A microslit detection sensor structure

Abstract

The application discloses a kind of micro gap detection sensor structures, it is related to the field of semiconductor technology, including: graphite plate, the recess for placing tin ball is equipped on the graphite plate, graphite mounting bracket is placed above the graphite plate;Graphite mounting bracket, the recess is equipped on the graphite mounting bracket surface, recess corresponds with the tin ball position on the graphite plate is placed;Light source, the light source is placed below the graphite plate, the light emitted by the light source is vertical light;Collection plate, the collection plate is placed on the graphite mounting bracket, the collection plate is equipped with the light signal receiver corresponding with the light source, when tin ball is not placed on the graphite plate, the light source passes through the graphite plate and the graphite mounting bracket and conducts light signal to the collection plate, when tin ball is placed on the graphite plate, the light source cannot pass through the graphite plate and the graphite mounting bracket and the collection plate cannot receive light signal.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging, and in particular to a micro-gap detection sensor structure. Background Technology

[0002] In the semiconductor packaging industry, ball-mounting machines are used when leading out chip solder joints. These machines are key equipment in semiconductor packaging and surface mount technology, their core function being to precisely place and fix tiny solder balls onto the pads of chips, substrates, or wafers. During operation, graphite molds are typically used to transfer the solder balls. The high-precision holes or grooves in the graphite molds restrict their position, preventing displacement during ball placement or reflow soldering. Detecting whether the ball-mounting machine has picked up a full load of solder balls is a crucial step in ensuring the final ball placement yield. Current technology uses a line scan camera to confirm this. A motor drives the line scan camera to perform a lateral scan of the ball-mounting head or area. When the line scan camera passes over the ball-mounting head or the substrate with the solder balls, it emits a laser line and precisely records the height of each point on this line. This laser data is fed back to the software algorithm. Locations with solder balls will reflect a steep, convex height curve; locations without solder balls will show a flat baseline. Based on the returned data, the software algorithm analyzes whether there are solder balls on the graphite mold.

[0003] However, the following problems still exist in the practical application of this engineering technology: Because it uses visual scanning to take pictures and then performs software algorithm detection, the detection time is relatively long as the number of detection points increases from tens of thousands to hundreds of thousands. This increases the hardware cost of the device and is inefficient. The entire device requires cameras, light sources, software algorithms and other assistance, and the overall structure is complex and costly. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a micro-slit detection sensor structure to solve the problems existing in the background art.

[0005] The present invention provides the following technical solution: a micro-gap detection sensor structure, comprising: a graphite plate, wherein the graphite plate is provided with a groove for placing a solder ball, and a graphite mounting bracket is placed above the graphite plate; A graphite mounting bracket is disposed above the graphite plate, and the surface of the graphite mounting bracket is provided with holes that correspond to the grooves on the graphite plate for placing solder balls. A light source is placed below the graphite plate, and the light emitted by the light source is perpendicular light; A light-gathering board is placed on the graphite mounting bracket. The light-gathering board is equipped with a light signal receiver corresponding to the light source. When no solder ball is placed on the graphite board, the light source passes through the graphite board and the graphite mounting bracket and transmits the light signal to the light-gathering board. When a solder ball is placed on the graphite board, the light source cannot pass through the graphite board and the graphite mounting bracket, and the light-gathering board cannot receive the light signal.

[0006] Preferably, it also includes a control board, wherein the acquisition board collects the optical signal and converts it into an electrical signal, and transmits the electrical signal to the control board. The control board is also provided with a transimpedance amplifier, which is used to convert the optical signal output by the acquisition board into a voltage signal. The input current of the transimpedance amplifier is less than 1pA, the noise density is less than 10nV / √Hz, and the measurement accuracy of the control board is between ±0.1% and ±0.01%.

[0007] Preferably, the light source is a red laser with a wavelength of 650nm-670nm.

[0008] Preferably, the laser on the light source is distributed in a single point and is placed below the graphite plate in a horizontally movable manner, and the optical signal receiver is set as a PIN photodiode.

[0009] Preferably, the groove on the graphite plate is configured as a blind hole with a light-transmitting aperture.

[0010] Preferably, the laser on the light source is distributed in a light curtain pattern, the light source covers the graphite plate, and the optical signal receiver is set as a CMOS image sensor or a CCD image sensor with noise less than 1 pW / √Hz.

[0011] Preferably, the grooves on the graphite plate are configured as through holes.

[0012] Preferably, the control board issues a missing ball alarm after receiving the electrical signal from the acquisition board.

[0013] Preferably, the light source does not contact the surface of the graphite plate.

[0014] Preferably, the graphite mounting bracket is provided with an independent aperture to block stray light from entering the acquisition plate.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention features a data acquisition board that receives light signals from a light source below a graphite plate and converts them into electrical signals. These electrical signals are then transmitted to a control board, which issues a missing ball alarm upon receiving the signal. This device is based on the principle of photoelectric sensing, has a simple structure, requires no software algorithm assistance, and has low equipment costs. The data acquisition board immediately converts the received light signal into an electrical signal and transmits it to the control board, resulting in fast processing speed and low latency compared to existing technologies, thus improving work efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Figure 2 This is the left view of the present invention.

[0018] Figure 3 This is a schematic diagram of the structure of the present invention from another angle.

[0019] The attached diagram is labeled as follows: 1. Graphite plate; 2. Graphite mounting bracket; 3. Light source; 4. Acquisition board; 5. Optical signal receiver; 6. Control board; 7. Transimpedance amplifier. Detailed Implementation

[0020] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0021] This invention provides a micro-slit detection sensor structure, such as... Figure 1-3 As shown, it includes: Graphite plate 1, with a groove for placing solder balls on graphite plate 1, and a graphite mounting bracket 2 placed on top of graphite plate 1; Graphite mounting bracket 3 has holes on its surface, which correspond to the grooves on the graphite plate 1 for placing solder balls. Light source 3 is placed below graphite plate 1, and the light emitted by light source 3 is perpendicular light; The acquisition board 4 is placed on the graphite mounting bracket 2. The acquisition board 4 is equipped with a light signal receiver 5 corresponding to the light source 4. When no solder ball is placed on the graphite plate 1, the light source 3 passes through the graphite plate 1 and the graphite mounting bracket 2 without obstruction and transmits the light signal to the acquisition board 4. When a solder ball is placed on the graphite plate 1, the light source 3 is blocked by the solder ball and cannot pass through the graphite plate 1 and the graphite mounting bracket 2, and the acquisition board 4 cannot receive the light signal.

[0022] Furthermore, it also includes a control board 6. The acquisition board 4 collects the optical signal and converts it into an electrical signal, which is then transmitted to the control board 6. The control board 6 is also equipped with a transimpedance amplifier 7, which is used to convert the optical signal output by the acquisition board 4 into an electrical signal. The input current of the transimpedance amplifier 7 is less than 1pA, the noise density is less than 10nV / √Hz, and the measurement accuracy of the control board 6 is between ±0.1% and ±0.01%.

[0023] In this embodiment, the solder balls placed on the graphite plate 1 are usually tiny spheres with a diameter of 0.3mm-0.76mm. The illumination range of ordinary light sources is relatively large, and the diameter of the light source illuminating the graphite plate 1 may reach several centimeters. At this time, the diameter of the light source is larger than the diameter of the solder balls. When the light source illuminates multiple solder balls at the same time, the acquisition board 4 will receive multiple light signals, which will affect the judgment.

[0024] In this embodiment, the light source 3 uses a red laser with a wavelength of 650nm-670nm. The infrared laser can be aimed at a single solder ball. When a solder ball is missing, the infrared laser at that position is not blocked by the solder ball, and the laser passes through the graphite plate 1 and the graphite mounting bracket 2 to illuminate the acquisition board 4. The acquisition board 4 receives the light signal emitted by the light source, converts the light signal into an electrical signal, and transmits it to the control board 6. After receiving the electrical signal emitted by the acquisition board 4, the control board 6 issues a missing ball alarm. When the solder balls are full, the laser of the light source 3 is blocked by the solder balls and cannot pass through the graphite plate 1 and the graphite mounting bracket 2. The acquisition board 4 does not receive the light signal, and the control board 6 does not issue an alarm.

[0025] Compared with existing technologies, this device does not require visual scanning and imaging or complex software algorithm detection. It has a simple structure, does not require complex hardware equipment, and has a lower cost. Existing technologies rely on image contrast. When the lighting is uneven, the camera may have difficulty identifying solder balls stably through image algorithms, which can easily lead to misjudgments. This device is based on the principle of light path occlusion and is not affected by image contrast. Compared with existing technologies, it has lower latency and does not need to wait for algorithm processing.

[0026] In another embodiment, the laser on the light source 3 is distributed in a single point and is placed below the graphite plate 1, which can be moved laterally. The optical signal receiver 5 is set as a PIN photodiode, and the groove on the graphite plate 1 is set as a blind hole with a light-transmitting hole. When the position of the solder ball to be tested on the graphite plate 1 is at the edge or center of the graphite plate, single-point laser detection is used. A single laser beam illuminates the solder ball, which is not easily interfered by adjacent lasers. When the test points are distributed in different areas, the solder balls in different areas can be tested by moving the light source, which is convenient and fast. The lasers on the single-point light source are independently distributed. When the laser at a certain point on the light source 3 is damaged, only the damaged laser needs to be replaced, which does not affect the operation of the lasers at other points. There is no need to stop the machine for repair, which is convenient for maintenance.

[0027] In another embodiment, when there are many solder balls to be tested on the graphite plate 1, the laser on the light source 3 is distributed in a light curtain manner, the light source 3 covers the graphite plate 1, the optical signal receiver 5 is set as a CMOS image sensor or CCD image sensor with noise less than 1 pW / √Hz, and the groove on the graphite plate 1 is set as a through hole. The entire testing process does not require moving the light source 3 to detect different points, the detection is faster, and it is suitable for assembly line work.

[0028] Furthermore, the graphite mounting bracket is equipped with an independent aperture to block stray light from entering the acquisition plate. By setting the aperture, the graphite mounting bracket 2 can ensure that the acquisition plate 4 can only receive the light source 3 that shines through the groove on the graphite plate directly below, and will not be interfered with by the stray light leaking from adjacent points or the light source 3 reflected from the side of the graphite plate 1.

[0029] Furthermore, to avoid damaging the precision solder balls on the surface of graphite plate 1, the light source 3 does not come into contact with the surface of graphite plate 1.

[0030] The working principle of this invention is as follows: During operation, the light source 3 illuminates the graphite plate 1. When there is a lack of solder balls at the location illuminated by the light source 3, the light source 3 passes through the graphite plate 1 and the graphite mounting bracket 2. The light source 3 that has passed through is received by the acquisition board 4. The acquisition board 4 converts the received light signal into an electrical signal and transmits the electrical signal to the control board 6. After receiving the electrical signal, the control board 6 issues a missing ball alarm. When there are solder balls on the graphite plate 1, the laser emitted by the light source 3 cannot pass through the graphite plate 1 and the graphite mounting bracket 2. The acquisition board 4 does not receive a light signal, and the control board 6 does not issue a missing ball alarm.

[0031] Several points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection" and "linkage" should be interpreted broadly, and can be mechanical or electrical connection, or internal connection between two components, or direct connection. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationship. When the absolute position of the described object changes, the relative positional relationship may change.

[0032] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or variations made by those skilled in the art based on the disclosure of the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A micro-slit detection sensor structure, characterized in that: include: A graphite plate (1) is provided with a groove for placing tin balls, and a graphite mounting bracket (2) is placed above the graphite plate (1). Graphite mounting bracket (2), the graphite mounting bracket (2) is placed above the graphite plate (1), the surface of the graphite mounting bracket (2) is provided with holes, the holes correspond to the grooves on the graphite plate (1) where solder balls are placed; Light source (3), the light source (3) is placed below the graphite plate (1), and the light emitted by the light source (3) is vertical light; A light-collecting plate (4) is placed on the graphite mounting bracket (2). The light-collecting plate (4) is equipped with a light signal receiver (5) corresponding to the light source (4). When no solder ball is placed on the graphite plate (1), the light source (3) passes through the graphite plate (1) and the graphite mounting bracket (2) and transmits the light signal to the light-collecting plate (4). When a solder ball is placed on the graphite plate (1), the light source (3) cannot pass through the graphite plate (1) and the graphite mounting bracket (2) and the light-collecting plate (4) cannot receive the light signal.

2. The micro-slit detection sensor structure according to claim 1, characterized in that: It also includes a control board (6), the acquisition board (4) collects optical signals and converts them into electrical signals, and transmits the electrical signals to the control board (6). The control board (6) is also equipped with a transimpedance amplifier (7), which is used to convert the optical signals output by the acquisition board (4) into electrical signals. The transimpedance amplifier (7) has an input current of less than 1pA and a noise density of less than 10nV / √Hz. The measurement accuracy of the control board (6) is between ±0.1% and ±0.01%.

3. The micro-slit detection sensor structure according to claim 1, characterized in that: The light source (3) is a red laser with a wavelength of 650nm-670nm.

4. The micro-slit detection sensor structure according to claim 3, characterized in that: The laser on the light source (3) is distributed in a single point and can be placed horizontally below the graphite plate (1). The optical signal receiver (5) is set as a PIN photodiode.

5. The micro-slit detection sensor structure according to claim 4, characterized in that: The groove on the graphite plate (1) is configured as a blind hole with a light-transmitting hole.

6. The micro-slit detection sensor structure according to claim 3, characterized in that: The laser on the light source (3) is distributed in a light curtain manner. The light source (3) covers the graphite plate (1). The optical signal receiver (5) is set as a CMOS image sensor or a CCD image sensor, and the noise is less than 1 pW / √Hz.

7. The micro-slit detection sensor structure according to claim 6, characterized in that: The groove on the graphite plate (1) is configured as a through hole.

8. The micro-slit detection sensor structure according to claim 1, characterized in that: After receiving the electrical signal from the acquisition board (4), the control board (6) issues a ball shortage alarm.

9. The micro-slit detection sensor structure according to claim 1, characterized in that: The light source (3) does not contact the surface of the graphite plate (1).

10. The microslit detection sensor structure according to claim 1, characterized in that: The graphite mounting bracket (2) is provided with an independent aperture hole to block stray light from entering the acquisition plate (4).

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