CN112635426A

CN112635426A - Lead frame for chip packaging

Info

Publication number: CN112635426A
Application number: CN202011498506.1A
Authority: CN
Inventors: 曾永响
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-12-17
Filing date: 2020-12-17
Publication date: 2021-04-09

Abstract

The invention discloses a lead frame for chip packaging, and belongs to the technical field of chip packaging. The utility model provides a lead frame for chip package, including the encapsulation seat, encapsulation seat top surface middle part is seted up has the chip groove, bilateral symmetry is equipped with two splint around the chip groove, two lead wire grooves have been seted up to chip groove both sides middle part symmetry, lead wire groove both sides inner wall upper end is symmetrical structure and has seted up a plurality of grooves that run through, it is equipped with the pin to run through the inslot and inlay, encapsulation seat top surface rear side is articulated to two adjacent positions that run through between the groove has the cardboard, two circular slots have been seted up to cardboard both sides outer wall front end symmetry, encapsulation seat top surface front side has set firmly two sideboard for the position symmetry of cardboard front end both sides, the sideboard inner wall inlays and is equipped with the snak link, the encapsulation seat top is. The invention improves the convenience of the chip packaging operation of the working personnel, avoids the problem of insufficient contact between the lead and the pin, and has strong practicability.

Description

Lead frame for chip packaging

Technical Field

The invention relates to the technical field of chip packaging, in particular to a lead frame for chip packaging.

Background

The chip package is a casing for mounting semiconductor integrated circuit chip, which plays the role of placing, fixing, sealing, protecting chip and enhancing electrothermal performance, and can be used as lead frame, i.e. bridge for communicating chip internal world with external circuit, the connection points on the chip are led to the pins of the package casing by wires, and these pins are connected with other devices by wires on the printed board.

Upon retrieval, patent publication No. CN210743938U discloses a lead frame for chip packaging, which has the following problems: 1. when the device fills the chip into the middle island, the lead wire work is needed to be carried out on the lead wire outside the chip, so that the chip is easily dropped out of the middle island, the position of the chip is required to be repeatedly adjusted, and unnecessary workload is increased; 2. in the process of leading out the lead on the chip by the conventional device, the lead is fixed simply, so that the problem of curling of the outer side part of the lead is caused, and the lead cannot be in full contact with the inner leg close to the outer side end after being packaged, so that the transmission efficiency of the chip is greatly influenced; 3. the device lacks enough heat dissipation and heat conduction area for the chip, so that the influence of heat on the transmission efficiency of the chip is difficult to reduce, and the service life of the chip is shortened; 4. in addition, the packaging of the chip in the prior art is complicated and unstable, the operation difficulty of the worker for packaging the chip is improved, and the convenience of chip packaging is reduced. In view of this, we propose a lead frame for chip packaging.

Disclosure of Invention

1. Technical problem to be solved

The present invention is directed to a lead frame for chip packaging to solve the above problems.

2. Technical scheme

A lead frame for chip packaging comprises a packaging seat, wherein a chip groove is formed in the middle of the top surface of the packaging seat, two clamping plates are symmetrically arranged on the front side and the rear side of the chip groove, two sliding blocks are symmetrically and fixedly arranged at two ends of each clamping plate, a sliding groove is formed in the position, opposite to the sliding blocks, of the inner wall of the chip groove, a tension spring is fixedly arranged between the inner side wall of each sliding block and the inner side wall of the sliding groove, two lead grooves are symmetrically formed in the middle of two sides of the chip groove, a plurality of through grooves are symmetrically formed in the upper ends of the inner walls of the two sides of each lead groove, pins are embedded in the through grooves, a clamping plate is hinged between the two adjacent through grooves on the rear side of the top surface of the packaging seat, two circular grooves are symmetrically formed in the front ends of the outer walls on two sides of the clamping plate, two side plates are, the middle part of the bottom surface of the packaging seat is provided with a plurality of heat dissipation grooves at equal linear intervals relative to the positions of the chip grooves, and a fixing assembly is arranged above the packaging seat.

Preferably, splint both sides outer wall and bottom surface respectively with chip groove both sides inner wall and bottom surface sliding contact, slider and spout are trapezoidal column structure, slider and spout sliding fit, lead wire groove half cylinder structure.

Preferably, the pin is an L-shaped structure, the bottom surface of the outer side end of the pin is flush with the bottom surface of the packaging seat, the clamping plate is of an arc-shaped structure with a downward concave surface, the spring fastener and the circular groove are both of hemispherical structures, the spring fastener is in clamping fit with the circular groove, and the heat dissipation groove is not communicated with the chip groove.

Preferably, the fixing component comprises a packaging cover, a top groove is formed in the middle of the bottom surface of the packaging cover relative to the chip groove, cover wire grooves are formed in the two sides of the top groove relative to the lead grooves, the cover wire grooves are of a semi-cylindrical structure, and the diameter of each cover wire groove is larger than that of the clamping plate.

Preferably, the four corners of the top surface of the top groove are provided with vertical grooves, the upper part of the top groove is provided with an extrusion pad, the outer wall of the extrusion pad is in sliding contact with the inner wall of the top groove, compression springs are fixedly arranged between the top surface of the extrusion pad and the vertical top surface of the top groove, the middle part of the top surface of the packaging cover is provided with a groove, and the bottom surface of the groove is arranged and fixedly provided with a plurality of heat dissipation columns in a square matrix relative to the top groove.

Preferably, a plurality of cross screws are inserted in the two sides of the bottom surface of the groove in a symmetrical structure, the lower ends of the cross screws penetrate through the bottom surface of the groove, extend to the lower side and penetrate into the packaging seat, screw holes are formed in the positions, corresponding to the cross screws, of the bottom surface of the groove and the top surface of the packaging seat, screw holes are formed in the positions, corresponding to the cross screws, of the bottom surface of the groove, and hidden grooves are formed in the positions, corresponding to the starting ends of the cross screws, of the upper ends.

Preferably, encapsulation lid bottom surface four corners department is symmetrical structure and has set firmly four connecting plates, connecting plate inner wall lower extreme has set firmly the joint piece, encapsulation seat top surface four corners department has seted up the spread groove for the position of connecting plate, the connecting plate inner wall closely laminates with the spread groove inner wall, the joint groove has been seted up for the position of joint piece to the spread groove inner wall, the joint piece is the semi-cylindrical structure with the joint groove, joint piece and joint groove joint cooperation.

3. Advantageous effects

Compared with the prior art, the invention has the advantages that:

1. the chip packaging device is provided with the packaging seat, when a worker packages a chip, the two clamping plates symmetrically arranged in the chip groove can be firstly poked along the sliding fit direction of the sliding block and the sliding groove, then the chip is placed between the two clamping plates in the chip groove, the chip can be clamped between the two clamping plates under the action of the contraction force of the extension spring, then the worker can conduct lead operation on a lead on the chip, the problem that the chip slides out of the chip groove when the lead is led does not occur, the convenience of the worker for packaging the chip is improved, the fixing firmness of the device when the chip is not welded is enhanced, and the chip packaging device is convenient and reliable.

2. According to the invention, the plurality of clamping plates are linearly arranged on the lead slot at equal intervals, the clamping plates are of circular arc structures, the inner diameter of each clamping plate is matched with the diameter of the wire connected on the chip, when a worker conducts lead operation, the wire can be clamped into the lead slot in advance, then the clamping plates are turned along the direction from inside to outside of the lead slot along the hinged position of the clamping plates and the packaging seat, the inner wall of each clamping plate extrudes the outer wall of the wire, and then the two circular slots symmetrically arranged on the outer wall of the front end of each clamping plate are clamped with the spring buckles arranged on the side plates, so that the positions of the clamping plates are limited and the wire is pressed to be prevented from being curled.

3. In the invention, the top groove is arranged at the position of the middle part of the bottom surface of the fixing component relative to the chip groove, the extrusion pad and the compression spring arranged in the top groove can enable the extrusion pad to play a role in pressing the chip in the chip groove after the fixing component is installed, so that the chip is more firmly limited in the chip groove, the heat conduction effect of the packaging seat and the packaging cover on the chip is improved, the heat generated by the chip during operation can be better conducted out through the extrusion pad and the compression spring, in addition, the bottom surface of the packaging seat and the top surface of the packaging cover are respectively provided with the heat dissipation groove and the groove at the positions relative to the chip groove and the top groove, the heat dissipation surface of the bottom surface of the chip can be enlarged through the heat dissipation groove, a plurality of heat dissipation columns fixedly arranged in the groove in a matrix manner can help to increase the heat dissipation surface of the top surface of the chip, the heat dissipation enhancement effect of the device on the chip, the service life of the chip is prolonged.

4. According to the invention, the four corners of the bottom surface of the packaging cover are fixedly provided with the four connecting plates, the packaging cover can be preliminarily positioned through the clamping matching of the clamping blocks on the inner walls of the connecting plates and the clamping grooves on the base, and after the clamping is finished, a worker can connect the cross screw and the screw hole through the screw thread along the hidden groove on the bottom surface of the groove, so that the packaging cover is not required to be distracted and stabilized in the process of screwing in the cross screw, the operation difficulty of the worker in packaging the chip is reduced, and the convenience of chip packaging is effectively improved.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic bottom view of the present invention;

FIG. 3 is an exploded view of the present invention;

FIG. 4 is an exploded view of the fixing assembly of the present invention;

FIG. 5 is a schematic view of a package base structure according to the present invention;

FIG. 6 is a schematic cross-sectional view of a package base according to the present invention;

FIG. 7 is a schematic view of a card board structure of the present invention.

The reference numbers in the figures illustrate: 1. a package base; 2. a chip slot; 3. a splint; 4. a slider; 5. a chute; 6. an extension spring; 7. a lead slot; 8. a through groove; 9. a pin; 10. clamping a plate; 11. a circular groove; 12. a side plate; 13. a spring buckle; 14. a heat sink; 15. a fixing assembly; 16. a package cover; 17. a top groove; 18. covering a wire groove; 19. a vertical slot; 20. pressing the cushion; 21. a compression spring; 22. a groove; 23. a heat-dissipating column; 24. a cross screw; 25. a screw hole; 26. hiding the groove; 27. a connecting plate; 28. a clamping block; 29. connecting grooves; 30. a clamping groove.

Detailed Description

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are to be construed broadly, e.g., "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1-7, the present invention provides a technical solution:

a lead frame for chip packaging comprises a packaging seat 1, a chip groove 2 is arranged in the middle of the top surface of the packaging seat 1, two clamping plates 3 are symmetrically arranged on the front side and the back side of the chip groove 2, two sliding blocks 4 are symmetrically and fixedly arranged at the two ends of the clamping plates 3, a sliding groove 5 is arranged on the inner wall of the chip groove 2 relative to the position of the sliding block 4, a tension spring 6 is fixedly arranged between the inner wall of the sliding block 4 and the inner wall of the sliding groove 5, two lead grooves 7 are symmetrically arranged in the middle of the two sides of the chip groove 2, a plurality of through grooves 8 are symmetrically arranged at the upper ends of the inner walls of the two sides of the lead grooves 7, pins 9 are embedded in the through grooves 8, a clamping plate 10 is hinged at the position between the two adjacent through grooves 8 on the back side of the top surface of the packaging seat 1, two circular grooves 11 are symmetrically arranged at the front ends of the outer walls of the two sides of the, the middle part of the bottom surface of the package base 1 is provided with a plurality of heat dissipation grooves 14 at equal intervals in a linear way relative to the positions of the chip grooves 2, the heat dissipation surface of the bottom surface of the chip can be enlarged through the heat dissipation grooves 14, and a fixing component 15 is arranged above the package base 1.

It is specific, 3 both sides outer walls of splint and bottom surface respectively with 2 both sides inner walls in chip groove and bottom surface sliding contact, slider 4 is trapezoidal column structure with spout 5,

slider

4 and 5 sliding fit of spout, 7 half cylinder structures in lead wire groove, when the staff is encapsulating the chip, can be earlier dialled along

slider

4 and 5 sliding fit's direction with two splint 3 that the symmetry was equipped with in the chip groove 2, place the position between two splint 3 in chip groove 2 afterwards, two splint 3 can be in the centre of the chip centre gripping under extension spring 6's contractile force effect this moment, then the staff alright carry out the lead wire operation to the wire on the chip, just can not take place the problem that leads to the chip to slide out chip groove 2 when the lead wire this moment, the convenient degree that the staff encapsulated the operation to the chip has been improved.

Furthermore, the pin 9 is an L-shaped structure, compared with the matching of an inner pin and an outer pin in the existing device, the pin 9 in the device can effectively enhance the transmission effect through an integrated structure, the bottom surface of the outer side end of the pin 9 is flush with the bottom surface of the package base 1, the clamping plate 10 is an arc-shaped structure with a downward concave surface, the spring buckle 13 and the circular groove 11 are both of a hemisphere structure, the spring buckle 13 is clamped and matched with the circular groove 11, the heat dissipation groove 14 is not communicated with the chip groove 2, when a worker conducts a wire leading operation, a wire can be firstly clamped into the wire leading groove 7, then the clamping plate 10 is overturned along the direction of the wire leading groove 7 from inside to outside along the position hinged with the package base 1, so that the inner wall of the clamping plate extrudes the outer wall of the wire, then the two circular grooves 11 symmetrically arranged on the outer wall of the front end of the clamping plate 10 are clamped and connected with the spring buckle 13 arranged on the side plate 12, thereby, such structure can effectually prevent that the wire from taking place the problem of curling before the encapsulation, has avoided the wire not enough with the contact of pin 9, prevents that the transmission efficiency of chip from receiving the influence, and the practicality is strong.

Further, the fixing component 15 comprises an encapsulation cover 16, a top groove 17 is formed in the middle of the bottom surface of the encapsulation cover 16 relative to the position of the chip groove 2, cover wire grooves 18 are formed in the positions, opposite to the lead grooves 7, of the two sides of the top groove 17, the cover wire grooves 18 are of a semi-cylindrical structure, the diameter of each cover wire groove 18 is larger than that of the corresponding clamping plate 10, the cover wire grooves 18 can enable the clamping plates 10 and the side plates 12 to be contained in the cover wire grooves, and the influence of the clamping plates 10 and the side plates 12 on the connection of the encapsulation cover 16 and the encapsulation seat.

Still further, 17 top surface four corners department has all seted up on the top groove 19, top groove 17 upper portion is equipped with the dummy block 20, dummy block 20 outer wall and 17 inner wall sliding contact in top groove, the dummy block 20 top surface and erect 19 top surfaces between the groove and have set firmly compression spring 21, encapsulation lid 16 top surface middle part has seted up recess 22, the recess 22 bottom surface is the square matrix for the position of top groove 17 arranges and has set firmly a plurality of radiating columns 23, arrange a plurality of radiating columns 23 that set firmly through the square matrix in the recess 22 and can help increasing chip top surface cooling surface, the heat dissipation reinforcing effect of this device to the chip has been improved to the at utmost, the effectual influence that has reduced the heat to chip transmission efficiency, the life of chip has been improved.

It is worth introducing that, recess 22 bottom surface both sides are the symmetrical structure and are inserted and are equipped with a plurality of cross screws 24, cross screw 24 lower extreme runs through recess 22 bottom surface and extends to the downside and run through into encapsulation seat 1, recess 22 bottom surface and encapsulation seat 1 top surface all seted up screw 25 for the position of cross screw 24, cross screw 24 and screw 25 screw thread screw 25, the position that is located the screw 25 upper end of recess 22 bottom surface for cross screw 24 initiating terminal has seted up hidden groove 26, hidden groove 26 can hide cross screw 24 initiating terminal in it, when preventing to connect this device with external equipment, the initiating terminal of cross screw 24 exposes can influence the installation or produce the problem of becoming flexible.

It is worth to be noted that, four connecting plates 27 are fixed at four corners of the bottom surface of the packaging cover 16 in a symmetrical structure, the lower end of the inner wall of the connecting plate 27 is fixed with a clamping block 28, the four corners of the top surface of the packaging seat 1 are provided with connecting grooves 29 corresponding to the positions of the connecting plates 27, the inner wall of the connecting plate 27 is tightly attached to the inner wall of the connecting groove 29, the inner wall of the connecting groove 29 is provided with a clamping groove 30 corresponding to the clamping block 28, the clamping block 28 and the clamping groove 30 are both in a semi-cylindrical structure, the clamping block 28 is clamped and matched with the clamping groove 30, after the lead is fixed, the packaging cover 16 can be preliminarily positioned by the clamping fit of the clamping block 28 at the inner wall of the connecting plate 27 and the clamping groove 30 on the base, after the clamping is completed, a worker can screw 24 and a screw hole 25 are screwed along the hidden groove 26 at the bottom, the operation difficulty of the working personnel for packaging the chip is reduced, and the convenience of chip packaging is effectively improved.

The working principle is as follows: when a worker packages a chip, the two clamping plates 3 symmetrically arranged in the chip groove 2 can be firstly poked away along the sliding fit direction of the sliding block 4 and the sliding groove 5, then the chip is placed at the position between the two clamping plates 3 in the chip groove 2, at the moment, the two clamping plates 3 can clamp the chip in the middle under the action of the contraction force of the extension spring 6, then the worker can carry out lead operation on a lead on the chip, at the moment, the problem that the chip slides out of the chip groove 2 when the lead is led does not occur, the convenience of the worker for packaging the chip is improved, the fixing firmness of the device when the chip is not welded is enhanced, the device is convenient and reliable, when the worker carries out the lead operation, the lead can be firstly clamped into the lead groove 7, and then the clamping plate 10 is turned over along the position where the clamping plate is hinged with the packaging seat 1 along the direction from inside to outside along the lead groove 7, the inner wall of the clamping plate 10 extrudes the outer wall of a wire, and then the two circular grooves 11 symmetrically arranged on the outer wall of the front end of the clamping plate 10 are clamped with the spring buckles 13 arranged on the side plate 12, so that the position of the clamping plate 10 is limited and the wire is pressed and cannot be curled, the structure can effectively prevent the wire from curling before packaging, avoid insufficient contact between the wire and the pins 9 and prevent the transmission efficiency of a chip from being affected, has strong practicability, after the wire is fixed, a worker can preliminarily position the packaging cover 16 by clamping and matching the clamping blocks 28 on the inner wall of the connecting plate 27 with the clamping grooves 30 on the base, and then the worker can connect the cross screw 24 with the screw hole 25 by screwing the cross screw 24 along the hidden groove 26 on the bottom surface of the groove 22, so that the package cover 16 is not needed to be separately centered and stabilized in the process of screwing the cross screw 24, and the operation difficulty of the worker for packaging the chip is reduced, the convenience of chip packaging is effectively improved, at the moment, the extrusion pad 20 and the compression spring 21 arranged in the top groove 17 can enable the extrusion pad 20 to play a pressing effect on the chip in the chip groove 2 after the fixing component 15 is installed, so that the chip is more firmly limited in the chip groove 2, the heat conduction effect of the packaging seat 1 and the packaging cover 16 on the chip is also improved, the heat generated by the chip during operation can be better conducted out through the extrusion pad and the compression spring, in addition, the bottom surface of the packaging seat 1 and the top surface of the packaging cover 16 are respectively provided with the radiating grooves 14 and the grooves 22 at the positions corresponding to the chip groove 2 and the top groove 17, the radiating surface of the bottom surface of the chip can be enlarged through the radiating grooves 14, the radiating columns 23 fixedly arranged in the square in the grooves 22 can help to increase the radiating surface of the top surface of the chip, and the radiating enhancement effect of the device on the chip is improved to the maximum extent, the influence of heat on the transmission efficiency of the chip is effectively reduced, and the service life of the chip is prolonged.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A lead frame for chip packaging, comprising a package base (1), characterized in that: a chip groove (2) is formed in the middle of the top surface of the packaging seat (1), two clamping plates (3) are symmetrically arranged on the front side and the rear side of the chip groove (2), two sliding blocks (4) are symmetrically and fixedly arranged at the two ends of each clamping plate (3), a sliding groove (5) is formed in the position, relative to each sliding block (4), of the inner wall of the chip groove (2), a tension spring (6) is fixedly arranged between the inner side wall of each sliding block (4) and the inner side wall of each sliding groove (5), two lead grooves (7) are symmetrically formed in the middle of the two sides of the chip groove (2), a plurality of through grooves (8) are symmetrically formed in the upper ends of the inner walls of the two sides of each lead groove (7), pins (9) are embedded in the through grooves (8), a clamping plate (10) is hinged to the position, relative to each two adjacent through grooves (8), of the rear side of the top surface of the packaging seat (, encapsulation seat (1) top surface front side has set firmly two sideboard (12) for the position symmetry of cardboard (10) front end both sides, sideboard (12) inner wall is inlayed and is equipped with snak link (13), encapsulation seat (1) bottom surface middle part is the position of relative chip groove (2) and is linear equidistant a plurality of radiating grooves (14) of having seted up, encapsulation seat (1) top is equipped with fixed subassembly (15).

2. The lead frame for chip packaging according to claim 1, wherein: splint (3) both sides outer wall and bottom surface respectively with chip groove (2) both sides inner wall and bottom surface sliding contact, slider (4) are trapezoidal column structure with spout (5), slider (4) and spout (5) sliding fit, lead wire groove (7) half cylinder structure.

3. The lead frame for chip packaging according to claim 1, wherein: pin (9) are L type structure, pin (9) outside end bottom surface and encapsulation seat (1) bottom surface parallel and level, cardboard (10) are the decurrent arc structure of concave surface, snak link (13) are the hemisphere structure with circular slot (11), snak link (13) and circular slot (11) joint cooperation, radiating groove (14) and chip groove (2) do not communicate.

4. The lead frame for chip packaging according to claim 1, wherein: the fixed component (15) comprises a packaging cover (16), wherein a top groove (17) is formed in the middle of the bottom surface of the packaging cover (16) relative to the position of the chip groove (2), cover wire grooves (18) are formed in the positions, opposite to the lead wire grooves (7), of the two sides of the top groove (17), the cover wire grooves (18) are of semi-cylindrical structures, and the diameter of the cover wire grooves (18) is larger than that of the clamping plates (10).

5. The lead frame for chip packaging according to claim 4, wherein: top groove (17) top surface four corners department has all seted up and has erect groove (19), top groove (17) upper portion is equipped with extrusion pad (20), extrusion pad (20) outer wall and top groove (17) inner wall sliding contact, compression pad (20) top surface and perpendicular groove (19) top surface between set firmly compression spring (21), encapsulation lid (16) top surface middle part is seted up flutedly (22), recess (22) bottom surface is the square matrix for the position of top groove (17) and arranges and set firmly a plurality of radiating columns (23).

6. The lead frame for chip packaging according to claim 5, wherein: recess (22) bottom surface both sides are the symmetrical structure and insert and be equipped with a plurality of cross screw (24), cross screw (24) lower extreme runs through recess (22) bottom surface and extends to the downside and run through into encapsulation seat (1), screw (25) have all been seted up for the position of cross screw (24) to recess (22) bottom surface and encapsulation seat (1) top surface, cross screw (24) and screw (25) screw thread screw (25), are located recess (22) bottom surface screw (25) upper end has seted up hidden groove (26) for the position of cross screw (24) initiating end.

7. The lead frame for chip packaging according to claim 6, wherein: encapsulation lid (16) bottom surface four corners department is symmetrical structure and has set firmly four connecting plates (27), connecting plate (27) inner wall lower extreme has set firmly joint piece (28), connecting groove (29) have been seted up for the position of connecting plate (27) to encapsulation seat (1) top surface four corners department, connecting plate (27) inner wall and connecting groove (29) inner wall closely laminate, joint groove (30) have been seted up for the position of joint piece (28) to connecting groove (29) inner wall, joint piece (28) are the semicylinder structure with joint groove (30), joint piece (28) and joint groove (30) joint cooperation.