43, and the plurality of probes 4 are sequentially fixed on the probe carrier 3, and the probe The tip 41 of the needle 4 protrudes downward through the lower window 32 in a cantilever shape, and then can be preliminarily fixed with the material of the cement 6 such as resin. Then stack the spacer plate 2 on the probe carrier 3, put a plurality of elastic thimbles 5 into the corresponding limit holes 22, and then assemble the circuit board 1 on the spacer plate 2, using bolts to penetrate the circuit board 1. The spacer plate 2 and the probe carrier 3 are locked to ensure that the two ends of the elastic thimble 5 are electrically connected to the circuit board 1 and the probe 4, and the overall assembly can be completed. Although only a single set of test structures is shown in the figure, it is actually a structure formed by stacking the circuit board 1, the spacer plate 2 and the probe carrier 3, and multiple test structures are distributed at the same time, which can detect multiple images at the same time. Test the wafer for testing. In addition, the size of the circuit board 1, the spacer plate 2, and the probe carrier 3 are approximately the same, and the strength of the stacked structure is better.

As shown in FIG. 7, it is a schematic diagram of the actual operation of the present invention. The present invention is mainly used for the test of the image sensor chip. The circuit board 1 is combined with the testing machine 7. The testing machine 7 longitudinally includes a light source 71, a diffuser 72 and an optical lens group 73. The wafer is located at the lowermost position, and the surface of the wafer has a plurality of image sensor chips 8 (only one is shown in the figure). During the test, the light provided by the lamp source 71 is projected onto the image sensor chip 8 through the diffuser 72 and the optical lens group 73. In this embodiment, the optical mirror The back focal length between the head group 73 and the image sensor chip 8 is less than 3 mm. Using the design of the present invention, the longitudinal dimension of the probe carrier 3 and the reinforcing area 23 is less than 2mm, or even only 1.5mm, which can carry the probe 4 to extend under the optical lens group 73, and then contact the image sensor chip 8 for correlation. Test to meet the needs of manufacturers.

The above descriptions are only used to explain the preferred embodiments of the present invention, and are not intended to restrict the present invention in any form. Therefore, any modification or change related to the present invention is made under the same spirit of the invention. , Should still be included in the scope of the present invention's intention to protect.

1: circuit board

11: Circuit contact

2: Interval fixed plate

22: Limit hole

3: Probe slide

31: Positioning group

311: positioning hole

33: containment area

34: upper layer piece

35: lower layer

4: Cantilever probe

41: Tip

42: The first positioning column

43: second positioning column

44: rib

5: Elastic thimble

6: Cement

Claims (7)

A micro-electromechanical structure of a probe card of an image sensor chip, comprising a circuit board, a spacer fixing plate, and a probe carrier that are fixed together from top to bottom; a plurality of probes are partially fixed to the probe in a horizontal manner A plurality of elastic thimble pins are confined in the spacer fixed plate, and the upper and lower ends of each elastic thimble are electrically connected to the circuit contacts of the circuit board and the corresponding probe; one end of the probe has The tip is bent downward and the body has a plurality of first positioning pillars and a second positioning pillar facing downwards. The probe carrier has a plurality of positioning groups corresponding to a plurality of the probes, and each positioning group consists of a plurality of positioning The first positioning post and the second positioning post of each probe are located in a plurality of the positioning holes of the corresponding positioning group, the tip can contact the wafer to be tested, and at least one of the positioning group There are at least three positioning holes, and the distribution positions of multiple positioning holes are not on the same straight line. When the probe installed here is located in the corresponding positioning holes by the first positioning pillar and the second positioning pillar, the The probe is curved. According to the micro-electromechanical structure of the probe card of the image sensor chip described in the first item of the patent application, the circuit board has at least one upper window, and the lower surface of the circuit board around the upper window has a plurality of the circuit contacts The spacer fixing plate has at least one middle window, and the spacer fixing plate has a plurality of limiting holes distributed around the middle window; the probe carrier has at least a lower window, on the probe carrier around the lower window The surface is provided with at least one accommodating area, a plurality of the positioning groups are located in the accommodating area; a plurality of the probes are fixed in the accommodating area, the elastic thimble is located in the corresponding limit hole, and The upper and lower ends of each elastic thimble are pressed on the circuit contact and the probe to form an electrical connection. The micro-electromechanical structure of the probe card of the image sensor chip described in the scope of the patent application, wherein the probe is fixed on the probe carrier with a cement, and the cement is composed of resin or resin and Mixture of ceramic powder. The micro-electromechanical structure of the probe card of the image sensor chip described in the scope of the patent application, wherein the probe carrier sheet includes an upper layer sheet and a lower layer sheet stacked and bonded, the upper layer sheet and the lower layer sheet All have the lower window, the lower sheet is distributed with a plurality of radial positioning groups centered on the lower window, each positioning group is composed of a plurality of positioning holes, and the upper sheet is placed around the lower window. A plurality of notches are connected, and the notches form the accommodating area after the upper layer sheet is combined with the lower layer sheet. The microelectromechanical structure of the probe card of the image sensor chip described in the first item of the patent application, wherein the spacer fixing plate is made of at least one of silicon nitride, silicon carbide, zirconia, and alumina. According to the MEMS structure of the probe card of the image sensor chip described in the first item of the patent application, the probe carrier is made of at least one of silicon nitride, silicon carbide, zirconia, and aluminum oxide. According to the micro-electromechanical structure of the probe card of the image sensor chip described in the first item of the patent application, the tip and the probe body are further connected with a rib, and the rib increases the strength of the region where the tip is located.

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