CN112888171A

CN112888171A - Method and device for processing blind slot of multilayer printed board

Info

Publication number: CN112888171A
Application number: CN202110068875.5A
Authority: CN
Inventors: 蒋瑶珮; 林玉敏; 边方胜; 伍泽亮; 龚小林; 卢军; 徐诺心; 谢国平; 向伟玮; 徐榕青
Original assignee: CETC 29 Research Institute
Current assignee: CETC 29 Research Institute
Priority date: 2021-01-19
Filing date: 2021-01-19
Publication date: 2021-06-01
Anticipated expiration: 2041-01-19
Also published as: CN112888171B

Abstract

The invention discloses a method and a device for processing blind grooves of a multilayer printed board, belongs to the technical field of printed board production, and is particularly suitable for manufacturing printed boards with a multi-quantity and low-depth blind groove structure. By adopting the cover film, the dry film for assistance and selective protection etching, copper bump structures for filling the blind grooves are manufactured on the cover film in batches in advance, and batch alignment filling of the copper bumps in the blind grooves is realized at one time in the alignment lamination and lamination processes; and after lamination, removing the covering film and the copper bumps below the covering film in batch at one time to obtain the processed blind groove structure. The scheme of the invention improves the filling efficiency of the blind slot gasket, overcomes the defect of low efficiency of manual independent removal of the blind slot gasket in the prior art, is especially suitable for manufacturing the blind slot multilayer printed board with structures with large quantity, low depth and small size, can improve the manufacturing efficiency and accuracy of the blind slot, and has better application prospect.

Description

Method and device for processing blind slot of multilayer printed board

Technical Field

The invention belongs to the technical field of printed board production, and particularly discloses a method and a device for processing blind grooves of a multilayer printed board, which are particularly suitable for manufacturing printed boards with a large-quantity and low-depth blind groove structure.

Background

The blind slot of the printed board refers to a cavity region which does not penetrate through the circuit board, and the space in the printed board can be effectively utilized. On one hand, the blind slot can realize the input and output ports of electric signals of all layers in the printed board; on the other hand, the adhesive tape is also used as a cavity and a carrier for adhering and mounting components such as chips, capacitors, resistors and the like. With the progress of components and assembly technology, the blind slot type printed wiring board is also developed towards diversification and structural complexity.

The common blind groove processing methods in the industry can be roughly divided into two types: a depth control milling method and an auxiliary gasket filling blind groove method. The processing mode of the depth control milling method is adopted, and the depth control milling is performed twice before and after lamination, so that the method is suitable for manufacturing a blind groove structure with larger depth. For a blind groove with low depth, the existing depth control precision is difficult to meet the processing requirement.

The method is another method for manufacturing the blind groove, and is widely adopted because the depth, the size and the size of the blind groove are not limited. The prior art discloses numerous improvements to the method of filling the auxiliary pad.

For example, patent CN102523684B discloses a method for manufacturing a PCB with a stepped groove, in which a blind groove is filled with a silica gel sheet having a boss shape, so that the overflow in the groove is good and the surface glue flow is prevented.

Patent CN102523685B discloses a manufacturing method of a PCB with a stepped groove, blind grooves are filled by adopting a special core plate + PP + PTFE three-layer composite gasket, and the problems that blind groove cavities and gaskets are different in height and glue flowing is not easy to control are solved by utilizing high buffering of middle-layer PP.

Patent CN103517582A discloses a multilayer circuit board and a manufacturing method thereof, wherein a blind groove is filled with a copper sheet and a peelable film composite gasket, and the gasket is taken out after laser grooving, so that the problems that port patterns are easily damaged by laser grooving and PP (polypropylene) flow adhesive are solved.

Patent CN102523688B discloses a method for manufacturing a PCB with a stepped groove, and the problem that silica gel gaskets are high in filling cost and easy to displace when placed is solved by filling blind grooves with gaskets made of PTFE materials.

Patent CN105682364B discloses a method for processing a stepped groove based on copper foil flow resistance, which fills a blind groove by a copper foil gasket with the height equal to that of the blind groove, and solves the problem of layer formation risk caused by glue overflow and high laser temperature of the conventional gasket filled blind groove.

The above-mentioned patent technology for manufacturing blind grooves by filling gaskets in the prior art mostly focuses on the design and improvement of gasket shape, gasket size, gasket material, and composite gasket structure, but does not relate to the specific implementation process of gasket filling.

In addition, the gasket filling in the prior art is still performed manually, and because the gasket and the inner core plate are likely to have certain warping deformation, the operation is difficult to perform, the time consumption is long, the gasket filling is easy to misplace and shift, and the forming quality of the blind groove is finally affected. In the aspect of filling and removing the blind grooves with large quantity and small size, the problems of large time consumption of manufacturing the blind groove gasket, low filling efficiency, easy dislocation of filling and the like are more prominent.

Disclosure of Invention

The invention aims to provide a method for processing and filling a gasket of a blind groove of a microwave multilayer printed board, which realizes batch manufacturing of the gasket of the blind groove and one-time filling and removal of the blind groove and solves the problem of low processing efficiency when a plurality of blind grooves with low depth, small size and special-shaped structures are processed in the prior art.

The technical scheme adopted by the invention is as follows:

a method for processing blind grooves of a multilayer printed board is characterized in that a cover film, a dry film for assistance and selective protective etching are adopted, copper lug structures for filling the blind grooves are manufactured on the cover film in batches in advance, and batch alignment filling of the copper lugs in the blind grooves is realized at one time in the alignment lamination and lamination processes; and after lamination, removing the covering film and the copper bumps below the covering film in batch at one time to obtain the processed blind groove structure.

The processing method specifically comprises the following steps:

(1) providing a copper plate 1, a cover film 2 and a dry film 3, and bonding the cover film 2, the copper plate 1 and the dry film 3 into a whole from top to bottom in the sequence of 'the cover film 2, the copper plate 1 and the dry film 3';

(2) windowing is carried out on the dry film 3 in a non-preset blind slot area to obtain a dry film windowing 31;

(3) etching copper treatment is carried out on the dry film windowing 31 area;

(4) removing the film, namely removing the dry film 32 at the residual preset blind groove area below the copper plate to form a multi-copper bump 11 structure with an isolated lower surface of the covering film 2;

(5) providing a first substrate 4 and a prepreg 5, respectively milling windows at preset blind groove positions of the first substrate 4 and the prepreg 5, and processing a corresponding first substrate through groove 41 and a corresponding prepreg through groove 51;

(6) aligning, laminating and laminating;

(7) and removing the inner blocks of the blind grooves in batches to obtain the blind groove structure.

Further, etching the dry film windowing 31 region of the dry film 3 by using an acidic etching solution or an alkaline etching solution used in the preparation of the printed circuit board, removing a copper plate in the dry film windowing 31 region, wherein the thickness of etching copper in the dry film windowing 31 region is the same as the depth of a preset blind groove structure, and the value range of the depth of the preset blind groove is 0.05-0.15 mm.

The sizes of the first substrate through groove 41 and the prepreg through groove 51 are the same as the size of the preset blind groove structure.

Further, the step (6) is specifically as follows:

and (3) aligning and laminating the covering film 2 containing the multi-copper bump 11, the first substrate 4, the prepreg 5 and the second substrate 6 from top to bottom in sequence, and bonding the covering film, the first substrate, the prepreg 5 and the second substrate into a whole under the conditions of high temperature and high pressure.

Further, in the step (7), the covering film 2 on the surface is removed, so that the copper bumps 11 bonded with the covering film 2 are taken out together, and the required blind groove structure 7 is formed.

In another aspect, the invention further provides a processing device, and the processing device is used for completing the processing method of the blind slot of any one of the multilayer printed boards.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

(1) according to the processing scheme of the blind groove of the multilayer printed board, the copper bump structures for filling the blind groove are manufactured in batches by adopting the modes of the cover film, the dry film assistance and the selective protection etching, and the efficiency of filling the blind groove gasket is improved by batch contraposition filling.

(2) According to the processing scheme of the blind slot of the multilayer printed board, the cover film and the copper bumps below the cover film can be removed in one step after lamination, and the defect of low efficiency in manual independent removal of the blind slot gasket in the prior art is overcome.

(3) The processing scheme of the blind slot of the multilayer printed board is particularly suitable for manufacturing the blind slot multilayer printed board with a structure with a plurality of blind slots, low depth and small size, can improve the efficiency and the accuracy of manufacturing the blind slot, and has better application prospect.

Drawings

Fig. 1 is a flow chart of processing a blind slot of a multilayer printed board according to an embodiment of the present invention.

FIG. 2 is a schematic view of the bonding of the cover film, the copper plate and the dry film according to the embodiment of the present invention;

fig. 3 is a schematic structural view of a dry film after windowing according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a structure after etching copper according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a decoiled film provided by the embodiment of the invention;

FIG. 6 is a schematic diagram of an alignment stack according to an embodiment of the present invention;

FIG. 7 is a schematic view of a laminated structure provided by an embodiment of the present invention;

FIG. 8 is a schematic diagram of removing the inner block of the blind slot according to an embodiment of the present invention;

fig. 9 is a schematic view of a blind groove structure according to an embodiment of the present invention.

The figures are numbered:

1-copper plate; 11-copper bumps; 2-a cover film; 3-drying the film; 31-dry film windowing; 32-presetting dry films in the blind groove areas; 4-a first substrate; 41-a first substrate through slot; 5-a prepreg; 51-prepreg through slots; 6-a second substrate; 61-blind in-groove line layer; 7-a blind groove structure; h-preset blind groove depth.

Detailed Description

In order to make the technical solutions of the present invention better understood, the following description of the technical solutions of the present invention with reference to the accompanying drawings of the present invention is made clearly and completely, and other similar embodiments obtained by a person of ordinary skill in the art without any creative effort based on the embodiments in the present application shall fall within the protection scope of the present application.

In the prior art, the blind groove is generally processed by firstly providing a blind groove lower sub-plate, and then completing the blind groove processing through the processes of upper sub-plate windowing, adhesive film/PP windowing, gasket manufacturing, laminating and gasket taking out. In the process, the problems that the gasket is difficult to align and adhere and easy to remove residual glue and the like exist in the filling of the gasket.

The embodiment of the invention provides a method for processing blind grooves of a multilayer printed board, which is characterized in that a covering film, a dry film auxiliary and selective protective etching mode is adopted, copper lug structures for filling the blind grooves are manufactured on the covering film in batch in advance, and batch alignment filling of the copper lugs in the blind grooves is realized at one time in the alignment lamination and lamination processes; and after lamination, removing the covering film and the copper bumps below the covering film in batch at one time to obtain the processed blind groove structure.

Example 1

Example 1 is a method for processing a blind via of a multilayer printed board using a coverlay film and a dry film, as shown in fig. 1, the method comprising:

(1) as shown in fig. 2, providing a copper plate 1, a cover film 2 and a dry film 3, and bonding the cover film 2, the copper plate 1 and the dry film 3 into a whole from top to bottom in the sequence of 'cover film 2, copper plate 1 and dry film 3';

the thickness of the copper plate 1 is the same as the depth h of the preset blind groove, and in a preferred embodiment, the value range of h is 0.05-0.15 mm.

The cover film 2 has single-sided adhesive property and can be adhered and fixed with the copper plate 1; the covering film 2 has high temperature resistance, and the material of the covering film includes but is not limited to a polyimide adhesive tape film and a polytetrafluoroethylene adhesive tape film;

the dry film 3 has photosensitivity.

(2) And (5) windowing the dry film 3.

Windowing the dry film 3 in a non-preset blind slot region by adopting an exposure and development mode of a printed circuit to obtain a dry film windowing 31, and only keeping the dry film 32 in the preset blind slot region;

the structure after windowing is shown in fig. 3;

(3) and carrying out etching copper treatment on the dry film windowing 31 area.

Etching the dry film windowing 31 region of the dry film 3 by using an acidic etching solution or an alkaline etching solution used in the preparation of the printed board, and removing the copper plate in the dry film windowing 31 region;

after etching the copper, the structure of the copper bump 11 is essentially formed after this step, as shown in fig. 4.

Wherein, the thickness of the etching copper in the dry film windowing 31 area is the same as the depth h of the preset blind groove.

(4) And (5) stripping the film.

And (3) removing the dry film 32 at the residual preset blind groove area below the copper plate by using an alkaline solution to form a multi-copper bump 11 structure with an isolated lower surface of the cover film 2, as shown in fig. 5.

For the copper bump 11, the size is 0-0.1 mm smaller than the size of the preset blind slot structure.

In one embodiment, the copper bump may be shaped, or may be a bump of different material, so as to achieve the technical effects of batch manufacturing and bump filling of the embodiments of the present invention. The invention is not limited in this regard.

(5) As shown in fig. 6, providing a first substrate 4 and a prepreg 5, milling windows at preset blind groove positions of the first substrate 4 and the prepreg 5, respectively, and processing a corresponding first substrate through groove 41 and a corresponding prepreg through groove 51;

the first substrate 4 is a single-sided board or a double-sided board and is used as a top substrate of a blind slot of a multilayer board;

(6) And (6) aligning, laminating and laminating.

Providing a second substrate 6 for serving as a bottom substrate of the blind slot of the multilayer board;

the second substrate 6 is a single-sided board, a double-sided board or a multilayer board; and a circuit pattern layer 61 is arranged at the position of a preset blind slot at the bottom of the second substrate 6.

The schematic diagram of the alignment lamination is shown in fig. 6, and the schematic diagram of the overall structure after lamination is shown in fig. 7.

(7) And removing the inner blocks of the blind grooves in batches to obtain the processed blind groove structure.

As shown in fig. 8, the cover film 2 on the surface is removed, so that the copper bumps 11 bonded with the cover film are taken out together to form the desired blind-groove structure 7, as shown in fig. 9, where h is the height of the predetermined blind-groove structure.

Example 2

After the processing of the blind groove structure 7 is preliminarily completed, the bottom graphical line and other lines of the blind groove structure 7 can be subjected to surface coating according to the actual production application requirements. Including but not limited to electroplated gold, electroless nickel gold, electroplated nickel gold, electroless nickel palladium gold, and the like.

And optionally, further milling the printing plate shape according to a preset size. The embodiment of the invention does not limit the specific way of the subsequent processing.

Example 3

The embodiment provides a processing device, and the processing device is used for completing the processing method of the blind slot of the multilayer printed board in any one of the previous embodiments.

While the foregoing is directed to embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention. Such as using a shaped copper bump, changing the material of the bump, etc., these modifications and finishes are also considered to be within the scope of the present invention.

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.

Claims

1. A multilayer printed board blind groove processing method is characterized in that a cover film, a dry film for assistance and selective protection etching are adopted, copper lug structures for blind groove filling are manufactured on the cover film in batch in advance, and batch alignment filling of copper lugs in blind grooves is realized at one time in the alignment lamination and lamination processes; and after lamination, removing the covering film and the copper bumps below the covering film in batch at one time to obtain the processed blind groove structure.

2. The method for processing the blind slot of the multilayer printed board according to claim 1, wherein the processing method specifically comprises the following steps:

(1) providing a copper plate, a cover film and a dry film, and bonding the cover film, the copper plate and the dry film into a whole from top to bottom according to the sequence of the cover film, the copper plate and the dry film;

(2) windowing the dry film in a non-preset blind slot area to obtain a dry film windowing;

(3) etching copper treatment is carried out on the dry film windowing region;

(4) removing the film, namely removing the dry film at the residual preset blind groove area below the copper plate to form a multi-copper-bump structure with an isolated lower surface of the covering film;

(5) providing a first substrate and a prepreg, respectively milling windows at preset blind groove positions of the first substrate and the prepreg, and processing a corresponding first substrate through groove and a corresponding prepreg through groove;

(6) aligning, laminating and laminating;

3. The method for processing the blind slot of the multilayer printed board as claimed in claim 2, wherein the thickness of the copper plate is the same as the depth of the preset blind slot.

4. The method for processing the blind slot of the multilayer printed board according to claim 2, wherein the cover film has single-sided adhesive property and can be fixedly adhered to a copper plate; and the covering film has high temperature resistance.

5. The method for processing the blind slot of the multilayer printed board according to claim 2, wherein the dry film has photosensitivity for performing the windowing process.

6. The method for processing the blind via of the multilayer printed board as claimed in claim 2, wherein the dry film windowing region of the dry film is etched by using an acidic etching solution or an alkaline etching solution used in the preparation of the printed board, the copper plate in the dry film windowing region is removed, and the thickness of the etched copper in the dry film windowing region is the same as the depth of the preset blind via structure.

7. The method for processing the blind slot of the multilayer printed board according to claim 2, wherein the through slot of the first substrate and the through slot of the prepreg have the same size as the preset blind slot structure.

8. The method for processing the blind slot of the multilayer printed board according to claim 2, wherein the step (6) is specifically as follows:

and aligning and laminating the covering film containing the multi-copper bump, the first substrate, the prepreg and the second substrate from top to bottom in sequence, and bonding the covering film, the first substrate, the prepreg and the second substrate into a whole under the conditions of high temperature and high pressure.

9. The method for processing the blind slot of the multilayer printed board as claimed in claim 2, wherein in step (7), the cover film on the surface is removed, so that the copper bump bonded with the cover film is taken out together to form the required blind slot structure.

10. A processing apparatus, characterized in that the processing apparatus is used for completing the processing method of the blind slot of the multilayer printed board of any one of claims 1 to 9.