CN113421961B - SQUID chip packaging structure device and packaging method - Google Patents

Abstract

The SQUID chip packaging structure device comprises a SQUID chip (1), a cold finger (2), a Dewar and an FPC (flexible printed Circuit) board (4) adhered to a heat-conducting metal gasket (3), wherein the SQUID chip (1) is adhered to the FPC (flexible printed Circuit) board (4), and the FPC (flexible printed Circuit) board (4) and the metal gasket (3) replace a traditional PCB (printed Circuit Board) board to serve as bottom packaging of the SQUID chip (1); the metal gasket (3) is adhered to the cold finger (2) and is attached to the cold finger (2); the SQUID chip (1) is convenient to replace; the FPC flexible circuit board (4) is thin in thickness and good in refrigerating effect.

Description

A SQUID chip packaging structure device and packaging method

Technical field:

The invention relates to a superconducting quantum interference device (Superconducting Quantum Interference Device, SQUID for short) chip packaging structure device and packaging method, in particular to a SQUID chip packaging structure device and packaging method used as a magnetic microscope (Magnetic Microscope) probe.

Background technique:

In recent years, due to the excellent spatial and magnetic field resolution of superconducting quantum interference devices and the inherent advantages of passive non-destructive testing, and with the development of integrated circuit technology, the magnetic scanning SQUID microscope (MSSM) technology that uses SQUID to detect the magnetic properties of samples has attracted a lot of attention. increasing interest of researchers.

According to whether the sample to be tested is in direct contact with the refrigerant, SSM is mainly divided into two types: cold finger type and immersion type. Among them, the cold finger type is less affected by the changes in the internal pressure of the Dewar and the cooling liquid level. Compared with the immersion type, it is more suitable for low-speed mobile platforms. Because most of the existing SQUID packages stick the chip to the PCB board through glue, and then glue the PCB to the cold finger. The advantage is that the cold finger has a simple design, which is convenient for testing devices of different configurations, but the disadvantage is that the PCB is thick, the heat conduction is poor, the refrigerant loss is fast, and it may not work in severe cases. Another packaging method is to directly paste the SQUID chip with glue and cold fingers. This method has good heat conduction, but the link between the chip and the external circuit is complicated, and the maintenance cost is high in the later period. Therefore, designing a solution with good heat conduction and convenient connection between the chip and the external circuit has always been one of the development directions of SSM technology.

Invention content:

The technical problem to be solved by the present invention is to provide a SQUID chip package structure device and a package method, especially a package structure device and a package method of a SQUID used as a probe of a magnetic microscope.

In order to solve the above-mentioned technical problems, a SQUID chip package structure device of the present invention, especially a SQUID package structure device used as a magnetic microscope probe, has the technical scheme:

A SQUID chip package structure device for making a magnetic microscope probe, comprising a SQUID chip and a cold finger, and the cold finger and a Dewar connected, characterized in that it also includes an FPC flexible circuit board pasted on a thermally conductive metal gasket, so the The SQUID chip is pasted on the FPC flexible circuit board, and the FPC flexible circuit board and the metal gasket replace the traditional PCB board circuit board as the bottom package of the SQUID chip; the metal gasket is pasted on the cold finger, and is connected with the cold finger. fit.

The following is a further scheme of a SQUID chip package structure device of the present invention, especially a SQUID package structure device used as a magnetic microscope probe:

The electrodes of the SQUID chip are connected with the electrodes of the FPC flexible circuit board through a bonding wire, and the FPC flexible circuit board is connected with the Dewar low-temperature connecting wire through a CNN connector; the metal gaskets are selected from copper gaskets.

The FPC flexible circuit board is provided with an accommodation groove for accommodating the SQUID chip, and low-temperature glue is added to the accommodation groove, and the SQUID chip is pasted on the accommodation groove on the FPC flexible circuit board; Glue with low temperature glue.

The FPC flexible circuit board has a first through hole, and the socket for connecting the FPC electrode and the low-temperature cable is inserted into the first through hole and soldered on the FPC flexible circuit board. At the same time, the socket is connected to the low-temperature cable and the FPC flexible circuit board; the metal gasket also has a second via hole at a corresponding position, the diameter of the second via hole is larger than that of the second via hole, and the plug row passes through the second via hole.

A fixing kit is arranged above the FPC flexible circuit board, and the fixing kit is provided with a gap at the position of the entire SQUID chip. The fixing kit includes at least 2 detachable connecting bolts extending downward, and the connecting bolts pass through the FPC flexible circuit board and are connected to each other. Metal gasket and fixed connection with cold fingers.

In order to solve the above-mentioned technical problem, the packaging method of a kind of SQUID chip of the present invention, especially a kind of technical scheme of the packaging method of the SQUID used as a magnetic microscope probe is:

A packaging method for a SQUID chip for making a magnetic microscope probe, comprising the SQUID chip and a cold finger, and the cold finger being connected to a Dewar, and characterized in that it also includes an FPC flexible circuit board pasted on a thermally conductive metal gasket, so that the The SQUID chip is pasted on the FPC flexible circuit board, and the FPC flexible circuit board and the metal gasket replace the traditional PCB board circuit board as the bottom package of the SQUID chip; the metal gasket is pasted on the cold finger, and is connected with the cold finger. fit.

The following is a packaging method of a SQUID chip of the present invention, especially a further scheme of the packaging method of a SQUID used as a magnetic microscope probe:

The electrodes of the SQUID chip are connected with the electrodes of the FPC flexible circuit board through a bonding wire, and the FPC flexible circuit board is connected with the Dewar low-temperature connecting wire through a CNN connector; the metal gaskets are selected from copper gaskets.

The FPC flexible circuit board is provided with an accommodation groove for accommodating the SQUID chip, and low-temperature glue is added to the accommodation groove, and the SQUID chip is pasted on the accommodation groove on the FPC flexible circuit board; Glue with low temperature glue.

The FPC flexible circuit board has a first through hole, and the socket for connecting the FPC electrode and the low-temperature cable is inserted into the first through hole and soldered on the FPC flexible circuit board. At the same time, the socket is connected to the low-temperature cable and the FPC flexible circuit board; the metal gasket also has a second via hole at a corresponding position, the diameter of the second via hole is larger than that of the second via hole, and the plug row passes through the second via hole.

A fixing kit is arranged above the FPC flexible circuit board, and the fixing kit is provided with a gap at the position of the entire SQUID chip. The fixing kit includes at least 2 detachable connecting bolts extending downward, and the connecting bolts pass through the FPC flexible circuit board and are connected to each other. Metal gasket and fixed connection with cold fingers.

The invention provides a SQUID chip packaging structure device and a packaging method, especially a packaging structure device and a packaging method for a SQUID used as a probe of a magnetic microscope. The most prominent advantages of the present invention are: 1) it is convenient to replace the chip; 2) the thickness of the FPC is thin and the cooling effect is good. The invention can improve the thermal conductivity on the basis of reducing the leads, so as to realize uniform heat conduction, simple manufacture, and improve the accuracy and stability of chip testing. At the same time, this design uses a small dewar to reduce the consumption of low-temperature liquid and make the test of the chip more convenient. It provides more excellent conditions for the application of superconducting electronics in magnetic field detection, and is a technology worthy of promotion in chip detection.

Because the thickness of the FPC flexible circuit board is only a few tens of um, and the thickness of the PCB circuit board is generally several mm, the thickness of the two is about a hundred times different, so the thermal conduction efficiency of the FPC flexible circuit board is much higher than that of the PCB circuit board. Avoid high temperature welding between low temperature wire and SQUID, protect the device, and improve the poor ohmic contact between SQUID and low temperature wire caused by the use of crimping scheme. At the same time, the design of the red copper plate at the bottom of the FPC reduces the possibility that the FPC is too thin and too flexible, and there is a gap between the FPC and the SQUID after multiple hot and cold cycles, which will eventually cause the package to fail. And thermally conductive metal gaskets, especially copper gaskets, have good thermal conductivity with cold fingers, and will not reduce the cooling effect of SQUID due to the addition of gaskets. It is beneficial to the integration, testing, replacement of accessories and post-maintenance of the multi-channel system in the later stage. The socket design avoids the winding of the low temperature wire at the connector and reduces the length of the trace. The fixing kit above the FPC increases the mechanical and thermal connection between the FPC and the cold finger; for the Dewar design with side windows and bottom windows, this kit avoids the FPC from sliding off the cold fingers due to the weight of the FPC.

Description of drawings

1 is a schematic diagram of a SQUID chip packaging structure device of the present invention;

Figure 2 is a schematic diagram of the FPC flexible circuit board and metal gasket;

3 is a schematic diagram of a SQUID chip packaging structure device provided with a fixing kit;

4 is a schematic diagram of a SQUID chip packaging structure device and an external circuit provided with a fixing kit;

The above drawings are schematic and do not correspond to actual scales.

The parts indicated by the numbers in each figure are: 1. SQUID chip; 2. Cold finger; 3. Metal gasket; 4. FPC flexible circuit board; 5. Bonding wire; 9. The first via hole; 10. The second via hole; 11. Fixing kit; 12. Notch; 13. Connecting bolt; 14. External circuit.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings.

As shown in FIG. 1 to FIG. 3 , the SQUID chip 1 package structure device for making a magnetic microscope probe of the present invention includes a SQUID chip 1 and a cold finger 2, and the cold finger 2 is connected to the Dewar, and also includes a thermal conductive metal pad pasted on The FPC flexible circuit board 4 on the sheet 3, the SQUID chip 1 is pasted on the FPC flexible circuit board 4, the FPC flexible circuit board 4 and the metal gasket 3 replace the traditional PCB board circuit board as the bottom package of the SQUID chip 1; the metal gasket 3. Paste it on the cold finger 2 and fit it with the cold finger 2. The electrodes of the SQUID chip 1 are connected to the electrodes of the FPC flexible circuit board 4 through the bonding wire 5, and the FPC flexible circuit board 4 is connected to the Dewar low temperature connecting wire through the CNN connector. Since the rigidity of the FPC flexible circuit board 4 is not enough, it is easy to deform due to its softness; the solution: Compensate for its strength by pasting a thermally conductive metal gasket 3 on the bottom surface of the SQUID chip 1, and the metal gasket 3 further improves the heat conduction effect. The material of the metal gasket 3 is preferably red copper, so the red copper gasket can be preferred.

The magnetic microscope involved in the present invention mainly includes two types of scanning type and array type according to its different imaging modes, and the scanning type magnetic microscope is also referred to as a magnetic scanning microscope for short. Although the specific structures of the scanning type and array type magnetic microscopes are different, the packaging structure and packaging method of the SQUID chips can all adopt the solution of the present invention.

As shown in FIG. 1 and FIG. 2 , an accommodating groove 6 for accommodating the SQUID chip 1 is opened on the FPC flexible circuit board 4 , and a low-temperature glue 7 is added to the accommodating groove 6 to paste the SQUID chip 1 on the FPC flexible circuit board 4 . slot 6. The metal gasket 3 and the cold finger 2 are also bonded with low temperature glue 7 . The FPC flexible circuit board 4 has a first through hole 9, and the socket 8 for connecting the electrodes of the FPC flexible circuit board 4r and the low-temperature cable is inserted into the first through hole 9 and welded on the FPC flexible circuit board 4. At the same time, the socket 8 Connect the low temperature cable to the FPC flexible circuit board 4 . The metal gasket 3 also opens a second via hole 10 at the corresponding position. The diameter of the second via hole 10 is larger than that of the first via hole 9. The plug 8 passes through the second via hole 10, and the external circuit 14 can be connected. 4 shown.

In addition, in order to fix the FPC flexible circuit board 4, especially for the Dewar with side windows and bottom windows, the FPC flexible circuit board 4 can be prevented from sliding off the cold finger 2, as shown in FIG. 3, above the FPC flexible circuit board 4 A fixing kit 11 can be provided. The fixing kit 11 has a gap 12 at the position of the entire SQUID chip 1. The fixing kit 11 includes at least two detachable connecting bolts 13 extending downward. The connecting bolts 13 pass through the FPC flexible circuit board 4 and are connected to each other. The metal gasket 3 is fixedly connected with the cold finger 2 . As shown in FIG. 4 , the plug-in row 8 passes through the second via hole 10 and is connected to the external circuit 14 .

The specific manufacturing steps are: (1) First, design the layout of the SQUID chip 1 and the FPC flexible circuit board 4 that is adapted, wherein the thickness of the FPC flexible circuit board 4 is designed to be 60um, and the SQUID chip 1 uses a SQUID magnetometer (gradiometer). The diameter of the via hole is designed to be 0.7mm, and the extension is 0.2mm. Use 0.6mm round gold-plated pin headers. The thickness of the copper backing plate is designed to be 0.2mm. The copper gasket is designed according to the FPC via hole, the via hole position is the same, and the diameter of the via hole is designed to be 1mm in diameter. (2) Take 0.5g of LakeShore IMI 7031Varnish low temperature glue, spread it evenly on the FPC, stick the chip firmly, and bake it. (3) Weld the socket 8 and the FPC flexible circuit board 4 firmly. (4) Use the Bonding machine model WEST-BOND 7476E to bond the SQUIDBias/Feedback/Heating and other functional PADs to the FPC, and do the electrical signal connection test. (5) Using low temperature glue 7, the FPC flexible circuit board 4 and the cold finger 2 are firmly bonded. (6) Use the fixing kit to firmly connect the FPC flexible circuit board 4 and the cold finger 2 to increase the mechanical stability. (7) Connect the low-temperature cable to the 4-pin pin of the FPC flexible circuit board, and test the continuity with the peripheral interface of the Dewar. (8) Assemble other kits such as Dewar Insert in the specified order. The whole small system is suspended with a bracket, and a 10-turn energized coil is placed under it, and its material is copper. The current passed through the coil is 100mA. The magnetic field generated by the energized coil is detected using a designed and packaged chip.

Claims (10)

1. A SQUID chip packaging structure device comprises a SQUID chip (1) and a cold finger (2), wherein the cold finger (2) is connected with a Dewar, and is characterized by further comprising an FPC (flexible printed circuit) board (4) adhered on a heat-conducting metal gasket (3), wherein the SQUID chip (1) is adhered on the FPC (flexible printed circuit) board (4), and the FPC (flexible printed circuit) board (4) and the metal gasket (3) replace a traditional PCB (printed circuit board) to serve as bottom packaging of the SQUID chip (1); the metal gasket (3) is adhered to the cold finger (2) and is attached to the cold finger (2).

2. The SQUID chip package structure device according to claim 1, wherein the electrodes of the SQUID chip (1) and the electrodes of the FPC flexible circuit board (4) are connected through Bonding wires (5), and the FPC flexible circuit board (4) is connected with a Dewar low temperature connection wire through a CNN connector; the metal gasket (3) is a red copper gasket.

3. The SQUID chip package structure device according to claim 1, wherein an accommodating groove (6) for accommodating the SQUID chip (1) is formed in the FPC flexible circuit board (4), a low-temperature glue (7) is added into the accommodating groove (6), and the SQUID chip (1) is adhered to the accommodating groove (6) on the FPC flexible circuit board (4); the metal gasket (3) and the cold finger (2) are also bonded by low-temperature glue (7).

4. The SQUID chip package structure device according to claim 1, wherein the FPC flexible circuit board (4) is provided with a first via hole (9), a socket (8) for connecting the electrode of the FPC flexible circuit board (4) and the low temperature cable is inserted into the first via hole (9) and is welded on the FPC flexible circuit board (4), and meanwhile, the socket (8) connects the low temperature cable and the FPC flexible circuit board (4); and a second through hole (10) is also formed in the corresponding position of the metal gasket (3), the aperture of the second through hole (10) is larger than that of the first through hole (9), and the power strip (8) penetrates through the second through hole (10).

5. The SQUID chip package structure device according to claim 1, wherein a fixing sleeve (11) is arranged above the FPC (4), the fixing sleeve (11) is provided with a notch (12) at the position of the whole SQUID chip (1), the fixing sleeve (11) comprises at least 2 detachable connecting bolts (13) extending downwards, and the connecting bolts (13) penetrate through the FPC (4) and the metal gasket (3) and are fixedly connected with the cold finger (2).

6. A SQUID chip packaging method comprises a SQUID chip (1) and a cold finger (2), wherein the cold finger (2) is connected with a Dewar, and is characterized by further comprising an FPC (flexible printed circuit) board (4) adhered on a heat-conducting metal gasket (3), wherein the SQUID chip (1) is adhered on the FPC (flexible printed circuit) board (4), and the FPC (flexible printed circuit) board (4) and the metal gasket (3) replace a traditional PCB (printed circuit board) to serve as bottom packaging of the SQUID chip (1); the metal gasket (3) is adhered to the cold finger (2) and is attached to the cold finger (2).

7. The SQUID chip packaging method according to claim 6, wherein the electrodes of the SQUID chip (1) are connected with FPC flexible circuit board electrodes through Bonding wires (5), and the FPC flexible circuit board (4) is connected with Dewar low-temperature connecting wires through a CNN connector; the metal gasket (3) is a red copper gasket.

8. The SQUID chip packaging method according to claim 6, wherein an accommodating groove (6) for accommodating the SQUID chip (1) is formed in the FPC flexible circuit board (4), a low-temperature glue (7) is added into the accommodating groove (6), and the SQUID chip (1) is adhered to the accommodating groove (6) in the FPC flexible circuit board (4); the metal gasket (3) and the cold finger (2) are also bonded by low-temperature glue (7).

9. The SQUID chip packaging method according to claim 6, wherein the FPC flexible circuit board (4) is provided with a first via hole (9), a socket (8) for connecting the FPC electrode and the low-temperature cable is inserted into the first via hole (9) and is welded on the FPC flexible circuit board (4), and meanwhile, the socket (8) is connected with the low-temperature cable and the FPC flexible circuit board (4); and a second through hole (10) is also formed in the corresponding position of the metal gasket (3), the aperture of the second through hole (10) is larger than that of the second through hole (10), and the power strip (8) penetrates through the second through hole (10).

10. The SQUID chip packaging method according to claim 6, wherein a fixing sleeve (11) is arranged above the FPC (4), a gap (12) is formed in the whole SQUID chip (1) by the fixing sleeve (11), the fixing sleeve (11) comprises at least 2 detachable connecting bolts (13) extending downwards, and the connecting bolts (13) penetrate through the FPC (4) and the metal gasket (3) and are fixedly connected with the cold finger (2).

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