CN117915574A

CN117915574A - Processing method of ladder golden finger circuit board and PCB

Info

Publication number: CN117915574A
Application number: CN202410098278.0A
Authority: CN
Inventors: 徐胜; 陈霞元; 聂亚雄; 易雁; 刘梦茹
Original assignee: Shengyi Electronics Co Ltd
Current assignee: Shengyi Electronics Co Ltd
Priority date: 2024-01-23
Filing date: 2024-01-23
Publication date: 2024-04-19

Abstract

The invention discloses a processing method of a stepped golden finger circuit board and a PCB, and relates to the technical field of PCB processing, wherein the processing method comprises the following steps: s10, providing a daughter board with a golden finger; s20, sticking an adhesive tape on the surface of the golden finger, stacking a gasket on the adhesive tape, and pressing to form a motherboard; s30, processing the mother board sequentially through a board drying process and a board grinding process, and processing a groove on the surface of the mother board at the position corresponding to the golden finger before the board grinding process so as to prevent the mother board from forming a bulge protruding out of the surface when entering the board grinding process; s40, grinding the mother board. Before the motherboard grinding process, a groove is processed on the surface of the motherboard at the position corresponding to the golden finger, so that the motherboard can be prevented from forming a bulge on the surface when entering the motherboard grinding process, and copper thinness caused by the bulge in the motherboard grinding process is avoided by reducing the thickness of the motherboard at a local position.

Description

Processing method of ladder golden finger circuit board and PCB

Technical Field

The invention relates to the technical field of PCB processing, in particular to a processing method of a stepped golden finger circuit board and a PCB.

Background

The multilayer printed circuit board with the stepped groove is called a stepped circuit board, and in order to meet the use requirement of the circuit board, a golden finger needs to be manufactured at the stepped position of the stepped circuit board. The conventional method of the prior ladder golden finger circuit board is to firstly manufacture a daughter board of the hierarchy where the golden finger is located, then attach an adhesive tape to the golden finger to prevent resin from flowing to the golden finger in the lamination process, pad a gasket with a certain thickness above the adhesive tape, take out the pad after finishing the motherboard, tear off the adhesive tape, and obtain the required ladder golden finger circuit board.

Since the surface of the board needs to be polished in the PCB manufacturing process, copper thinning problems occur after copper at the top and bottom of the stepped gold finger position is polished, which affects the use of downstream customers.

Disclosure of Invention

The invention aims to provide a processing method of a stepped golden finger circuit board and a PCB, which are used for solving one or more technical problems in the prior art and at least providing a beneficial selection or creation condition.

The technical scheme adopted for solving the technical problems is as follows:

the invention provides a processing method of a stepped golden finger circuit board, which comprises the following steps:

S10, providing a daughter board with a golden finger;

S20, sticking an adhesive tape on the surface of the golden finger, stacking a gasket on the adhesive tape, and pressing to form a motherboard;

S30, processing the mother board sequentially through a board drying process and a board grinding process, and processing a groove on the surface of the mother board at the position corresponding to the golden finger before the board grinding process so as to prevent the mother board from forming a bulge protruding out of the surface when entering the board grinding process;

S40, grinding the mother board.

The beneficial effects of the invention are as follows: before the mother board grinding process, a groove is processed on the surface of the mother board at the position corresponding to the golden finger, so that the surface of the mother board is prevented from being formed with a bulge when the mother board enters the grinding process, and the copper thinness caused by the bulge in the grinding process is avoided by reducing the plate thickness at the local position.

As a further improvement of the above technical solution, one side of the groove extends to the inner side edge of the golden finger, and the other side of the groove extends to the outer side edge of the golden finger or beyond. When the step groove is milled and uncovered in the golden finger area, the groove is only required to be deepened continuously.

As a further improvement of the above technical solution, the outer side of the gold finger area of the daughter board is provided with a waste area, and step S30 further includes: and forming a through hole in the waste area, wherein the size of the groove is set to cover the through hole at the same time when the groove is processed. And through holes are additionally formed in the waste material area and are communicated with the grooves, so that no liquid medicine remains in the grooves in the production process. Through the combined action of the groove and the through hole, the problem that the board cannot be dried and the board is polluted is also prevented while the risk of generating copper thinness is avoided. After the golden finger is uncovered, the through holes are removed along with the waste material areas, and the finished product is not affected.

As a further improvement of the technical scheme, the groove is deeply milled by adopting a milling machine, wherein the milling machine comprises a CCD lens, and the CCD lens is positioned through the through hole. Thus, the positioning and processing precision can be improved.

As a further improvement of the technical scheme, the groove is positioned above the gasket, and the depth H2 of the groove is more than or equal to 0.2mm. This arrangement ensures that the gasket is not completely removed and that the protrusions 201 do not protrude above the upper surface of the motherboard 200.

As a further improvement of the above technical solution, the mother board further includes an electroplating process after the baking process, and the processing of the grooves is performed after the electroplating process. This prevents the grooves from being coated with a copper layer after machining.

As a further improvement of the above technical solution, after step S40, the method further includes making an outer layer circuit on the motherboard.

As a further improvement of the technical scheme, after the outer layer circuit is manufactured, the method further comprises deepening the grooves so as to uncover the golden fingers.

As a further improvement of the technical scheme, the widths of the adhesive tape and the gasket are set to be larger than the width of the golden finger. The adhesive tape and the gasket are conveniently removed when the golden finger is uncovered.

The invention also provides a PCB which is manufactured by adopting the processing method of the ladder golden finger circuit board.

Drawings

The invention is further described below with reference to the drawings and examples;

fig. 1 is a schematic structural diagram of a daughter board according to embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a motherboard obtained after the daughter boards of fig. 1 are pressed together;

FIG. 3 is a schematic diagram of a prior art master during a lapping process;

FIG. 4 is a schematic diagram of a golden finger area gap generating structure according to the embodiment 1 of the present invention;

FIG. 5 is a schematic view of the structure of embodiment 1 after processing grooves;

FIG. 6 is a schematic diagram of the structure of the target ladder golden finger circuit board of the embodiment 1 of the present invention;

fig. 7 is a schematic structural view of a motherboard of embodiment 2 of the present invention;

fig. 8 is a schematic diagram of the structure of embodiment 2 of the present invention after processing grooves.

Detailed Description

Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present invention, but not to limit the scope of the present invention.

In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

In the description of the present invention, a number means one or more, and a plurality means two or more, and more, less, more, etc. are understood to exclude this number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

Example 1:

Referring to fig. 1 to 6, embodiment 1 provides a processing method of a stair-step gold finger circuit board, which includes the following steps:

S10, providing a daughter board 100 with a golden finger 110;

s20, sticking an adhesive tape 300 on the surface of the golden finger 110, stacking a gasket 400 above the adhesive tape 300, and pressing to form a motherboard 200;

S30, processing the mother board 200 sequentially through a baking process and a grinding process, wherein before the grinding process, a groove 210 is processed on the surface of the mother board 200 at a position corresponding to the golden finger 110 so as to avoid that the mother board 200 is formed with a protrusion 201 protruding from the surface when entering the grinding process;

s40, grinding the mother board 200.

In this embodiment, the daughter board 100 is formed by laminating a plurality of core boards, the core boards are copper-clad boards, the core boards are laminated to form the daughter board 100 after finishing the circuit pattern manufacture, and the daughter board 100 is subjected to the processes of drilling, electroplating, plugging and the like, then the circuit pattern manufacture and the golden finger manufacture of the outer layer of the daughter board are performed, and finally the daughter board formed with the golden finger 110 is obtained.

As shown in fig. 1, which is a schematic diagram of a structure in which a golden finger 110 is formed on one side of a daughter board 100, in step S10 of the present embodiment, a circuit pattern and the golden finger 110 are fabricated on the upper surface of the daughter board 100, the circuit pattern is not fabricated on the lower surface of the daughter board 100, and the daughter board 100 is used as a lower board of a subsequent motherboard.

In step S20, as shown in fig. 2, the surface of the golden finger 110 is covered with the adhesive tape 300, and the pad 400 is stacked above the adhesive tape 300 and then pressed to form the motherboard 200. To facilitate subsequent removal of the tape 300 and the spacer 400, the width of the tape 300 and the spacer 400 is greater than the width of the gold finger 110.

After the mother board 200 is formed, the mother board 200 is sequentially subjected to processing procedures such as drilling, drying, electroplating, plugging, grinding and the like. As shown in fig. 3, the method for polishing the surface of the mother board after plugging the mother board is to pass the mother board 200 between the roller and the brush.

The inventors of the present invention have found during research and practice that the protrusions 201 are caused by vaporization of moisture and expansion of gas in the gold finger area during the baking of the motherboard 200. As shown in fig. 3 to 4, in production, gaps may be generated between the adhesive tape and the golden finger, and between the adhesive tape and the backing plate, for example, in order to avoid that the adhesive of the adhesive tape is adhered to the golden finger and is not easy to remove, the adhesive tape adopts a weak-viscosity adhesive tape, and although the adhesive tape can be prevented from being polluted by too strong adhesive force, the weak adhesive tape may generate gaps between the adhesive tape and the bonding surface of the golden finger; for example, after the gold finger 110 is fabricated on the surface of the daughter board 100, the surface of the gold finger 110 further includes a solder mask layer 111 and a gold layer 112, and the height difference between the solder mask layer 111 and the gold layer 112 may also cause gaps between the adhesive tape and the gold finger, and between the adhesive tape and the pad.

If gaps exist between the adhesive tape and the golden finger, and between the adhesive tape and the backing plate, when the motherboard 200 passes through the baking process, the gas in the gaps expands after being heated after the baking, so that the adhesive tape and the backing plate arch upwards, and finally the surface of the motherboard 200 deforms in the area corresponding to the golden finger, and the bulges 201 protruding from the surface are formed. As shown in fig. 3, in the motherboard 200 with protrusions, when the pressure roller 500 is pressed against the protrusions 201 of the motherboard during the motherboard grinding process after the motherboard is plugged, downward pressure is applied to the protrusions, and only the gold finger area of the motherboard 200 is protruded in the length direction of the pressure roller 500, so that the line contact between the pressure roller 500 and the motherboard 200 is changed to point contact, that is, the pressure roller 500 is in point contact with only the protrusions of the motherboard. In this way, the pressure exerted by the press roller 500 on the protrusion is large, which results in an increase in contact pressure between the copper surface of the lower surface of the master 200 opposite to the protrusion 201 and the brush 600, and eventually the copper layer on the protrusion 201 of the master 200 wears and thins, and the copper layer on the lower surface of the master 200 also wears and thins at the position corresponding to the gold finger, and even the copper layer is completely worn away.

Therefore, after the daughter board 110 is pressed to form the mother board 200, a groove 210 is processed on the surface of the mother board 200 at the position corresponding to the golden finger 110 before the mother board 200 is polished, so that the formation of the protrusions 201 on the surface of the mother board 200 when the mother board 200 enters the polishing process can be avoided, and further, the copper thinness caused by the protrusions 201 in the polishing process can be avoided.

It will be appreciated that the machining of the recess 210 may be performed between the baking and milling steps or prior to the baking step. When the groove 210 is processed between the drying process and the grinding process, the drying plate forms the protrusion 201 on the surface of the mother board 200, and then removes the protrusion 201 through the groove, resulting in the structure shown in fig. 5; when the groove 210 is processed before the drying process, the groove 210 is processed first, so that the protrusion 201 is formed inside the groove (not shown) during the drying process, and does not protrude from the upper surface of the master 200, and thus does not affect the grinding process.

It will be appreciated that the size of the recess 210 may be set according to the actual size of the protrusion 201 of the motherboard; the machining size may be set to be uniform. Preferably, as shown in fig. 5, one side of the groove 210 extends to the inner edge of the gold finger 110, and the other side of the groove 210 extends to the outer edge of the gold finger 110 or beyond, that is, the groove 210 is sized to cover at least the gold finger window area of the finished step gold finger circuit board. It is understood that the gold finger window area refers to a slot consistent with the boundary of the arrangement area of the gold finger 110. Therefore, when the step groove is milled and uncovered in the golden finger area, the groove 201 is only required to be deepened continuously.

Further, the distance H1 between the surface of the motherboard 200 and the pad 400 is greater than the depth H2 of the groove 210, that is, the groove 210 is located above the pad 400, so as to prevent the pad from being cut, which may affect the removal of the cover by the gold finger. While the groove 210 is located above the gasket 400, the depth H2 of the groove 210 is greater than or equal to 0.2mm, so that the arrangement can ensure that the gasket is complete and the protrusions 201 cannot protrude from the upper surface of the motherboard 200. If the depth of the recess 210 is too small, the protrusion 201 may still protrude from the surface of the motherboard. The distance H1 and the depth H2 are calculated or measured from a position where the surface of the motherboard 200 is not deformed.

As described above, after the mother board 200 is formed, the mother board 200 is sequentially subjected to the processing steps of drilling, drying, plating, plugging, grinding, etc., and the processing of the grooves 210 may be performed between the drying step and the grinding step, or may be performed before the drying step. Further, the processing of the recess 210 may be performed between the plating process and the grinding process of the motherboard 200, or may be performed between the baking process and the plating process of the motherboard 200. Preferably, the plating process is performed after the motherboard 200. This is because, when disposed before the plating process of the motherboard 200, the grooves 210 are also plated with a copper layer at the time of plating the motherboard 200, which is required to be milled off in a later process, and if disposed after the plating process, the step of removing the copper layer from the grooves 210 can be omitted, optimizing the production process.

Further, after step S40, the method further includes performing outer layer circuit fabrication on the motherboard 200.

Further, after the outer layer circuit is manufactured, the golden finger 110 is uncovered. Specifically, the step groove is continuously milled on the basis of the groove 210, so that the depth of the groove 210 is deepened until the gasket 400 is exposed, and the adhesive tape 300 attached to the surface of the golden finger is torn off after the gasket 400 is taken out.

The outer side of the golden finger area of the daughter board 100 is provided with a scrap area 220, and as shown in fig. 1-2, the right side of the scrap area boundary 221 is the scrap area 220. After the golden finger 110 is uncovered, the waste region 220 is removed, and the through hole 230 is removed together with the waste region 220, thereby obtaining the target step golden finger circuit board shown in fig. 6.

In addition, the invention also provides a PCB which is manufactured by adopting the processing method of the ladder golden finger circuit board.

Example 2:

Referring to fig. 7 to 8, embodiment 2 is different from embodiment 1 in that step S30 of embodiment 2 further includes: the through holes 230 are formed in the scrap region 220, and in particular, the mother board 200 is processed in the through holes 230 of the scrap region 220 in a drilling process before drying. Then, when the groove 210 is processed, the groove 210 is sized to cover both the gold finger fenestration area and the through-hole 230 of the finished stepped gold finger circuit board. That is, as shown in fig. 8, the other side of the groove 210 extends in the outer direction of the gold finger 110 until the through hole 230 is formed in the groove 210. In this embodiment, the thickness of the plate at the local position is reduced by the groove 210, and meanwhile, the via hole is additionally arranged in the waste material area and is communicated with the groove 210, so that no liquid medicine remains in the groove in the production process, and the liquid medicine is discharged outwards through the groove 210. Through the combined action of the grooves 210 and the through holes 230, the problems that the board cannot be dried and the board is polluted are prevented while the risk of generating copper thinness is avoided.

Further, in step S30, the groove 210 is deeply milled by using a milling machine, which includes a CCD lens for processing and positioning operations, so that positioning and processing accuracy can be improved. In this embodiment, the through hole 230 is used as a positioning hole, and the CCD lens is positioned through the through hole 230.

While the preferred embodiment of the present application has been described in detail, the application is not limited to the embodiments, and various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the application, and these modifications and substitutions are intended to be included in the scope of the present application as defined in the appended claims.

Claims

1. The processing method of the stepped golden finger circuit board is characterized by comprising the following steps of:

s10, providing a daughter board (100) with a golden finger (110);

S20, sticking an adhesive tape (300) on the surface of the golden finger (110), stacking a gasket (400) on the adhesive tape (300) and pressing to form a mother board (200);

S30, processing the mother board (200) sequentially through a baking process and a polishing process, wherein a groove (210) is processed on the surface of the mother board (200) at a position corresponding to the golden finger (110) before the polishing process, so as to prevent the mother board (200) from forming a bulge (201) protruding from the surface when entering the polishing process;

S40, grinding the mother board (200).

2. The method of claim 1, wherein one side of the groove (210) extends to an inner edge of the gold finger (110), and the other side of the groove (210) extends to or beyond an outer edge of the gold finger (110).

3. The method for processing the stair golden finger circuit board according to claim 2, wherein the outer side of the golden finger area of the daughter board (100) is provided with a scrap area (220), and step S30 further includes: and forming a through hole (230) in the waste region (220), wherein the size of the groove (210) is set to cover the through hole (230) at the same time when the groove (210) is processed.

4. A method of processing a stair gold finger circuit board according to claim 3, characterized in that the recess (210) is deep milled using a milling machine comprising a CCD lens positioned through the through hole (230).

5. The method for processing the stair-step gold finger circuit board according to claim 1, wherein the groove (210) is located above the gasket (400), and the depth H2 of the groove (210) is greater than or equal to 0.2mm.

6. The method of claim 1, wherein the motherboard (200) further comprises an electroplating process after the baking process, and the processing of the groove (210) is performed after the electroplating process.

7. The method according to claim 1, further comprising, after step S40, fabricating an outer layer circuit on the motherboard (200).

8. The method of claim 7, further comprising deepening the recess (210) to uncover the gold finger (110) after the outer layer circuit is completed.

9. The method of claim 1, wherein the widths of the adhesive tape (300) and the pad (400) are set to be larger than the width of the gold finger (110).

10. A PCB, characterized in that the PCB is manufactured by the processing method of the stair gold finger circuit board according to any one of claims 1 to 9.