JP2003332720A - Multilayer printed wiring board and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board and a method of manufacturing the same, which are capable of easily compensating a solder resist for alignment accuracy, improving pads in adhesion, and enabling the solder resist to be well formed. <P>SOLUTION: The multilayer printed wiring board is equipped with the mounting pad 14 composed of a lower pad 14b whose diameter is twice or above as large as the alignment tolerance of the solder resist 16 to a design criterion and an upper pad 14c whose diameter is twice or above as small as the alignment tolerance. The wiring board is also equipped with the solder resist 16b which is so formed in size as to be laid across the design criterion corresponding parts of the adjacent pads. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board having a mounting pad for mounting a surface mounting component and a method for manufacturing the same, and in particular, a low mounting accuracy of a solder resist is compensated by the shape of the mounting pad. The present invention relates to a multilayer printed wiring board that can be used.

[0002]

2. Description of the Related Art For example, in order to form a solder resist for a mounting pad portion for mounting surface mounting components such as BGA (ball grid array) and CSP (chip size package or chip scale package), the outer periphery of the mounting pad is covered by several tens of μm. It is roughly divided into a method of forming the mounting pad and a method of forming the mounting pad with a clearance of several tens of μm, but in the former case, when mounting a component, a step of the solder resist occurs on the mounting pad, In most cases, the latter method is used for the reason that the mountability of the component is deteriorated, or soldering can be performed only on the surface of the mounting pad, and thus the joint reliability of the component is low.

Here, the latter mounting pad portion will be briefly described with reference to FIG. FIG. 5A is a schematic plan view showing a part of a plurality of mounting pads 14 formed in an enlarged manner, FIG.
FIG. 5B is a schematic cross-sectional explanatory view in which the space between the mounting pads 14 in FIG. 5A is further enlarged, and the mounting tolerance of the mounting pad 14 having the diameter u and the solder resist (hereinafter, simply referred to as a matching tolerance). clearance 16c consisting of r,
The diameter u and the combined tolerance r are added (2r as the diameter
Solder resist 16 having a punched pattern of diameter s (added) and solder resist 16b between mounting pads 14 having a size of 2r.

[0004]

As described above, in the latter case, the solder resist 16 does not project from the surface of the mounting pad 14, and the clearance 16c causes the solder to also flow around the side surface of the mounting pad 14. Therefore, the mountability and the joint reliability of the parts are excellent, but the diameter u of the mounting pad 14 is reduced due to the demand for high-density wiring, which reduces the adhesion to the substrate and reduces the mounting pad 14 concerned. However, there is a problem that it is easily peeled off. Also, the solder resist 16 with low alignment accuracy
When forming, clearance 1 consisting of alignment tolerance r
Since it is necessary to form the wiring circuit between the mounting pads 14, the wiring circuit may be exposed if the solder resist 16 deviates to the maximum (alignment tolerance r). Had the problem that there is.

The present invention has been made in view of the above problems, and it is an object of the present invention to form a solder resist having low alignment accuracy without fear of peeling of the mounting pad due to reduction in diameter of the mounting pad. As a supplementary means, it is not necessary to use a means such as a clearance that is likely to cause a problem, and it is possible to easily supplement the alignment accuracy of the solder resist, and a multilayer printed wiring board excellent in pad adhesion and solder resist formability and the same. It is intended to provide a manufacturing method.

[0006]

To achieve the above object, the present invention according to claim 1 is a multilayer printed wiring board having a mounting pad for mounting a surface mounting component, wherein the mounting pad is a design standard. From the lower pad part that has a diameter that is at least twice the matching tolerance of the solder resist with respect to the value, and the upper pad part that has a diameter that is at least twice the matching tolerance of the solder resist with respect to the design standard value of the mounting pad. The multilayer printed wiring board is characterized in that the solder resist is formed in such a size that the portion corresponding to the design reference value of the adjacent mounting pad is formed.

As a result, the solder resist does not project from the surface of the pad (upper part of the pad), and the solder also wraps around the side surface of the upper part of the pad, so that the mountability and joint reliability of the parts can be improved. it can. In addition, the solder resist formation with low alignment accuracy can be easily supplemented by the shape of the mounting pad (that is, the pad area is always constant with respect to the deviation of the solder resist, so stable component mounting is possible). . Further, even if the solder resist is maximally displaced when a wiring circuit is formed between the mounting pads, it is possible to prevent the wiring circuit from being exposed. Further, since the solder resist is coated on the lower part of the pad, the mounting pad can be prevented from peeling off, and the solder bridge can be prevented because the upper part of the pad and the solder resist can be formed at substantially the same height. it can.

According to a second aspect of the present invention, there is provided a thickness of an etching interface of a wiring circuit including the lower pad portion,
The fine wiring circuits in the wiring circuit have the same thickness,
Further, the thickness is composed of a metal foil preliminarily laminated on an insulating layer and a thickness of electroless plating for forming a through hole and / or a blind via hole for connecting wiring layers. The multilayer printed wiring board as described in 1.

As a result, even when a fine wiring circuit is formed adjacent to a wiring circuit having a large conductor thickness, the flow of the etching solution is improved, so that the fine wiring circuit can be easily obtained even in the subtractive method.

The present invention according to claim 3 is a method of manufacturing a multilayer printed wiring board having a mounting pad for mounting a surface mounting component on a surface layer and a through hole and / or a blind via hole for connecting wiring layers. And a step of forming a through hole and / or a non-through hole in an insulating substrate having a metal foil laminated on an insulating layer, and a step of electrically connecting the through hole and / or the non-through hole by an electroless plating treatment, An opening is provided in the through hole and / or the blind via hole and the land forming portion thereof, and the diameter of the mounting pad forming portion is smaller than the design tolerance of the mounting pad by more than twice the tolerance of the solder resist. And a step of forming a plating resist, and an electrolytic plating process using the underlying conductive layer composed of the metal foil and the electroless plating layer as a plating lead. By applying the step of depositing electrolytic plating in the opening of the plating resist, and after peeling the plating resist, the alignment tolerance of the solder resist with respect to the design side surface of the electrolytic plating and the design reference value of the mounting pad. A step of forming an etching resist on the underlying conductive layer and other wiring circuit forming portions having a diameter that is at least twice as large, and a step of etching away the underlying conductive layer exposed from the etching resist,
A method for manufacturing a multilayer printed wiring board, which comprises a step of forming a solder resist with a dimension corresponding to a design reference value-corresponding portion of an adjacent mounting pad after peeling off the etching resist.

This makes it possible to easily manufacture a multi-layer printed wiring board having a mounting pad capable of accommodating the solder resist alignment tolerance and a fine wiring circuit by the subtractive method.

The present invention according to claim 4 is the multilayer printed wiring board according to claim 3, wherein the opening of the plating resist is provided in a portion excluding the fine wiring circuit forming portion. It is a manufacturing method.

Thus, a multilayer printed wiring board in which a fine wiring circuit is formed adjacent to a wiring circuit having a thick conductor can be easily manufactured by the subtractive method.

The present invention according to claim 5 is the method for manufacturing a multilayer printed wiring board according to any one of claims 3 to 4, characterized in that the circuit formation is subjected to etching treatment using a liquid etching resist. is there.

As a result, the etching resist can be made to follow the electrolytic plating forming portion of the wiring circuit.
It is possible to prevent the resist from not adhering to the step portion of the electrolytic plating.

The present invention according to claim 6 is the method for manufacturing a multilayer printed wiring board according to claim 5, wherein the liquid etching resist is a positive etching resist.

By using a positive type liquid etching resist, not only in the holes where light cannot reach easily,
The etching resist can be easily formed even on the plating step portion where the resist film thickness is unstable.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. The same parts and dimensions as in FIG. 5 are designated by the same reference numerals. Figure 1 (a)
1A is a schematic plan view showing a part of a plurality of mounting pads 14 that are enlarged, and FIG. 1B is a schematic cross-sectional view showing a part of the mounting pads 14 shown in FIG.
The design reference value 14a of the mounting pad 14 having the diameter u (the design reference value 14a corresponds to the dimension of the mounting pad 14 shown in FIG. 5) and the alignment tolerance r of the solder resist 16 with respect to the design reference value 14a. Large (2 as diameter
pad lower step portion 14b having a diameter (larger than r), and a design reference value 14 formed on the pad lower step portion 14b.
A pad upper step portion 14c having a diameter t which is smaller than the matching tolerance r of the solder resist 16 by 2r (smaller by 2r as a diameter) and a solder resist 16 having a punching pattern having the diameter u are provided between the mounting pads 14. The solder resist 16b is formed so as to cover a portion corresponding to the design reference value 14a of the adjacent mounting pad 14, that is, to cover the lower pad portion 14b by the tolerance r.

Next, a method of manufacturing a multilayer printed wiring board on which the mounting pad and the solder resist having the above structure are formed will be described with reference to FIG. First, as shown in FIG. 2A, the inner layer wiring circuit 2 including the via bottom land 1 and the like is formed in the inner layer. Next, the interlayer insulating layer 3 and the metal foil 4 are laminated on the inner layer in which the inner wiring circuit 2 is formed, or the resin-coated metal foil 5 in which the metal foil 4 is laminated on the interlayer insulating layer 3 is laminated. (See FIG. 2 (b)). Next, the non-through hole 6 that reaches the via bottom land 1 by laser processing or the like.
Are perforated (see FIG. 2 (c)). Next, electroless plating 7
After the non-through hole 6 is electrically connected by
(D)), the plating resist 10 having the openings 9 formed in the blind via hole 13 and the pad upper step 14c forming portion shown in FIG. 2 (h) is formed (see FIG. 2 (e)).
Here, the opening 9 of the plating resist 10 formed in the formation portion of the pad upper step portion 14c is aligned with the solder resist 16 to be formed later with respect to the design reference value 14a of the mounting pad 14 having the diameter u. The diameter t is smaller by the tolerance r (smaller by 2r as the diameter) (see FIG. 1). Next, as shown in FIG. 2F, the opening 9 is subjected to electrolytic plating by using the underlying conductive layer 8 made of the metal foil 4 and the electroless plating 7 as a plating lead.
Electrolytic plating 11 is deposited on. Next, after the plating resist 10 is peeled off, as shown in FIG. 2G, the front side surface of the electrolytic plating 11 and the pad lower step portion 14b forming portion, and another wiring circuit forming portion including the fine wiring circuit 15 and the like. Then, an etching resist 12 is formed. Here, the etching resist 1 formed on the pad lower step portion 14b forming portion
2 is a solder resist 16 formed later with respect to the design reference value 14a of the mounting pad 14 having the diameter u.
It is formed with a diameter s which is larger by the matching tolerance r of (larger by 2r as a diameter) (see FIG. 1). Next, the underlying conductive layer 8 exposed from the etching resist 12 is removed by etching, and then the etching resist 12 is peeled off to form a fine wiring circuit 15, a blind via hole 13, a pad lower step portion 14b and a pad upper step portion on the outer layer. The laminated board of FIG. 2 (h) on which the mounting pads 14 and the like made of 14c are formed is obtained. Next, the solder resist 16 is formed so that the solder resist 16b is formed to have a dimension corresponding to the design reference value 14a of the mounting pad 14 adjacent thereto (FIG. 1).
reference). As a result, the multilayer printed wiring board 17 shown in FIG. 2 (i) is obtained.

The most remarkable point in the present invention is that the structure of the mounting pad is such that the lower part of the pad having a diameter which is at least twice the matching tolerance of the solder resist with respect to the design reference value of the mounting pad, and the mounting pad. The solder resist has a two-layer structure consisting of a pad upper part having a diameter smaller than the design tolerance of the solder resist by more than twice the design tolerance, and the solder resist is formed to have a dimension corresponding to the design criteria of the adjacent mounting pad. It is in. As a result, as shown in FIG.
As shown in (b), even when the solder resist 16 is displaced to the maximum (alignment tolerance r), the mounting pad 1
Since the exposed area of 4 is always constant, stable component mounting is possible, and since the lower pad portion 14b is covered with the solder resist 16, peeling of the mounting pad can be prevented.

In the description of the embodiments of the present invention, the single-sided buildup wiring board is used for description, but the configuration is not limited to this, and a double-sided buildup wiring board or a double-sided wiring board may be used. Absent. As an example of the mounting pad, a mounting pad for mounting a surface mounting component such as BGA in which electrodes are arranged in a grid pattern is used.
As shown in FIGS. 1A and 1B, the mounting pad 14 for mounting a chip resistor, a chip capacitor, etc. is also shown in FIG.
The same effect can be obtained by adopting the same configuration as.

[0022]

EXAMPLE An example of the present invention will be described with reference to FIG.
First, an inner layer wiring circuit composed of via bottom lands and the like was formed by a general subtractive method (FIG. 2A).
reference). Next, a resin-coated copper foil (made by Sumitomo Bakelite Co., Ltd .: APL) in which a copper foil having a thickness of 12 μm is laminated on an interlayer insulating layer having a thickness of 60 μm on the inner layer on which the inner layer wiring circuit is formed
-4001) (see FIG. 2B), a non-through hole reaching the via bottom land was punched by a carbon dioxide laser (see FIG. 2C). Next, after performing desmearing with a potassium permanganate-based desmear solution, electroless copper plating having a thickness of about 0.3 μm was formed to make the non-through holes conductive (FIG. 2 (d)). reference). Next, a 30 μm thick photosensitive plating resist film (NIT230 manufactured by Nichigo Morton Co., Ltd.) is laminated,
After exposure at 80 mj, development was performed to form a plating resist in which openings were provided in the blind via hole and the pad upper step formation portion (see FIG. 2E). Here, the opening diameter of the upper part of the pad was set to 320 μm. Next, as shown in FIG. 2 (f), an electrolytic copper plating process is performed by using an underlying conductive layer made of copper foil and electroless copper plating as a plating lead, so that the opening has a thickness of 20 μm.
Electrolytic copper plating was deposited. Next, after removing the plating resist, a positive type liquid etching resist is applied over the entire surface by electrodeposition, and exposed and developed to form the front side surface of electrolytic copper plating and the lower part of the pad, and a fine wiring circuit, etc. An etching resist was formed on the wiring circuit forming portion (see FIG. 2G). Here, the diameter of φ480 μm is used to form the etching resist in the lower part of the pad.
It was formed to be m. Next, after removing the underlying conductive layer exposed from the etching resist by etching, the etching resist is peeled off to form a fine wiring circuit, a blind via hole, and a diameter of 320 μm on the outer layer.
The laminated plate of FIG. 2 (h) was obtained in which the mounting pads and the like consisting of the pad upper step and the φ480 μm pad lower step were formed.
Then, the design reference value (φ40
0 μm) to form a solder resist (that is, a φ400 μm solder resist removal pattern is formed on the lower part of the φ480 μm pad), so that the alignment accuracy is low (in this embodiment, the mounting pad design standard is used). (Adjustment tolerance of ± 40 μm from the value) Fig. 2 which compensates the solder resist formation with the shape of the mounting pad
A multilayer printed wiring board of (i) was obtained.

[0023]

EFFECTS OF THE INVENTION By using the multilayer printed wiring board having the mounting pad for mounting the surface mount component according to the present invention, the solder resist formation with low alignment accuracy can be easily supplemented by the shape of the mounting pad. Moreover, since the solder resist is coated on a part of the pad, peeling of the mounting pad can be prevented. Further, since all the etching interfaces including the mounting pad are formed thin and the fine wiring circuit can be formed by the subtractive method, the multilayer printed wiring board having the mounting pad can be easily manufactured at low cost. can do.

[Brief description of drawings]

1A is a schematic plan cross-sectional explanatory view showing a part of a mounting pad of a multilayer printed wiring board of the present invention, and FIG.
The schematic sectional explanatory drawing which expanded and displayed between the mounting pads of (a).

FIG. 2 is a schematic sectional process explanatory view showing the method for manufacturing a multilayer printed wiring board according to the present invention.

FIG. 3 (a) is a schematic plan view when the solder resist in the mounting pad portion of the multilayer printed wiring board of the present invention is maximally displaced, and FIG. 3 (b) is a schematic cross-sectional view between the mounting pads of FIG. 3 (a). Fig.

FIG. 4A is a schematic plan view showing another mounting pad example of the multilayer printed wiring board of the present invention, and FIG. 4B is a schematic cross-sectional explanatory view between the mounting pads of FIG. 4A.

5A is a schematic plan explanatory view showing a part of mounting pads of a conventional multilayer printed wiring board, and FIG. 5B is a schematic sectional explanatory view enlargedly showing between the mounting pads of FIG. 5A.

[Explanation of symbols]

1: Land at the bottom of the via 2: Inner layer wiring circuit 3: Interlayer insulation layer 4: Metal foil 5: Metal foil with resin 6: Non-through hole 7: Electroless plating 8: Base conductive layer 9: opening 10: Plating resist 11: Electrolytic plating 12: Etching resist 13: Blind via hole 14: Mounting pad 14a: Design standard value 14b: Lower part of pad 14c: Upper part of pad 15: Fine wiring circuit 16, 16b: Solder resist 16c: Clearance 17: Multilayer printed wiring board

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/46 H05K 3/46 Z H01L 23/12 N FF term (reference) 5E314 AA24 BB06 BB11 BB12 CC06 DD04 FF01 FF17 FF19 GG12 GG17 GG22 5E319 AA03 AB05 AC01 AC13 AC17 BB02 CC22 CD04 CD41 GG05 GG09 5E346 AA01 AA12 AA15 AA17 AA35 AA42 AA43 BB01 GG15 EE15 BB15 BB15 BB15 BB17 BB15 BB17 BB17 BB17 BB15 BB17 BB17 BB17

Claims (6)

[Claims] 1. A multilayer printed wiring board having a mounting pad for mounting a surface mount component, the mounting pad comprising:
2 of the matching tolerance of the solder resist with respect to the design standard value
It consists of a pad lower part with a diameter more than twice as large, and an upper pad part with a diameter twice or more smaller than the solder resist alignment tolerance with respect to the design standard value of the mounting pad.
A multilayer printed wiring board, wherein the solder resist is formed in such a size that the solder resist is applied to a portion corresponding to the design reference value of the adjacent mounting pad. 2. The thickness of the etching interface of the wiring circuit including the lower pad portion is the same as the thickness of the fine wiring circuit in the wiring circuit, and the thickness is previously laminated on the insulating layer. The multilayer printed wiring board according to claim 1, comprising a metal foil and a thickness of electroless plating for forming a through hole and / or a blind via hole connecting the wiring layers. 3. A method for manufacturing a multilayer printed wiring board comprising a mounting pad for mounting a surface mounting component on a surface layer and a through hole and / or a blind via hole for connecting between wiring layers, wherein a metal foil is used as an insulating layer. A step of forming a through hole and / or a non-through hole in the laminated insulating substrate; a step of electrically connecting the through hole and / or the non-through hole by an electroless plating process; and at least a through hole and / or a blind via hole. A step of forming a plating resist in which an opening is provided in the land forming portion and an opening having a diameter that is twice or more smaller than a matching tolerance of the solder resist with respect to a design reference value of the mounting pad is provided in the mounting pad forming portion. And an electrolytic plating process using the underlying conductive layer composed of the metal foil and the electroless plating layer as a plating lead. Step of depositing electrolytic plating in the opening of the resist, and after peeling the plating resist, the diameter range more than twice the solder resist alignment tolerance with respect to the design reference value of the front surface of the electrolytic plating and the mounting pad. A step of forming an etching resist on the underlying conductive layer inside and other wiring circuit forming parts, a step of etching away the underlying conductive layer exposed from the etching resist, and a step of removing the etching resist and then adjoining A method of manufacturing a multilayer printed wiring board, comprising the step of forming a solder resist in a dimension corresponding to a portion corresponding to the design reference value of the mounting pad. 4. The method for manufacturing a multilayer printed wiring board according to claim 3, wherein the opening of the plating resist is provided in a portion excluding the fine wiring circuit forming portion. 5. The method for manufacturing a multilayer printed wiring board according to claim 3, wherein the circuit formation is performed by etching using a liquid etching resist. 6. The liquid etching resist is a positive type etching resist.
A method for manufacturing the multilayer printed wiring board according to.