JP4838155B2 - Method for manufacturing printed circuit board - Google Patents

Description

  The present invention relates to a printed circuit board manufacturing method, and more particularly to a method for uniformly plating a single-wafer substrate with high production efficiency.

  Conventionally, in a method for manufacturing a printed circuit board, a so-called reel-to-reel method is used in which a long resin film is wound on a reel from both ends, and various processes are performed on the resin film while winding from one reel to the other. (For example, refer to Patent Document 1). In the reel-to-reel method, since the current line is uniformly applied from the anode in the plating tank to the continuous film for the substrate in the plating process, the in-plane uniformity of the formed plating film is relatively good at ± 10%. is there. On the other hand, in this reel-to-reel system, a hole forming process such as NC drilling, which is a technique for forming a through hole for wiring such as a through hole on a printed board, is performed at any time while feeding a film roll for a substrate by a predetermined size. there were. For this reason, the number of drilling operations is required as many as the number of printed boards to be produced, and there is a problem that the production efficiency is greatly reduced in the process before the plating process. In addition, since the punching process needs to be performed by a reel-to-reel method, an initial investment such as a punching device applicable to the reel-to-reel method is required.

  Compared with such a reel-to-reel manufacturing method, the single-wafer printed circuit board manufacturing method can reduce the number of punching operations. In other words, the single-wafer printed circuit board manufacturing method has an advantage that a drilling operation such as NC drilling can be performed collectively in a state where a plurality of single-wafer substrates are stacked. As described above, the production method of the single-wafer printed circuit board has an advantage that the production efficiency can be improved, and the cost of the mass-produced printed circuit board can be reduced.

  As a specific example of a method of manufacturing a printed circuit board that performs sheet processing in this manner, a method that is performed in the following procedures (1) to (4) is known (see, for example, Patent Document 2).

(1) A plurality of substrates formed by cutting a long substrate film is formed.

(2) A plurality of substrates are overlapped to form through holes in a lump.

(3) The substrate on which the through holes are formed is plated one by one to form conductive material layers on both sides of the through holes and the substrate (plating process step).

(4) A patterning process for forming circuit patterns on the conductive material layers on both sides is performed while connecting and elongating the plated substrates to each other and elongating the substrates in the longitudinal direction by a reel-to-reel method.

In the above-described printed circuit board manufacturing method, as shown in FIG. 10, the separated substrates S are each handled by the grips G and suspended, and then immersed in the copper plating tank T in order to perform the plating process (3 ) Is processed by the single wafer method.
JP 2005-89799 A JP 2006-222172 A

  In the above-described method for manufacturing a single-wafer printed circuit board, current lines (indicated by arrows in the figure) from the anode A disposed in the copper plating tank T are formed at the end of the substrate S as shown in FIG. In order to concentrate, the uniformity of the film thickness of the copper plating film formed on the surface of the substrate S was ± 20%. In order to improve the film thickness uniformity of the copper plating film, as shown in FIG. 12, the distance between the substrates S is reduced to avoid the concentration of current lines at the ends of the substrates S, or the periphery of the substrate S A device has been devised such as mounting a frame-shaped copper jig on the top. However, even with such a device, the film thickness uniformity of the copper plating film is still ± 15%. Further, when a copper jig is mounted around the substrate S, there is a problem that current lines are excessively concentrated on the copper jig and the original plating film thickness of the substrate S becomes too thin. FIG. 9 shows the thickness distribution within one substrate when copper plating is performed with a copper jig mounted on a single substrate. As shown in FIG. 9, when a copper jig is used, regions having thicknesses of 80-90, 90-100, 100-110, and 110-120 are distributed in one substrate. That is, regions having different plating film thicknesses are distributed over four levels, and the film thickness uniformity is low.

  Moreover, in the manufacturing method of the above-mentioned single wafer type printed circuit board, since the plating process is performed in the copper plating tank in a state where the weight of the board is suspended only by the grip, compared with the above-described long resin film. The substrate is likely to be locally bent and deformed, and as a result, there is a problem that the film thickness of the conductive material layer such as copper formed by plating is not uniform.

  In particular, the problem that the plating film thickness varies affects the uniformity of the circuit pitch. If the film uniformity by plating is good, the variation of the circuit pitch is also reduced, and thereby the amount of overetching can be suppressed.

  In recent years, along with the mass production of printed circuit boards used in mobile phones, etc., circuit patterns have been increasingly miniaturized. By making the conductive material layer formed by plating uniformly thin, the aspect ratio of the wiring pattern can be optimized. There is an urgent need to improve circuit pattern reliability by reducing the amount of overetching.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a printed circuit board manufacturing method that has high production efficiency, high in-plane uniformity of a plating film, and can cope with miniaturization of circuit patterns.

  The present invention is a method for manufacturing a printed circuit board, wherein a step of forming connection through-holes in a state where a plurality of substrates are stacked, and a plurality of the substrates formed with the connection through-holes are connected with a tape. A continuous substrate that is processed into a roll and wound into a roll; a direct plating process is performed on the entire surface of the continuous substrate while the continuous substrate is being unwound; and a continuous substrate that has been subjected to the direct plating process. And a step of performing a plating process while paying out.

  The tape base material is preferably made of polypropylene, and more preferably plasma-treated as a surface activation treatment.

  According to the present invention, the in-plane uniformity of the plating film thickness can be improved without reducing the production efficiency of the printed circuit board.

  Hereinafter, details of a method of manufacturing a printed circuit board according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the method of manufacturing a printed circuit board according to the present embodiment includes a step of forming through holes as through holes for connection in a lump by NC drilling in a state where a plurality of substrates are stacked (step S1) A step of connecting a plurality of substrates with through holes connected with tape so as to connect them one by one, processing them into a continuous substrate and winding it into a roll (step S2), and direct plating on the entire surface while feeding out the continuous substrate A process (step S3) of performing a roll-up process, and a process of performing a plating process (step S4) while feeding out a continuous substrate subjected to the direct plating process. In the printed circuit board manufacturing method according to the present embodiment, the printed circuit board is manufactured through a post-processing process (step S5) such as a circuit patterning process after the plating process.

  Hereinafter, a method for manufacturing a printed circuit board according to the present embodiment will be described in the order of steps. First, as shown in FIG. 2, a plurality of substrates 10 are prepared. In the present embodiment, a rectangular substrate having a size of 250 mm × 330 mm is prepared as the substrate 10. This board | substrate 10 uses the double-sided copper foil board | substrate with which the copper foil 12 was bonded together on both surfaces of the polyimide base material 11 as a base material. In the present embodiment, the thickness of the polyimide base material 11 is 25 μm and the thickness of the copper foil is 12 μm. However, the thickness is not limited to these.

  Next, as shown in FIG. 2, a plurality of substrates 10 are stacked and NC drilling is performed to open through holes 13 as connection through holes collectively at predetermined locations on the substrate 10 (step S <b> 1).

  Thereafter, as shown in FIG. 3, the plurality of substrates 10 are arranged so as to be adjacent to each other so as to be continuous in one direction, and the substrates 10 are resin tapes from both sides in a state where the edges of each side abut each other. The long continuous substrate 30 is produced by connecting at 20. In the present embodiment, the resin tape 20 is affixed to both sides of the abutting portion between the substrates 10, but only one side may be used.

  In the present embodiment, as shown in FIG. 4, the resin tape 20 includes a propylene substrate 21 subjected to plasma treatment as a tape substrate, and an adhesive layer 22 provided on one side of the propylene substrate 21. And consist of Here, as the propylene substrate 21, a substrate having a width of 15 mm and a thickness of 35 μm was used. In the present embodiment, the adhesive layer 22 is made of an acrylic adhesive, and the thickness thereof is set to 25 μm. And as shown in FIG. 5, the continuous substrate 30 is wound up in roll shape from the one end side of a longitudinal direction. (Step S2).

  Next, a known direct plating process is performed while feeding the roll-shaped continuous substrate 30 (step S3). In this direct plating process, a direct plating film 41 is formed inside the through hole of the continuous substrate 30 and on the surface of the resin tape 20 including the adhesive layer 21. As described above, in this embodiment, since the direct plating film 41 is formed on the continuous substrate 30 and the resin tape 20, similarly to the long roll-shaped double-sided copper foil film, the conductivity is uniform in the longitudinal direction. It becomes a roll equipped with. In particular, in order to attach the direct plating film 41 to the resin tape 20 in this way, it is effective to use the polypropylene base material 21 as the tape base material, and it is particularly effective to subject the polypropylene base material 21 to plasma treatment. is there.

  Next, a copper plating process is performed on the continuous substrate 30 by a reel-to-reel method (step S4). As a result, a copper plating layer 42 is formed on the direct plating film 41 including the inside of the through hole 13. In this embodiment, a grip-feed reel-to-reel type copper plating apparatus is used for the copper plating step. By using a grip-feed reel-to-reel copper plating apparatus, a copper plating film is easily formed on the surface of the resin tape 20. Therefore, in this Embodiment, the continuous substrate 30 improves the uniformity of a copper plating film similarly to the case where a long double-sided copper foil resin film is copper-plated. In this embodiment, the film thickness uniformity per substrate is within ± 10%.

  After that, various post-processing steps such as circuit pattern formation are performed on the continuous substrate 30 on which the copper plating layer 42 is formed (step S5), and the resin tape 20 is removed to complete the production of the printed circuit board (not shown). To do.

  FIG. 8 shows the film thickness distribution of the copper plating layer 42 in the printed circuit board produced by the printed circuit board manufacturing method according to the present embodiment. As shown in FIG. 8, in the method for manufacturing a printed circuit board according to the present embodiment, two regions having a thickness of 80-90 and 90-100 are distributed. That is, as shown in FIG. 8, since the regions with different plating film thicknesses are distributed within two levels, the film thickness uniformity is compared with the conventional example in which copper plating is performed using the copper jig shown in FIG. (In the conventional example shown in FIG. 9, the thickness is distributed over four levels), it can be seen that it has improved.

  In the present embodiment, since NC drilling is performed collectively in a state where a plurality of substrates 10 are stacked before the copper plating process, the production efficiency can be improved.

  In addition, since the direct plating process and copper plating process are reel-to-reel methods, processing can be performed in a state where local tension is not applied or distortion is unlikely to occur, so a printed circuit board with high film thickness uniformity is manufactured. be able to.

  In the present embodiment, by using such a resin tape 20, the direct plating film 41 can be uniformly attached to the whole, and thereby the uniformity of the film thickness of the copper plating layer 42 is ± 10. % Became possible.

  In the printed circuit board manufacturing method of the present embodiment, the in-plane uniformity of the copper plating layer 42 is high, and it is possible to cope with miniaturization of circuit patterns.

It is a flowchart explaining the outline of the manufacturing method of the printed circuit board which concerns on embodiment of this invention. It is sectional drawing which shows the state which laminated | stacked the several board | substrate and performed NC drilling collectively in the manufacturing method of the printed circuit board which concerns on embodiment of this invention. It is sectional drawing which shows the state which connected the board | substrates with the resin tape after NC drilling in the manufacturing method of the printed circuit board which concerns on embodiment of this invention. It is sectional drawing of the resin tape used with the manufacturing method of the printed circuit board concerning embodiment of this invention. It is a perspective view which shows the state which is winding up the continuous substrate in the manufacturing method of the printed circuit board which concerns on embodiment of this invention. It is sectional drawing which shows the state which performed the direct plating process to the continuous substrate connected with the manufacturing method of the printed circuit board which concerns on embodiment of this invention. It is sectional drawing which shows the state which performed the copper plating process to the continuous substrate connected with the manufacturing method of the printed circuit board which concerns on embodiment of this invention. It is a figure which shows distribution of the film thickness of the copper plating layer at the time of performing a copper plating process with the manufacturing method of the printed circuit board concerning embodiment of this invention. It is a figure which shows distribution of the film thickness of the copper plating layer at the time of performing a copper plating process on the conventional single-wafer board | substrate using a copper jig. It is explanatory drawing which shows the copper plating process process of the conventional single wafer board | substrate. It is explanatory drawing which shows distribution of the electric current line at the time of arrange | positioning sheet | seat board | substrates apart and performing a copper plating process. It is explanatory drawing which shows distribution of the current line at the time of arrange | positioning sheet | seat board | substrates close together and performing a copper plating process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Board | substrate 11 Polyimide base material 12 Copper foil 13 Through hole 20 Resin tape 21 Propylene base material 21 Polypropylene base material 22 Adhesive layer 30 Continuous substrate 41 Direct plating film | membrane 42 Copper plating layer

Claims (5)

Forming a through-hole for connection in a state where a plurality of substrates are laminated;
Connecting the plurality of substrates having the through-holes for connection with a tape, processing them into a continuous substrate and winding them into a roll; and
A step of performing direct plating treatment on the entire surface while rolling out the continuous substrate and winding it into a roll;
Performing a plating process while feeding out the continuous substrate subjected to the direct plating process;
A printed circuit board manufacturing method comprising:   The method for manufacturing a printed circuit board according to claim 1, wherein the tape is formed by laminating an adhesive layer on a tape base material.   The printed circuit board manufacturing method according to claim 2, wherein the tape base material is made of polypropylene.   The method for producing a printed circuit board according to claim 2, wherein a surface activation treatment is performed on the tape base material.   5. The printed circuit board manufacturing method according to claim 4, wherein the surface activation treatment is a plasma treatment.

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