JP2013062440A - Printed board and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent peeling or expansion of a substrate during reflow or an environment test while preventing warpage of the substrate.SOLUTION: A printed board 100 includes a multilayer structure where a second substrate 20 is laminated on a first substrate 10 through an adhesive layer 9. The first substrate 10 includes a first wiring layer 12 and a first electrode layer 13 which are formed on an entire surface 11a of a first resin base material 11, and a through hole 14 is formed on the first electrode layer 13. A second substrate 20 includes a second wiring layer 22 and a second electrode layer 23 which are formed on an entire surface 21a of a second resin base material 21. A through hole 24 is formed on the second electrode layer 23. Even if volatile components and water components included in the adhesive layer 9 or the like occur and water components intruding from the exterior of the substrate expand when the printed board is exposed to a high temperature during reflow or the like, those components are effectively discharged from the resin base materials 11, 21 to the exterior through the through holes 14, 24 of the first and second electrode layers 13, 23.

Description

  The present invention relates to a printed circuit board on which, for example, an electronic component is surface-mounted, and a method for manufacturing the same.

  Conventionally, in a printed circuit board having a resin base material, a conductive layer, and an adhesive layer, the organic adhesive and the volatile component of the resin base material included in the adhesive layer at the time of environmental tests such as reflow, moisture absorption reflow test, thermal shock test, etc. In some cases, moisture expands or moisture enters from the outside of the substrate, causing peeling or swelling of the substrate. In particular, it may occur when these printed boards are laminated to form a multilayer. In order to prevent such inconvenience, the printed circuit board disclosed in the following Patent Document 1 has a structure in which through holes are formed in a place where the substrate is easily peeled off or swollen, for example, to evaporate evaporated volatile components and moisture. It has become.

JP 2008-186896 A

  However, in the printed circuit board disclosed in Patent Document 1, it is necessary to form a through hole or the like in the surface layer where the substrate is easily peeled or swollen. For this reason, when the printed circuit board is multi-layered, the structure is insufficient to release the organic adhesive, volatile components and moisture in the layers, and moisture that has entered from the outside, effectively peeling and swelling the substrate. It becomes difficult to suppress it.

  In addition, since the linear expansion coefficient is different between the resin base material and the conductive layer, it is possible to prevent warping of the substrate with a higher residual copper ratio, but when a printed circuit board with a high residual copper ratio is multilayered, Similarly, the structure is insufficient to escape the organic adhesive, volatile components and moisture of the underlying layer, or moisture that has entered from the outside.

  The present invention provides a printed circuit board capable of preventing the above-described problems caused by the prior art, preventing the substrate from warping, and preventing the substrate from peeling or swelling during reflow or environmental testing, and a method for manufacturing the same. The purpose is to do.

  The printed circuit board according to the present invention includes a first resin base, a first wiring layer and a first electrode layer formed on the entire surface of the first resin base, and the first wiring layer and the first electrode layer. An adhesive layer formed on the first resin substrate and a second resin substrate formed in close contact with the adhesive layer, and a through hole is formed in the first electrode layer. It is characterized by that.

  According to the printed board according to the present invention, the first wiring layer and the first electrode layer are entirely formed on the first resin base, and the first electrode exists between the adhesive layer and the second resin base. A through hole is formed in the layer. For this reason, even if it is exposed to high temperatures during reflow or environmental tests, etc., even if volatile components and moisture contained in the adhesive layer or the like, or moisture that has entered from the outside expands, it passes through the through hole of the first electrode layer. It is efficiently discharged from the first and second resin base materials to the outside of the substrate. Thereby, peeling and swelling of the substrate can be minimized. Further, since the first wiring layer and the first electrode layer are formed on the entire surface of the first resin base material, the remaining copper ratio is high and the warpage of the substrate can be prevented.

  In one embodiment of the present invention, the first electrode layer comprises a ground electrode or a dummy electrode.

  In another embodiment of the present invention, a second wiring layer and a second electrode layer are formed on the surface of the second resin base opposite to the contact surface with the adhesive layer, and the second electrode layer has a through hole. A hole is formed.

  In still another embodiment of the present invention, the through hole of the second electrode layer is formed coaxially with the through hole of the first electrode layer.

  The printed circuit board manufacturing method according to the present invention includes a first resin base material, a first wiring layer and a first electrode layer formed on the first resin base material, and the first wiring layer and the first electrode layer. A printed circuit board manufacturing method comprising: an adhesive layer formed on the first resin base material; and a second resin base material formed in close contact with the adhesive layer, the first resin base material The first wiring layer and the first electrode layer are formed on the entire surface, a through hole reaching the first resin base material is formed in the first electrode layer, and the second resin base material is connected to the first resin base material. It is characterized by laminating on a resin substrate via the adhesive layer.

  According to the method for manufacturing a printed circuit board according to the present invention, the first wiring layer and the first electrode layer are formed on the entire surface of the first resin base material, and the first electrode layer reaches the first resin base material. After forming the holes, the second resin base material is laminated on the first resin base material via the adhesive layer. For this reason, moisture can be efficiently discharged from the first and second resin base materials to the outside of the substrate through the through-holes of the first electrode layer during reflow, and the substrate is prevented from warping as described above. It is possible to manufacture a printed circuit board that can minimize peeling and swelling.

  In one embodiment of the present invention, prior to laminating the second resin base material on the first resin base material, on the surface opposite to the contact surface of the second resin base material with the adhesive layer, A second wiring layer and a second electrode layer are formed, and a through hole reaching the second resin base material is formed in the second electrode layer.

  In another embodiment of the present invention, the through hole of the second electrode layer is formed coaxially with the through hole of the first electrode layer.

  According to the present invention, it is possible to prevent the substrate from peeling or swelling during reflow or environmental testing while preventing the substrate from warping.

It is a top view which shows the structure of the printed circuit board which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the same printed circuit board. It is a flowchart which shows the manufacturing process of the printed circuit board. It is sectional drawing which shows the printed circuit board in order of a manufacturing process. It is sectional drawing which shows the printed circuit board in order of a manufacturing process.

  Hereinafter, a printed circuit board and a manufacturing method thereof according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view showing the structure of a printed circuit board according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the structure of the printed circuit board. FIG. 2 shows a part of the printed board in cross section. As shown in FIGS. 1 and 2, the printed circuit board 100 according to the present embodiment has a multilayer structure in which a second substrate 20 is stacked on an adhesive layer 9 on a first substrate 10, for example. The first substrate 10 includes a first wiring layer 12 and a first electrode layer 13 that are entirely formed on one surface 11 a of the first resin base material 11.

  The first electrode layer 13 is made of, for example, a ground (GND) electrode or a dummy electrode, and is electrically insulated from the first wiring layer 12. In the first electrode layer 13, a through hole 14 reaching the one surface 11 a of the first resin base material 11 is formed. The through hole 14 is formed in the first electrode layer 13 within a range of 0.5 mm to 2.0 mm from the side end surface of the first substrate 10, for example. In this example, the other surface 11 b of the first resin base material 11 constitutes the bottom surface of the printed circuit board 100.

  On the other hand, like the first substrate 10, the second substrate 20 includes a second wiring layer 22 and a second electrode layer 23 formed entirely on one surface 21 a of the second resin base material 21. . An adhesive layer 9 that bonds the first substrate 10 and the second substrate 20 is formed between the other surface 21 b of the second resin base material 21 and the one surface 11 a of the first resin base material 11. ing.

  In addition, a via hole 8 reaching the second wiring layer 22 and the second electrode layer 23 is formed in the second resin base material 21 and the adhesive layer 9 of the second substrate 20. The first and second wiring layers 12 and 22 and the first and second electrode layers 13 and 23 are electrically connected to each other by an inner via 7 formed in the via hole 8.

  The second electrode layer 23 includes a through hole 24 formed in the same configuration as the through hole 14 of the first electrode layer 13. The through hole 24 of the second electrode layer 23 is formed at a position coaxial with the through hole 14 of the first electrode layer 13, for example. Each through hole 14, 24 is formed with a diameter φ of 10 μm to 30 μm, for example.

  The first and second resin base materials 11 and 21 are made of an insulating resin such as polyimide resin, and the wiring layers 12 and 22 and the electrode layers 13 and 23 are formed by patterning a conductive material such as copper foil. As the first and second substrates 10 and 20, for example, a single-sided copper-clad laminate (single-sided CCL), a double-sided copper-clad laminate (double-sided CCL), or the like may be used. The adhesive layer 9 is made of an organic adhesive containing a volatile component such as an epoxy adhesive or an acrylic adhesive.

  The printed circuit board 100 according to the present embodiment is configured as described above, and has the following operational effects. That is, even when volatile components and moisture contained in the adhesive layer 9 and the like are exposed to a high temperature during reflow or the like, or moisture that has entered from the outside of the substrate expands, these will not pass through the first electrode layer 13. It is efficiently discharged from the first resin base material 11 through the hole 14.

  Similarly, moisture is efficiently discharged from the through hole 24 of the second electrode layer 23 to the outside of the substrate through the second resin base material 21. Moreover, since the adhesive which comprises the contact bonding layer 9 has penetrated in the through hole 14, an anchor effect acts and the adhesive force of each board | substrate 10 and 20 can be improved. Thereby, peeling and swelling of the substrate can be minimized. Further, since the wiring layers 12 and 22 and the electrode layers 13 and 23 are formed on the entire surface of the resin base materials 11 and 21, the remaining copper ratio of the substrates 10 and 20 is high and the warp of the entire substrate is caused. Can be prevented.

  The present applicant conducted the following moisture absorption reflow test on the printed circuit board 100 configured as described above. That is, the printed circuit board 100 was left for 192 hours in a test environment (atmosphere of temperature 30 ° C., relative humidity 60%, peak temperature 260 ° C. during reflow). As a result, no warping or swelling of the substrate could be confirmed. On the other hand, when a printed circuit board without the through hole 14 was left in the same test environment, it was confirmed that swelling occurred and peeling occurred.

  The printed circuit board 100 according to this embodiment is manufactured as follows, for example. FIG. 3 is a flowchart showing manufacturing steps of the printed circuit board. 4 and 5 are cross-sectional views showing the printed circuit board in the order of the manufacturing process. First, as shown to Fig.4 (a), the resin base material 11 (21) in which the conductor layer 6 was formed in the whole surface on one surface 11a (21a) is prepared (step S100).

  Next, by applying a resist on the surface opposite to the surface 11a (21a) of the conductor layer 6 and performing etching after exposure / development, as shown in FIG. A predetermined mask pattern 5 is formed (step S102). Then, etching or the like is performed to form the wiring layer 12 (22) and the electrode layer 13 (23) as shown in FIG. 4C (step S104).

  Thereafter, the mask pattern 5 is removed by chemical treatment or the like, and as shown in FIG. 4D, through holes 14 (24) are formed in the electrode layer 13 (23) using an excimer laser or the like (step S106). By repeating the processing so far, the first and second substrates 10 and 20 having the first and second resin base materials 11 and 21 on which the wiring layer 12 (22) and the like are formed can be obtained.

  Next, as shown in FIG. 4E, the adhesive sheet 9 with the mask (mask portion is omitted) is pasted on the other surface 21b of the second resin base material 21 to form the adhesive layer 9 (step S108). ). Then, as shown in FIG. 4F, via holes 8 are formed in the adhesive layer 9 and the second resin base material 21 by laser processing or the like (step S110).

  After that, as shown in FIG. 5G, the inner via 7 is formed by filling the via hole 8 with a conductive paste or the like (step S112). Note that as a material of the conductive paste, various solders, ACF, silver paste, a mixed material of these pastes, a paste material mixed with a trace amount of different metals, and the like can be used. Moreover, as a filling method of the conductive paste, for example, a printing method, a spin coating method, a spray coating method, a disperance method, a laminating method, and a method using these in combination can be used.

  Finally, as shown in FIG. 5 (h), the second substrate 20 is aligned and superposed on the first substrate 10, and for example, a separately prepared third substrate 30 or fourth substrate 40 is provided. The printed circuit board 100 is manufactured by sequentially stacking and heating and pressurizing and performing a lamination process (step S114). Note that although the printed circuit board 100 shown in FIG. 5H has a four-layer structure, the printed circuit board 100 having a multilayer structure can be manufactured by changing the number of stacked substrates.

  As described above, according to the printed circuit board according to the above-described embodiment, it is possible to prevent the substrate from being peeled or swollen during reflow or an environmental test while preventing the substrate from warping. In addition, although the above demonstrated the example which applied this invention to the printed circuit board using resin base materials, such as a polyimide, even when using resin base materials, such as an epoxy resin and paper phenol, this invention is applicable. . Moreover, although the through holes 14 and 24 of the electrode layers 13 and 23 are formed at the coaxial positions, they may be formed at arbitrary locations where the substrate easily swells, such as a location near the inner via 7.

7 inner via 8 via hole 9 adhesive layer 10 first substrate 11 first resin base material 11a, 11b surface 12 first wiring layer 13 first electrode layer 14 through hole 20 second substrate 21 second resin base material 21a, 21b surface 22 Second wiring layer 23 Second electrode layer 24 Through hole 100 Printed circuit board

Claims (7)

A first resin base material; a first wiring layer and a first electrode layer formed entirely on the first resin base material; and the first resin base material covering the first wiring layer and the first electrode layer. An adhesive layer formed thereon, and a second resin substrate formed in close contact with the adhesive layer,
A through hole is formed in the first electrode layer.   The printed circuit board according to claim 1, wherein the first electrode layer includes a ground electrode or a dummy electrode.   A second wiring layer and a second electrode layer are formed on the surface of the second resin substrate opposite to the contact surface with the adhesive layer, and a through hole is formed in the second electrode layer. The printed circuit board according to claim 1 or 2.   The printed board according to claim 3, wherein the through hole of the second electrode layer is formed at a position coaxial with the through hole of the first electrode layer. A first resin base material, a first wiring layer and a first electrode layer formed on the first resin base material, and formed on the first resin base material so as to cover the first wiring layer and the first electrode layer A method for producing a printed circuit board comprising: an adhesive layer formed; and a second resin substrate formed in close contact with the adhesive layer,
Forming the first wiring layer and the first electrode layer entirely on the first resin substrate;
Forming a through hole reaching the first resin base material in the first electrode layer;
The method for producing a printed circuit board, wherein the second resin base material is laminated on the first resin base material via the adhesive layer.   Prior to laminating the second resin base material on the first resin base material, a second wiring layer and a second electrode layer are provided on the surface of the second resin base material opposite to the contact surface with the adhesive layer. 6. The method of manufacturing a printed circuit board according to claim 5, wherein a through hole is formed and a through hole reaching the second resin base material is formed in the second electrode layer.   7. The method of manufacturing a printed circuit board according to claim 5, wherein the through hole of the second electrode layer is formed at a position coaxial with the through hole of the first electrode layer.

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