High-speed communication card edge connector

Abstract

The utility model provides a high-speed communication card edge connector, which comprises an insulating body, an upper row of terminals and a lower row of terminals, the upper row of terminals and the lower row of terminals are respectively embedded into the insulating body from the rear side surface and the front side surface of the insulating body, and the front side surface of the insulating body is provided with an electronic card insertion port positioned between the upper row of terminals and the lower row of terminals. The upper-row terminal comprises a signal terminal and a grounding terminal, a grounding piece I embedded and fixed in the insulating body is arranged between the upper-row terminal and the lower-row terminal, a grounding piece II embedded and fixed in the insulating body is also arranged between the upper-row terminal and the lower-row terminal, and the grounding piece I is provided with a plurality of elastic contact parts I; the grounding piece II is provided with a plurality of elastic contact parts II; the grounding terminals of the upper row of terminals are simultaneously contacted and conducted with one elastic contact part I and one elastic contact part II; the high-speed communication card edge connector can achieve a good internal signal shielding effect and effectively solve the problem of poor contact caused by rigid contact.

Description

Technical Field

[0001] The utility model belongs to the field of connectors, and in particular relates to a high-speed communication card edge connector. Background Art

[0002] The transmission rate of PCIe 4.0 version is required to reach 16Gbps, and the transmission rate of PCIe 5.0 version is required to reach 32Gbps. The M.2 connector mainly uses PCIe signals. The current version of M.2 is 5.0, which uses PCIe5.0 signals. Under such high transmission rate requirements, the shielding effect of the connector must be done well.

[0003] Chinese patent CN202211420095.3 discloses a high-speed signal connector, including an insulating body, an upper row of terminals and a lower row of terminals respectively embedded in the insulating body from the rear side and the front side of the insulating body, and a shielding shell covering the top surface, left and right sides and the rear side of the insulating body. A grounding sheet is embedded and fixed in the insulating body between the upper row of terminals and the lower row of terminals.

[0004] A grounding spring is provided on the rear wall of the shielding shell covering the rear side of the insulating body. A grounding terminal is provided between every two pairs of signal terminals of the upper row of terminals. The inner surface of the grounding terminal of the upper row of terminals is in contact with the grounding sheet, and the outer surface of the grounding terminal of the upper row of terminals is in contact with the grounding spring.

[0005] The above-mentioned high-speed signal connector has a grounding plate embedded and fixed in the insulating body between the upper row of terminals and the lower row of terminals, and a grounding spring is provided on the rear wall of the shielding shell covering the rear side of the insulating body. The grounding terminals of the upper row of terminals are respectively in contact with the grounding plate and the grounding spring, thereby effectively reducing the loss of signal transmission under high-speed and high-frequency requirements, effectively reducing the interference between the internal signal terminals of the connector, effectively reducing the interference of external signals on the internal signal terminals of the connector, and effectively reducing the resonance of the signal. However, the grounding plate and the grounding terminal are in rigid contact, and the rigid contact has the problem of poor contact; in addition, there is only one grounding plate in the insulating body, and the internal signal shielding effect is limited. Therefore, it needs to be improved. Utility Model Content

[0006] The utility model aims to provide a high-speed communication card edge connector to solve the problems raised in the above-mentioned background technology.

[0007] In order to achieve the above purpose, the technical solution used in this utility model is:

[0008] A high-speed communication card edge connector comprises an insulating body and an upper row of terminals and a lower row of terminals respectively embedded in the insulating body from the rear side and the front side of the insulating body, the front side of the insulating body has an electronic card insertion interface located between the upper row of terminals and the lower row of terminals, the upper row of terminals includes a signal terminal and a grounding terminal, a grounding plate 1 is embedded and fixed in the insulating body between the upper row of terminals and the lower row of terminals, and a grounding plate 2 is embedded and fixed in the insulating body between the upper row of terminals and the lower row of terminals, the grounding plate 1 is provided with a plurality of elastic contact portions 1, the grounding plate 2 is provided with a plurality of elastic contact portions 2, and at least one grounding terminal of the upper row of terminals is in contact and conduction with one of the elastic contact portions 1 and one of the elastic contact portions 2 at the same time.

[0009] Furthermore, the grounding plate includes a main body, which includes a plurality of spaced-apart flat plates, a groove is provided in the insulating body corresponding to each flat plate, adjacent grooves are separated by a partition wall, the intervals between adjacent flat plates match the partition wall, the lower ends of the plurality of flat plates are connected as a whole through a connecting portion, each flat plate is provided with two openings, and one side of each opening is connected to the elastic contact portion.

[0010] Furthermore, each of the upper ends of the flat plates is connected to a bending portion, which is formed by first bending the upper end of the flat plate backward and then upward, and the bending portion forms a gap between the flat plate and the rear wall of the embedded groove, and the elastic contact portion is located at the gap.

[0011] Furthermore, the two openings on each of the flat plates are vertically arranged and parallel to each other, each elastic contact portion is parallel to the flat plate, the lower end of each elastic contact portion is a free end, the upper end of each elastic contact portion is bent forward to form an upward inclined bending portion, and the upper end of the upward inclined bending portion is connected to the upper edge of the opening.

[0012] Furthermore, each of the flat plates is provided with a vertical hole between the two openings, and the middle side walls of the vertical hole are connected by a transverse connecting portion.

[0013] Furthermore, the bottom surface of the insulating body is recessed upward to form a retaining groove for fixing the second grounding plate, and the retaining groove is located between the embedding groove and the rear side surface of the insulating body. The second grounding plate includes a plate body fixed in the retaining groove, and a plurality of the second elastic contact portions are spaced apart on the lower side of the plate body.

[0014] Furthermore, a plurality of interference spring sheets are arranged at intervals on the lower side of the sheet body and are fixed by interference with the inner wall of the retaining groove.

[0015] Furthermore, it also includes a shielding shell covering the insulating body, and the rear wall of the shielding shell covering the rear side of the insulating body is provided with a grounding spring sheet, and the grounding terminal that is in contact and conductive with the elastic contact part 1 and the elastic contact part 2 at the same time is also in contact and conductive with the grounding spring sheet.

[0016] Furthermore, there are two grounding springs on the shielding shell that are in contact with and conductive with each grounding terminal.

[0017] Furthermore, two rows of punch holes are formed on the shielding shell by stamping, each punch hole in the upper row corresponds to each punch hole in the lower row, and the lower edge of each punch hole in the upper row and the lower edge of each punch hole in the lower row are connected to a grounding spring sheet.

[0018] Compared with the prior art, the beneficial effects of the utility model are mainly reflected in:

[0019] (1) By adopting the grounding plate 1 and the grounding plate 2, each grounding terminal of the upper row of terminals is simultaneously in contact with an elastic contact portion 1 of the grounding plate 1 and an elastic contact portion 2 of the grounding plate 2, so as to achieve a good internal signal shielding effect; the setting of the elastic contact portion 1 and the elastic contact portion 2 enables them to form elastic contact with the grounding terminal, and the elastic contact method makes the contact between the grounding terminal and the elastic contact portion 1 and the elastic contact portion 2 closer, effectively solving the problem of poor contact caused by rigid contact.

[0020] (2) By forming a bent portion at the upper end of the flat plate, a gap is formed between the flat plate and the rear wall of the groove, thereby providing a space for elastic deformation of the elastic contact portion.

[0021] (3) By setting the lower end of the elastic contact part 1 as a free end and connecting the upper end to the upper side of the opening, the grounding plate can be directly installed into the insulating body from the bottom of the insulating body, which is easy to assemble.

[0022] (4) The second grounding plate uses an interference spring, which can provide holding force to prevent the second grounding plate from falling out of the retaining groove.

[0023] (5) A shielding shell is added on the basis of grounding plate 1 and grounding plate 2. The shielding shell can shield external signals, so that the high-speed communication card edge connector has a double shielding effect inside and outside, effectively preventing signal interference.

[0024] (6) Two grounding springs are used on the shielding shell to form elastic contact with each grounding terminal, effectively preventing poor contact and improving the shielding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a three-dimensional schematic diagram of the high-speed communication card edge connector of the utility model combined with an electronic card and a circuit board;

[0026] Figure 2 It is a three-dimensional exploded schematic diagram of a high-speed communication card edge connector;

[0027] Figure 3 It is a three-dimensional exploded schematic diagram of a high-speed communication card edge connector and a grounding plate 1 and a grounding plate 2;

[0028] Figure 4It is a three-dimensional combination diagram of a high-speed communication card edge connector, a grounding plate 1 and a grounding plate 2.

[0029] Figure 5 Schematic diagram of shielding case Figure 1 ;

[0030] Figure 6 Schematic diagram of shielding case Figure 2 ;

[0031] Figure 7 A three-dimensional diagram of the insulating body Figure 1 ;

[0032] Figure 8 A three-dimensional diagram of the insulating body Figure 2 ;

[0033] Fig. 9 A three-dimensional diagram of the insulating body Figure 3 ;

[0034] Fig.10 It is a side view of the upper row of terminals and the lower row of terminals;

[0035] Fig.11 It is a three-dimensional diagram of the upper row of terminals;

[0036] Fig.12 This is the front view of the upper row of terminals;

[0037] Fig.13 is a three-dimensional diagram of grounding plate 1;

[0038] Fig.14 is a three-dimensional diagram of ground plate 2;

[0039] Fig.15 It is a cross-sectional schematic diagram of a high-speed communication card edge connector.

[0040] Description of the accompanying reference numerals: electronic card 1, circuit board 2, insulating body 3, electronic card plug-in interface 31, foolproof portion 32, slot 1 33, slot 2 34, embedding slot 35, partition wall 36, holding slot 37, connecting slot 38, upper row terminal 4, non-high-speed signal terminal 4a, high-speed signal terminal 4b, contact portion 41, connecting portion 42, welding portion 43, holding portion 44, lower row terminal 5, shielding shell 6, sealing surface 6a, grounding spring 61 , stamping hole 62, folded edge 63, upper bent discount plate 64, lower bent discount plate 65, buckle arm 66, grounding plate 7, gap a, main body 71, flat plate 711, bending portion 712, connecting portion 713, opening 714, elastic contact portion 1 715, upper oblique bending portion 716, vertical hole 718, horizontal connecting portion 719, fixed foot 8, grounding plate 2 9, sheet body 91, elastic contact portion 2 92, interference spring piece 93, straight sheet 94. DETAILED DESCRIPTION

[0041] In order to facilitate a better understanding of the purpose, structure, features and functions of the present invention, the present invention is further described in conjunction with the accompanying drawings and specific implementation methods.

[0042] like Figure 1-15 As shown, the high-speed communication card edge connector is provided for an electronic card 1 to be inserted and fixed flatly by welding on a circuit board 2. The high-speed communication card edge connector comprises an insulating body 3, an upper row of terminals 4 and a lower row of terminals 5 respectively embedded in the insulating body 3 from the rear side and the front side of the insulating body 3, and a shielding shell 6 covering the top surface, left and right sides and the rear side of the insulating body 3. Between the upper row of terminals 4 and the lower row of terminals 5, there are grounding plates 1 7 and 2 9 embedded and fixed in the insulating body 3.

[0043] The front side of the insulating body 3 has an electronic card insertion interface 31 located between the upper row of terminals 4 and the lower row of terminals 5. The electronic card insertion interface 31 has an anti-mistake portion 32, which is close to one end of the insulating body 3 and away from the other end of the insulating body 3. The front and rear surfaces of the insulating body 3 have terminal fixing grooves, which are distributed on both sides of the anti-mistake portion 32. Slot positions 1 33 are recessed on the left and right sides of the front side of the insulating body 3. Slot positions 2 34 are recessed on the left and right sides of the rear side of the insulating body 3, and the two slot positions 2 34 are connected to the two slot positions 1 33. A fixing foot 8 is fixed in each of slot positions 1 33 and slot position 2 34. The bottom surface of the insulating body 3 is recessed upward at the rear side to form a plurality of embedded grooves 35, and adjacent embedded grooves 35 are separated by partition walls 36. The bottom surface of the insulating body 3 is recessed upward to form a retaining groove 37, which is located between the embedding groove 35 and the rear side surface of the insulating body 3. A plurality of connecting grooves 38 are opened on the retaining wall between the retaining groove 37 and the rear side surface of the insulating body 3, and each connecting groove 38 is connected to the terminal fixing groove of the grounding terminal G that fixes the upper row of terminals 4 on the insulating body 3.

[0044] The rear wall of the shielding shell 6 covering the rear side of the insulating body 3 is provided with a grounding spring piece 61, and a grounding terminal G is provided between every two pairs of signal terminals S of the upper row of terminals 4. The inner surface of the grounding terminal G of the upper row of terminals 4 is in contact with the grounding plate 1 7 and the grounding plate 2 9, and the outer surface of the grounding terminal G of the upper row of terminals 4 is in contact with the grounding spring piece 61.

[0045] The upper row of terminals 4 includes non-high-speed signal terminals 4a and high-speed signal terminals 4b, wherein the non-high-speed signal terminals 4a are located between the anti-mistake portion 32 and one end of the insulating body 3 close to the anti-mistake portion 32, and the high-speed signal terminals 4b are located between the anti-mistake portion 32 and the other end of the insulating body 3 away from the anti-mistake portion 32. Both the non-high-speed signal terminals 4a and the high-speed signal terminals 4b include signal terminals S and grounding terminals G, and each grounding terminal G of the high-speed signal terminal 4b is in contact and conduction with the grounding sheet 1 7, the grounding sheet 2 9, and the grounding spring 61 at the same time. Each grounding terminal G of the non-high-speed signal terminal 4a is not in contact and conduction with the grounding sheet 1 7, the grounding sheet 2 9, and the grounding spring 61.

[0046] The upper row terminals 4 and the lower row terminals 5 have the same structure, and both include a contact portion 41, a connecting portion 42 and a welding portion 43. The welding portions 43 of the upper row terminals 4 and the lower row terminals 5 are both welded flat on the circuit board 2. The connecting portions 42 of the upper row terminals 4 and the lower row terminals 5 are connected between the contact portion 41 and the welding portion 43, and each connecting portion 42 extends vertically toward the same side to form two upper and lower retaining portions 44. The retaining portion 44 on the lower side of the grounding terminal G of the upper row terminal 4 penetrates the rear wall of the embedding groove 35, and the inner surface of the retaining portion 44 is in contact and conduction with the grounding plate 7.

[0047] The position of the non-high-speed signal terminal 4a at the rear wall of the shielding shell 6 is a closed surface 6a, and the position of the high-speed signal terminal 4b at the rear wall of the shielding shell 6 is formed by punching two rows of punching holes 62, each punching hole 62 in the upper row corresponds to each punching hole 62 in the lower row, and the lower edge of each punching hole 62 in the upper row and the lower edge of each punching hole 62 in the lower row are connected to a grounding spring 61. There are two grounding springs 61 on the shielding shell 6 that are in contact with each grounding terminal G. The upper end of the grounding spring 61 is a free end, and the lower end of the grounding spring 61 is connected to the lower side of the punching hole 62. The grounding spring 61 is an inclined spring. The left and right walls and the rear wall of the shielding shell 6 are connected to the top wall of the shielding shell 6. The left and right walls are bent toward the outer surface of the rear wall to form folded edges 63. The folded edges 63 of the left and right walls are folded on the outer surface of the rear wall. The left and right sides of the rear wall are also bent to form folded edges 63 folded on the inner surfaces of the left and right walls. The folded edges 63 are used to increase the strength of the shielding shell 6. The front sides of the left and right walls are bent toward each other to form an upward bending discount plate 64 and a downward bending discount plate 65. The downward bending discount plate 65 and the upward bending discount plate 64 are staggered front and back. The downward bending discount plate 65 and the upward bending discount plate 64 are both buckled on the front side of the insulating body 3. The lower end of the downward bending discount plate 65 is bent backward to form a buckle arm 66, and the buckle arm 66 is buckled on the top wall of the slot position 1 33.

[0048] The grounding plate 1 7 comprises a main body 71, which comprises a plurality of spaced flat plates 711. An embedding groove 35 is provided in the insulating body 3 corresponding to each flat plate 711. Each flat plate 711 is embedded and fixed in an embedding groove 35. The interval between adjacent flat plates 711 matches the partition wall 36. The upper end of each flat plate 711 is connected to a bending portion 712. Each bending portion 712 is formed by bending backward and then upward from the upper end of each flat plate 711. After the bending portion 712 is formed, a gap a is formed between the flat plate 711 and the rear wall of the embedding groove 35. The lower ends of the plurality of flat plates 711 are connected as a whole through a connecting portion 713. Two vertically arranged and mutually parallel openings 714 are provided on each flat plate 711. The upper side of each opening 714 is connected to an elastic contact portion 1 715. The elastic contact portion 1 715 is located at the gap a. The gap a is used to provide deformation space for the elastic contact portion 1 715. Each elastic contact part 715 is parallel to the plate 711, the lower end of each elastic contact part 715 is a free end, the upper end of each elastic contact part 715 is bent forward to form an upward oblique bending part 716, and the upper end of the upward oblique bending part 716 is connected to the upper side of the opening 714. The inner surface of the retaining part 44 of each grounding terminal G of the upper row of terminals 4 is in contact and conductive with one of the elastic contact parts 715. A vertical hole 718 is also formed between the two openings 714 on each plate 711, and the middle two side walls of the vertical hole 718 are connected by a horizontal connecting part 719.

[0049] The grounding sheet 2 9 includes a sheet body 91 fixed in the holding groove 37, and a plurality of elastic contact portions 2 92 are arranged at intervals on the lower side of the sheet body 91. Each elastic contact portion 2 92 passes through the corresponding connecting groove 38 and contacts and conducts with the inner surface of the connecting portion 42 below the holding portion 44 on the lower side of the corresponding grounding terminal G of the upper row of terminals 4. A plurality of interference springs 93 are also arranged at intervals on the lower side of the sheet body 91 to interfere and fix with the inner wall of the holding groove 37. The interference springs 93 can provide a holding force to prevent the grounding sheet 2 9 from falling out of the holding groove 37. A plurality of straight sheets 94 are also arranged at intervals on the lower side of the sheet body 91. The straight sheets 94 and the interference springs 93 cooperate to abut against the two opposite side walls of the holding groove 37 to further prevent the grounding sheet 2 9 from falling out of the holding groove 37.

[0050] Compared with the prior art, the beneficial effects of the utility model are mainly reflected in: by adopting the grounding plate 1 7 and the grounding plate 2 9, each grounding terminal G of the upper row of terminals 4 is simultaneously in contact with an elastic contact part 1 715 of the grounding plate 1 7 and an elastic contact part 2 92 of the grounding plate 2 9, so as to achieve a good internal signal shielding effect; the setting of the elastic contact part 1 715 and the elastic contact part 2 92 enables them to form elastic contact with the grounding terminal, and the elastic contact mode makes the contact between the grounding terminal G and the elastic contact part 1 715 and the elastic contact part 2 92 closer, effectively solving the problem of poor contact caused by rigid contact. By forming a bending part 712 at the upper end of the flat plate 711, a gap a is formed between the flat plate 711 and the rear wall of the groove 35, so that a space for elastic deformation of the elastic contact part 1 715 can be provided. By setting the lower end of the elastic contact part 1 715 as a free end and the upper end connected to the upper side of the opening 714, the grounding plate 1 7 can be directly installed into the insulating body 3 from the bottom of the insulating body 3, and the assembly is simple. A shielding shell 6 is added on the basis of the grounding plate 1 7 and the grounding plate 2 9. The shielding shell 6 can shield external signals, so that the high-speed communication card edge connector has a double shielding effect inside and outside, effectively preventing signal interference. Two grounding springs 61 are used on the shielding shell 6 to form elastic contact with each grounding terminal G, effectively preventing poor contact and improving the shielding effect.

[0051] In other embodiments, the shielding shell 6 is not provided.

[0052] In other embodiments, no spacing may be set between adjacent flat plates 711, and every two adjacent flat plates 711 are connected together to form a main body 71 in the shape of an integral flat plate. The bending portions 712 at the upper ends of every two adjacent flat plates 711 are also connected together to form an integral bending portion. A slot is provided at the partition wall 36 to clamp the main body 71, and the slot is connected to the embedding groove 35, and the elastic contact portion 715 is provided on the main body between adjacent partition walls 36.

[0053] In other embodiments, the upper end of each elastic contact portion 715 can be set as a free end, and the lower end of each elastic contact portion 715 can be set as a downwardly inclined bending portion, and the lower end of the downwardly inclined bending portion is connected to the lower side of the opening 714.

[0054] In other embodiments, there may be only one grounding spring 61 on the shielding shell 6 that is in contact with and conductive with each grounding terminal G.

[0055] In other embodiments, the high-speed signal terminal 4 b of the upper row of terminals 4 may have only one ground terminal G that is in contact and conductive with both an elastic contact portion 1 715 of the grounding plate 7 and an elastic contact portion 2 92 of the grounding plate 2 9 .

[0056] In other embodiments, the high-speed signal terminal 4b of the upper row of terminals 4 has only one ground terminal G that is in contact and conductive with an elastic contact portion 715 of the grounding plate 7 and an elastic contact portion 2 92 of the grounding plate 2 9. At the same time, the ground terminal G is also in contact and conductive with one or two grounding spring plates 61 of the shielding shell 6.

[0057] The present invention is described above in conjunction with the best embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations based on the essence of the present invention.

Claims

1. A high-speed communication card edge connector, comprising an insulating body and upper and lower terminals respectively embedded in the insulating body from the rear side and the front side of the insulating body, wherein the front side of the insulating body has an electronic card insertion interface located between the upper and lower terminals, the upper terminals include signal terminals and ground terminals, and a grounding plate is embedded and fixed in the insulating body between the upper and lower terminals, characterized in that: There is also a grounding plate 2 embedded and fixed in the insulating body between the upper row of terminals and the lower row of terminals. The grounding plate 1 is provided with multiple elastic contact parts 1, and the grounding plate 2 is provided with multiple elastic contact parts 2. At least one grounding terminal of the upper row of terminals is in contact and conductive with one of the elastic contact parts 1 and one of the elastic contact parts 2 at the same time.

2. The high-speed communication card edge connector according to claim 1, characterized in that: The grounding plate includes a main body, which includes a plurality of spaced-apart flat plates. An embedding groove is arranged in the insulating body corresponding to each flat plate. Adjacent embedding grooves are separated by a partition wall. The intervals between adjacent flat plates match the partition wall. The lower ends of the plurality of flat plates are connected as a whole through a connecting portion. Each flat plate is provided with two openings, and one side of each opening is connected to the elastic contact portion.

3. The high-speed communication card edge connector according to claim 2, characterized in that: The upper end of each flat plate is connected to a bending portion, which is formed by first bending the upper end of the flat plate backward and then bending upward. The bending portion forms a gap between the flat plate and the rear wall of the embedded groove, and the elastic contact portion is located at the gap.

4. The high-speed communication card edge connector according to claim 2, characterized in that: The two openings on each of the flat plates are vertically arranged and parallel to each other, each elastic contact portion is parallel to the flat plate, the lower end of each elastic contact portion is a free end, the upper end of each elastic contact portion is bent forward to form an upward inclined bending portion, and the upper end of the upward inclined bending portion is connected to the upper edge of the opening.

5. The high-speed communication card edge connector according to claim 4, characterized in that: Each of the flat plates is provided with a vertical hole between the two openings, and the middle two side walls of the vertical hole are connected by a transverse connecting portion.

6. The high-speed communication card edge connector according to claim 2, characterized in that: The bottom surface of the insulating body is recessed upward to form a retaining groove for fixing the second grounding plate. The retaining groove is located between the embedding groove and the rear side surface of the insulating body. The second grounding plate includes a plate body fixed in the retaining groove. A plurality of the second elastic contact portions are spaced apart on the lower side of the plate body.

7. The high-speed communication card edge connector according to claim 6, characterized in that: A plurality of interference spring sheets are also arranged at intervals on the lower side of the sheet body and are fixed with interference with the inner wall of the holding groove.

8. The high-speed communication card edge connector according to any one of claims 1 to 7, characterized in that: It also includes a shielding shell covering the insulating body, wherein the rear wall of the shielding shell covering the rear side of the insulating body is provided with a grounding spring sheet, and the grounding terminal that is in contact and conductive with the elastic contact part 1 and the elastic contact part 2 at the same time is also in contact and conductive with the grounding spring sheet.

9. The high-speed communication card edge connector according to claim 8, characterized in that: There are two grounding springs on the shielding shell that are in contact with and conductive with each grounding terminal.

10. The high-speed communication card edge connector according to claim 9, characterized in that: The shielding shell is punched to form two rows of punching holes, each punching hole in the upper row corresponds to each punching hole in the lower row, and the lower edge of each punching hole in the upper row and the lower edge of each punching hole in the lower row are connected to a grounding spring.

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