TWI782406B - Burn-in board provided with backside cooling mechanism - Google Patents

Abstract

The disclosure provides a burn-in board including a circuit board, a first thermal conducting interface, a second thermal conducting interface and a fan. The first thermal conducting interface contacts with a backside of the circuit board at an area corresponding to a DUT. The second conducting interface is vertically stacked on the first conducting interface, and the first conducting interface and the second conducting interface are different materials. The fan electrically couples to the backside of the circuit board and configured to provide a lateral airflow along the backside.

Description

Burn-in circuit board with backside cooling mechanism

The present invention relates to a burn-in device, in particular to a main circuit board included in the burn-in device for a test device (DUT), which is provided with a back heat dissipation mechanism.

In the semiconductor or PCB industry, Burn-In is a process of testing wafers or wafers. A plurality of wafers or wafers will be correspondingly installed on the test sockets on the burn-in board to test various parameters. Such as temperature, stress, frequency, etc., to detect any failures in the subsequent process due to design, material, process or manufacturing defects.

The packaged integrated circuit (IC) usually needs to go through a burn in test for a certain period of time to ensure that the IC product can operate in a harsh environment. The first figure shows a schematic diagram of a known burn-in socket. A packaged chip (100) is accommodated on a base (102) fixed on the main circuit board (101) of the burn-in device and electrically connected to a plurality of signal contacts (not shown). A cover (103) equipped with a heat dissipation unit presses the chip (100) and contacts the top of the chip (100) with a contact interface (1031). Generally speaking, the heat dissipation unit of the cover (103) is formed by a plurality of heat dissipation fins (1032) arranged in a specific form, and these heat dissipation fins (1032) are connected to the contact interface (1031), thereby preventing the burn-in Heat accumulated on top of the wafer (100) during operation is conducted to the heat sink via the contact interface (1031). Thermal fins (1032), released to air. In the known design, there is an additional fan provided on the cooling fins (1032) to increase convection, or a plurality of pipes to help heat conduction are provided between the contact interface (1031) and the cooling fins (1032), thereby Improve the heat dissipation capacity of the burn-in socket. With the advent of the 5G and AI era, the demand for high-power ICs has increased, and the burn-in test for high-power ICs has become more stringent. For example, during the burn-in process, the heat generated by a high-power IC chip, such as a heat source greater than 1500 watts, may not be able to meet the test of this type of device with the above-mentioned design.

The so-called burn-in board (BIB) is mainly composed of multiple above-mentioned burn-in sockets electrically connected to a circuit board with a larger size (ie, the main circuit board 101 ). The circuit board has a front side and a back side, and the burner sockets are uniformly arrayed on the front side of the circuit board, so the front side of the circuit board is the main operation interface. There are still some electronic components on the back of the circuit board, but in order to avoid interfering with the front of the burner board stacked below, usually there will not be too many electronic components on the back. It should be understood that there will be other electronic components on the circuit board, which will also generate heat according to the power of the burn-in test signal, and inhibit the heat dissipation effect of the above-mentioned poor base, and eventually cause the temperature of the entire burn-in board to be too high, which may cause Up to 60 degrees or more. It can be seen from this that the design of the general burn-in board mainly configures the heat dissipation mechanism on the front of the circuit board, such as the burn-in socket itself. However, the heat generated by the wafer (100) during testing is also transferred towards the back of the circuit board. In the absence of a heat dissipation mechanism on the back of the burn-in board, the efficiency of heat dissipation is not good, causing the burn-in device to automatically power off due to the protection mechanism and terminate the test. The burn-in boards are usually stacked vertically in a machine for testing, so it is not suitable to add a heat dissipation method that is too large on the back of the circuit board, otherwise the machine must be forced to accommodate a small number of burn-in boards. At best, the machine has its own convection mechanism to handle the heat from the back of the burner board.

Therefore, the development of a burn-in circuit board with a backside heat dissipation mechanism, which is suitable for vertical stacking in the machine, is an urgent problem to be solved.

The purpose of the present invention is to provide a burn-in circuit board, comprising: a circuit board with a front and a back, the front is used to hold a device under test, and the device under test is electrically coupled with the circuit board; a first A heat conduction interface, contacting the back of the circuit board corresponding to an area of the device under test; a second heat conduction interface, vertically stacked with the first heat conduction interface, and the first heat conduction interface and the second heat conduction interface are made of different materials; and a fan electrically coupled to the back of the circuit board and configured to provide a lateral airflow along the back.

In a specific embodiment, the burn-in circuit board further includes: a holding mechanism, located on the back of the circuit board at a position corresponding to the device under test, for holding the first heat-conducting interface.

In a specific embodiment, the burn-in circuit board further includes: a third heat conduction interface, vertically stacked with the first heat conduction interface and the second heat conduction interface, so that the second heat conduction interface is interposed between the first heat conduction interface and the second heat conduction interface Between the two heat-conducting interfaces.

In a specific embodiment, the burn-in circuit board further includes: a fourth heat conduction interface disposed on the back of the circuit board and at least surrounding the third heat conduction interface.

In a specific embodiment, the first heat conduction interface is indium sheet or thermal paste.

In a specific embodiment, the second heat conduction interface is a vapor chamber in contact with the first heat conduction interface.

In a specific embodiment, the third heat conduction interface is a plurality of heat dissipation fins, and there is a first fin pitch between adjacent heat dissipation fins.

In a specific embodiment, the fourth heat conduction interface is a plurality of heat dissipation fins, and there is a second fin pitch between adjacent heat dissipation fins, and the second fin pitch is greater than the first fin pitch.

In a specific embodiment, the fourth heat conduction interface has a channel, the channel crosses the plurality of fins of the fourth heat conduction interface, and is perpendicular to the plurality of fins of the fourth heat conduction interface, and the fan is fixed on in this channel.

In one embodiment, the lateral airflow passes through the first fin pitch, the second fin pitch and the channel.

In a specific embodiment, the third heat conduction interface and the fourth heat conduction interface are integrated into a single heat conduction interface.

In a specific embodiment, the covering area of the fourth heat conducting interface is larger than the covering area of the third heat conducting interface, so that the structure of the burn-in circuit board is strengthened.

100: chip

101: Main circuit board

102: base

103: cover body

1031: contact interface

1032: cooling fins

200: circuit board

2001: Front

2002: back

202: Device under test

204, 204a, 204b: holding structure

205: The first thermal interface

206, 206a, 206b: the second thermal interface

207, 207a, 207b: the third thermal interface

208: The fourth thermal interface

209: channel

210: fan

211: thermal interface

The present invention can be further understood with reference to the following drawings and descriptions. Non-limiting and non-exhaustive examples are described with reference to the following drawings. The components in the drawings are not necessarily in actual size; the emphasis is on illustrating the structures and principles.

The first figure shows a schematic diagram of a known burn-in socket.

The second figure is a schematic diagram of a burn-in circuit board with a back heat dissipation mechanism of the present invention.

The third figure shows the perspective view of the back side of the burn-in circuit board of the present invention.

The fourth figure shows a perspective sectional view according to the section line of the third figure.

The fifth figure shows a partial exploded view of the embodiment of the third figure.

The sixth figure shows another exploded view of the embodiment of the third figure.

The seventh figure is another embodiment of the present invention, showing a perspective view of the back side of the burn-in circuit board.

The eighth figure shows a partial exploded view of the embodiment of the seventh figure.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain exemplary embodiments are shown by way of illustration. However, claimed subject matter may be embodied in many different forms, and thus constructions of covered or claimed subject matter are not limited to any example embodiments disclosed in this specification; the example embodiments are merely illustrations. Likewise, the invention resides in providing a reasonably broad scope for claimed subject matter as claimed or covered. Among other things, for example, claimed subject matter may be embodied as a method, apparatus, or system. Thus, embodiments may take the form of, for example, hardware, software, firmware or any combination of these (known not to be software).

The term "in one embodiment" used in this specification does not necessarily refer to the same embodiment, and the use of "in other (some/some) embodiments" in this specification does not necessarily refer to different embodiments. It is intended, for example, that claimed subject matter includes combinations of all or some of the exemplified embodiments.

The second figure is a schematic block diagram of the burn-in circuit board of the present invention. The burn-in circuit board of the present invention includes a circuit board (200, also called a main circuit board), such as a printed circuit board. The circuit board ( 200 ) can provide a data bus for transmitting signals, as well as conductive lines and many electronic components, which will not be described one by one here.

The circuit board (200) has a front side (2001) and a back side (2002). The front side (2001) is used to hold a device under test (202, DUT), such as a packaged chip. Although only the device under test (202) is shown contacting the front side (2001) in the figure, those skilled in the art should understand the burner socket (such as the first The shown combination of base 102 and cover 103) has been omitted from the figure for simplicity. The back side (2002) is generally the downward facing surface, which still has some electronic components or structures corresponding to the front side (2001) electronic components.

The back (2002) has at least one holding structure (204). In one embodiment, the holding structure ( 204 ) is a rectangular frame, which can be fixed to the back side ( 2002 ) and corresponds to the position of the device under test ( 202 ) through known locking means. The holding structure (204) also has the function of strengthening the back (2002) structure. In the front (2001) operation, as shown in the first figure, the cover (103) will press down and apply force to the circuit board (200), and the holding structure (204) can prevent the circuit board (200) from being deformed by pressing down. The mounted holding structure (204) exposes a part of the backside (2002), which covers at least the bottom of the device to be tested (202).

The burn-in circuit board of the present invention also includes a first heat conduction interface (205), which is arranged in the holding structure (204) and contacts the back side (2002) of the circuit board (200) with one surface, thereby conducting the device under test (202) ) bottom heat. In one embodiment, the first thermal interface ( 205 ) can be selected from one of thermal interface materials (TIM) or a thermal conductive patch. The first heat conduction interface (205) is a thinner layer of heat conduction material, and its main function is to fill the micro-gap and holes on the surface of the hardware when two hardwares are bonded, thereby reducing the thermal contact resistance of heat transfer . Therefore, in a preferred embodiment of the present invention, a first thermally conductive interface (205) exists. The first heat conduction interface (205) can be an indium sheet or heat dissipation paste, wherein heat dissipation paste is non-conductive, and is more suitable as the first heat conduction interface (205) of the present invention.

The burn-in circuit board of the present invention also includes a second heat conduction interface (206), which is vertically stacked with the first heat conduction interface (205) and contacts a surface of the first heat conduction interface (205) with a surface, thereby conducting the first heat conduction The heat of the interface (205). Preferably, the second heat conducting interface ( 206 ) is a vapor chamber.

The burn-in circuit board of the present invention also includes a third heat conduction interface (207), which is vertically stacked with the second heat conduction interface (206) and contacts a surface of the second heat conduction interface (206) with a surface, thereby conducting The heat of the second thermal interface (206). In one embodiment, the third heat conducting interface (207) is composed of a plurality of cooling fins.

According to the above configuration, the back side (2002) of the burn-in circuit board of the present invention can provide a horizontal airflow through the third heat conduction interface (207) to enhance the heat dissipation effect. Specific means will be described below.

Figure 3 shows a partial perspective view of a specific embodiment of the backside of the burn-in circuit board of the present invention, taking a test position with four devices to be tested on the front side as an example. The fourth figure is a cross-sectional perspective view according to the dotted line in the third figure. Figure 5 and Figure 6 show exploded views from different viewing angles of the embodiment in Figure 3 respectively. It should be understood that none of these figures show the burn-in receptacle that exists on the front of the board to keep the figures simple. The burn-in circuit board of the present invention also includes a fourth heat conduction interface (208), which is fixed to the back side (2002) of the circuit board and surrounds the holding mechanism (204a, 204b), the second heat conduction interface (206a, 206b) . The third heat conducting interface (207a, 207b). Preferably, when the fourth heat-conducting interface (208) is fixed to the back side of the circuit board (2002), the fourth heat-conducting interface (208) contacts the heat-generating electronic components (2003) connected to the back side (2002), such as for providing signals to The power module of the test device. Here, the first heat conducting interface is omitted and not shown. The fourth heat conduction interface ( 208 ) is composed of a flat plate and a plurality of heat dissipation fins, and the heat dissipation fins of the fourth heat conduction interface ( 208 ) extend along a first lateral direction (such as the x direction in the third figure). The third heat conduction interface (207a, 207b) also has a plurality of heat dissipation fins, which also extend along the first lateral direction. As shown in the figure, there is a first fin spacing between adjacent heat dissipation fins in the third heat conduction interface (207a, 207b), and a second distance between adjacent heat dissipation fins in the fourth heat conduction interface (208). Fin pitch, and the first fin pitch is smaller than the second fin pitch.

The fourth heat conducting interface (208) also forms a channel (209), which extends along a second lateral direction (such as the y direction in the third figure). Both the first and second lateral directions are parallel to the back (2002), but the first and second lateral directions may be orthogonal. In one embodiment, the channel (209) may pass through the heat dissipation fins of the fourth heat conduction interface (208), but not pass through the heat dissipation fins of the third heat conduction interface (207a, 207b). The present invention is not limited to a single channel, nor is the channel limited to a single direction.

As shown in the figure, the burn-in circuit board of the present invention further includes at least one fan (210), which is disposed in the channel (209) and electrically coupled to the circuit board. The fan (210) shown in this embodiment includes a main fan providing larger airflow, and secondary fans on both sides of the main fan providing smaller airflow. The main fan can be located in a center of the four third heat conduction interfaces, so that it is adjacent to the cooling fins of the fourth heat conduction interface (208) in the x direction, and adjacent to the secondary fan in the y direction. The secondary fan is respectively adjacent to the fins of the third heat conduction interface (207a, 207b) and the fin of the fourth heat conduction interface (208) in the x direction, and adjacent to the main fan in the y direction. The channels (209) can extend all the way to opposite edges of the backside (2002) of the circuit board. Thus, the lateral airflow provided by the fan (210) can pass along the first lateral direction (x-direction) through the fin spacing of the third and fourth heat-conducting interfaces, and along the second lateral direction (y-direction) through the channel (209), leaving the scope of the circuit board. Thus, heat dissipation on the back of the burn-in circuit board can be improved by this means.

The seventh figure and the eighth figure show another embodiment of the present invention, which integrates the aforementioned third heat conduction interface (207) and fourth heat conduction interface (208) into a plurality of heat conduction interfaces (211), and each heat conduction interface ( 211) covers the corresponding holding structure (204) and its surrounding electronic components, and can be disassembled independently. One side of each heat conduction interface (211) is provided with a plurality of fins, and the side of the heat conduction interface (211) facing the back side of the circuit board (2002) is connected with the aforementioned second heat conduction interface (206) for matching contact and holding The heat generating area on the back side (2002) of the circuit board of the structure (204). The channel (209) as mentioned above and a plurality of fans arranged along the channel (209) are also formed between two adjacent heat-conducting interfaces (211). Compared with the aforementioned combination of the third heat conduction interface ( 207 ) and the fourth heat conduction interface ( 208 ), such a monolithic heat conduction interface configuration has a more direct heat conduction effect. In possible configurations, the thermal interface ( 211 ) can provide different fin sizes for different positions (such as close to the fixed frame or electronic components).

According to at least the description of the above-mentioned embodiments, it can be seen that the burn-in circuit board provided by the present invention has a better heat dissipation mechanism on the back of the circuit board. That is, the heat accumulated on the backside of the circuit board can be dissipated through the combination of the thermal interface and the fan. In addition, the combination of these thermally conductive interfaces also enhances the structural strength of the circuit board. The burn-in receptacle, located on the front of the circuit board, can be manipulated to apply pressure to the circuit board, which causes the circuit board to bend. The heat conduction interface provided by the present invention, especially the heat conduction interface of the heat dissipation fin is hard compared to the material of the circuit board and can cover a larger backside area (such as the coverage area of the fourth heat conduction interface is larger than the coverage area of the third heat conduction interface), Therefore, the circuit board can resist the pressing down operation of the burner socket.

Although the foregoing invention has been described in certain detail for purposes of clarity of understanding, it will be understood that certain changes and modifications may be practiced within the scope of the claims claimed. Accordingly, the above embodiments are illustrative only and not limiting, and the invention is not limited to the details illustrated herein but may be modified within the scope of the appended claims and equivalents.

2002: back

208: The fourth thermal interface

209: channel

Claims (13)

A burn-in circuit board, comprising: a circuit board with a front and a back, the front is used to hold a device under test, and the device under test is electrically coupled with the circuit board; a first thermal interface, contacting The back of the circuit board corresponds to an area of the device under test; a holding mechanism is a rectangular frame located at a position corresponding to the device under test on the back of the circuit board, for holding the first thermal interface and strengthening the circuit board mechanical strength; and a second heat conduction interface, vertically stacked with the first heat conduction interface, and the first heat conduction interface and the second heat conduction interface are made of different materials. The burn-in circuit board as claimed in claim 1, further comprising: a fan electrically coupled to the back side of the circuit board and configured to provide a lateral air flow along the back side. The burn-in circuit board according to claim 2, further comprising: a third heat conduction interface, vertically stacked with the first heat conduction interface and the second heat conduction interface, so that the second heat conduction interface is interposed between the first heat conduction interface and the second heat conduction interface between the third thermal interface. The burn-in circuit board according to claim 3 further includes: a fourth heat conduction interface disposed on the back of the circuit board and at least surrounding the third heat conduction interface. The burn-in circuit board as described in claim 4, wherein the first heat-conducting interface is an indium sheet or heat-dissipating paste. The burn-in circuit board according to claim 5, wherein the second heat conduction interface is a temperature uniform plate in contact with the first heat conduction interface. The burn-in circuit board according to claim 6, wherein the third heat conducting interface is a plurality of heat dissipation fins, and there is a first fin pitch between adjacent heat dissipation fins. The burn-in circuit board as described in claim 7, wherein the fourth heat conduction interface is a plurality of heat dissipation fins, and there is a second fin pitch between adjacent heat dissipation fins, and the second fin pitch is greater than the First fin pitch. The burn-in circuit board as described in claim 8, wherein the fourth heat conduction interface has a channel, the channel spans the plurality of fins of the fourth heat conduction interface, and is positively aligned with the plurality of fins of the fourth heat conduction interface Cross, the fan is fixed in the channel. The burn-in circuit board as claimed in claim 9, wherein the lateral air flow passes through the first fin pitch, the second fin pitch and the channel. The burn-in circuit board as described in claim 4, wherein the third heat conduction interface and the fourth heat conduction interface are integrated into a single heat conduction interface. The burn-in circuit board as described in claim 4, wherein the covering area of the fourth heat-conducting interface is larger than the covering area of the third heat-conducting interface, so that the structure of the burn-in circuit board is strengthened. The burn-in circuit board as described in claim 11, wherein the side of the single heat conduction interface facing the back side of the circuit board is connected with the second heat conduction interface for matching and contacting the back side of the circuit board of the holding mechanism hot area.

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