CN117279214A - Circuit board back drilling processing method - Google Patents
Circuit board back drilling processing method Download PDFInfo
- Publication number
- CN117279214A CN117279214A CN202311215715.4A CN202311215715A CN117279214A CN 117279214 A CN117279214 A CN 117279214A CN 202311215715 A CN202311215715 A CN 202311215715A CN 117279214 A CN117279214 A CN 117279214A
- Authority
- CN
- China
- Prior art keywords
- hole
- circuit board
- tin
- drilling
- metallized
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000005553 drilling Methods 0.000 title claims abstract description 59
- 238000003672 processing method Methods 0.000 title claims abstract description 10
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 38
- 229910052802 copper Inorganic materials 0.000 claims abstract description 32
- 239000010949 copper Substances 0.000 claims abstract description 32
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000007747 plating Methods 0.000 claims abstract description 13
- 238000005530 etching Methods 0.000 claims abstract description 7
- 239000011347 resin Substances 0.000 claims abstract description 5
- 229920005989 resin Polymers 0.000 claims abstract description 5
- 239000002893 slag Substances 0.000 claims description 4
- 238000009713 electroplating Methods 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 2
- 238000013461 design Methods 0.000 abstract description 6
- 239000000463 material Substances 0.000 abstract description 4
- 230000007547 defect Effects 0.000 description 3
- 238000001465 metallisation Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/0011—Working of insulating substrates or insulating layers
- H05K3/0044—Mechanical working of the substrate, e.g. drilling or punching
- H05K3/0047—Drilling of holes
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
- H05K3/06—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding the conductive material being removed chemically or electrolytically, e.g. by photo-etch process
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
- H05K3/423—Plated through-holes or plated via connections characterised by electroplating method
- H05K3/424—Plated through-holes or plated via connections characterised by electroplating method by direct electroplating
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
- H05K3/425—Plated through-holes or plated via connections characterised by the sequence of steps for plating the through-holes or via connections in relation to the conductive pattern
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/02—Details related to mechanical or acoustic processing, e.g. drilling, punching, cutting, using ultrasound
- H05K2203/0214—Back-up or entry material, e.g. for mechanical drilling
Abstract
The invention discloses a circuit board back drill processing method, which comprises the following steps: s1, drilling a through hole in a circuit board, plating copper on the through hole and forming a metalized hole; s2, tin plating the whole board surface of the metallized hole and the circuit board surface; s3, performing depth control drilling on the tinned metallized holes, and drilling tin on the hole walls of the non-conducting layers; s4, etching the copper of the holes exposed by drilling tin out of the metallized holes; s5, removing tin from the surface of the circuit board and the holes of the metallized holes to form back drilling holes. The method is different from the traditional method that the hole copper is directly drilled by using the drill needle larger than the through hole, the hole copper of the conducting layer is protected by tin, the non-conducting layer tin is drilled, the hole copper at the position is chemically etched, the hole wall base material of the non-conducting layer cannot be damaged, the aperture of the metallized hole of the conducting layer is equal to that of the non-metallized hole of the non-conducting layer, the design requirement of a high-precision product is improved, and the problems of air bubble hiding, concave short circuit and the like of a resin hole in the corner of a big small hole in a conventional back drilling mode are solved.
Description
Technical Field
The application relates to the field of circuit boards, in particular to a circuit board back drilling processing method.
Background
With the development of electronic products to high density and high precision, the product volume is smaller and the device density is larger and larger. The most effective method for improving the density of the circuit board is to reduce the number of through holes and accurately arrange blind holes and buried holes. When the blind hole and the buried hole are crossed, a back drilling process is generally selected for processing. The back drilling is to drill the hole copper of the non-conducting layer through the metallized through hole, and only the hole copper of the conducting layer is reserved.
At present, a common back drilling process in the industry is to manufacture the back drilling process by adopting a through hole drill needle plus 0.2mm to 0.3mm on the basis of a through hole, however, the alignment precision cannot meet the design requirement of high-precision products, and meanwhile, the problems of air bubbles hiding at corners or concave short circuit after hole plugging and the like are easily caused due to overlarge difference between large and small holes of a conducting layer and a non-conducting layer after back drilling.
Therefore, a circuit board back drilling processing method is needed, the problem that the current back drilling process cannot meet the design requirement of high-precision products and is easy to cause hole plugging defects is solved, the back drilling is realized without drilling a base material, and the aperture of a metallization hole of a conducting layer is equal to the aperture of a non-metallization hole of a non-conducting layer.
Disclosure of Invention
The invention provides a circuit board back drilling processing method, which mainly aims to solve the problems that the existing back drilling process cannot meet the design requirement of high-precision products and is easy to cause hole plugging defects.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the embodiment of the application provides a circuit board back drilling processing method, which comprises the following steps:
s1, drilling a through hole in a circuit board, plating copper on the through hole and forming a metalized hole;
s2, tin plating is carried out on the whole board surface of the metallized hole and the circuit board surface;
s3, performing depth control drilling on the plated metallized holes, and drilling tin on the hole walls of the non-conducting layers;
s4, etching the copper of the holes exposed by drilling tin out of the metallized holes;
s5, removing tin from the board surface of the circuit board and the holes of the metallized holes and forming back drilling holes.
In some possible embodiments, the ratio of the board thickness aperture of the circuit board is less than 8.
In some possible embodiments, the single point copper thickness of the metallized holes formed after electroplating is a minimum of 25 μm and the average copper thickness is greater than 27.5 μm, and the tin thickness of the metallized holes after tin plating is 2 μm to 5 μm.
In some possible embodiments, in step S3, after tin on the hole wall of the non-conductive layer of the metallized hole is drilled, the tin slag in the metallized hole is removed by rinsing.
In some possible embodiments, the diameter of the drill point for performing the depth-control drilling is smaller than the aperture of the through hole and larger than the aperture of the metallized hole after tinning.
In some possible embodiments, the diameter of the drill point for performing the depth control drilling is 0.05mm smaller than the aperture of the through hole.
In some possible embodiments, after step S5, step S6 is further included: and (5) plugging the back drilling hole with resin and grinding.
Compared with the prior art, the invention at least comprises the following beneficial effects:
according to the circuit board back drilling processing method, unlike the traditional method that hole copper is directly drilled by a drill needle larger than a through hole, the method is characterized in that the hole copper of a conducting layer is protected by tin, the non-conducting layer tin is drilled, the hole copper at the position is chemically etched, the hole wall base material of the non-conducting layer cannot be damaged, the hole diameter of a conducting layer metalized hole is equal to that of the non-conducting layer non-metalized hole, the design requirement of a high-precision product is improved, and the problems of air bubble hiding, concave short circuit and the like of a resin hole at the corner of a big small hole in a conventional back drilling mode are solved.
Drawings
The invention will be further described with reference to the accompanying drawings, in which embodiments do not constitute any limitation of the invention, and other drawings can be obtained by one of ordinary skill in the art without inventive effort from the following drawings.
Fig. 1 is a flow chart of the present invention.
Fig. 2 is a schematic cross-sectional view of a prior art circuit board of a back drilling process.
Fig. 3 is a schematic cross-sectional view of a preliminary wiring board according to an embodiment of the present invention.
Fig. 4 is a schematic cross-sectional view of a circuit board according to an embodiment of the present invention after drilling a through hole.
Fig. 5 is a schematic cross-sectional view of a circuit board after copper plating in accordance with one embodiment of the present invention.
Fig. 6 is a schematic cross-sectional view of a circuit board according to an embodiment of the present invention after tin plating.
Fig. 7 is a schematic cross-sectional view of a circuit board according to an embodiment of the invention with tin on the walls of the via holes drilled away.
Fig. 8 is a schematic cross-sectional view of a circuit board after etching hole copper in accordance with an embodiment of the present invention.
Fig. 9 is a schematic cross-sectional view of a circuit board according to an embodiment of the invention after tin stripping.
The marks in the figure are as follows: 1-a through hole; 2-copper; 3-tin; 4-a substrate; 5-controlling the depth drilling.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
The applicant found that in the field of circuit boards, as shown in fig. 2, the conventional back drilling process directly uses a drill needle larger than a through hole to drill away hole copper, so that the design requirement of high-precision products cannot be met, and the problem of hole plugging defect is easily caused.
In view of this, referring to fig. 1 to 9, the present embodiment provides a circuit board back drilling method, including the steps of:
s1, preparing a multilayer circuit board needing back drilling, drilling a through hole at the position of the circuit board needing back drilling, and plating the through hole with copper of a needed hole and forming a metallized hole by adopting a copper plating process method as shown in FIG. 5;
s2, as shown in FIG. 6, tin plating is carried out on the whole board surface of the metallized holes and the circuit board surface, and bare copper is protected by tin;
s3, as shown in FIG. 7, performing depth control drilling on the tinned metallized hole by using a high-precision drilling machine, and drilling tin on the hole wall of the non-conducting layer to expose copper on the hole wall of the non-conducting layer;
s4, as shown in FIG. 8, etching the circuit board, and removing the exposed hole copper by etching the tin in the metallized hole, wherein the hole copper of the conducting layer and the copper of other parts of the circuit board are prevented from being etched due to tin coverage protection;
s5, as shown in FIG. 9, removing tin on the board surface of the circuit board and the wall of the metallization hole conducting layer and forming a back drilling hole.
Particularly, the circuit board back drilling processing method is suitable for circuit boards with the plate thickness and aperture ratio smaller than 8, and a certain quality abnormality risk can occur when the plate thickness and aperture ratio is too large. In addition, in order to ensure excellent yield of the back drilling circuit board produced by the method and reduce the risks of abnormal quality and even scrapping of the circuit board, in the embodiment, the single-point copper thickness of the metallized holes formed after electroplating needs to be ensured to be the minimum value of 25 mu m, the average copper thickness needs to be larger than 27.5 mu m, and in addition, the tin thickness of the hole walls of the metallized holes after tinning is 2 mu m to 5 mu m.
In addition, in step S3, after tin on the hole wall of the non-conductive layer of the metallized hole is drilled, the tin slag in the metallized hole needs to be removed, so as to avoid the tin slag blocking the metallized hole or affecting the subsequent etching of the copper on the non-conductive layer hole.
In particular, the diameter of the drill point for depth control drilling needs to be smaller than the aperture of the through hole and larger than the aperture of the metalized hole narrowed after tinning, so that tin on the wall of the non-conducting layer of the metalized hole can be drilled away and the base material of the non-conducting layer cannot be drilled. Preferably, the diameter of the drill point for depth control drilling is 0.05mm smaller than the aperture of the through hole, so that the drill point has a good drilling effect and can also achieve alignment precision.
In some embodiments, step S5 is followed by step S6: and (3) plugging the back drilling hole with resin, grinding, and plugging the back drilling hole.
The above examples illustrate only one embodiment of the invention, which is described in more detail and is not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (7)
1. The circuit board back drilling processing method is characterized by comprising the following steps of:
s1, drilling a through hole in a circuit board, plating copper on the through hole and forming a metalized hole;
s2, tin plating is carried out on the whole board surface of the metallized hole and the circuit board surface;
s3, performing depth control drilling on the plated metallized holes, and drilling tin on the hole walls of the non-conducting layers;
s4, etching the copper of the holes exposed by drilling tin out of the metallized holes;
s5, removing tin from the board surface of the circuit board and the holes of the metallized holes and forming back drilling holes.
2. The circuit board backdrilling method of claim 1, wherein the ratio of plate thickness to aperture of the circuit board is less than 8.
3. The method of circuit board backdrilling of claim 2, wherein the metallized holes formed after electroplating have a minimum single point copper thickness of 25 μm and an average copper thickness of greater than 27.5 μm and the metallized holes have a tin thickness of 2 μm to 5 μm after tin plating.
4. The method according to claim 2, wherein in step S3, after tin on the wall of the non-conductive layer of the metallized hole is drilled, the tin slag in the metallized hole is removed by rinsing.
5. The method for processing the back drill of the circuit board according to claim 2, wherein the diameter of the drill needle for performing the depth-control drilling is smaller than the aperture of the through hole and larger than the aperture of the metallized hole after tinning.
6. The method of claim 5, wherein the diameter of the drill point for performing the depth-control drilling is 0.05mm smaller than the aperture of the through hole.
7. The circuit board backdrilling method according to any one of claims 1 to 6, further comprising, after step S5, step S6: and (5) plugging the back drilling hole with resin and grinding.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311215715.4A CN117279214A (en) | 2023-09-19 | 2023-09-19 | Circuit board back drilling processing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311215715.4A CN117279214A (en) | 2023-09-19 | 2023-09-19 | Circuit board back drilling processing method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117279214A true CN117279214A (en) | 2023-12-22 |
Family
ID=89202026
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311215715.4A Pending CN117279214A (en) | 2023-09-19 | 2023-09-19 | Circuit board back drilling processing method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117279214A (en) |
-
2023
- 2023-09-19 CN CN202311215715.4A patent/CN117279214A/en active Pending
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| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
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