JP2016181623A - Method for manufacturing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a printed wiring board, by which a resist film in a through-hole can be partially removed with high accuracy so as to form a conductor films divided in a plurality of numbers in a circumferential direction of the through-hole.SOLUTION: The method for manufacturing a printed wiring board includes steps of: forming a through-hole preparatory hole 5A penetrating top and back surfaces of an insulating resin plate 2; forming a metal plating film 4 on at least an inner wall surface of the through-hole preparatory hole 5A; forming a resist film 6 on the inner wall surface of the through-hole 5 where the metal plating film 4 is formed; partially removing the resist film 6 on the inner wall surface of the through-hole 5 to divide the resist film into a plurality of numbers in a circumferential direction of the through-hole 5; removing the metal plating film 4 exposed from the resist film 6; and removing the resist film 6 remaining on the inner wall surface of the through-hole 5. The step of partially removing the resist film 6 on the inner wall surface of the through-hole 5 is carried out by irradiating inside the through-hole 5 with laser light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a printed wiring board.

Conventionally, through-holes have been used to connect the front and back surfaces and inner layers of printed wiring boards on which chip components and the like are mounted. On the inner wall of the through hole, a metal plating film is formed over the entire surface as a conductor to connect the circuit on the front and back surfaces and the circuit on the inner layer. One through hole holds only one net.
Also, as shown in Patent Document 1, a plating film (conductor film) formed on the inner wall of the through hole is divided into a plurality of through holes in the circumferential direction of the through hole and connected to corresponding wiring patterns on the front and back sides. There are divided through holes (half through holes).
Such a halved through hole is divided by removing the conductor film on the inner wall surface of the through hole in parallel with the axial direction. Each of the divided conductor films is cut in a circuit. The half through-hole is also used for manufacturing a printed wiring board in which a side circuit (side electrode) for external connection is formed on an end surface by cutting the printed wiring board at a portion of the through hole ( Patent Document 2).

As a manufacturing method for forming a through hole, a method including the following steps (i) to (iv) has been used.
(I) Form a plating film and a resist film on the inner wall surface of the through hole. (Ii) Expose the inner wall surface of the through hole to form a divided region. (Iii) Remove the exposed resist film by development, and a plated film in the divided region. (Iv) Remove the exposed plating film by etching, and peel off the remaining resist film. For exposure, a special lens (prism sheet) is used to irradiate light at a predetermined position on the inner wall surface of the through hole. The This special lens converts incident light, which is parallel light, into transmitted light scattered in one direction so that light can be irradiated only in a specific direction.

However, since the size of the prism is determined in advance and the position cannot be finely adjusted according to the arrangement of the through hole, it is difficult to irradiate light to a predetermined position (divided region) in the through hole as intended. There was also a problem that the removal of water became insufficient.
Further, when a prism is used, since it is scattered light, it is difficult to expose a fine region, and it is difficult to form a small-diameter half through hole.

JP-A-8-195539 JP 2006-229033 A

  The subject of this invention provides the manufacturing method of the printed wiring board which can remove the resist film in a through hole partially with high precision, and can form the conductor film divided | segmented into the circumferential direction of the through hole into plurality. That is.

The present invention has been completed in order to solve the above problems, and has the following configuration.
(1) A step of forming a through hole pilot hole penetrating the front and back surfaces of the insulating resin plate, a step of forming a metal plating film on at least the inner wall surface of the through hole lower hole, and a through hole in which the metal plating film is formed A step of forming a resist film on the wall surface, a step of partially removing the resist film on the inner wall surface of the through hole and dividing the resist film into a plurality of portions in the circumferential direction of the through hole, and a step of removing the metal plating film exposed from the resist film And a step of removing the resist film remaining on the inner wall surface of the through hole, wherein the partial removal of the resist film on the inner wall surface of the through hole is performed by placing a laser in the through hole. A method for producing a printed wiring board, which is performed by irradiation.
(2) The metal plating film is formed from the inner wall surface of the through hole to the front and back surfaces of the insulating resin plate, and a resist film is formed on the surface of the metal plating film formed on the front and back surfaces of the insulating resin plate. Resist remaining on the front and back surfaces of the insulating resin plate when removing the resist film and metal plating film communicating with the plurality of parts divided in the circumferential direction of the through hole and further removing the resist film remaining on the inner wall surface of the through hole The method for manufacturing a printed wiring board according to (1), wherein the land is also formed by removing the film.
(3) The manufacturing method of the printed wiring board as described in (1) or (2) whose diameter of the said through hole is 0.85-0.15 mm.
(4) After removing the resist film remaining on the inner wall surface of the through-hole, the printed wiring board is cut at the through-hole divided region to form end face through-holes at the sides or corners of the printed wiring board ( The manufacturing method of the printed wiring board in any one of 1)-(3).

According to the method for manufacturing a printed wiring board of the present invention, the resist film at a predetermined position in the through hole can be accurately removed by using a laser instead of the exposure by the prism, so there is no remaining metal plating film. Etching with high accuracy becomes possible.
Further, by using a laser, it is easy to remove a resist film in a fine region. For example, a conductor film divided into a plurality of through holes having a small diameter can be accurately formed.

(A) is a top view which shows an example of the printed wiring board obtained by the manufacturing method of this invention, (b) is the sectional view on the A-A 'line of (a). (A)-(d) is process explanatory drawing which shows one Embodiment of the manufacturing method of the printed wiring board concerning this invention. (E)-(g) is process explanatory drawing continued from FIG. (A)-(d) is process explanatory drawing which shows the manufacturing method of the printed wiring board shown in FIG. 2, FIG. 3 in detail. (E)-(g) is process explanatory drawing continued from FIG. It is a perspective view which shows an example of the end surface through hole in this invention.

  FIG. 1A is a plan view showing a through hole 5 portion of the printed wiring board 10. As shown in FIG. 1B, the printed wiring board 10 includes a through hole 5 penetrating the front and back surfaces of the insulating resin plate 2, and the inner wall surface of the through hole 5 is partially non-conductive in a slit shape. A metal plating film 4 (for example, a conductor film such as a copper plating film) divided into two pieces is formed. Lands 8 that are continuous with the respective metal plating films 4 are formed on the front and back surfaces of the printed wiring board 10, and are connected to a wiring pattern (not shown) on the front and back surfaces of the insulating resin plate 2.

Examples of the resin that forms the insulating resin plate 2 include epoxy resin, bismaleimide-triazine resin, polyimide resin, polyphenylene ether (PPE) resin, phenol resin, polytetrafluoroethylene (PTFE) resin, silicon resin, polybutadiene resin, Examples thereof include polyester resin, melamine resin, urea resin, polyphenylene sulfide (PPS) resin, polyphenylene oxide (PPO) resin, and the like. Two or more of these resins may be mixed. The resin forming the insulating resin plate 2 may include the above-described inorganic filler, and an organic filler made of a phenol resin or a methacrylic resin.
Further, the printed wiring board 10 may be a laminated board including not only the insulating resin board 2 but also an insulating board and the insulating resin boards 2 laminated on both sides of the insulating board. This laminated plate is formed by pressing or the like after the insulating resin plate 2 is laminated on the insulating plate.

  The printed wiring board 10 is a double-sided printed wiring board in FIG. 1B, but is not limited thereto, and may be a build-up layer with an increased number of layers. Furthermore, the present invention is not limited to build-up printed wiring boards, and can be applied to ordinary multilayer printed wiring boards, bonded multilayer printed wiring boards, and multiple multilayer printed wiring boards. Further, although omitted in the drawing, it goes without saying that other than the divided through holes, they are electrically connected by normal through holes or vias penetrating the conductor layers.

  The through hole 5 is drilled or laser processed so as to penetrate the front and back surfaces of the insulating resin plate 2 to form a through hole lower hole 5A, and the metal plating film 4 and resist are formed on the inner wall surface of the through hole lower hole 5A. The film 6 is provided, and the resist film 6 is selectively removed with a laser.

  The metal plating film 4 is preferably a copper plating film from the viewpoint of ease of processing such as etching.

Next, a method for manufacturing a printed wiring board according to this embodiment will be described. This method for manufacturing a printed wiring board includes the following steps (I) to (VI).
(I) Step of forming through hole pilot holes penetrating front and back surfaces of insulating resin plate (II) Step of forming metal plating film on front and rear surfaces of insulating resin plate and inner wall surface of through hole lower hole (III) Insulating resin Step of forming a resist film on the front and back surfaces of the plate and the inner wall surface of the through hole (IV) A pattern mask is disposed in at least one opening of the through hole, ultraviolet rays are irradiated from the opening of the pattern mask, and the laser is transmitted through the through hole. The resist film on the inner wall surface of the through hole is partially removed and developed to remove the resist in the exposed portion and divided into a plurality of portions in the circumferential direction of the through hole. (V) Exposed from the resist film Etching process to remove the plated metal film (VI) Process to remove the resist film remaining on the inner wall surface of the through hole

  A method for producing a printed wiring board according to the present invention will be described with reference to the drawings. As shown in FIG. 2A, an insulating resin plate 2 is prepared. The insulating resin plate 2 is suitably a double-sided copper-clad laminate in which copper foils are laminated on the front and back. Copper foil thickness shall be 12 micrometers, for example. Laser processing or drilling is performed on the insulating resin plate 2 to form a through-hole lower hole 5A penetrating the insulating resin plate 2, and the inner wall surface of the through-hole lower hole 5A and the front and rear surfaces 2A and 2B of the insulating resin plate 2 are formed. A metal plating film 4 is provided. Next, as shown in FIG. 2B, a resist film 6 is laminated on the surface of the metal plating film 4. As the resist film 6, for example, an electrodeposition resist is suitable for forming the resist film 6 on the inner wall surface of the through hole 5. The electrodeposition resist used in the present embodiment is a negative type, and for example, P-1000 manufactured by Nippon Paint Co., Ltd. can be used.

Next, as shown in FIG. 2C, a pattern mask 70 is placed on the through hole 5 in the surface 2A of the insulating resin plate 2, and the surface 2A is exposed by irradiating ultraviolet rays UV.
Next, as shown in FIG. 2 (d), the front and back of the insulating resin plate 2 are reversed, and another pattern mask is formed on the through hole 5 on the back surface 2B of the through hole 5 as shown in FIG. 3 (e). 70 'is placed and exposed by irradiating with ultraviolet UV.
Next, as shown in FIG. 3F, after removing the pattern mask 70 ', the resist film 6 on the inner wall surface of the through hole 5 is partially removed by irradiating the laser beam L with a laser device.

  Thereafter, development is performed to remove the resist film other than the exposed portion, and then the exposed metal plating film 4 is removed by etching. Finally, the remaining resist film 6 is peeled off, and the metal plating film 4 is separated in the divided regions 7. The printed wiring board 10 having the half through-hole 5 in which the (conductor film) is divided in the circumferential direction is obtained. On the front and back surfaces of the printed wiring board 10, lands 8 that are continuous with the metal plating film 4 of the through holes 5 are formed. (Fig. 3 (g))

The laser device for providing the divided region 7 in the through hole 5 moves the irradiation position by numerical control of XY. Since the laser beam is excellent in directivity, the divided region 7 can be formed in the through hole 5 with high accuracy. Further, it can be applied even if the through hole 5 has a small diameter due to the characteristics of the laser beam. Usually, the diameter of the through hole is 0.85 to 0.15 mm, preferably 0.35 to 0.15 mm. It is good.
The laser beam L may be irradiated only from either the front or back surface of the insulating resin plate 2 as long as the resist film 6 on the inner wall surface of the through hole 5 can be removed.

It is preferable to adjust the output (energy) of the laser beam L so as not to scrape the metal plating 4 but to scrape only the resist film 6 on the surface.
As the kind of the laser L, CO ₂ laser, and the like UV-YAG laser.

  4 (a) to 4 (d) and FIGS. 5 (e) to 5 (k) are diagrams showing in more detail the manufacturing method of the printed wiring board shown in FIGS. 2 and 3, and each figure is an insulating resin plate. 2 shows a front surface 2A, a cross section of the insulating resin plate 2, and a back surface 2B of the insulating resin plate 2. The cross-sectional view is a cross-sectional view taken along the line B-B ′ of FIG. 4A, and the B-B ′ line is omitted hereinafter.

  As shown in FIG. 4A, through-holes 5 penetrating the front and back surfaces are provided in the insulating resin plate 2, and the metal plating film 4 is formed on the front and back surfaces 2A and 2B of the insulating resin plate 2 and the inner wall surface of the through-hole 5. Further, the surface of the metal plating film 4 is covered with a resist film 6 with an electrodeposition resist.

  Next, as shown in FIG. 4B, a light-shielding pattern mask 70 having slits 71 is arranged on the surface of the insulating resin plate 2 and irradiated with ultraviolet rays UV, so that other than the surface land 21 of the insulating resin plate 2. To expose

Next, as shown in FIG. 4C, a pattern mask 70 ′ having a slit 73 on the back surface of the edge resin plate 2 is disposed, and the surface land 21 ′ is exposed by irradiating ultraviolet rays UV.
The insulating resin plates 2 exposed from the front and back surfaces are in a state where the surface lands 21 and 21 ′ on both sides and the inner wall surface of the through hole 5 are partially exposed.
Next, as shown in FIG. 4D, after removing the pattern mask 70 ', the resist film 6 on the inner wall surface of the through hole 5 is partially removed by irradiating the laser beam L with a laser device.

  Next, as shown in FIG. 5E, the exposed resist film 6 is removed with a developing solution, and the metal plating film 4 on the inner wall surface of the through hole 5 below the divided region 7 is partially exposed.

  Next, as shown in FIG. 5F, the exposed metal plating film 4 is removed by etching. Next, as shown in FIG. 5G, when the resist film 6 remaining on the inner wall surface of the through hole 5 is peeled off, the electrical connection between the circuits in the circumferential direction of the inner wall surface is cut off at the lower part of the divided region 7. The through hole 5 is completed. The resist film 6 can be peeled off with, for example, a sodium hydroxide solution.

  The through-hole 5 can also be formed by cutting the printed wiring board 10 in the divided region 7 to form the end face through-hole 51 at the side or corner of the printed wiring board 10. FIG. 6 shows an end face through hole 51 formed in a side portion of the printed wiring board 10, and the metal plating film 4 on the inner wall surface of the through hole is exposed to the outside to form a side electrode of the printed wiring board 10. ing. Such an end face through hole 51 is mainly used for external connection or the like.

As described above, according to the method for manufacturing a printed wiring board of the present invention, the resist film 6 at a predetermined position on the inner wall surface of the through-hole 5 can be formed with a laser that can move the irradiation position freely, instead of the exposure by the conventional prism. Since the metal plating film 4 in the through hole 5 can be removed by etching because the metal plating film 4 in the through hole 5 can be removed by etching, the plating film residue does not remain, and the through hole 5 is reliably electrically connected in the divided region 7. Can be divided into
Further, since the prism is not used, the exposure light does not become scattered light, the fine circuit can be easily exposed, and a through hole having a smaller diameter can be formed.

  Further, the number of divisions of the metal plating film 4 (conductor film) divided in the circumferential direction of the through hole 5 is not particularly limited. However, since a high-precision multi-division is possible by using a laser, the number of divisions is more than two. For example, even 6 divisions are possible.

  In the above embodiment, a negative electrodeposition resist is used, but a positive electrodeposition resist may be used. In this case, it is necessary to use a mask having a reverse pattern to that shown in the figure. Others are the same as the above-mentioned embodiment.

2 Insulating resin plate 4 Metal plated film 5 Through hole 5A Through hole pilot hole 6 Resist film 7 Divided region 8 Land 21, 21 'Surface land 70, 70' Pattern mask 71, 73 Slit 9 Solder resist 10 Printed wiring board 51 End surface through Hall UV UV L Laser light

Claims (4)

Forming a through-hole pilot hole penetrating the front and back surfaces of the insulating resin plate;
Forming a metal plating film on at least the inner wall surface of the through-hole lower hole;
Forming a resist film on the inner wall surface of the through hole formed with the metal plating film;
A process of partially removing the resist film on the inner wall surface of the through hole and dividing the resist film into a plurality in the circumferential direction of the through hole;
Removing the exposed metal plating film from the resist film;
A method of manufacturing a printed wiring board including a step of removing the resist film remaining on the inner wall surface of the through hole,
The method for manufacturing a printed wiring board, wherein the partial removal of the resist film on the inner wall surface of the through hole is performed by irradiating the through hole with a laser.   The metal plating film is formed from the inner wall surface of the through hole to the front and back surfaces of the insulating resin plate, a resist film is formed on the surface of the metal plating film formed on the front and back surfaces of the insulating resin plate, and then the through hole is formed. Remove the resist film and metal plating film communicating with the part divided into multiple parts in the circumferential direction, and also remove the resist film remaining on the front and back surfaces of the insulating resin plate when removing the resist film remaining on the inner wall surface of the through hole The printed wiring board manufacturing method according to claim 1, wherein the land is formed.   The printed wiring board manufacturing method according to claim 1, wherein a diameter of the through hole is 0.85 to 0.15 mm.   The resist film remaining on the inner wall surface of the through hole is removed, and then the printed wiring board is cut at the divided region of the through hole to form an end surface through hole at a side or corner of the printed wiring board. 4. A method for producing a printed wiring board according to any one of 3 above.

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