JP2007150111A - Wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board excellent in an adhesion without causing a delamination of a conductive layer when a filler is filled in a through-hole and the conductive layer is provided on it. <P>SOLUTION: The wiring board comprises a core part 2 with a tubular through-hole conductor 30 and a filling material 31 for filling the inside of it formed is provided in a through-hole 12 for penetrating through in a plate thickness direction. The filling material 31 of the wiring board 1 comprises a resin material including an inoraganic filler, the ten points average roughness (Rz) regulated by the JIS-B-0601 at the end surface 31a of the filling material 31 fills Rz≤X/2 when the average particle diamter of the inorganic filler is X(μm), and the end surface 31a of the filling material 31 is covered by a cap conductor 21 connected to the through-hole conductor 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wiring board.

  The wiring board has a large number of conductors (electrodes) used for mounting electronic components such as LSIs and IC chips on one main surface, and a large number of conductors for connection to a motherboard on the other main surface. (Electrodes) and connection terminals (for example, solder balls) installed thereon are provided. In such a type of wiring board, downsizing and increase in the number of connection terminals (for example, the number of balls) are required in order to achieve high integration and high density of electronic components such as LSIs, IC chips or chip capacitors to be mounted. Is being promoted.

As a prior art, in Patent Document 1, as an internal structure of a wiring board having a high-density wiring function, a filler is filled in a through hole formed in an insulating substrate, and a conductor layer is provided thereon, A device in which a via conductor directly connected to a conductor layer is formed is disclosed. According to this technique, a via conductor can be formed also on a through hole, so that high integration and high density of wiring can be achieved.
JP-A-6-275959

  However, in Patent Document 1, a fluid organic precursor such as a polyfunctional epoxy resin is cited as the filler. In this case, the filler is formed on the end surface of the through-hole filler under severe conditions such as high temperature and humidity. There is a problem in that delamination of the conductive layer occurs and reliability of electrical connection between the via conductor and the through-hole conductor directly connected to the conductive layer cannot be obtained.

  The occurrence of delamination is caused by the difference in coefficient of thermal expansion generated between the resin material and the metal material (the resin material is larger than that of the metal material). For example, when the wiring board 1 is heated (see FIG. 5A), the through hole conductor 30 that is a metal material, the resin material 25 that constitutes the core portion 2 that is a resin material, and the through hole 12 are filled. The filler 31 to be expanded expands in the plate thickness direction. At this time, since the thermal expansion coefficient of the surrounding resin material (resin material 25 and filler 30) with which the through-hole conductor is in contact is larger than the thermal expansion coefficient of the through-hole conductor 30, the lid-shaped conductor 21 is pushed up. On the other hand, when the wiring board is cooled (see FIG. 5B), a phenomenon opposite to that when the wiring board is heated occurs. The lid-like conductor 21 is pulled down by contraction of the resin material (resin material 25 and filler 30). Due to this temperature cycle, excessive stress concentration occurs in the lid-like conductor 21, and as shown in FIG. 5C, a gap 50 is created between the lid-like conductor 21 and the end face 31a of the filler. That is, the lid-like conductor 21 is peeled off (delaminated) from the end face 31a of the filler.

  Therefore, a wiring board that does not lower the connection reliability between the lid-like conductor 21 and the end face 31a of the filler under such conditions is required, and the adhesion strength between the lid-like conductor 21 and the end face 31a of the filler is further increased. It is generally known that the end face 31a of the filler is roughened and the end face 31a is roughened to give the lid conductor an anchor effect. However, even if the end face of the filler is roughened and the lid conductor has an anchor effect, the lid conductor may be peeled off (delamination) from the end face of the filler. There was a problem that sufficient adhesive strength with sufficient properties could not be obtained.

  An object of the present invention has been made in view of the above circumstances, and when a through hole is filled with a filler and a conductor layer is provided thereon, the conductor layer does not cause delamination and adheres closely. An object of the present invention is to provide a wiring board having excellent properties.

Means and effects for solving the problems

In order to solve the above problems, the wiring board of the present invention is:
A wiring board including a core part in which a cylindrical through-hole conductor and a filler filling the inside thereof are formed in a through-hole penetrating in the plate thickness direction,
The filler is composed of a resin material containing an inorganic filler. When the average particle size of the inorganic filler is X (μm), the ten-point average roughness (Rz) defined in JIS-B-0601 on the end face of the filler. ) Satisfies Rz ≦ X / 2, and the end face of the filler is covered with a lid-like conductor connected to the through-hole conductor.

  According to the present invention, the ten-point average roughness Rz defined in JIS-B-0601 of the end face of the filler is made half or less of the average particle diameter of the inorganic filler contained in the filler, thereby roughening the surface. Since it is possible to sufficiently secure a region in contact with and adhering to the filler of the inorganic filler that is partially exposed from the end face of the filler, it is possible to prevent the inorganic filler from falling off the filler. Therefore, since the inorganic filler does not fall off from the filler, the lid-like conductor can be provided in a more closely contacted state on the end face of the filler. That is, even if excessive stress concentration occurs due to the above temperature cycle, a lid-like conductor having good adhesion can be provided on the end face of the filler without causing delamination, and as a result, a high density with excellent electrical connectivity. It becomes possible to provide a simple wiring board.

The wiring board of the present invention is
The ten-point average roughness (Rz) of the end face of the filler can be set to X / 3 ≦ Rz. Thereby, it can be set as the surface roughness from which sufficient anchor effect is acquired by making the average roughness Rz of the end surface of a filler into 1/3 or more of the average particle diameter of the inorganic filler contained in a filler. Therefore, the lid-like conductor can be provided in a state of being in close contact with the end face of the filler. That is, even if excessive stress concentration occurs due to the above temperature cycle, a lid-like conductor having good adhesion can be provided on the end face of the filler without causing delamination, and as a result, a high density with excellent electrical connectivity. It becomes possible to provide a simple wiring board

  In addition, it is desirable that the average particle diameter of the inorganic filler such as silica filler contained in the filler satisfies the range of 2 μm to 5 μm. More preferably, it is desirable that the average particle size of the inorganic filler satisfies the range of 2 μm to 4 μm. When the average particle size of the inorganic filler is too large, when the end face of the filler is roughened, the area where the inorganic filler is exposed from the end face becomes wide, and the area that is in contact with the filler is sufficiently bonded. Since it cannot be ensured, the inorganic filler falls off the filler, and as a result, sufficient adhesion with the lid-like conductor cannot be expected. On the other hand, if the average particle size of the inorganic filler is too small, the surface roughness is also small, so that the surface roughness having a sufficient anchor effect cannot be obtained, and sufficient adhesion with the lid-like conductor cannot be expected.

The wiring board of the present invention is
A via conductor embedded in a resin insulating layer formed on the main surface of the core portion and connected to a lid-like conductor may be provided, and the via conductor may be located on the through hole. Also, the via conductor can be located in the central region on the through hole.

  As described above, since the thermal expansion coefficient is different between the resin material and the metal material, a difference in thermal expansion coefficient also occurs between the via conductor (metal material) and the resin insulating layer (resin material). Affected by expansion and contraction. When this via conductor is formed on the lid-like conductor, a greater stress is generated by the lid-like conductor than when the via conductor is not formed on the lid-like conductor, and the lid-like conductor is peeled off from the end face of the filler (de- Easy to laminate). Further, the stress is greatest when the via conductor is formed in the central region on the through hole, and the lid-like conductor is easily peeled (delaminated) from the end face of the filler. In the wiring board of the present invention, a via conductor can be stably provided on the lid-like conductor without causing delamination even under such circumstances, and further, on the through hole where stress is most greatly generated. Via conductors can also be provided in the central region. Here, on the through hole in the present invention, the direction in which the resin insulating layer is formed (laminated) from the core portion in the plate thickness direction is upward.

The wiring board of the present invention is
Via conductors are respectively embedded in two or more resin insulation layers formed on the main surface of the core, and the via conductors are connected in the thickness direction to form a stacked via, and the stacked via is formed on the lid-shaped conductor. Can be located. Normally, a stacked via is formed by connecting a plurality of via conductors in the thickness direction, and the distance between the metal material that is the via conductor and the resin material that is the resin insulating layer is long (the area is large). A large stress is generated by the lid-like conductor connected to the lowermost via conductor. However, even in such a situation, the stacked conductor can be stably provided on the lid-shaped conductor without causing the delamination of the lid-shaped conductor from the end face of the filler.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a cross-sectional structure of a wiring board 1 according to an embodiment of the present invention. The wiring board 1 has both surfaces MP1 of a plate-like core (core part) 2 made of a heat-resistant resin plate (for example, bismaleimide-triazine resin plate), a fiber reinforced resin plate (for example, glass fiber reinforced epoxy resin), or the like. , MP2 are respectively formed with core conductor layers M1, M11 having a predetermined wiring pattern. These core conductor layers M1 and M11 are formed as surface conductor patterns that cover most of the surface of the plate-like core 2, and are used as a power supply layer or a ground layer. On the other hand, the plate-like core 2 is formed with a through-hole 12 drilled by a drill or the like, and an inner surface plating layer (through-hole conductor) 30 for connecting the core conductor layers M1 and M11 to each other is formed on the inner wall surface. ing.

  Further, in the through hole 12, a resin hole filling material (filler) 31 such as an epoxy resin containing an inorganic filler such as a silica filler having an average particle diameter X (μm) of 2 to 5 μm is provided inside the through hole conductor 30. The end surface 31a of the filling material 31 has a ten-point average roughness (Rz) defined in JIS-B-0601 of X / 3 ≦ Rz ≦ X / 2 (in this embodiment, 2. 5 μm or less). On the end face 31a of the filler 31, a lid-like conductor 21 made of Cu plating connected to the end of the through-hole conductor 30 is formed in close contact with the roughened end face 31a.

  In addition, on the upper layers of the core conductor layers M1 and M11, wiring laminated portions L1 and L2 including the core conductor layers M1 and M11 are formed. Specifically, first resin insulation layers (build-up resin insulation layers) V1 and V11 made of a photosensitive or thermosetting resin composition 6 are formed. Further, first conductor layers M2 and M12 having metal wirings 7 each having a predetermined pattern are formed on the surface by Cu plating. The core conductor layers M1 and M11 and the first conductor layers M2 and M12 are interconnected by vias 34, respectively. The via 34 is filled with Cu plating in a via hole (see FIG. 3) formed in the first resin insulation layer V1, and the core conductor layers M1, M11 and the first conductor layers M2, M12 are formed by the formed via conductor. It is connected. As shown in FIG. 1, the via 34 is connected to the lid-like conductor 21 and is formed on the through hole 12.

  Similarly, second resin insulation layers (build-up resin insulation layers) V2 and V12 using the photosensitive or thermosetting resin composition 6 are formed on the first conductor layers M2 and M12, respectively. On the surface, second conductor layers M3 and M13 having metal terminal pads 10 and 17 are formed. The first conductor layers M2, M12 and the second conductor layers M3, M13 are connected to each other through vias 34. In the via 34, a Cu hole is filled in a via hole (see FIG. 3) formed in the second resin insulating layer V2, and the core conductor layers M2, M12 and the second conductor layers M3, M13 are formed by the formed via conductor. Is connected. Further, as shown in FIG. 1, the via 34 is connected to a via 34 (formed on the through hole 12 connected to the lid-like conductor 21) formed in the first resin insulating layer, and The via 34 is formed so as to be continuous with the plate thickness direction. Thereby, a stacked via connected to the lid-like conductor 21 and positioned on the through hole 12 is formed.

  On the surface MP1 of the plate-like core 2, the core conductor layer M1, the first resin insulation layer V1, the first conductor layer M2, and the second resin insulation layer V2 are laminated to form the first wiring laminated portion L1. On the surface MP2 of the plate-like core 2, the core conductor layer M11, the first resin insulation layer V11, the first conductor layer M12, and the second resin insulation layer V12 are laminated to form the second wiring laminated portion L2. Yes. Each of the wiring laminated portions L1 and L2 is formed by alternately laminating resin insulating layers and conductive layers, and metal terminal pads 10 and 17 are formed on the main surface CP on the side far from the plate-like core 2, respectively. Has been.

  Next, solder resist layers SR1 and SR2 having openings 8a and 18a are formed on the main surface CP far from the plate-like core 2 so that the metal terminal pads 10 and 17 are exposed inside. . Specifically, the solder resist layers SR1 and SR2 are formed on the second resin insulation layers V2 and V12 and the third conductor layers M3 and M13 using the photosensitive or thermosetting resin compositions 8 and 18, respectively. . Further, when the solder resist layers SR1 and SR2 are made of a photosensitive resin, the openings 8a and 18a are formed by exposing and developing with ultraviolet rays while being masked in a predetermined pattern. When a thermosetting resin is used, it is formed by drilling with a laser or plasma. As described above, the wiring board 1 is formed.

  The metal terminal pad 10 on the first wiring laminated portion L1 side constitutes a solder pad that is a pad for flip-chip connection of an integrated circuit chip or the like, and includes a solder bump 11. The metal terminal pad 17 on the second wiring laminated portion L2 side is used as a back surface pad for connecting the wiring board itself to a mother board or the like by a pin grid array (PGA) or a ball grid array (BGA). is there. Further, in the wiring board 1, the signal transmission path extends from the metal terminal pad 10 formed on one main surface side (first wiring laminated portion L 1 side) of the plate-like core 2 to the other main surface side (second wiring laminated portion). L2 side) is formed so as to reach the metal terminal pad 17 formed on the L2 side.

  Next, a method for manufacturing the wiring board 1 of the present invention will be described with reference to FIGS. First, a through-hole 12 is drilled in a plate-like core 2 formed of a heat-resistant resin plate (for example, bismaleimide-triazine resin plate) or a fiber reinforced resin plate (for example, glass fiber reinforced epoxy resin) by a method such as a drill. (See step 1). Next, electroless plating is performed on the inner peripheral surface of the through hole and both surfaces MP1 and MP2 of the plate-like core 2, and electrolytic plating is performed thereon to form a conductor layer.

  Next, a resin hole filling material (filler) 31 such as an epoxy resin containing an inorganic filler such as silica filler having an average particle diameter of 2 to 5 μm is printed and filled in the through-hole conductor 30, and this is heated and half-heated. Harden. Thereafter, excess resin swelled from both main surfaces MP1 and MP2 of the plate-like core 2 is removed by polishing (see step 2). Then, the end surface 31a of the filler 31 filled in the through-hole conductor 30 is roughened with a roughening solution such as a potassium permanganate solution in order to improve the adhesion of the plating. At this time, when the ten-point average roughness Rz defined in JIS-B-0601 of the end face 31a of the filler is set to be not more than half of the average particle diameter of the silica filler contained in the filler 31, the adhesiveness to the end face 31a is excellent. Cu plating can be applied. Further, the through-hole filler 31 is formed by heat-curing a semi-cured resin material (filler). (See step 3).

  Here, when the end surface 31a of the filler is roughened using a roughening liquid, the resin material (filler) is swollen in advance with a liquid containing an organic solvent, washed with water, and then roughened with a potassium permanganate solution or the like. Roughening treatment is performed by dipping in a liquefying solution. In this case, the surface roughness of the end surface 31a of the filler can be adjusted by the temperature and processing time for performing the swelling treatment and the roughening treatment.

  Next, a Cu plating layer (conductor layer) is further formed on both surfaces of the plate-like core 2, that is, on the core conductor layers M1 and M11 and the end face 31a of the filler. Specifically, electroless plating is performed and electrolytic plating is performed thereon. Then, an etching resist layer having a predetermined pattern is formed on the core conductor layer, and the conductor layer exposed from the resist layer is removed by etching, whereby a core conductor having a predetermined pattern is formed on both surfaces MP1 and MP2 of the plate core 2. Layers M1 and M11 are formed, and a lid-like conductor 21 having a substantially disk shape in plan view is formed on the end face 31a of the filler and the end of the through-hole conductor 30 (see step 4).

  Next, resin insulation layers V1 and V11 made of a photosensitive or thermosetting resin composition 6 or the like are formed on the core conductor layers M1 and M11 and the lid-like conductor 21. After that, for example, predetermined positions of the resin insulating layers V1 and V11 (here, located on the lid-like conductor) are perforated with a laser or plasma (when a thermosetting resin is used) to form the resin insulating layers V1 and V11. A via hole 34h is formed on the bottom surface through which the core conductor layers M1 and M11 such as the lid-like conductor 21 are exposed. Alternatively, a via hole 34h that exposes the core conductor layers M1 and M11 such as the lid-like conductor 21 is formed on the bottom surface by being masked in a predetermined pattern and exposed and developed with ultraviolet rays (when a photosensitive resin is used) (step 5). reference).

  Next, in the same manner as described above, a Cu plating layer (conductor layer) is formed on the resin insulating layers V1 and V11, and the via hole 34h is filled with Cu plating to form a via 34 that is a filled via. . Specifically, electroless plating is performed and electrolytic plating is performed thereon. Thereafter, an etching resist layer having a predetermined pattern is formed on the plating layer, and the plating layer exposed from the resist layer is removed by etching to form the first conductor layers M2 and M12 including the via 34 (see step 6). . By this step, the core conductor layer M1 and the conductor layer M2 are connected by the plurality of vias 34. By repeating this, the insulating layers V2, V12, the second conductor layers M3, M13, and the solder resist layers SR1, SR11 can be stacked, and the wiring stacked portions L1, L2 can be formed (steps). 7).

  Further, as shown in FIG. 3 (step 7), when the via 34 is formed in the second resin insulating layers V2 and V12, the position (plate thickness) connected to the via 34 formed in the first resin insulating layers V1 and V11. A stacked via can be formed on the lid-like conductor 21 by forming a pattern at a position continuous in the direction).

Hereinafter, the following experiment was performed in order to confirm the effect of the present invention. The test samples used are as follows.
First, an epoxy resin containing a silica filler in which a through hole having a diameter of 300 μm is drilled in a plate-shaped core (Matsushita Electric Works: Matsushita R-1515T) having a thickness of 0.8 mm and adjusted to an average particle diameter of 5 μm in the above-described process. Is filled in the through-hole conductor. 20 samples are prepared.

  Next, the filling material filled in the through holes was evaluated by roughening treatment under the following three samples in four conditions. In Example 1, a swelling treatment at about 70 ° C. for about 5 minutes was performed, followed by a roughening treatment at about 70 ° C. for about 6 minutes with potassium permanganate. In Example 2, a swelling treatment at about 70 ° C. for about 10 minutes was performed, followed by a roughening treatment at about 70 ° C. for about 14 minutes with potassium permanganate. In Example 3, a swelling treatment at about 70 ° C. for about 14 minutes was performed, followed by a roughening treatment at about 70 ° C. for about 14 minutes with potassium permanganate. In Comparative Example 1, after a swelling treatment at about 70 ° C. for about 15 minutes, a roughening treatment at about 70 ° C. for about 21 minutes was performed with potassium permanganate. After this roughening treatment, the ten-point average roughness (Rz) defined in JIS-B-0601 was measured.

Next, a lid-like conductor made of Cu plating having a thickness of 25 (error ± 0 to 5 μm) μm was formed by electroless plating and electrolytic plating on the end surface of the roughened filler.
Subsequently, the lid-like conductor (plated portion) was cut out to a width of 10 mm, and the lid-like conductor was pulled in the vertical direction with respect to the substrate, and this was measured as peel strength (adhesion strength). Table 1 shows the ten-point average roughness Rz (μm) and peel strength (kgf / cm 2), which are the results of this test. Table 1 shows the average peel strength (kgf / cm 2) of Examples 1 to 3 and Comparative Example 1. Note that the peel strength indicates a conversion value when the thickness of the Cu plating is 25 μm. FIG. 4 is a diagram corresponding to Table 1, and shows the peel strength (kgf / cm 2) in Examples 1 to 3 and Comparative Example 1.

Next, as a result of the example, when the ten-point average roughness (Rz) is about half of the average particle diameter of the silica filler, specifically about 2.5 μm (Example 3), Comparative Example 1 (10-point average) The peel strength (adhesion strength) was better than the roughness (Rz) of 2.8 to 3.0 μm. Moreover, as can be seen from the results in Table 1, when the ten-point average roughness (Rz) is less than or equal to half of the average particle diameter of the silica filler (Examples 1 to 3), the peel strength increases as Rz increases. There was a trend. On the other hand, when the ten-point average roughness (Rz) is more than half of the average particle diameter of the silica filler, the peel strength clearly tends to be lowered. That is, when the ten-point average roughness (Rz) is larger than half of the average particle diameter of the silica filler, sufficient peel strength cannot be obtained due to the dropping of the silica filler.
The peel strength (adhesion strength) was particularly good when the thickness was 2.0 μm or more and 2.5 μm or less (2X / 5 ≦ Rz ≦ X / 2). When the ten-point average roughness (Rz) was less than 1.6 μm, the silica filler did not fall off, but the roughness could not be sufficiently obtained, so that sufficient peel strength could not be obtained.

  In addition, in this invention, it is not limited to the said Example, It can also be set as the Example variously changed within the range of this invention according to the objective and the use.

The figure which shows an example of the cross-section of the wiring board which concerns on this invention. Manufacturing process explanatory diagram of a wiring board according to the present invention Wiring board manufacturing process explanatory diagram following FIG. Figure corresponding to Table 1 Diagram explaining defects in wiring board

Explanation of symbols

1 Wiring board (resin wiring board)
2 Plate core (core part)
12 through-hole 21 lid-shaped conductor 30 through-hole conductor 31 filler 31a end face 34 via conductor 50 gap

Claims (5)

A wiring board including a core part in which a cylindrical through-hole conductor and a filler filling the inside thereof are formed in a through-hole penetrating in the plate thickness direction,
The filler is composed of a resin material containing an inorganic filler. When the average particle diameter of the inorganic filler is X (μm), the ten-point average roughness defined in JIS-B-0601 on the end face of the filler ( Rz) satisfies Rz ≦ X / 2, and the end face of the filler is covered with a lid-like conductor connected to the through-hole conductor.   The wiring board according to claim 1, wherein a ten-point average roughness (Rz) of an end face of the filler is X / 3 ≦ Rz.   A resin insulating layer formed on a main surface of the core portion, and a via conductor embedded in the resin insulating layer and connected to the lid-shaped conductor, wherein the via conductor is located on the through hole. The wiring board according to 1 or 2.   The wiring board according to claim 3, wherein the via conductor is located in a central region on the through hole.   Two or more resin insulation layers are formed on the main surface of the core portion via a conductor layer, the via conductors are connected in the plate thickness direction to form a stacked via, and the stacked via is positioned on the lid-like conductor. The wiring board according to claim 3 or 4.

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