CN113163622B - Thermoplastic polyimide subtraction process for ultrathin rigid-flexible printed circuit board - Google Patents
Thermoplastic polyimide subtraction process for ultrathin rigid-flexible printed circuit board Download PDFInfo
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- CN113163622B CN113163622B CN202010073328.1A CN202010073328A CN113163622B CN 113163622 B CN113163622 B CN 113163622B CN 202010073328 A CN202010073328 A CN 202010073328A CN 113163622 B CN113163622 B CN 113163622B
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- 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
- H05K3/36—Assembling printed circuits with other printed circuits
- H05K3/361—Assembling flexible printed circuits with other printed circuits
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- 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
- H05K3/0017—Etching of the substrate by chemical or physical means
- H05K3/0026—Etching of the substrate by chemical or physical means by laser ablation
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- 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
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- 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
- H05K3/0094—Filling or covering plated through-holes or blind plated vias, e.g. for masking or for mechanical reinforcement
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- 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
- H05K3/022—Processes for manufacturing precursors of printed circuits, i.e. copper-clad substrates
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- 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
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- 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
- H05K3/46—Manufacturing multilayer circuits
- H05K3/4644—Manufacturing multilayer circuits by building the multilayer layer by layer, i.e. build-up multilayer circuits
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- 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
- H05K3/46—Manufacturing multilayer circuits
- H05K3/4688—Composite multilayer circuits, i.e. comprising insulating layers having different properties
- H05K3/4691—Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers
Abstract
A thermoplastic polyimide subtraction process of an ultrathin rigid-flex board comprises the following steps: selecting a hard metal plate as a substrate, and forming holes in the hard plate area; plugging holes with resin and grinding; laminating the first TPI layer, the second TPI layer and the copper foil on two sides; copper reduction and drilling are carried out on the copper foil pressed in the step 3); carrying out copper deposition and whole-plate copper plating; exposing and developing; etching to remove the uncovered copper of the dry film in the non-circuit area, and stripping; pressing the third TPI layer and the copper foil on the back; copper reduction and drilling are carried out on the copper foil pressed in the step 9); carrying out copper deposition and whole-plate copper plating; exposing and developing; etching to remove the uncovered copper of the dry film in the non-circuit area; demoulding; laser TPI; exposing and developing; etching the metal plate; demoulding; and (5) solder resist. The invention has simple and reasonable process and easy processing, and the prepared rigid-flexible board has the characteristics of thinner thickness, high strength, difficult deformation, high production efficiency and lower cost.
Description
Technical Field
The invention relates to the technical field of circuit board production, in particular to a TPI subtraction process of an ultrathin rigid-flex board.
Background
With the continuous progress of technology, the functional requirements on electronic products are higher and higher, and meanwhile, the appearance is also very important to be short, small, light and thin, so that circuit boards with multilayer integrated functions are adopted more and more, and particularly, a rigid-flex board is developed rapidly in recent years. In the preparation process of the rigid-flex board, a plurality of problems still exist, the production difficulty is high, the process is complex, the cost is high, the defects of poor binding force, deformation and layering exist, the product percent of pass and the performance are not greatly broken through all the time, and especially in the preparation of the ultrathin rigid-flex board, the problems exist more, and the method is concentrated on the following aspects:
firstly, a prepreg formed by combining epoxy resin and glass fiber is used as a hard board supporting layer, if the strength of a product is to be improved, the thickness of PP (polypropylene) needs to be increased, so that the size in the Z direction is increased, and the product is thickened;
the conventional cover film is formed by combining epoxy resin glue and polyimide, the epoxy resin glue is bonded with a product, and the cover film needs to meet the bending requirement, so that the modulus, the tensile strength and the Tg point of the glue layer are lower, and the integral strength of a soft board area is limited under the condition of the same thickness;
thirdly, the hard board layer of the conventional rigid-flexible board is provided with epoxy resin glue, Polyimide (PI) of a covering film, epoxy resin of a glass fiber prepreg, silicon dioxide filler, solder resist ink and the like, the materials are of many types, the thermal expansion coefficients are difficult to match, and the deformation is difficult to control after reflow soldering;
fourthly, the traditional metal reinforcements such as steel sheets, copper sheets and the like are bonded through a conductive adhesive, so that the product and the metal reinforcements are bonded and conducted, the conductive adhesive is a mixture of resin and conductive particles, the conductive adhesive is easy to absorb moisture at normal temperature, and the conductive particles are oxidized to influence the conductivity; after reflow soldering high-temperature processing, the resin is easy to expand to influence the conductivity, and the poor board explosion can be caused seriously;
fifthly: in the routing bonding process, the supporting strength of a product is one of important influence factors of routing quality when a cleaver is pressed down, the supporting force of the product is good, the routing yield is high, a resin layer covering a film is arranged in a traditional soft and hard combination plate structure, the strength is low, and the routing effect can be influenced.
Therefore, a new ultrathin plate preparation process needs to be designed to meet the production requirements.
Disclosure of Invention
The invention aims to solve the technical problem of providing a thermoplastic polyimide subtraction process of an ultrathin rigid-flexible printed circuit board which is simple and reasonable in process and easy to process.
The technical scheme adopted by the invention for solving the technical problems is as follows: a thermoplastic polyimide subtraction process of an ultrathin rigid-flex board is characterized by comprising the following steps:
1) selecting a hard metal plate as a substrate, and obtaining an opening in the hard plate area of the metal substrate by etching, mechanical drilling or laser drilling;
2) carrying out resin hole plugging and grinding on the opening position of the hard plate area of the metal substrate;
3) laminating a first TPI layer, a second TPI layer and copper foil on two surfaces of a metal plate;
4) copper reduction and drilling are carried out on the copper foil pressed in the step 3);
5) carrying out copper deposition and whole-plate copper plating;
6) exposure and development: pressing a photosensitive dry film on two sides, and exposing circuits on the two sides to realize pattern transfer; after developing, removing the dry film in the non-circuit area;
7) the subtraction process comprises the following steps: etching to remove the copper uncovered by the dry film in the non-circuit area;
8) removing the dry film, and forming two-sided circuits on the first TPI layer and the second TPI layer;
9) pressing a third TPI layer and a copper foil on the back of the electroplated circuit board;
10) copper reduction and drilling are carried out on the copper foil pressed in the step 9);
11) carrying out copper deposition and whole-plate copper plating, and pasting an anti-electroplating adhesive tape on the other surface;
12) exposure and development: pressing a photosensitive dry film on one surface, pasting an electroplating-resistant adhesive tape on the other surface, and exposing a circuit on one surface to realize pattern transfer; after developing, removing the dry film in the non-circuit area;
13) the subtraction process comprises the following steps: etching to remove the uncovered copper of the dry film in the non-circuit area;
14) removing the dry film, and forming a single-sided circuit on the third TPI layer;
15) the laser process comprises the following steps: removing the first TPI layer in the middle non-hard board area and the tail hard board area on the metal substrate;
16) exposure and development: pressing photosensitive dry films on two sides, and exposing on one side to realize pattern transfer; after developing, removing the dry film in the non-hard plate area of the metal substrate;
17) the subtraction process comprises the following steps: etching to remove the hard metal plate on the non-hard plate area of the metal substrate;
18) removing the dry film to form an ultrathin soft and hard combined plate structure;
19) and (3) screen printing solder resist: printing ink to obtain a solder resist screen printing layer, and obtaining the ultrathin rigid-flexible printed circuit board.
Preferably, the hard metal plate in step 1) is a steel plate, a copper plate, a nickel plate or other hard metal plates, and the optimal thickness is 90-110 um.
As a modification, the step 1) of opening is obtained by etching, mechanical drilling or laser drilling.
As a modification, the hard board areas in step 2) refer to a head part and a tail part, and the product is exemplified by a head part opening; and grinding is to grind the resin convex part at the opening of the hole until the resin is flush with the hard metal plate.
As an improvement, in the step 3), the first TPI layer, the second TPI layer and the copper foil are pressed by vacuum pressing or ordinary quick pressing, the first TPI layer and the second TPI layer are made of thermoplastic polyimide materials, and the optimal thickness is 18-22 um.
As an improvement, the step 4) and the step 10) of copper reduction refer to that the opposite copper is thinned to form a copper material layer with the thickness of 1-3 um; the drilling is laser drilling.
Preferably, the step 5) is used for copper deposition and whole-plate copper plating, and the optimal thickness of the copper deposition and the whole-plate copper plating is 10-20 um.
As an improvement, the exposure line in the step 6) is film exposure or LDI machine exposure, and pattern transfer is realized.
As a modification, the step 7), step 13) subtraction process: and etching to remove the copper uncovered by the dry film in the non-circuit area.
As an improvement, in the step 9), the pressing of the third TPI layer and the copper foil adopts vacuum pressing or ordinary quick pressing, the third TPI layer is made of a thermoplastic polyimide material, and the optimal thickness is 18-22 um.
Preferably, the step 11) is carried out by copper deposition and whole-plate copper plating, and the other side is pasted with an anti-electroplating adhesive tape, wherein the optimal thickness of the copper deposition and the whole-plate copper plating is 10-20 um.
As an improvement, the exposure circuit in the step 12) is film exposure or LDI machine exposure, so as to realize pattern transfer; the other side is pasted with an anti-electroplating adhesive tape to prevent the etching liquid from biting the circuit, thereby playing a role in protection.
As a modification, the step 15) is a laser process: and removing the first TPI layer in the middle non-hard board area and the tail hard board area on the metal substrate.
As an improvement, the single-sided exposure in the step 16) is film exposure or LDI machine exposure, and pattern transfer is realized.
As a refinement, the step 17) subtraction process: and etching to remove the hard metal plate on the non-hard plate area of the metal substrate.
Preferably, the optimal thickness of the printing ink in the step 19) is 15-30 um.
The product described herein is a three-layer laminate that can be prepared by repeating the steps 9)10)11)12) above if a multilayer preparation is to be performed.
Compared with the prior art, the invention has the advantages that: the steel plate, the copper plate or the nickel plate is used as the substrate, so that the supporting force during chip mounting can be increased, and the deformation of the chip can be reduced; the steel plate, the copper plate or the nickel plate is embedded into the circuit board, so that the requirements of grounding, heat dissipation and supporting can be met, and the strength of the hard board is greatly improved by taking metal as a hard board processing layer; the steel plate, the copper plate or the nickel plate are directly connected with the circuit through the copper conductor, the grounding conduction resistance value can be below 1 omega, and the change caused by the high temperature of reflow soldering can be avoided; the insulating material adopts pure PI, so that the processing is easy, the material is single, and the CTE matching degree is higher; TPI materials are used, and the process is mature based on the traditional etching subtraction process; a layer of copper is directly pressed on the TPI, then the copper is thinned to form a copper material layer with the thickness of 1-3 mu m, compared with the conventional copper precipitation seed copper, the copper material layer which is directly hot-pressed has better bonding force and smooth surface, and the aim of electroplating thin copper can be achieved. The invention has simple process and easy processing, and the prepared rigid-flexible board has the characteristics of thinner thickness, high strength, difficult deformation, high production efficiency and lower cost.
Drawings
Fig. 1.1 to 1.2 are flow charts of a TPI subtraction process according to an embodiment of the present invention, in which (1) is a steel plate input, in which (2) is a hole, in which (3) is a resin hole, in which (4) is a grinding, in which (5) is a pressing of the first and second TPI layers and the copper foil, in which (6) is a copper reduction and drilling, and in which (7) is a copper deposition and a full-plate copper plating; in the figure, (8) is exposure development, in the figure, (9) is etching, in the figure, (10) is stripping, in the figure, (11) is single-side pressing third TPI layer and copper foil, in the figure, (12) is copper reduction and drilling, in the figure, (13) is copper deposition and plate copper plating; in the drawing, (14) is exposure development, (15) is etching, (16) is stripping, (17) is laser TPI, (18) is exposure development, (19) is etching, (20) is stripping, and (21) is solder resist.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
As shown in fig. 1.1-1.2, the structure of the ultrathin soft and hard combined board of this embodiment is divided into three parts, namely a head hard board part a, a soft board connecting band region B and a tail hard board region C, wherein the thickness requirement of the head hard board part a of a conventional board is 0.3-0.4mm, the thickness requirement of the tail hard board region C is 0.3-0.45mm, and the thickness requirement of the soft board connecting band region B is 0.08-0.12 mm; the thickness of the head hard plate part A of the ultrathin soft and hard combined plate is required to be 0.2-0.3mm, the thickness of the tail hard plate area C is required to be 0.15-0.2mm, and the thickness of the soft plate connecting belt area B is required to be 0.04-0.08mm, and the specific preparation process comprises the following steps:
1) selecting a hard metal plate as a substrate, wherein the hard metal plate in the step 1) is a steel plate, a copper plate or a nickel plate, and the optimal thickness of the hard metal plate is 90-110um, the metal plate in the embodiment example is recommended to be a steel plate 1, and the thickness of the steel plate 1 is 100 um; and etching, mechanically drilling or laser drilling is adopted in the hard board area of the metal substrate to obtain an opening 11, see fig. 1.1(1), (2);
2) plugging the hole 11 in the step 1) with resin 12, and grinding; the product is exemplified by a head opening, the opening 11 is filled with resin, the resin 12 is usually plugged by an epoxy resin material, and then the resin convex part at the opening of the opening 11 is ground until the height of the resin 12 is flush with the hard metal plate, see fig. 1.1(3), (4);
3) pressing a first TPI layer 2 and a copper foil 3, a second TPI layer 2.1 and a copper foil 3.1 on two sides of a steel plate 1, wherein the pressing of the first TPI layer 2 and the copper foil 3, and the second TPI layer 2.1 and the copper foil 3.1 adopts vacuum pressing or common quick pressing, the first TPI layer 2 and the second TPI layer 2.1 are made of thermoplastic polyimide materials, the optimal thickness is 18-22 mu m, and the first TPI layer and the second TPI layer are respectively arranged between the surface of the steel plate 1 and the copper foils 3 and 3.1, as shown in figure 1.1 (5);
4) reducing copper and drilling; thinning the copper foil 3 and the copper foil 3.1 which are pressed in the step 3) to form a copper material layer with the thickness of 1-3 um; the drilling is laser drilling; a hole with a diameter smaller than that of the metal plate open hole 11 is processed in the open hole 11, so that a new through hole 10 is formed, and a blind hole 10.1 is formed between the first TPI layer 2 and the copper foil 3 and the second TPI layer 2.1 and the copper foil 3.1 on the steel plate 1, see fig. 1.1 (6);
5) copper deposition and whole-plate copper plating are carried out, the optimal thickness of the copper deposition and the copper plating is 10-20um, and a copper material layer 4 is filled on the hole wall of the new via hole 10 in an electroplating mode and is communicated with a copper foil 3 and a copper foil 3.1 of surface copper; the blind hole 10.1 is filled with copper material in the hole by electroplating, and is communicated with the copper foil 3 and the copper foil 3.1 of the surface copper, as shown in fig. 1.1 (7);
6) exposure and development: pressing a photosensitive dry film 5 on two sides and exposing circuits on two sides to realize pattern transfer, exposing the exposed circuits by adopting film exposure or an LDI machine, and removing the dry film in a non-circuit area after developing, which is shown in figure 1.1 (8);
7) the subtraction process comprises the following steps: etching to remove the uncovered copper of the dry film in the non-circuit area, see fig. 1.1 (9);
8) removing the dry film 5, and forming a two-sided first circuit layer 13 on the first and second TPI layers, see fig. 1.1 (10);
9) laminating a third TPI layer 6 and a copper foil 7 on the back surface of the electroplated circuit board, wherein the third TPI layer 6 and the copper foil 7 are laminated by vacuum lamination or common quick lamination, the third TPI layer 6 is made of a thermoplastic polyimide material, the optimal thickness is 18-22um, and the third TPI layer 6 below the steel plate 1 is pressed and connected with a second TPI layer 2.1 through a gap of a copper foil of a first circuit layer 13 in the laminating process at a position between the surface of the steel plate 1 and the copper foil 7, as shown in (11) of figure 1.1;
10) reducing copper and drilling; thinning the copper foil 7 pressed in the step 9) to form a copper material layer with the thickness of 1-3 um; drilling is to use laser drilling to form blind holes 10.2 in the third TPI layer 6 and the copper foil 7 on the first circuit layer 13, and the blind holes are shown in (12) of FIG. 1.2;
11) copper deposition and whole-plate copper plating are carried out, the optimal thickness of the copper deposition and the copper plating is 10-20um, the blind hole 10.2 is filled with copper materials in the blind hole in an electroplating mode and is communicated with the copper foil 8 of the surface copper, and an electroplating resistant adhesive tape can be attached to the other surface of the blind hole, which is shown in a figure 1.2 (13);
12) exposure and development: pressing a photosensitive dry film 9 on the lower surface, pasting an electroplating-resistant adhesive tape on the other surface, exposing a circuit on a single surface to realize pattern transfer, exposing by adopting film exposure or LDI machine exposure, and removing a dry film in a non-circuit area after developing, which is shown in figure 1.2 (14);
13) the subtraction process comprises the following steps: etching away the copper covered by the dry film in the non-wiring area, see fig. 1.2 (15);
14) removing the dry film 9, and forming a second circuit layer 14 on the third TPI layer, see fig. 1.2 (16);
15) the laser process comprises the following steps: removing the first TPI layer 2 of the middle non-hard board region B and the tail hard board region C on the metal substrate, see fig. 1.2 (17);
16) exposure and development: pressing photosensitive dry films 20 on two sides, exposing on a single side to realize pattern transfer, and removing dry films in non-hard plate areas of the metal substrate after developing, which is shown in figure 1.2 (18);
17) the subtraction process comprises the following steps: etching to remove the hard metal plate on the non-hard plate area of the metal substrate, see fig. 1.2 (19);
18) removing the dry film 20 to form an ultra-thin soft and hard combined board structure, see fig. 1.2 (20);
19) and (3) screen printing solder resist: printing ink to obtain a solder mask silk-screen layer 30, wherein the optimal thickness of the printing ink is 15-30um, and performing surface treatment, testing, appearance and the like to obtain the ultrathin soft and hard combined board, which is shown in figure 1.2 (21).
The ultrathin rigid-flexible combined board prepared by the invention has the following main characteristics:
firstly, the product thickness in the Z direction is thinner, and the size in the XY direction is smaller;
secondly, TPI material is used, and the process is mature based on the traditional etching subtraction process;
thirdly, the insulating material is pure PI, so that the processing is easy, the material is single, and the thermal expansion coefficients are easy to match;
metal materials such as steel sheets/copper sheets and the like are directly embedded below the top layer, so that the supporting force during chip mounting can be increased, and the chip deformation is reduced;
and fifthly, directly pressing a layer of copper on the TPI, then thinning the copper to form a copper material layer with the thickness of 1-3 mu m, wherein compared with the conventional copper precipitation seed copper, the copper material layer directly hot-pressed has better bonding force and smooth surface, and can achieve the aim of electroplating thin copper.
Sixthly, metal materials such as steel sheets/copper sheets and the like are embedded into the circuit board, so that the requirements of grounding, heat dissipation and supporting can be met, and the strength of the circuit board is greatly improved by taking metal as a hard board processing layer;
seventhly, metal materials such as steel sheets/copper sheets and the like are directly connected with the circuit through a copper conductor, the grounding conduction resistance value can be below 1 omega, and the change caused by the high temperature of reflow soldering is avoided.
Claims (16)
1. A thermoplastic polyimide subtraction process of an ultrathin rigid-flex board is characterized by comprising the following steps:
1) selecting a hard metal plate as a substrate, and obtaining an opening in the hard plate area of the metal substrate by etching, mechanical drilling or laser drilling;
2) carrying out resin hole plugging and grinding on the opening position of the hard plate area of the metal substrate;
3) laminating a first TPI layer, a second TPI layer and copper foil on two surfaces of a metal plate;
4) copper reduction and drilling are carried out on the copper foil pressed in the step 3);
5) carrying out copper deposition and whole-plate copper plating;
6) exposure and development: pressing a photosensitive dry film on two sides, and exposing circuits on the two sides to realize pattern transfer; after developing, removing the dry film in the non-circuit area;
7) the subtraction process comprises the following steps: etching to remove the uncovered copper of the dry film in the non-circuit area;
8) removing the dry film, and forming two-sided circuits on the first TPI layer and the second TPI layer;
9) pressing a third TPI layer and a copper foil on the back of the electroplated circuit board;
10) copper reduction and drilling are carried out on the copper foil pressed in the step 9);
11) carrying out copper deposition and whole-plate copper plating, and pasting an anti-electroplating adhesive tape on the other surface;
12) exposure and development: pressing a photosensitive dry film on one surface, pasting an electroplating-resistant adhesive tape on the other surface, and exposing a circuit on one surface to realize pattern transfer; after developing, removing the dry film in the non-circuit area;
13) the subtraction process comprises the following steps: etching to remove the uncovered copper of the dry film in the non-circuit area;
14) removing the dry film, and forming a single-sided circuit on the third TPI layer;
15) the laser process comprises the following steps: removing the first TPI layer in the middle non-hard board area and the tail hard board area on the metal substrate;
16) exposure and development: pressing photosensitive dry films on two sides, and exposing on one side to realize pattern transfer; after developing, removing the dry film in the non-hard plate area of the metal substrate;
17) the subtraction process comprises the following steps: etching to remove the hard metal plate on the non-hard plate area of the metal substrate;
18) removing the dry film to form an ultrathin soft and hard combined plate structure;
19) and (3) screen printing solder resist: printing ink to obtain a solder resist screen printing layer, and obtaining the ultrathin rigid-flexible printed circuit board.
2. The TPI subtraction process according to claim 1, wherein: the hard metal plate in the step 1) is a steel plate, a copper plate or a nickel plate, and the optimal thickness of the hard metal plate is 90-110 um.
3. The TPI subtraction process according to claim 1, wherein: the holes in the step 1) are obtained by etching, mechanical drilling or laser drilling.
4. The TPI subtraction process according to claim 1, wherein: and 3) laminating the first TPI layer and the second TPI layer in the step 3) with the copper foil by vacuum lamination or ordinary rapid lamination, wherein the first TPI layer and the second TPI layer are made of thermoplastic polyimide materials, and the optimal thickness is 18-22 um.
5. The TPI subtraction process according to claim 1, wherein: the step 4) and the step 10) of copper reduction refer to that the opposite copper is thinned to form a copper material layer with the thickness of 1-3 um; the drilling is laser drilling.
6. The TPI subtraction process according to claim 1, wherein: and 5) performing copper deposition and whole-plate copper plating, wherein the optimal thickness of the copper deposition and the copper plating is 10-20 um.
7. The TPI subtraction process according to claim 1, wherein: and 6) exposing the film or the LDI machine to realize pattern transfer.
8. The TPI subtraction process according to claim 1, wherein: the step 7) and the step 13) are subjected to a subtraction process: and etching to remove the copper uncovered by the dry film in the non-circuit area.
9. The TPI subtraction process according to claim 1, wherein: and 9) laminating the third TPI layer and the copper foil in the step 9) by adopting vacuum lamination or ordinary quick lamination, wherein the third TPI layer is made of a thermoplastic polyimide material, and the optimal thickness is 18-22 um.
10. The TPI subtraction process according to claim 1, wherein: and 11) performing copper deposition and whole-plate copper plating, and pasting an anti-electroplating adhesive tape on the other surface, wherein the optimal thickness of the copper deposition and the whole-plate copper plating is 10-20 mu m.
11. The TPI subtraction process according to claim 1, wherein: the exposure line in the step 12) is film exposure or LDI machine exposure, and graph transfer is realized; the other side is pasted with an anti-electroplating adhesive tape to prevent the etching liquid from biting the circuit, thereby playing a role in protection.
12. The TPI subtraction process according to claim 1, wherein: the step 15) of laser process: and removing the first TPI layer in the middle non-hard board area and the tail hard board area on the metal substrate.
13. The TPI subtraction process according to claim 1, wherein: and 16) performing single-side exposure in the step 16) to film exposure or LDI machine exposure to realize pattern transfer.
14. The TPI subtraction process according to claim 1, wherein: the step 17) of the subtraction process: and etching to remove the hard metal plate on the non-hard plate area of the metal substrate.
15. The TPI subtraction process according to claim 1, wherein: the optimal thickness of the printing ink in the step 19) is 15-30 um.
16. The TPI subtraction process according to claim 1, wherein: the steps 9), 10), 11) and 12) can be repeated, thus obtaining the multilayer laminated structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010073328.1A CN113163622B (en) | 2020-01-22 | 2020-01-22 | Thermoplastic polyimide subtraction process for ultrathin rigid-flexible printed circuit board |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010073328.1A CN113163622B (en) | 2020-01-22 | 2020-01-22 | Thermoplastic polyimide subtraction process for ultrathin rigid-flexible printed circuit board |
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| Publication Number | Publication Date |
|---|---|
| CN113163622A CN113163622A (en) | 2021-07-23 |
| CN113163622B true CN113163622B (en) | 2022-05-06 |
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| CN114206030A (en) * | 2021-12-06 | 2022-03-18 | 博罗县精汇电子科技有限公司 | Production process of thin rigid-flex board |
| CN115643696B (en) * | 2022-08-23 | 2024-02-13 | 宁波华远电子科技有限公司 | Preparation process of circuit board |
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| KR101726950B1 (en) * | 2015-07-29 | 2017-04-14 | 영풍전자 주식회사 | Manufacturing method of printed circuit board |
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