JP2002134890A - Method for manufacturing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a printed wiring board excellent in connection and reliability by forming solder bumps having uniform shape and height in which defects like void are not present and mutual short circuits are not generated. SOLUTION: This method for manufacturing a multilayer printed wiring board is provided with steps (a), (b), (c) and (d). The step (a) is a first solder paste printing process wherein solder paste is printed at least one time, and recessed type apertures for forming solder bumps are filled with solder paste. The step (b) is a solder paste pressing process wherein the whole or a part of a solder paste layer on a solder resist layer is pressed. The step (c) is a solder paste flattening process wherein the surface of the solder paste buried by the steps (a) and (b) is made flat. The step (d) is a second solder paste printing process wherein printing of solder paste is performed one or more times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board characterized by a method of printing a solder paste in a solder bump forming opening of a solder resist layer.

[0002]

2. Description of the Related Art A multilayer printed wiring board called a so-called multilayer build-up wiring board is manufactured by a semi-additive method or the like.
m on a resin substrate reinforced with glass cloth, etc.
It is manufactured by alternately laminating a conductor circuit made of copper or the like and an interlayer resin insulating layer. The connection between the conductor circuits via the interlayer resin insulation layer of the multilayer printed wiring board is performed by via holes.

Conventionally, build-up multilayer printed wiring boards have been manufactured by a method disclosed in, for example, Japanese Patent Application Laid-Open No. 9-130050. That is, first, a through hole is formed in the copper-clad laminate to which the copper foil is attached, and then a through hole is formed by performing an electroless copper plating process. Subsequently, the surface of the substrate is etched into a conductor pattern using a photolithography technique to form a conductor circuit. Next, on the surface of the formed conductor circuit,
After forming a roughened surface by electroless plating or etching, forming an insulating resin layer on the conductor circuit having the roughened surface, performing exposure and development processing to form a via hole opening, and then UV After curing and main curing, an interlayer resin insulating layer is formed.

Further, after performing a roughening treatment on the interlayer resin insulating layer with an acid or an oxidizing agent, a thin electroless plating film is formed, a plating resist is formed on the electroless plating film, and then an electrolytic plating is performed. Then, etching is performed after the plating resist is stripped to form a conductive circuit connected to the lower conductive circuit by a via hole. After repeating this, finally form a solder resist layer to protect the conductor circuit, apply plating etc. to the exposed part for connection with electronic components such as IC chip and motherboard etc. and solder After the pad for bump formation, IC
A build-up multilayer printed wiring board is manufactured by printing solder paste on an electronic component side such as a chip to form solder bumps. Further, if necessary, solder bumps are formed on the motherboard.

[0005]

A solder bump forming pad formed on a solder resist layer has a flat pad formed on a flat conductor circuit and a pad formed on a via hole with a center at a center of 10 to 120 μm. There are two types having a depression of the diameter.

When a solder paste is filled with a solder paste, the pad near the dent may not be filled completely depending on the viscosity of the solder paste. In some cases, voids may be formed in and near the voids.

The voids formed in the solder bumps are:
During reflow or when heat is generated when an electronic component such as an IC chip is operated, it diffuses or expands.
There has been a problem that the solder bumps and the pads for forming the solder bumps are peeled or cracked, which adversely affects the connectivity and reliability.

In recent years, as electronic components such as IC chips have become higher in density and higher in integration, solder bumps on substrates have been similarly reduced in pitch and finer, so that the adverse effects of voids also appear significantly. It has become.

As a method of reducing the voids, a method of lowering the viscosity of the solder paste can be considered. In this method, although the voids of the solder bumps are reduced, the uniformity of the shape and height of the solder bumps is impaired. As a result, there arises a problem that connection with an electronic component such as an IC chip becomes defective, or that a solder paste bleeds into the surface of the solder resist layer during printing, causing a short circuit between solder bumps.

Further, a method of changing the opening diameter of a mask used when printing solder paste, a peak temperature, a residual heat temperature,
Although a method of changing reflow conditions such as a conveyor speed, a method of reducing voids by changing printing conditions such as a squeegee speed and a printing pressure, and the like can be considered, it is difficult to obtain a desired result with such a method. there were.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems, and as a result, the printing of the solder paste has been divided into at least two times and the first solder paste printing has been performed.
After the solder paste is printed on the solder bump forming opening and the periphery thereof, the voids are driven out to completely fill the solder bump forming opening with the solder paste. Make the surface of the paste and the surface of the solder resist layer almost flush with each other,
Furthermore, by performing the second solder paste printing,
Solder bumps with excellent uniformity in shape and height can be formed, there is no short circuit between each other, and multilayer printed wiring boards having solder bumps with excellent connection reliability with external connection components can be manufactured. And arrived at an invention having the following content as a gist configuration.

That is, in the first method of manufacturing a multilayer printed wiring board according to the present invention, an interlayer resin insulating layer and a conductive circuit are laminated on a substrate on which a conductive circuit is formed, and then the conductive circuit is formed on the uppermost conductive circuit. Providing a solder resist layer having a plurality of openings for forming solder bumps, and printing a solder paste in the openings for forming solder bumps to form solder bumps, wherein at least the following (a) ~
The step (d) is performed. (A) a first solder paste printing step in which solder paste is printed one or more times and a solder paste is filled in a concave solder bump forming opening, and (b) the entire surface of the solder paste layer on the solder resist layer Or a solder paste pressing step of pressing a part of the surface; (c) a solder paste flattening step of flattening the surface of the solder paste filled through the steps (a) and (b);
(D) A second solder paste printing step in which the solder paste is printed one or more times.

In the first solder paste printing step of the method for manufacturing a multilayer printed wiring board according to the first aspect of the present invention,
On the solder resist layer, after placing a mask having an opening in a portion facing the solder bump forming opening,
It is desirable to print solder paste.

In a second method of manufacturing a multilayer printed wiring board according to the present invention, an interlayer resin insulating layer and a conductive circuit are laminated on a substrate on which a conductive circuit is formed, and then a plurality of conductive circuits are formed on the uppermost conductive circuit. A method of manufacturing a multilayer printed wiring board, comprising: providing a solder resist layer having openings for forming solder bumps; and printing a solder paste in the openings for forming solder bumps to form solder bumps. The step d) is performed. (A) a first solder paste printing step in which solder paste is applied to the entire surface of the solder resist layer by one or more times of solder paste printing, and the solder paste is filled into openings for forming solder bumps; A solder paste pressing step of pressing the entire surface or a part of the surface of the solder paste layer on the layer, (c) removing the solder paste other than the solder paste filled in the opening for forming the solder bump, and removing the solder paste surface and the solder resist. A solder paste removing step of making the surface of the layer substantially flush with the surface, and (d) a second solder paste printing step of printing the solder paste one or more times.

A third method for manufacturing a multilayer printed wiring board is as follows.
After laminating and forming an interlayer resin insulating layer and a conductive circuit on the substrate on which the conductive circuit is formed, a solder resist layer having a plurality of solder bump forming openings is provided on the uppermost conductive circuit. A method for manufacturing a multilayer printed wiring board in which a solder paste is formed by printing a solder paste in an opening for use, wherein at least the following steps (a) to (d) are performed. (A) a first solder paste printing step of printing a solder paste at least once in a predetermined area including a plurality of solder bump forming openings on a solder resist layer and filling the solder bump forming openings with the solder paste; (B) a solder paste pressing step of pressing the entire surface or a part of the surface of the solder paste layer on the solder resist layer; and (c) removing a solder paste other than the solder paste filled in the solder bump forming opening, and removing the solder paste. A solder paste removing step in which the surface of the solder paste layer and the surface of the solder resist layer are made substantially flush with each other, and (d) a second solder paste printing step in which solder paste is printed one or more times.

In the first solder paste printing step of the third method for manufacturing a multilayer printed wiring board, an opening is formed on the solder resist layer at a portion opposed to a predetermined region including a plurality of openings for forming solder bumps. It is desirable to print the solder paste after placing the mask having the following.

In the second solder paste printing step of the first, second or third multilayer printed wiring board manufacturing method, an opening is formed on the solder resist layer at a portion facing the opening for forming the solder bump. It is desirable to print the solder paste after placing the mask having it.

In the first, second or third method for producing a multilayer printed wiring board, the viscosity of the solder paste to be printed in the first solder paste printing step is determined by adjusting the viscosity of the solder to be printed in the second solder paste printing step. Desirably lower than the viscosity of the paste.

In the first solder paste printing step of the first, second or third method of manufacturing a multilayer printed wiring board, a first solder paste printing is performed, and a solder bump forming opening having a recess on the bottom surface thereof is formed. Only the solder paste is printed to such an extent that the recessed portion is filled, and by the second printing of the solder paste, the entire surface of the solder resist layer is completely filled with the concave-shaped opening for forming the solder bump. It is desirable to apply a solder paste.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a first method of manufacturing a printed wiring board according to the present invention, an interlayer resin insulating layer and a conductive circuit are formed on a substrate on which a conductive circuit is formed, and then the uppermost conductive circuit is formed. A solder resist layer having a plurality of openings for forming solder bumps, and printing a solder paste in the openings for forming solder bumps to form solder bumps. ) To (d)
Is carried out. (A) a first solder paste printing step in which solder paste is printed one or more times and a solder paste is filled in a concave solder bump forming opening, and (b) the entire surface of the solder paste layer on the solder resist layer Or a solder paste pressing step of pressing a part of the surface; (c) a solder paste flattening step of flattening the surface of the solder paste filled through the steps (a) and (b);
(D) A second solder paste printing step in which the solder paste is printed one or more times.

In the method of manufacturing a multilayer printed wiring board according to the first aspect of the present invention, the solder bump forming opening is completely filled with the solder paste by passing through the first solder paste printing step and the solder paste pressing step. After that, the surface of the solder paste and the surface of the solder resist layer in the opening for forming the solder bumps are made substantially flush with each other, and further,
Since the second solder paste printing process is performed, solder bumps having a uniform shape and height, having no defects such as voids, and having no short-circuit between each other can be formed. An excellent printed wiring board can be manufactured.

Hereinafter, a method for manufacturing a printed wiring board according to the first aspect of the present invention will be described. The method of manufacturing a multilayer printed wiring board according to the present invention is characterized by a step of printing a solder paste in an opening for forming a solder bump provided in a solder resist layer, that is, the steps (a) to (d). Therefore, this step will be described first with reference to the drawings, and all the manufacturing steps for manufacturing a multilayer printed wiring board will be described later.

FIG. 1 is a partial sectional view schematically showing the steps (a) to (d) in the method for manufacturing a multilayer printed wiring board according to the present invention. In the step (a) (first solder paste printing step), a solder paste is printed one or more times on a substrate provided with a solder resist layer 114 having openings 106 for forming solder bumps, thereby forming a concave solder. Filling the bump forming opening 106 with the solder paste 117 (FIG. 1)
(A)). In the drawing, 102 is an interlayer resin insulating layer,
105 is a conductor circuit, 107 is a via hole, and 116 is a solder pad. In this step, the solder paste 117 is filled into the openings 106 for forming the solder bumps. To reliably fill the solder bump forming openings 106, a larger amount of solder paste is printed than the volume of the solder bump forming openings. Therefore, after completion of the first solder paste printing step, the printed solder paste has a shape partially raised above the surface of the solder resist layer (shown as solder paste 1117 in the figure).

In the first solder paste printing step, it is desirable to place a mask having an opening on a portion facing the solder bump forming opening on the solder resist layer, and then print the solder paste. By placing the mask and selectively printing the solder paste in the solder bump forming openings, the solder paste does not adhere to the surface of the solder resist layer other than the solder bump forming openings and the periphery thereof, so that the This is because it is not necessary to remove the solder paste attached to the solder resist layer surface in the process.

The type of the mask is not particularly limited, and all materials used for a print mask for manufacturing a printed wiring board and other print masks can be used. Specifically, for example, a metal mask made of a nickel alloy, a nickel-cobalt alloy, SUS, or the like;
Examples include a plastic mask made of an epoxy resin, a polyimide resin, or the like. Further, as a method of manufacturing a mask, etching, additive processing, laser processing, or the like can be given.

The opening of the mask may be formed so as to have a wall surface perpendicular to the solder resist layer, but a taper is formed such that the diameter gradually increases toward the solder resist layer side. Is desirable. This is because the solder paste has excellent removability, and the solder bump forming opening can be more reliably filled with the solder paste.

The solder paste used in the first solder paste printing step is not particularly limited, and any solder paste generally used in the manufacture of printed wiring boards can be used. Specifically, for example, Sn: Pb (weight ratio) = 6
3:37, Sn: Pb: Ag = 62: 36: 2, Sn:
Ag = 96.5: 3.5, Sn and Sb
And the following. Further, the particle size of the solder particles is preferably 2 to 40 μm, and particularly preferably 5 to 20 μm.

The viscosity of the solder paste is desirably lower than the viscosity of the solder paste to be printed in a second solder paste printing step described later. This is because by increasing the fluidity of the solder paste, the solder paste can be reliably filled into the openings for forming the solder bumps.
In particular, an opening for forming a solder bump having a depression on the bottom surface can be reliably filled. Also, when the solder bump forming opening is filled with a highly fluid solder paste,
Voids are less likely to occur when the solder bumps are formed.
Examples of a method of reducing the viscosity of the solder paste include a method of increasing the amount of a solvent added to the solder paste, increasing the content of the flux, and reducing the particle size of the solder particles. Further, the viscosity of the solder paste may be the same as the viscosity of the solder paste printed in the second solder paste printing step.

In the first solder paste printing step, the solder paste is printed in such an amount that only the solder bump forming opening having a recess on the bottom surface is filled with the recess in the first solder paste printing. The paste may be printed, and the solder paste may be printed in the second solder paste printing so that the concave solder bump forming opening is completely filled.

A conductive circuit is exposed on the bottom surface of the solder bump forming opening formed in the solder resist layer, and usually, the exposed surface of the conductive circuit (the bottom surface of the solder bump forming opening) is plated. Thus, a pad for forming a solder bump (hereinafter, also referred to as a solder pad) is formed. Here, when the solder pad is formed on the via hole of the conductor circuit, the shape of the solder pad has a depression in a part thereof. When the solder paste is filled into the solder bump forming opening having a depression on the bottom surface as described above, the solder paste is divided into two times to perform the solder paste printing. Can be more reliably filled.

When printing the solder paste, a printing squeegee is usually used. The material of the printing squeegee is not particularly limited, and for example, a material generally used for printing a printed wiring board such as rubber such as polyethylene; metal such as iron and stainless steel; and ceramic can be used. Among them, rubber having a hardness of 60 ° or more is desirable because it has elasticity and has a high followability to unevenness (undulation) on the substrate surface, so that solder paste can be more reliably printed in the openings. Metals are preferred because they are not easily reduced and foreign substances are hardly mixed into the solder paste due to wear.

The squeegee may have various shapes such as a flat shape and a square shape. To the squeegee of the above shape
By making the cuts as appropriate, the filling property of the solder paste can be improved. The thickness of the squeegee is not particularly limited, but is usually preferably 10 to 30 mm.
5 to 25 mm is more desirable. This is because there is no warping or bending even if printing is repeated. In the case of a metal squeegee, the thickness is desirably 50 to 300 μm.

The printing of the solder paste may be performed using a closed squeegee unit. Examples of such a squeegee include an air press-fit type, a roller press-fit type, and a piston press-fit type. When forming solder bumps in which the distance between adjacent solder bumps is 200 μm or less, it is difficult to form a solder paste layer capable of forming such solder bumps using ordinary squeegee printing. It is desirable to use a closed squeegee unit. Also, among the closed squeegee units, a piston press-fit type is preferable because of its excellent printing pressure stability.

After completion of the first solder paste printing step,
The step (b) (a solder paste pressing step) is performed.
In this step, by pressing the entire surface or a part of the surface of the solder paste layer on the solder resist layer,
The solder bump forming openings are completely filled with the solder paste, and voids formed in the first solder paste printing step are removed.

In the first solder paste printing step,
Since only the solder paste is printed using the above-described method, the solder paste is not completely filled depending on the shape of the opening for forming the solder bump (the diameter of the opening or the presence or absence of a depression on the bottom surface), and the opening for forming the solder bump is not provided. There is a possibility that voids or the like may be formed on the surface. If a void is formed in the opening for forming the solder bump, the void is diffused or expanded due to heat generated during reflow or when an electronic component such as an IC chip is operated. Peeling or cracks occur in the solder bumps, which adversely affects connectivity and reliability.

Accordingly, leaving the void generated in the opening for forming the solder bump as it is as described above leads to a decrease in the connectivity and reliability of the multilayer printed wiring board to be manufactured. In the method for manufacturing a multilayer printed wiring board of the present invention, in order to perform the solder paste pressing step,
Even if a void is generated in the first solder paste printing step, the void can be completely removed in this step, and the solder bump forming opening can be completely filled with the solder paste.

In this step, the entire surface or a part of the surface of the solder paste layer on the solder resist layer is pressed. Specifically, the solder paste pressing step includes, for example, applying a plate-shaped press member 130 to the entire surface or a part of the surface of the solder paste layer 117 on the solder resist layer for about 1 to 30 seconds. Pressing is performed (see FIG. 1B). The pressing force at the time of pressing the pressing member may be a pressing force that can completely remove the voids in the openings for forming solder bumps and completely fill the solder paste. 1MPa
What is necessary is just to press with a pressing force of 2.0 MPa. When the above-mentioned press member is pressed against a part of the surface of the solder paste layer on the solder resist layer, the above-mentioned press member presses against a region including all formed solder bump forming openings. This is because the purpose is to completely fill the solder bump forming opening with the solder paste. When the pressing member is pressed against the solder paste layer on the solder resist layer, the operation of pressing the pressing member may be performed once or may be performed in two or more steps.

The material of the press member is not particularly limited, and includes metal, plastic, and the like.
Fluororesin, silicone resin and the like are desirable. They are,
This is because the wettability to the solder paste is poor and the solder paste does not easily adhere. When the press member has good wettability with respect to the solder paste, the solder paste may adhere to the press member. When the solder paste adheres to the press member as described above, the solder bump may be attached in the first solder paste printing step. This is because the solder paste printed on the formation openings is removed, and when the solder bumps are formed through a post-process, the shape of the solder bumps may not be uniform.

It is preferable that the press member has a curved surface shape at an end of a surface in contact with the solder paste layer on the solder resist layer. This is because the solder paste filled in the solder resist layer and the opening for forming the solder bump is not damaged.

The solder paste pressing step may be performed by pressing the solder paste layer on the solder resist layer with a roller, instead of pressing the above-mentioned pressing member. Specifically, it can be performed by running a roller on the surface of the solder paste layer on the solder resist layer, or by passing a substrate having the solder paste layer between the rollers.

The pressing force when pressing the solder paste layer on the solder resist layer with a roller is a pressing force capable of removing voids in the openings for forming solder bumps and completely filling the solder paste. More specifically, the pressing may be performed with a pressing force of 0.1 MPa to 2.0 MPa.

The material of the above-mentioned roller is not particularly limited, and examples thereof include metal, plastic, and ceramic. Specific examples include fluorine resin and silicone resin. Among these, a fluororesin is preferable because the wettability to the solder paste is poor and the solder paste does not easily adhere.

After the first solder paste printing step and the solder paste pressing step, the step (c) (solder paste flattening step) is performed. In this step, at the end of the first solder paste printing step and the solder paste pressing step, the solder paste 1117 that has not been filled in the openings for forming the solder bumps is removed. This solder paste 111
7, the solder paste surface 117a is flattened and the filled solder paste surface 11a is removed.
7a and the surface of the solder resist layer are made substantially coplanar (see FIG. 1 (c)).

As a method for removing the solder paste 1117, any method that can achieve the flattening of the surface of the solder paste as described above may be used, and more specifically, a method using a squeegee or cleaning paper is used. can do. Further, when the solder paste is attached to the surface of the solder resist layer except for the wall surface of the opening for forming the solder bump, the attached solder paste may be removed in this step.

In order to avoid the need for performing the solder paste flattening step, the solder paste does not have a raised shape from the surface of the solder resist layer, and
The solder paste may be filled in such an amount as to completely fill the opening for forming the solder bump. However, in order to fill such an amount of the solder paste, the printing amount of the solder paste must be strictly controlled for each opening for forming the solder bump, so that the management items at the time of printing increase, and the printing amount also increases. When an error occurs, the error leads to a decrease in the quality of the multilayer printed wiring board. As a result, using such a method leads to a decrease in the yield, which is disadvantageous economically. Becomes Therefore, although the number of processing steps increases,
After printing a sufficient amount of solder paste to fill the opening, a solder paste pressing step is performed to completely fill the solder paste, and further, a step of removing the solder paste not filled in the solder bump forming opening is performed. The production method of the present invention is economically superior.

After flattening the surface of the solder paste, the step (d) (second solder paste printing step)
Through the steps (a) to (c), a solder paste layer is formed on the solder bump forming opening filled with the solder paste, and the solder bump 127 is formed by reflowing the printed solder paste ( FIG. 1D). The solder paste can be printed using a printing squeegee or a closed squeegee unit, as in the first solder paste printing step.

In the second solder paste printing step, it is desirable to print a solder paste after placing a mask having an opening at a portion corresponding to a solder bump forming portion. By performing printing using a mask, a solder paste layer having excellent uniformity in shape, height, and the like can be formed.

As the type of the mask used in the second solder paste printing step, the same mask as that used in the first solder paste printing step can be used. It is desirable that the mask used in the second solder paste printing step also has a tapered shape in which the diameter is increased toward the solder resist layer, similarly to the mask used in the first solder paste printing step.

In the case where the solder paste is printed using a mask in the first and second solder paste printing steps, the mask used in the first solder paste printing step and the mask used in the second solder paste printing step are used. It is desirable that the mask has the same opening diameter or that the mask used in the first solder paste printing step is smaller.

When the opening diameters of the masks used in the first and second solder paste printing steps are the same, the same mask can be used in both the steps, which is economically advantageous and is advantageous in terms of printing. The device itself can be made compact.

When the opening diameter of the mask used in the first solder paste printing step is smaller than the opening diameter of the mask used in the second solder paste printing step, the following effects are obtained. That is, the first solder paste printing step
This is a step for surely filling the openings for forming the solder bumps, and the excess printed solder paste is removed in a later step. Therefore, when the opening diameter of the mask is reduced, the amount of solder paste to be printed is reduced, so that the solder paste can be easily removed in a later step, and the amount of solder paste to be removed can be reduced. Further, by using a mask having an opening having a diameter slightly larger than the opening diameter of the opening for forming the solder bump, it is possible to cope with an alignment deviation at the time of printing, and it is possible to more reliably fill the solder paste. In some cases, a mask having an opening having the same diameter as the opening for forming the solder bump can be used. Note that the misalignment is a misalignment between the solder bump forming opening and the printed solder paste due to variations in the finishing accuracy of the substrate and the mask, and variations in the printing accuracy of the printing machine.

On the other hand, the second solder paste printing step is a step performed for forming a solder paste layer having excellent uniformity in shape, height and the like. In this step, it is desirable to print a solder paste having a high viscosity, as described later. Therefore, a solder paste layer having a desired shape can be formed by using a mask having an opening capable of printing a sufficient amount of solder paste.

The composition of the solder paste used in the second solder paste printing step is not particularly limited, and may be the same as the solder paste used in the first solder paste printing step.

The viscosity of the solder paste printed in the second solder paste printing step is desirably the same as or higher than the viscosity of the solder paste printed in the first solder paste printing step. １５０150 Pa · s, more preferably 50-100 Pa · s. Specifically, the viscosity of the solder paste to be printed in the second solder paste printing step is 25 ° C.
It is desirable to be 150 to 350 Pa · s. When the viscosity is less than 150 Pa · s, the solder paste cannot be printed in a desired shape, a solder bump having a uniform shape cannot be formed, or the solder paste bleeds on the surface of the solder resist layer during printing. This may cause a short circuit of the formed solder bump. On the other hand, if the viscosity exceeds 350 Pas, it may not be possible to print the solder paste in a desired shape, and particularly when printing the solder paste using a mask, since the solder paste has low removability, A portion where the solder paste cannot be printed may occur.

In the second solder paste printing step, the printing of the solder paste may be performed once or may be performed a plurality of times. Whether printing of the solder paste is completed once or multiple times depends on the distance between the formed solder bumps, the height and shape of the solder bumps, the composition of the solder paste, the particle size of the solder particles, and the like. Although it cannot be generally said, for example, when the distance between the formed solder bumps is extremely small, it is desirable to perform printing a plurality of times. It is desirable to perform printing once.

This is because when a solder paste is printed in a single printing operation using a mask, when the distance between the formed solder bumps is small, the distance between the openings of the mask becomes short. In such a case, the mechanical strength of the mask is weakened, and the mask may be damaged or warped when printing the solder paste. In particular, when the opening of the mask has a taper whose diameter increases toward the back side of the mask, the mechanical strength of the mask is likely to be reduced.

In the second solder paste printing step, as a specific method of performing the solder paste printing in a plurality of times, for example, the following method can be used. FIGS. 2A and 2B are cross-sectional views schematically showing an example of a method for printing a solder paste in the second solder paste printing step.

As shown in FIG. 2A, an opening is formed only in a portion opposed to a part of all the solder bump forming openings.
Using a mask 224 in which the distance between the openings is wide,
The first solder paste printing in the second solder paste printing step is performed to form a solder paste layer 227a. Then, as shown in (b), in the second printing, the solder not printed first is printed. A printing process is performed using a mask 225 having an opening formed in a portion facing the opening for forming a bump to form a solder paste layer 227b.

In a mask in which the distance between the openings is widened, the mechanical strength of the mask can be kept sufficiently high. Here, "the spacing between the openings was widened"
This means that the space between the openings of the mask is wider than that in the case where the openings are formed in the portion of the mask that faces all the solder bump forming openings.

Specifically, when performing the second solder paste printing step using a mask, for example, in the first printing,
Using a mask having an opening at a portion opposite to the opening for forming the solder bumps in the separate row, a solder paste layer is formed on the opening for forming the solder bumps in the separate row, and the remaining openings for forming the solder bumps are formed by the second printing. A solder paste layer is formed thereon.

In the second and subsequent printings, it is desirable to use a mask having a concave portion (hereinafter also referred to as a counterbore) in a portion on the back side of the mask facing the previously formed solder paste layer. By using the mask 225 (see FIG. 2B) on which the counterbore 225a is formed,
Solder paste layer 227 previously printed with mask 225
This is because it is possible to prevent the short circuit caused by the solder paste adhering to the back side of the mask and subsequently adhering to the surface of the solder resist layer 214, while eliminating the damage of a.

Through the steps (a) to (d), a solder paste layer for providing solder bumps having excellent uniformity in shape, height, etc., and no short circuit between them is generated. Can be formed.

Next, all the manufacturing steps of the method for manufacturing a multilayer printed wiring board according to the present invention will be described in the order of steps. (1) In the method for manufacturing a multilayer printed wiring board according to the present invention, first, a conductive circuit is formed on a substrate. In particular,
For example, after a solid conductor layer is formed by performing electroless plating or the like on both surfaces of the substrate, an etching resist corresponding to the conductor circuit pattern is formed on the conductor layer, and then the etching resist is formed. I just need. After the electroless plating is performed, the thickness of the conductor layer may be increased by performing the electrolytic plating. As the substrate, a resin substrate is desirable, and specific examples thereof include a glass epoxy substrate, a polyimide substrate, a bismaleimide-triazine resin substrate (BT resin substrate), and a fluororesin substrate. Further, a copper-clad laminate, an RCC substrate, or the like may be used as a substrate on which a solid conductor layer is formed.

When performing the above-described electroless plating, if necessary, a through-hole is formed in advance on the insulating substrate, and the electroless plating is also performed on the wall surface of the through-hole. Alternatively, a through hole may be provided to electrically connect the conductor circuits sandwiching the substrate. When a through hole is formed, it is desirable to fill the through hole with a resin filler.

(2) Next, if necessary, the surface of the conductor circuit is subjected to a roughening treatment. As a roughening treatment method, for example,
A blackening (oxidation) -reduction treatment, an etching treatment using a mixed solution containing an organic acid and a cupric complex, a treatment by Cu-Ni-P needle-like alloy plating, and the like can be used.

(3) Next, an uncured resin layer made of a thermosetting resin or a resin composite is formed on the conductor circuit, or a resin layer made of a thermoplastic resin is formed. The uncured resin insulating layer may be formed by applying uncured resin by using a roll coater, a curtain coater, or the like, or may be formed by thermocompression bonding an uncured (semi-cured) resin film. Good. Further, a resin film in which a metal layer such as a copper foil is formed on one surface of an uncured resin film may be attached. The resin layer made of a thermoplastic resin is desirably formed by thermocompression bonding a resin molded body formed into a film.

When applying the uncured resin, a heat treatment is applied after the resin is applied. By performing the heat treatment, the uncured resin can be thermally cured. The thermosetting may be performed after forming a via hole opening and a through hole described later.

Specific examples of the thermosetting resin used in forming such a resin layer include, for example, epoxy resin, phenol resin, polyimide resin, polyester resin, bismaleimide resin, polyolefin resin, polyphenylene ether resin and the like. No.

Examples of the epoxy resin include cresol novolak epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, phenol novolak epoxy resin, alkylphenol novolak epoxy resin, biphenol F epoxy resin, and naphthalene epoxy resin. Resin, dicyclopentadiene type epoxy resin, epoxidized product of condensate of phenols and aromatic aldehyde having phenolic hydroxyl group,
Triglycidyl isocyanurate, alicyclic epoxy resin and the like. These may be used alone or in combination of two or more. Thereby, it becomes excellent in heat resistance and the like.

Examples of the polyolefin resin include polyethylene, polystyrene, polypropylene, polyisobutylene, polybutadiene, polyisoprene, cycloolefin resin, and copolymers of these resins. Among them, cyclo-dielectric materials have low dielectric constant and dielectric loss tangent, are unlikely to cause signal delay and signal error even when a high-frequency signal in the GHz band is used, and are excellent in mechanical characteristics such as rigidity. Olefin resins are desirable.

As the cycloolefin resin, 2
Homopolymers or copolymers of monomers comprising -norbornene, 5-ethylidene-2-norbornene or derivatives thereof are desirable. As the above derivative, the above 2-
Examples include those in which an amino group for forming a crosslink, a maleic anhydride residue, or a maleic acid-modified one is bonded to a cycloolefin such as norbornene. Examples of monomers for synthesizing the copolymer include ethylene and propylene. Further, the polyolefin resin may include an organic filler.

Examples of the polyphenylene ether resin include a thermoplastic polyphenylene ether resin having a repeating unit represented by the following chemical formula (1) and a thermosetting polyphenylene ether resin having a repeating unit represented by the following chemical formula (2) And the like.

[0073]

Embedded image

(In the formula, n represents an integer of 2 or more.)

[0075]

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(In the formula, m represents an integer of 2 or more. R ¹ and R ² represent a methylene group, an ethylene group or a —C
Represents H ₂ —O—CH ₂ —, both of which may be the same or different. )

The thermoplastic polyphenylene ether resin having a repeating unit represented by the above chemical formula (1) has a structure in which a methyl group is bonded to a benzene ring, but the polyphenylene ether which can be used in the present invention. The resin may be a derivative in which the above-mentioned methyl group is substituted with another alkyl group such as an ethyl group, or a derivative in which hydrogen of a methyl group is substituted with fluorine.

Examples of the thermoplastic resin include polyethersulfone and polysulfone. Further, the composite of the thermosetting resin and the thermoplastic resin (resin composite) is not particularly limited as long as it contains a thermosetting resin and a thermoplastic resin, and specific examples thereof include, for example, And a resin composition for forming a roughened surface.

The resin composition for forming a roughened surface includes, for example, an uncured heat-resistant resin matrix which is hardly soluble in a roughening solution comprising at least one selected from acids, alkalis and oxidizing agents. Examples thereof include those in which a substance soluble in a roughening liquid comprising at least one selected from an acid, an alkali, and an oxidizing agent is dispersed. Note that the terms "sparingly soluble" and "soluble" are referred to as "soluble" for convenience when a substance having a relatively high dissolution rate is immersed in the same roughening solution for the same time, and the relative dissolution rate is relatively low. The slower one is called "poorly soluble" for convenience.

The heat-resistant resin matrix is preferably a matrix capable of maintaining the shape of the roughened surface when the roughened surface is formed on the interlayer resin insulating layer using the roughening solution. , Thermoplastic resins, and composites thereof. Further, a photosensitive resin may be used. This is because, in a step of forming a via hole opening described later, the opening can be formed by exposure and development processing.

The thermosetting resin includes, for example, epoxy resin, phenol resin, polyimide resin, polyolefin resin, fluorine resin and the like. When the thermosetting resin is photosensitized, the thermosetting group is subjected to a (meth) acrylation reaction using methacrylic acid, acrylic acid, or the like. Particularly, a (meth) acrylate of an epoxy resin is desirable. Further, an epoxy resin having two or more epoxy groups in one molecule is more desirable. In addition to being able to form the above-described roughened surface, it is also excellent in heat resistance and the like, so that stress is not concentrated on the conductor circuit even under heat cycle conditions, and the conductor circuit and the interlayer resin insulation layer Peeling hardly occurs between the substrate and the substrate.

Examples of the thermoplastic resin include phenoxy resin, polyether sulfone, polysulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenyl ether, polyether imide and the like. These may be used alone or in combination of two or more.

The substance soluble in the roughening liquid comprising at least one selected from the above-mentioned acids, alkalis and oxidizing agents is selected from inorganic particles, resin particles, metal particles, rubber particles, liquid resin and liquid rubber. It is desirable that it is at least one kind.

Examples of the inorganic particles include aluminum compounds, calcium compounds, potassium compounds, magnesium compounds, and silicon compounds. These may be used alone or in combination of two or more.

Examples of the aluminum compound include alumina and aluminum hydroxide. Examples of the calcium compound include calcium carbonate and
Calcium hydroxide and the like, as the potassium compound, for example, potassium carbonate and the like, as the magnesium compound, for example, magnesia, dolomite, basic magnesium carbonate, talc and the like,
Examples of the silicon compound include silica and zeolite. These may be used alone or 2
More than one species may be used in combination.

The alumina particles can be dissolved and removed with hydrofluoric acid, and calcium carbonate can be dissolved and removed with hydrochloric acid. Further, sodium-containing silica and dolomite can be dissolved and removed with an alkaline aqueous solution.

The resin particles include, for example, those made of a thermosetting resin, a thermoplastic resin and the like. When immersed in a roughening liquid comprising at least one selected from acids, alkalis and oxidizing agents, There is no particular limitation as long as the dissolution rate is faster than the heat-resistant resin matrix,
Specifically, for example, amino resin (melamine resin, urea resin, guanamine resin, etc.), epoxy resin, phenol resin, phenoxy resin, polyimide resin, polyphenylene resin, polyolefin resin, fluororesin, bismaleimide-triazine resin and the like can be mentioned. Can be These may be used alone or in combination of two or more.

It is necessary that the resin particles have been subjected to a curing treatment in advance. If not cured, the resin particles will dissolve in the solvent that dissolves the resin matrix, so they will be uniformly mixed, and it will not be possible to selectively dissolve and remove only the resin particles with an acid or oxidizing agent. is there.

The metal particles include, for example, gold, silver,
Examples include copper, tin, zinc, stainless steel, aluminum, nickel, iron, lead, and the like. These may be used alone or in combination of two or more. The metal particles may have a surface layer coated with a resin or the like in order to ensure insulation.

Examples of the rubber particles include acrylonitrile-butadiene rubber, polychloroprene rubber, polyisoprene rubber, acrylic rubber, polysulfur-based rigid rubber, fluorine rubber, urethane rubber, silicone rubber, ABS resin and the like.

As the rubber particles, for example, various modified polybutadiene rubbers such as polybutadiene rubber, epoxy-modified, urethane-modified, (meth) acrylonitrile-modified, etc., and (meth) acrylonitrile-butadiene rubber containing a carboxyl group can be used. Can also. These soluble substances may be used alone or in combination of two or more.

As the liquid phase resin, an uncured solution of the thermosetting resin can be used. Specific examples of such a liquid phase resin include, for example, an uncured epoxy oligomer and an amine-based curing agent. And the like. Examples of the liquid phase rubber include the above-mentioned polybutadiene rubber, various modified polybutadiene rubbers such as epoxy-modified, urethane-modified and (meth) acrylonitrile-modified, and uncured solutions such as (meth) acrylonitrile-butadiene rubber containing a carboxyl group. Can be used.

When the photosensitive resin composition is prepared by using the liquid resin or the liquid rubber, the heat-resistant resin matrix and the soluble substance are not uniformly compatible (that is, the phases are separated). As such, these materials need to be selected. By mixing a heat-resistant resin matrix and a soluble substance selected according to the above criteria, a state in which "islands" of liquid-phase resin or liquid-phase rubber are dispersed in the "sea" of the heat-resistant resin matrix Alternatively, a photosensitive resin composition in which "islands" of a heat-resistant resin matrix are dispersed in a "sea" of a liquid phase resin or a liquid phase rubber can be prepared.

(4) Next, when forming an interlayer resin insulating layer using a thermosetting resin or a resin composite as the material, an uncured resin insulating layer is subjected to a curing treatment, and a via hole is formed. An opening is formed to form an interlayer resin insulation layer. The via hole opening is desirably formed by laser processing. The laser processing may be performed before the curing processing or may be performed after the curing processing. In the case where an interlayer resin insulating layer made of a photosensitive resin is formed, an opening for a via hole may be provided by performing exposure and development processes. In this case, the exposure and development processes are performed before the above-described curing process.

When forming an interlayer resin insulation layer using a thermoplastic resin as the material, a via hole opening is formed in the resin layer made of the thermoplastic resin by laser processing to form an interlayer resin insulation layer. be able to.

At this time, as a laser to be used, for example, a carbon dioxide gas laser, an excimer laser, a UV laser,
An AG laser and the like can be mentioned. These lasers may be properly used in consideration of the shape of the via hole opening to be formed.

When forming the via hole opening,
By irradiating laser light with a hologram excimer laser through a mask, a large number of via hole openings can be formed at once. Further, when the via hole opening is formed using a short-pulse carbon dioxide laser, the amount of resin remaining in the opening is small, and the damage to the resin at the periphery of the opening is small.

By irradiating a laser beam through an optical lens and a mask, a large number of via hole openings can be formed at once. This is because a plurality of portions can be simultaneously irradiated with laser light having the same intensity and the same irradiation angle through the optical lens and the mask.

The through-hole formed in the mask is desirably a perfect circle in order to make the spot shape of the laser beam a perfect circle, and the diameter of the through-hole is desirably about 0.1 to 2 mm. When the carbon dioxide laser is used, the pulse interval is desirably 10 ⁻⁴ to 10 ⁻⁸ seconds. The time for irradiating the laser for forming the opening is preferably 10 to 500 μsec. In the case where the via hole opening is formed by laser light, particularly when a carbon dioxide gas laser is used, desmearing is desirably performed.

The thickness of the interlayer resin insulating layer formed by the above method is not particularly limited, but is preferably 5 to 50 μm. Further, the opening diameter of the via hole opening is not particularly limited, but is usually preferably 40 to 200 μm.

After the formation of the interlayer resin insulating layer, if necessary, a through hole may be formed through the interlayer resin insulating layer and the substrate. The through holes may be formed by drilling, laser processing, or the like. When such a through-hole is formed, in a later step, when forming the thin-film conductor layer on the surface of the interlayer resin insulating layer, the thin-film conductor layer is also formed on the wall surface of the through-hole, whereby Not only between the two conductor circuits sandwiching the interlayer resin insulation layer but also between the two conductor circuits and the two conductor circuits formed on both sides of the substrate, a total of four conductor circuits are electrically connected. Can be formed. By connecting the conductor circuits in this way, the signal transmission distance can be shortened,
Signal delay and the like hardly occur, which leads to improvement in performance of the multilayer printed wiring board.

(5) Next, the surface of the interlayer resin insulating layer including the inner wall of the opening for the via hole and the inner wall of the through hole when the through hole is formed in the above-mentioned step, if necessary, may be acid or oxidized. A roughened surface is formed using an agent. Examples of the acid include sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and formic acid. Examples of the oxidizing agent include chromic acid, chromic sulfuric acid, and permanganates such as sodium permanganate. Further, the formation of the roughened surface may be performed by using a plasma treatment or the like.

After forming the roughened surface, it is desirable to neutralize the surface of the interlayer resin insulating layer using an aqueous solution of an alkali or the like or a neutralizing solution. This is because the next step can be prevented from being affected by an acid or an oxidizing agent.

(6) Next, the surface of the interlayer resin insulating layer including the inner wall of the opening for the via hole and the inner wall of the through hole when the through hole is formed in the above-described step, if necessary, may be acid or acid. A roughened surface is formed using an oxidizing agent or the like. The roughened surface is formed in order to enhance the adhesion between the interlayer resin insulating layer and the thin film conductor layer formed thereon. In the case where there is a property, it may not be formed.

(7) Next, a thin film conductor layer is formed on the surface of the interlayer resin insulation layer provided with the via hole opening. The thin film conductor layer can be formed using a method such as electroless plating, sputtering, or vapor deposition. In addition, when the roughened surface is not formed on the surface of the interlayer resin insulating layer, it is preferable that the thin film conductor layer is formed by sputtering. When the thin film conductor layer is formed by electroless plating, a catalyst is previously applied to the surface to be plated. Examples of the catalyst include palladium chloride.

The thickness of the thin-film conductor layer is not particularly limited, but is preferably 0.6 to 1.2 μm when the thin-film conductor layer is formed by electroless plating. 0.1 to 1.0 μm is desirable. When the through-hole is formed in the step (4), a through-hole can be formed by forming a thin film conductor layer made of metal also on the inner wall surface of the through-hole in this step.

In the case where a thin film conductor layer is formed on the inner wall surface of the through hole to form a through hole as described above, it is preferable that the inside of the through hole is thereafter filled with a resin filler. Examples of the resin filler include a resin composition containing an epoxy resin, a curing agent, and inorganic particles.

When the inside of the through hole is filled with a resin filler, a cover plating layer covering the resin filler may be formed on the through hole, and when the cover plating layer is formed, the cover plating layer may be formed. Since a via hole and a solder pad can be formed directly on the plating layer, the signal transmission distance can be shortened.

(8) Next, a plating resist is formed on a part of the thin-film conductor layer using a dry film, and then electroplating is performed using the thin-film conductor layer as a plating lead. To form an electroplating layer. At this time, the via hole opening may be filled with electroplating to form a field via structure, or after filling the via hole opening with a conductive paste, a lid plating layer may be formed thereon to form a field via structure. .

(9) After forming the electroplating layer, the plating resist is peeled off, and the thin film conductor layer made of metal existing under the plating resist is removed by etching to form an independent conductor circuit. Examples of the etchant include a sulfuric acid-hydrogen peroxide aqueous solution, an aqueous solution of a persulfate such as ammonium persulfate, ferric chloride, cupric chloride, and hydrochloric acid. Further, a mixed solution containing the above-described cupric complex and an organic acid may be used as an etching solution.

Further, a conductor circuit may be formed by using the following method instead of the method described in the above (8) and (9). That is, after forming an electroplating layer on the entire surface of the thin film conductor layer, an etching resist is formed using a dry film on a part of the electroplating layer, and thereafter, an electroplating layer under an etching resist non-formed portion and An independent conductor circuit may be formed by removing the thin-film conductor layer by etching and then removing the etching resist.

(10) Thereafter, the above steps (3) to (9) are repeated to produce a substrate having the uppermost conductive circuit formed on the interlayer resin insulating layer.

(11) Next, a solder resist layer having a plurality of openings for forming solder bumps is formed on the substrate including the uppermost conductive circuit. Specifically, after the uncured solder resist composition is applied by a roll coater or a curtain coater, or the solder resist composition formed into a film is pressed, the solder bumps are formed by laser processing or exposure and development processing. Openings are formed and, if necessary, a curing treatment is performed to form a solder resist layer.

The solder resist layer can be formed using, for example, a solder resist composition containing a polyphenylene ether resin, a polyolefin resin, a fluororesin, a thermoplastic elastomer, an epoxy resin, a polyimide resin, or the like. Specific examples include, for example, the same resins as those used for the interlayer resin insulating layer.

Examples of the solder resist composition other than those described above include, for example, novolak-type epoxy resin (meth) acrylate, imidazole curing agent, bifunctional (meth) acrylate monomer, and molecular weight of 500 to 50.
A paste-like fluid containing a polymer of about 00 (meth) acrylate, a thermosetting resin such as a bisphenol-type epoxy resin, a photosensitive monomer such as a polyvalent acrylic monomer, a glycol ether-based solvent, and the like. It is desirable that the viscosity is adjusted to 1 to 10 Pa · s at 25 ° C. Examples of the (meth) acrylate of the novolak epoxy resin include an epoxy resin obtained by reacting glycidyl ether of phenol novolak or cresol novolak with acrylic acid, methacrylic acid, or the like.

The difunctional (meth) acrylic acid ester monomer is not particularly limited, and examples thereof include acrylic acid and methacrylic acid esters of various diols, and commercially available products of Nippon Kayaku Co., Ltd. R-604,
PM2, PM21 and the like.

The above solder resist composition may contain an elastomer or an inorganic filler. Due to the elastomer compounded, the formed solder resist layer absorbs or relieves the stress even when stress acts on the solder resist layer due to the flexibility and rebound resilience of the elastomer. As a result, it is possible to suppress the occurrence of cracks and peeling in the solder resist layer after the electronic component such as an IC chip is mounted on the manufacturing process of the multilayer printed wiring board or the manufactured multilayer printed wiring board. Even when cracks occur, the cracks hardly grow large.

The laser used for forming the solder bump forming opening may be the same as the laser used for forming the via hole opening described above.

Next, a solder pad is formed on the surface of the conductor circuit exposed at the bottom surface of the opening for forming a solder bump, if necessary. The solder pad can be formed by coating the surface of the conductor circuit with a corrosion-resistant metal such as nickel, palladium, gold, silver, and platinum. Specifically, it is desirable to form with metal, such as nickel-gold, nickel-silver, nickel-palladium, and nickel-palladium-gold. Further, the solder pad is, for example,
It can be formed using a method such as plating, vapor deposition, electrodeposition, etc. Among them, plating is preferable because of excellent uniformity of the coating layer.

(12) Next, a solder paste layer is formed by performing the above-described steps (a) to (d) on a solder resist layer having a solder pad on the bottom surface of the solder bump forming opening. A solder paste is formed by performing a reflow process on the solder paste layer. The reflow process may be performed after the first and second solder paste printing processes, or after the solder paste pressing process, or once after the solder paste removing process,
It may be performed again after the second solder paste printing step is completed.

Before the reflow process is performed on the solder paste layer formed in the second solder paste printing step,
Conductive pins may be attached to the solder paste layer to form a PGA (Pin Grid Array) for connecting to external terminals. In addition, a plasma treatment with oxygen, carbon tetrachloride, or the like may be performed as needed for a character printing process for forming a product recognition character or the like or for modifying a solder resist layer.

Next, a method for manufacturing a multilayer printed wiring board according to the second aspect of the present invention will be described. The method for manufacturing a multilayer printed wiring board according to the second aspect of the present invention is a method for manufacturing a multilayer printed wiring board, comprising: laminating and forming an interlayer resin insulating layer and a conductive circuit on a substrate on which a conductive circuit is formed; A method of manufacturing a multilayer printed wiring board, wherein a solder resist layer having an opening for forming is provided, and a solder paste is printed on the opening for forming a solder bump to form a solder bump, at least the following (a) to (d) Performing a process. (A) a first solder paste printing step in which solder paste is applied to the entire surface of the solder resist layer by one or more times of solder paste printing, and the solder paste is filled into openings for forming solder bumps; A solder paste pressing step of pressing the entire surface or a part of the surface of the solder paste layer on the layer, (c) removing the solder paste other than the solder paste filled in the opening for forming the solder bump, and removing the solder paste surface and the solder resist. A solder paste removing step of making the surface of the layer substantially flush with the surface, and (d) a second solder paste printing step of printing the solder paste one or more times.

In the second method of manufacturing a multilayer printed wiring board according to the present invention, the solder bump forming opening is completely filled with the solder paste by passing through the first solder paste printing step and the solder paste pressing step. After that, the surface of the solder paste and the surface of the solder resist layer in the opening for forming the solder bumps are made substantially flush with each other, and further,
Since the second solder paste printing process is performed, solder bumps having a uniform shape and height, having no defects such as voids, and having no short-circuit between each other can be formed. An excellent multilayer printed wiring board can be manufactured.

The method for manufacturing a multilayer printed wiring board according to the second aspect of the present invention is different from the method for manufacturing a multilayer printed wiring board according to the first aspect of the present invention in that the steps (a) to (d), Only the printing process is different. Specifically, in the first method for manufacturing a multilayer printed wiring board of the present invention, in the first solder paste printing step, after selectively filling the solder paste in the concave-shaped solder bump forming opening, the solder paste The surface is flattened, and further, a solder paste layer that becomes a solder bump after reflow is formed. On the other hand, in the method for manufacturing a multilayer printed wiring board according to the second invention, the solder paste After the solder paste is filled into the openings for forming the solder bumps by printing the solder paste on the entire surface of the resist layer, the surface of the solder paste is flattened and the solder paste layer is formed. Therefore, here, only the steps (a) to (d) in the method for manufacturing a multilayer printed wiring board according to the second embodiment of the present invention will be described, and the description of all the manufacturing steps for manufacturing the multilayer printed wiring board will be omitted. .

FIG. 3 is a partial sectional view schematically showing steps (a) to (d) in the second method for manufacturing a multilayer printed wiring board according to the present invention. In the step (a) (first solder paste printing step), the solder bump forming openings 306 are formed.
Solder paste is applied at least once on the entire surface of the solder resist layer 314 having a solder paste, and the solder paste 317 is filled in the concave-shaped solder bump forming openings 306 (FIG. 3).
(A)). In the drawing, 302 is an interlayer resin insulating layer,
305 is a conductor circuit, 307 is a via hole, and 316 is a solder pad. In this step, an amount of solder paste that can completely fill the solder bump forming openings 306 is printed on the entire surface of the solder resist layer 314. Therefore, after the first solder paste printing step is completed, the printed solder paste is filled in the openings for forming the solder bumps and applied to the entire surface of the solder resist layer.

The solder paste used in the first solder paste printing step is not particularly limited. For example, the same solder paste as used in the first manufacturing method of the present invention can be used. Further, it is desirable that the viscosity of the solder paste used in this step is lower than the viscosity of the solder paste printed in the second solder paste printing step, as in the case of the first manufacturing method of the present invention. In some cases, the viscosity may be the same as the viscosity of the solder paste printed in the second solder paste printing step.

In the first solder paste printing step, as in the first manufacturing method of the present invention, in the first printing of the solder paste, only the solder bump forming opening having a recess on the bottom surface is formed. The solder paste may be printed in such an amount that the recessed portion is filled, and then printed in the second solder paste printing so as to completely fill the concave solder bump forming opening. When the first solder paste printing is performed, after a mask having an opening at a portion opposite to the opening for forming a solder bump having a depression on the bottom surface is placed on the solder resist layer, the solder paste is printed. It is desirable.

When printing the solder paste, a printing squeegee is usually used. As the printing squeegee, for example, the same printing squeegee as that used in the first manufacturing method of the present invention can be used. Further, a closed squeegee unit can be used.

After completion of the first solder paste printing step,
The step (b) (a solder paste pressing step) is performed.
In this step, by pressing the entire surface or a part of the surface of the solder paste layer on the solder resist layer,
The solder bump forming openings are completely filled with the solder paste, and voids formed in the first solder paste printing step are removed.

In the first solder paste printing step,
Since only the solder paste is printed using the above-described method, the solder paste is not completely filled depending on the shape of the opening for forming the solder bump (the diameter of the opening or the presence or absence of a depression on the bottom surface), and the opening for forming the solder bump is not provided. Voids may be formed in If voids are formed in the openings for forming solder bumps, the connectivity and reliability of the multilayer printed wiring board may be adversely affected as described above.

However, in the method for manufacturing a multilayer printed wiring board according to the second aspect of the present invention, since the above-described solder paste pressing step is performed, even if a void is generated in the first solder paste printing step, the void is completely formed in this step. The solder bump forming opening is completely filled with the solder paste.

As a specific method of performing the solder paste pressing step, the same method as the method used in the solder paste pressing step of the first manufacturing method of the present invention can be used. That is, the press member 330 whose shape is a plate is
This is performed by pressing the entire surface or a part of the surface of the solder resist layer 314 for about 1 to 20 seconds (FIG. 3).
(B)). In this case, as in the first manufacturing method of the present invention, the pressing member may be pressed with a pressing force of 0.1 to 2.0 MPa. Further, as in the solder paste pressing step of the first manufacturing method of the present invention, a method of pressing with a roller may be used instead of the method of pressing the pressed member.

After the solder paste pressing step is completed, the step (c) (a solder paste removing step) is performed. In this step, the solder paste 1317 other than the solder paste filled in the solder bump forming openings is removed from the solder paste printed in the first solder paste printing step, thereby flattening the solder paste surface 317a,
The surface 317a of the filled solder paste and the surface of the solder resist layer are made substantially flush (see FIG. 3C).

As a method for removing the solder paste 1317 other than the solder paste filled in the opening for forming the solder bump, a method similar to the method used in the solder paste flattening step of the first manufacturing method of the present invention, that is, A method of removing the solder paste using a squeegee, cleaning paper, or the like can be used.

The solder paste is not applied to portions other than the solder bump forming openings, and the solder bump forming openings are completely filled, so that the solder paste removing step is not required. Alternatively, the solder paste may be printed in such an amount that the surface of the solder paste and the surface of the solder resist layer are substantially flush with each other. However, in order to print such an amount of solder paste, since the amount of solder paste to be printed must be strictly controlled for each solder bump forming opening, the number of management items during printing increases, and
Even when an error occurs in the printing amount, the error leads to a decrease in the quality of the multilayer printed wiring board. As a result, using such a method leads to a decrease in the yield, which is economically disadvantageous. It will be. Therefore, although the number of processing steps increases, after printing a sufficient amount of solder paste on the solder resist layer to fill the openings for forming the solder bumps, the surface of the solder paste and the surface of the solder resist layer substantially disappear. The manufacturing method of the present invention using the method of removing the solder paste so as to be on the same plane is economically superior.

In the solder paste removing step, the solder paste on the solder resist layer surface (excluding the solder bump forming openings) is removed so that the solder paste printed on portions other than the solder bump forming openings does not remain. There is a need to. If the solder paste remains on the surface of the solder resist layer, when the solder paste is reflowed in a later step, the solder paste moves and adheres to the adjacent solder paste layer, and the shape of the formed solder bump is uniform. In some cases, or may cause short-circuiting between solder bumps formed in a later process. Therefore, in order to reliably remove the solder paste on the surface of the solder resist layer, for example, a method of first removing the solder paste using a squeegee, and then removing the solder paste again using cleaning paper, or the like, is used. Is desirable.

After the surface of the solder paste was flattened, the step (d) (second solder paste printing step) was performed to fill the solder paste through the steps (a) and (b). A solder paste layer is formed on the opening for forming a solder bump, and further, a solder bump 327 is formed by reflowing the printed solder paste (FIG. 3).
(D)). This step can be performed using the same method as the second solder paste printing step of the first manufacturing method of the present invention. In particular, the distance between adjacent solder bumps is 2
When forming a solder bump of not more than 00 μm, a solder paste layer capable of forming such a solder bump is:
Since it is difficult to form the squeegee using ordinary squeegee printing, it is desirable to form the squeegee using a closed squeegee unit. Except for performing the steps (a) to (d), a multilayer printed wiring board having excellent connectivity and reliability is obtained by using the same method as the first method for manufacturing a multilayer printed wiring board of the present invention. Can be manufactured.

Next, a method for manufacturing a multilayer printed wiring board according to the third aspect of the present invention will be described. The method for manufacturing a multilayer printed wiring board according to the third aspect of the present invention is a method for manufacturing a multilayer printed wiring board, comprising: forming an interlayer resin insulating layer and a conductive circuit on a substrate on which the conductive circuit is formed; A method of manufacturing a multilayer printed wiring board, wherein a solder resist layer having an opening for forming is provided, and a solder paste is printed on the opening for forming a solder bump to form a solder bump, at least the following (a) to (d) Performing a process. (A) a first solder paste printing step of printing a solder paste at least once in a predetermined area including a plurality of solder bump forming openings on a solder resist layer and filling the solder bump forming openings with the solder paste; (B) a solder paste pressing step of pressing the entire surface or a part of the surface of the solder paste layer on the solder resist layer; and (c) removing a solder paste other than the solder paste filled in the solder bump forming opening, and removing the solder paste. A solder paste removing step in which the surface of the solder paste layer and the surface of the solder resist layer are made substantially flush with each other, and (d) a second solder paste printing step in which solder paste is printed one or more times.

In the third method for manufacturing a multilayer printed wiring board according to the present invention, the solder bump forming opening is completely filled with the solder paste by passing through the first solder paste printing step and the solder paste pressing step. Then, the surface of the solder paste and the surface of the solder resist layer of the opening for forming the solder bumps are made substantially flush with each other, and further,
Since the second solder paste printing process is performed, solder bumps having a uniform shape and height, having no defects such as voids, and having no short-circuit between each other can be formed. An excellent printed wiring board can be manufactured.

The method of manufacturing a multilayer printed wiring board according to the third aspect of the present invention differs from the method of manufacturing a multilayer printed wiring board of the first aspect of the present invention in the steps (a) to (d), Only the printing process is different.

Specifically, in the first method for manufacturing a multilayer printed wiring board according to the present invention, in the first solder paste printing step, after selectively filling the solder paste into the concave solder bump forming openings, In contrast, the surface of the solder paste is flattened, and a solder paste layer that becomes a solder bump after reflow is formed. On the other hand, in the third method for manufacturing a multilayer printed wiring board of the present invention, a first solder paste printing step is performed. After filling the solder paste into the solder bump forming opening by printing the solder paste in a predetermined area including the plurality of solder bump forming openings on the solder resist layer, flattening the solder paste surface and forming the solder paste layer Is formed. Accordingly, here, only the steps (a) to (d) in the third method for manufacturing a multilayer printed wiring board of the present invention will be described, and the description of all the manufacturing steps for manufacturing the multilayer printed wiring board will be omitted. I do.

FIG. 4A is a plan view schematically showing an example of a multilayer printed wiring board manufactured by the manufacturing method of the present invention, and FIG. 4B is a plan view of a portion of the multilayer printed wiring board shown in FIG. It is sectional drawing. As shown in FIGS. 4A and 4B,
In the multilayer printed wiring board 400, there is a region (solder bump area) where the solder bumps 427 are densely formed on the IC chip connection surface 400a. Normally, when an IC chip is mounted on a multilayer printed wiring board, the IC chip is mounted near the center of the multilayer printed wiring board 400 (FIG. 4A).
Therefore, the solder bumps 427 are densely formed near the center of the solder resist layer 414. In such a case, the solder resist layer 4
By printing the solder paste in the vicinity of the center of 14 by the first printing step of the manufacturing method of the present invention and passing through the remaining steps, a solder bump can be suitably formed. In FIG. 4, reference numeral 405 denotes a conductor circuit, 407 denotes a via hole, and 402 denotes an interlayer resin insulating layer.

In the first solder paste printing step, the “constant area including a plurality of solder bump forming openings” for printing the solder paste is preferably an area slightly larger than the solder bump area. Specifically, a region larger by 1 to 20 mm than the solder bump area is desirable, and a region larger by 5 to 10 mm than the solder bump area is more desirable. This is for surely printing the solder paste in the openings for forming the solder bumps. The solder bump area refers to a rectangular area including a solder bump having a distance of 300 μm or less from an adjacent solder bump.

FIG. 5 is a partial sectional view schematically showing the steps (a) to (d) in the third method of manufacturing a multilayer printed wiring board according to the present invention. In the step (a) (first solder paste printing step), the solder paste is applied at least once to a predetermined area on the solder resist layer 514 including the plurality of openings 506 for forming solder bumps. Solder paste 5 in and around bump formation opening 506
17 is printed (see FIG. 5A). In the figure, 50
2 is an interlayer resin insulation layer, 505 is a conductor circuit, 507 is a via hole, and 516 is a solder pad. In this step,
An amount of solder paste equal to or more than that capable of completely filling the solder bump forming openings 506 is applied to the solder resist layer 5.
14 is printed in a fixed area. Therefore, after completion of the first solder paste printing step, the printed solder paste exists in the openings for forming the solder bumps, and excess solder paste exists in the peripheral portion.

Further, in the first solder paste printing step, an opening is formed on the solder resist layer at a portion opposed to a fixed region for printing the solder paste (a fixed region including a plurality of openings for forming solder bumps). It is desirable to print the solder paste after placing the mask having it. By mounting the mask and printing the solder paste, the solder paste does not adhere to the surface of the solder resist layer except for a certain area including the opening for forming the solder bump, and the solder paste is applied to the surface of the solder resist layer in a later process. This is because it is not necessary to remove the attached solder paste.

The material of the mask is not particularly limited.
The same material as the material of the mask used in the first manufacturing method of the present invention can be used. In addition, as a method for manufacturing a mask, etching, additive processing, laser processing, or the like can be given.

In the mask used in this step, the opening of the mask may be formed so as to have a wall surface perpendicular to the solder resist layer, but the diameter gradually increases toward the solder resist layer side. It is desirable that a taper having such a shape is formed.

The solder paste used in the first solder paste printing step is not particularly limited.
Examples include the same solder paste as used in the first production method of the present invention. Further, the viscosity of the solder paste used in this step is the same as in the case of the first manufacturing method of the present invention.
It is desirable that the viscosity is lower than the viscosity of the solder paste printed in the second solder paste printing step. In some cases, the viscosity may be the same as the viscosity of the solder paste printed in the second solder paste printing step.

In the first solder paste printing step, as in the first manufacturing method of the present invention, in the first printing of the solder paste, only the solder bump forming opening having a depression on the bottom surface is formed. The solder paste may be printed in such an amount that the recessed portion is filled, and then printed in the second solder paste printing so as to completely fill the concave solder bump forming opening. When the first solder paste printing is performed, after a mask having an opening at a portion opposite to the opening for forming a solder bump having a depression on the bottom surface is placed on the solder resist layer, the solder paste is printed. It is desirable.

When printing the solder paste, a printing squeegee is usually used. As the printing squeegee, for example, the same printing squeegee as that used in the first manufacturing method of the present invention can be used. Further, a closed squeegee unit can be used.

After completion of the first solder paste printing step,
The step (b) (a solder paste pressing step) is performed.
In this step, by pressing the entire surface or a part of the surface of the solder paste layer on the solder resist layer,
The solder bump forming openings are completely filled with the solder paste, and voids formed in the first solder paste printing step are removed.

In the first solder paste printing step,
Since only the solder paste is printed using the above-described method, the solder paste is not completely filled depending on the shape of the opening for forming the solder bump (the diameter of the opening or the presence or absence of a depression on the bottom surface), and the opening for forming the solder bump is not provided. Voids may be formed in If voids are formed in the openings for forming solder bumps, the connectivity and reliability of the multilayer printed wiring board may be adversely affected as described above.

However, in the third method of manufacturing a multilayer printed wiring board according to the present invention, since the above-mentioned solder paste pressing step is performed, even if a void is generated in the first solder paste printing step, the void is completely formed in this step. The solder bump forming opening is completely filled with the solder paste.

As a specific method of performing the solder paste pressing step, the same method as the method used in the solder paste pressing step of the first manufacturing method of the present invention can be used. That is, the press member 530 whose plate shape is
This is performed by pressing the entire surface or a part of the surface of the solder resist layer 514 for about 1 to 20 seconds (FIG. 5).
(B)). In this case, as in the first manufacturing method of the present invention, the pressing member may be pressed with a pressing force of 0.1 to 2.0 MPa. Further, as in the solder paste pressing step of the first manufacturing method of the present invention, a method of pressing with a roller may be used instead of the method of pressing the pressed member.

After the solder paste pressing step is completed, the step (c) (a solder paste removing step) is performed. In this step, the solder paste 1517 other than the solder paste filled in the solder bump forming openings is removed from the solder paste printed in the first solder paste printing step, thereby flattening the solder paste surface 517a,
The surface 517a of the filled solder paste and the surface of the solder resist layer are made substantially flush (see FIG. 5C).

As a method for removing the solder paste 1517 other than the solder paste filled in the opening for forming the solder bump, a method similar to the method used in the solder paste flattening step of the first manufacturing method of the present invention, that is, A method of removing the solder paste using a squeegee, cleaning paper, or the like can be used.

The solder paste is not applied to portions other than the solder bump forming openings, and the solder bump forming openings are completely filled so that the solder paste removing step is not required. Alternatively, the solder paste may be printed in such an amount that the surface of the solder paste and the surface of the solder resist layer are substantially flush with each other. However, in order to print such an amount of solder paste, since the amount of solder paste to be printed must be strictly controlled for each solder bump forming opening, the number of management items during printing increases, and
Even when an error occurs in the printing amount, the error leads to a decrease in the quality of the multilayer printed wiring board. As a result, using such a method leads to a decrease in the yield, which is economically disadvantageous. Become. Therefore, although the number of processing steps increases,
After printing a sufficient amount of solder paste on the solder resist layer to fill the openings for forming solder bumps, remove the solder paste so that the surface of the solder paste and the surface of the solder resist layer are substantially flush with each other. The production method of the present invention using the above method is economically superior.

In the solder paste removing step, the solder paste on the solder resist layer surface (excluding the solder bump forming openings) is removed so that the solder paste printed on portions other than the solder bump forming openings does not remain. There is a need to. If the solder paste remains on the surface of the solder resist layer, when the solder paste is reflowed in a later step, the solder paste moves and adheres to the adjacent solder paste layer, and the shape of the formed solder bump is uniform. In some cases, or may cause short-circuiting between solder bumps formed in a later process. Therefore, in order to reliably remove the solder paste on the surface of the solder resist layer, for example, a method of first removing the solder paste using a squeegee, and then removing the solder paste again using a cleaning paper, or the like, is used. Is desirable.

After the surface of the solder paste was flattened, the step (d) (second solder paste printing step) was performed, whereby the solder paste was filled through the steps (a) to (c). A solder paste layer is formed on the opening for forming a solder bump, and further, a solder bump 527 is formed by reflowing the printed solder paste (FIG. 5).
(D)).

This step can be performed using the same method as the second solder paste printing step of the first manufacturing method of the present invention. In particular, the distance between adjacent solder bumps is 20
When forming a solder bump having a thickness of 0 μm or less, it is difficult to form a solder paste layer that can form such a solder bump using ordinary squeegee printing. It is desirable to form. Except for performing the steps (a) to (d), a multilayer printed wiring board having excellent connectivity and reliability is obtained by using the same method as the first method for manufacturing a multilayer printed wiring board of the present invention. Can be manufactured.

Further, the third method of manufacturing a multilayer printed wiring board of the present invention can be suitably used for manufacturing a multilayer printed wiring board designed to form solder bumps or the like on almost the entire surface of a solder resist layer. Can be. This will be briefly described below with reference to the drawings.

FIG. 6 is a plan view schematically showing a part of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention. In manufacturing a multilayer printed wiring board, a plurality of multilayer printed wiring boards are usually manufactured simultaneously. That is, a conductor circuit and an interlayer resin insulating layer are sequentially laminated on a large-sized substrate by using the above-described method, and then a solder resist layer and solder bumps are formed. Each section 601 has a conductor circuit (not shown) of a desired design,
The assembly 600 of the multilayer printed wiring board on which the solder bumps 627 and the like are formed is manufactured. Next, the assembly 600 of the multilayer printed wiring board is divided into the sections 601 (ie,
By cutting along the dotted line in FIG. 6, one multilayer printed wiring board is obtained.

As described above, when an assembly of multilayer printed wiring boards is manufactured, (a) of the manufacturing method of the present invention is used.
The solder bump can be formed through the steps (d) to (d). In this case, in the first solder paste printing step, the area where the solder paste is printed is defined as a section to be a multilayer printed wiring board (the area 601 solidified by a dotted line in FIG. 6), so that the multilayer printed wiring board is assembled. Since the solder paste is not printed on the area to be discarded when the body 600 is cut, the consumption of the solder paste can be reduced as compared with the case where the solder paste is applied to the entire surface of the substrate. Since it is not necessary to remove the solder paste in the area to be discarded, it is economically advantageous. As described above, when a plurality of multilayer printed wiring boards in which openings for forming solder bumps are densely provided near the center of the solder resist layer are manufactured at the same time, in the first solder paste printing process, The solder paste may be printed only in the vicinity of the center of the section 601 to be formed.

[0164]

The present invention will be described in more detail below. Example 1 A. Preparation of Resin Film for Interlayer Resin Insulation Layer Bisphenol A type epoxy resin (Epoxy equivalent 46
9. Yuka Shell Epoxy Epicoat 1001) 30
Parts by weight, 40 parts by weight of a cresol novolak type epoxy resin (epoxy equivalent: 215, Epicron N-673 manufactured by Dainippon Ink and Chemicals, Inc.) Light KA-705
2) 30 parts by weight were dissolved by heating in 20 parts by weight of ethyl diglycol acetate and 20 parts by weight of solvent naphtha while stirring, and epoxidized polybutadiene rubber (Denalex R-45EPT manufactured by Nagase Kasei Kogyo Co., Ltd.) was added thereto.
15 parts by weight, 1.5 parts by weight of a crushed product of 2-phenyl-4,5-bis (hydroxymethyl) imidazole, 2 parts by weight of finely divided silica, and 0.5 part by weight of a silicon-based antifoaming agent are added, and an epoxy resin composition is added. Was prepared. The resulting epoxy resin composition is applied on a 38 μm-thick PET film using a roll coater so that the thickness after drying becomes 50 μm, and then dried at 80 to 120 ° C. for 10 minutes to form an interlayer resin. A resin film for an insulating layer was produced.

B. Preparation of Resin Composition for Filling Through Holes 100 parts by weight of a bisphenol F type epoxy monomer (manufactured by Yuka Shell Co., Ltd., molecular weight: 310, YL983U), the average particle size of which surface is coated with a silane coupling agent is 1.6 μm, S whose maximum particle diameter is 15 μm or less
iO ₂ spherical particles (CRS 1101- manufactured by Adtech Co., Ltd.)
CE) 72 parts by weight and 1.5 parts by weight of a leveling agent (Perenol S4 manufactured by San Nopco) are placed in a container, and the mixture is stirred and mixed to have a viscosity of 30 to 80 Pa at 25 ° C.
・ The resin filler of s was prepared. In addition, as a curing agent, an imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals)
6.5 parts by weight were used.

C. Method for manufacturing printed wiring board (1) 0.8 mm thick glass epoxy resin or BT
A starting material was a copper-clad laminate in which 18 μm copper foils 8 were laminated on both sides of a substrate 1 made of (bismaleimide triazine) resin (see FIG. 7A). First, the copper-clad laminate was drilled, subjected to an electroless plating treatment, and etched in a pattern to form a lower conductor circuit 4 and a through hole 9 on both surfaces of the substrate 1.

(2) The substrate on which the through hole 9 and the lower conductor circuit 4 are formed is washed with water and dried,
(10 g / l), NaClO ₂ (40 g / l), Na ₃
A blackening treatment using an aqueous solution containing PO ₄ (6 g / l) as a blackening bath (oxidizing bath), NaOH (10 g / l), Na
A reduction treatment was performed using an aqueous solution containing BH ₄ (6 g / l) as a reduction bath, and roughened surfaces 4 a and 9 a were formed on the entire surface of the lower conductor circuit 4 including the through holes 9 (see FIG. 7B). ).

(3) Next, after preparing the resin composition for filling through-holes described in B above, the resin composition was adjusted by the following method.
Within 4 hours, a layer of the resin filler 10 was formed in the through-hole 9 and on the non-conductive-circuit-formed portion on one side of the substrate 1 and the outer edge of the conductive circuit 4. That is, first, the resin composition for filling a through hole was pushed into the through hole using a squeegee, and then dried at 100 ° C. for 20 minutes. Next, a mask having an opening corresponding to the conductor circuit non-forming portion is placed on the substrate, and a layer of the resin filler 10 is formed in the conductor circuit non-forming portion having a concave portion using a squeegee. ℃,
It was dried for 20 minutes (see FIG. 7 (c)).

(4) One surface of the substrate after the treatment of the above (3) is subjected to belt sander polishing using # 600 belt abrasive paper (manufactured by Sankyo Rikagaku Co., Ltd.) to form the surface of the inner layer copper pattern 4 and the through holes 9. Polishing was performed so that the resin filler 10 did not remain on the land surface, and then buffing was performed to remove scratches caused by the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate.
Next, heat treatment was performed at 100 ° C. for 1 hour and at 150 ° C. for 1 hour to cure the resin filler 10.

In this manner, the surface layer of the resin filler 10 formed in the through-hole 9 and the portion where the conductor circuit is not formed and the surface of the lower conductor circuit 4 are flattened, and the resin filler 10 and the side surface of the lower conductor circuit 4 are flattened. 4a is firmly adhered through the roughened surface, and the inner wall surface 9a of the through hole 9 and the resin filler 10
Was firmly adhered through the roughened surface to obtain an insulating substrate (see FIG. 7D). That is, by this step, the surface of the resin filler 10 and the surface of the lower conductive circuit 4 become flush with each other.

(5) After the above substrate was washed with water and acid degreased,
Soft etching is performed, and then an etching solution is sprayed on both surfaces of the substrate to etch the surface of the lower conductive circuit 4 and the land surface and the inner wall of the through-hole 9, so that the entire surface of the lower conductive circuit 4 is roughened. Surface 4a, 9a
Was formed (see FIG. 8A). In addition, as an etching solution, an etching solution (Mec etch bond, manufactured by Mec Co.) comprising 10 parts by weight of an imidazole copper (II) complex, 7 parts by weight of glycolic acid, and 5 parts by weight of potassium chloride was used.

(6) On both sides of the substrate, a resin film for an interlayer resin insulating layer slightly larger than the substrate prepared in the above A was placed on the substrate, and the pressure was 0.4 MPa, the temperature was 80 ° C., and the pressure bonding time was 10 seconds. After temporary crimping and cutting under the conditions, further, using a vacuum laminator device by the following method,
Thereafter, the interlayer resin insulation layer 2 was formed by thermosetting (see FIG. 8B). That is, a resin film for an interlayer resin insulation layer is placed on a substrate and the degree of vacuum is 67 Pa and the pressure is 0.
This was pressed and attached under the conditions of 4 MPa, a temperature of 80 ° C., and a pressing time of 60 seconds, and then thermally cured at 170 ° C. for 30 minutes.

(7) Next, a CO ₂ gas laser having a wavelength of 10.4 μm is used to pass a beam diameter of 4.0 through a mask having a through hole having a thickness of 1.2 mm formed on the interlayer resin insulating layer 2.
8 mm, a top hat mode, a pulse width of 8.0 μsec, a diameter of a through hole of the mask of 1.0 mm, and a one-shot condition, a via hole opening 6 of 80 μm in diameter was formed in the interlayer resin insulating layer 2 (FIG. c)).

(8) Further, the substrate in which the via hole opening 6 was formed was heated at 80 ° C. containing 60 g / l of permanganic acid.
The surface of the interlayer resin insulation layer 2 including the inner wall of the via hole opening 6 was roughened by dissolving and removing the epoxy resin particles present on the surface of the interlayer resin insulation layer 2 for 10 minutes. FIG. 8 (d)).

(9) Next, the substrate after the above treatment was immersed in a neutralizing solution (manufactured by Shipley) and washed with water. Further, by applying a palladium catalyst (manufactured by Atotech) to the surface of the substrate subjected to the surface roughening treatment (roughening depth: 3 μm), the surface of the interlayer resin insulating layer 2 and the inner wall surface of the via hole opening 6 are formed. Catalyst nuclei were deposited.

(10) Next, the substrate was immersed in an electroless copper plating aqueous solution having the following composition, and the thickness of the substrate was reduced to 0.6 to
A 3.0 μm electroless copper plating layer 12 was formed.
(A)). [Electroless plating aqueous solution] NiSO ₄ 0.003 mol / l tartaric acid 0.200 mol / l copper sulfate 0.030 mol / l HCHO 0.050 mol / l NaOH 0.100 mol / l α, α'-bipyridyl 40 mg / l Polyethylene glycol (PEG) 0.10 g / l [Electroless plating conditions] 40 minutes at a liquid temperature of 35 ° C

(11) A commercially available photosensitive dry film was stuck on the electroless copper plating layer 12, and a mask was
The plating resist 3 having a thickness of 20 μm was provided by exposing at 00 mJ / cm ² and developing with an aqueous 0.8% sodium carbonate solution (see FIG. 9B).

(12) Then, the substrate was washed with water at 50 ° C., degreased, washed with water at 25 ° C., further washed with sulfuric acid, and then subjected to electrolytic copper plating under the following conditions. The layer 13 was formed (see FIG. 9C). [Electroplating aqueous solution] sulfuric acid 2.24 mol / l copper sulfate 0.26 mol / l additive 19.5 ml / l (manufactured by Atotech Japan, Capparaside HL) [electroplating conditions] current density 1 A / dm ² hours 65 minutes Temperature 22 ± 2 ℃

(13) Further, 5% of plating resist 3
After stripping and removing with an aqueous NaOH solution, the electroless plating film 12 under the plating resist 3 is dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide, and the electroless copper plating film 1 is removed.
9 and an 18 μm thick independent upper conductor circuit 5 (including via holes 7) composed of an electroplating film 2 and an electrolytic plating film 13 (FIG. 9).
(D)).

(14) By repeating the above steps (5) to (13), an upper interlayer resin insulation layer 2 and an upper conductor circuit 5 (including via holes 7) were further formed (FIG. 10 ( a) to FIG. 11 (a)). Thereafter, a roughened surface was formed on the surface of the upper conductive circuit 5 using an etchant. In addition, as an etching solution, a product made by MEC,
A Mech etch bond was used (see FIG. 11B).

(15) Next, a cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) so as to have a concentration of 60% by weight was used. Oligomer for imparting properties (molecular weight: 4000) 46.6
7 parts by weight, 80% by weight dissolved in methyl ethyl ketone
Of bisphenol A type epoxy resin (manufactured by Yuka Shell Co., Ltd.
Trade name: Epicoat 1001) 15.0 parts by weight, imidazole hardener (manufactured by Shikoku Chemicals, trade name: 2E4MZ-C)
N) 1.6 parts by weight, 3.0 parts by weight of a polyacrylic monomer as a photosensitive monomer (trade name: R604, manufactured by Nippon Kayaku Co., Ltd.), and similarly polyvalent acrylic monomer (trade name: DPE6A, manufactured by Kyoei Chemical Co., Ltd.) ) 1.5 parts by weight, 0.71 part by weight of a dispersion defoaming agent (manufactured by San Nopco, S-65) in a container,
A mixed composition was prepared by stirring and mixing, and 2.0 parts by weight of benzophenone (manufactured by Kanto Kagaku) as a photopolymerization initiator and Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer were added to the mixed composition. By adding 0.2 parts by weight, a solder resist composition having a viscosity adjusted to 2.0 Pa · s at 25 ° C. was obtained. The viscosity was measured using a B-type viscometer (Tokyo Keiki Co., Ltd., D
VL-B type, 60 min ^-1 (rpm), the rotor No. Rotor N for 4, 6 min ^-1 (rpm)
o. According to 3.

(16) Next, the above-mentioned solder resist composition is applied to both sides of the multilayer wiring board in a thickness of 20 μm.
After performing a drying process at 70 ° C. for 20 minutes and at 70 ° C. for 30 minutes, the thickness 5 on which the pattern of the solder pad is drawn is 5
The mm photomask is brought into close contact to the solder resist layer was exposed to ultraviolet rays of 1000 mJ / cm ^2, and developed with DMTG solution to form openings with a diameter of 80 [mu] m. Then, at 80 ° C. for 1 hour, at 100 ° C. for 1 hour, 12
Heat treatment was performed at 0 ° C. for 1 hour and at 150 ° C. for 3 hours to cure the solder resist layer, thereby forming a solder resist layer 14 having an opening for forming a solder bump and having a thickness of 20 μm. Note that the opening diameter of the solder bump forming opening is 80 μm, and the distance between adjacent solder bump forming openings is 150 μm. In addition, as the solder resist composition, a commercially available solder resist composition can be used.

(17) Next, sodium persulfate as the main component
The etchant whose etching ability is 2 μm per minute
And etch the solder
-Immerse the substrate on which the resist layer 14 is formed for 1 minute
A roughened surface with an average roughness (Ra) of 1 μm or less
Formed. Further, this substrate was coated with nickel chloride (2.3).
× 10^-1mol / l), sodium hypophosphite (2.8
× 10^-1mol / l), sodium citrate (1.6 ×
10 ^-1mol / l) and pH = 4.5
Immersion in a plating solution for 20 minutes, and a 5 μm thick
A nickel plating layer 15 was formed. In addition, the board
Potassium gold cyanide (7.6 × 10^-3mol / l), salt
Ammonium iodide (1.9 × 10^-1mol / l), quenched
Sodium acid (1.2 × 10^-1mol / l), phosphorus hypophosphite
Sodium acid (1.7 × 10^-1mol / l)
Immerse in a gold plating solution at 80 ° C for 7.5 minutes,
0.03 μm thick gold plating on the nickel plating layer 15
The layer 16 was formed to form a solder pad.

(18) Thereafter, the solder resist layer 14
A mask having an opening having a diameter of 100 μm was placed on a portion opposed to all the openings for forming solder bumps, and solder paste was printed on the openings for forming concave solder bumps using a piston press-fit printing machine. . The solder paste printed here mainly contains solder having a particle size of 5 to 20 μm in which Sn: Ag is blended at a weight ratio of 96.5: 3.5, and the viscosity thereof is adjusted to 200 Pa · s. It is.
Further, after printing the solder paste, the solder resist layer 14
Pressing member made of fluororesin on the entire upper surface for 5 seconds,
By pressing with a pressing force of 0.5 MPa, the opening for forming the solder bump was completely filled with the solder paste, and the void in the opening for forming the solder bump was removed.

(19) Next, of the solder paste filled in the step (18), the portion of the solder paste raised from the surface of the solder resist layer was removed by using a stainless steel squeegee to fill the solder paste. The surface of the solder paste was flattened, and the surface of the solder paste was made flush with the surface of the solder resist layer.

(20) Next, a mask similar to the mask used in the step (18) is placed on the solder resist layer 14, and the solder paste is printed by a piston press-fit printing machine. A layer was formed. The solder paste filled here was Sn: Ag in a weight ratio of 96.
5: 3.5 mainly containing solder having a particle size of 5 to 20 μm mixed at 3.5 and having a viscosity adjusted to 250 Pa · s.

(21) Thereafter, the above (18) to (20)
The solder paste printed in the step of (1) was reflowed at 250 ° C., and was further subjected to flux cleaning to obtain a multilayer printed wiring board provided with solder bumps (FIG. 11C).
reference).

Example 2 A. In the same manner as in Example 1, production of a resin film for an interlayer resin insulating layer and preparation of a resin composition for filling through holes were performed.

B. Production of multilayer printed wiring board (1) Glass epoxy resin or BT with a thickness of 0.8 mm
A starting material was a copper-clad laminate in which an 18 μm copper foil 32 was laminated on both sides of an insulating substrate 30 made of (bismaleimide triazine) resin (see FIG. 12A).
First, the copper-clad laminate is etched into a lower-layer conductor circuit pattern, so that the lower-layer conductor circuit 34 is formed on both sides of the substrate.
Was formed (see FIG. 12B).

(2) Substrate 3 on which lower conductor circuit 34 is formed
After washing with water and drying, NaOH (10 g / l),
NaClO ₂ (40 g / l), Na ₃ PO ₄ (6 g / l)
a blackening treatment using an aqueous solution containing l) as a blackening bath (oxidizing bath);
And NaOH (10 g / l), NaBH ₄ (6 g / l
1), a roughening surface 34a was formed on the surface of the lower conductor circuit 34 (FIG. 12).
(C)).

(3) Next, the resin film for an interlayer resin insulating layer prepared in the above A was laminated by vacuum-compression bonding at 0.5 MPa while heating to a temperature of 50 to 150 ° C. Was formed (see FIG. 12D). Further, a through-hole 35 having a diameter of 300 μm is formed on the substrate 30 to which the resin film layer 50α is attached by drilling.
Was formed (see FIG. 12E).

(4) Next, on the resin film layer 50α,
Through a mask in which a 1.2 mm thick through hole is formed,
Using a CO ₂ gas laser with a wavelength of 10.4 μm, a beam diameter of 4.0 mm, a top hat mode, and a pulse width of 8.0 μ
Under the condition of a diameter of the through-hole of the mask of 1.0 mm and one shot, an opening 52 for a via hole having a diameter of 80 μm was formed in the resin film layer 50α to form an interlayer resin insulating layer 50 (see FIG. 13A). .

(5) The substrate in which the via hole opening 52 was formed was immersed in a solution containing 60 g / l of permanganic acid at 80 ° C. for 10 minutes, and the wall surface of the through-hole 35 was subjected to desmear treatment. By dissolving and removing the epoxy resin particles present on the surface of the insulating layer 50, the surface including the inner wall surface of the via hole opening 52 has a roughened surface 50a,
52a was formed (see FIG. 13B).

(6) Next, the substrate after the above treatment was immersed in a neutralizing solution (manufactured by Shipley) and washed with water. Further, by applying a palladium catalyst to the surface of the substrate which has been subjected to the surface roughening treatment (roughening depth: 3 μm), the surface of the interlayer resin insulating layer 50 (including the inner wall surface of the via hole opening 52), and A catalyst nucleus was attached to the wall surface of the through hole 35 (not shown). That is, palladium chloride (Pb)
The catalyst was applied by immersion in a catalyst solution containing Cl ₂ ) and stannous chloride (SnCl ₂ ) to precipitate palladium metal.

(7) Next, the substrate is immersed in an electroless copper plating aqueous solution having the following composition, and the surface of the interlayer resin insulating layer 50 (including the inner wall surface of the via hole opening 52) and
An electroless copper plating film 42 having a thickness of 0.6 to 3.0 μm was formed on the wall surface of the through hole 35 (see FIG. 13C). [Electroless plating aqueous solution] NiSO ₄ 0.003 mol / l tartaric acid 0.200 mol / l copper sulfate 0.030 mol / l HCHO 0.050 mol / l NaOH 0.100 mol / l α, α'-bipyridyl 100 mg / l Polyethylene glycol (PEG) 0.10 g / l [Electroless plating conditions] 40 minutes at a liquid temperature of 34 ° C

(8) Next, a commercially available photosensitive dry film is attached to the substrate on which the electroless copper plating film 42 has been formed.
A mask was placed and exposed at 100 mJ / cm ² .
By developing with an 8% aqueous sodium carbonate solution,
A plating resist 43 having a thickness of 20 μm was provided (FIG. 13).
(D)).

(9) Then, the substrate was washed with water at 50 ° C., degreased, washed with water at 25 ° C., further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions. An electrolytic copper plating film 44 having a thickness of 20 μm was formed on the formation portion (see FIG. 13E). [Electroplating solution] Sulfuric acid 2.24 mol / l Copper sulfate 0.26 mol / l Additive 19.5 ml / l (Atotech Japan, Capparaside GL) [Electroplating conditions] Current density 1 A / dm ² hours 65 minutes Temperature 22 ± 2 ℃

(10) Next, 5% of plating resist 43
After stripping and removing with KOH, the electroless plating film under the plating resist 43 is dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide, and the through holes 36 and
The upper conductor circuit 45 (including the via hole 46) was formed (see FIG. 14A).

(11) Next, the substrate 30 on which the through holes 36 and the like are formed is immersed in an etching solution,
6, and upper layer conductor circuit (including via hole 46)
Roughened surfaces 36a and 46a were formed on the surface of FIG.
(B)). As an etching solution, Mech etch bond manufactured by Mec Co. was used.

(12) Next, after the resin composition for filling a through hole described in the above A is prepared, the wall surface thereof is formed within the through hole 36 and one side of the substrate within 24 hours after preparation by the following method. Filler 4 in via hole 46
0 and 54 layers were formed. That is, first, the resin composition for filling a through hole was pushed into the through hole using a squeegee, and then dried at 100 ° C. for 20 minutes. Next, a mask having an opening corresponding to the via hole 46 is placed on the substrate, and a resin composition for filling a through hole is filled in the via hole 46 using a squeegee. Drying was performed. Further, similarly, the resin composition for filling a through-hole was also filled in the via hole 46 on the other surface of the substrate (see FIG. 14C).

(13) Next, buffing is performed on both surfaces of the substrate after the processing of the above (12), and the resin fillers 40 and 54 exposed from the through holes 36 and the via holes 46 are formed.
The surface of the layer was flattened. Then at 100 ° C. for 1 hour,
By performing a heat treatment at 150 ° C. for 1 hour, the layers of the resin fillers 40 and 54 were cured (see FIG. 14D).

(14) Next, a palladium catalyst (not shown) is applied to the surface of the interlayer resin insulation layer 50 and the exposed surfaces of the resin fillers 40 and 54 by performing the same treatment as in the above (6). did. Next, an electroless plating process is performed under the same conditions as in the above (7), and the electroless plating film 5 is formed on the surface of the interlayer resin insulating layer 50 and the exposed surfaces of the resin fillers 40 and 54.
No. 6 was formed (see FIG. 15A).

(15) Next, a plating resist having a thickness of 20 μm was provided on the electroless plating film 56 by the same method as in the above (8) (not shown). Furthermore, the above (9)
Electroplating was performed under the same conditions as described above to form an electroplated film 57 in the portion where the plating resist was not formed. Thereafter, the plating resist and the electroless plating film 56 existing thereunder are removed, and a lid plating layer 58 composed of the electroless plating film 56 and the electrolytic plating film 57 is formed on the through holes 36 and the via holes 46. It was formed (see FIG. 15B).

(16) Next, a roughened surface 58a was formed on the surface of the lid plating layer 58 by using the etching solution (mech etch bond) used in the above (11) (see FIG. 15C). (17) Next, by repeating the above steps (3) to (7), an upper interlayer resin insulation layer 60 and a conductor circuit (including via holes 66) are further formed, and a multilayer wiring board is obtained ( FIG. 15D). In this step, no through hole was formed.

(18) Next, an opening for forming a solder bump was formed in the same manner as (16) and (17) in Example 1, and a solder resist layer 60 having a solder pad 66 was formed on the bottom surface. (See FIGS. 16A to 16C).
The opening diameter of the solder bump forming opening was 80 μm, and the distance between adjacent solder bump forming openings was 150 μm.
It is.

(19) Thereafter, the solder resist layer 14
A mask having an opening having a diameter of 90 μm was placed on a portion opposed to all the openings for forming solder bumps, and solder paste was printed on the openings for forming the concave solder bumps using a piston press-fit printing machine. . The solder paste filled here mainly contains solder having a particle size of 5 to 20 μm in which Sn: Ag is blended in a weight ratio of 96.5: 3.5.
The viscosity was adjusted to 200 Pa · s. Further, after printing the solder paste, the solder paste layer on the solder resist layer 14 is coated with a roller made of fluororesin by 0.3 mm.
By pressing with a pressing force of MPa, the openings for forming solder bumps were completely filled with the solder paste, and voids in the openings for forming solder bumps were removed.

(20) Next, of the solder paste filled in the above step (19), the portion of the solder paste raised from the surface of the solder resist layer was removed by using a stainless steel squeegee to fill the solder paste. The surface of the solder paste was flattened, and the surface of the solder paste was made flush with the surface of the solder resist layer. Further, the filled solder paste was reflowed at 250 ° C.

(21) A mask having an opening having a diameter of 100 μm is placed on one side of the solder resist layer 14 at a portion facing all the openings for forming solder bumps, and soldering is performed using a press-fitting press of a piston type. A solder paste layer was formed by printing the paste. The solder paste filled here was Sn: Ag in a weight ratio of 96.5: 3.5.
Containing mainly solder having a particle size of 5 to 20 μm, the viscosity of which is adjusted to 250 Pa · s.

On the other side of the solder resist layer 14, a solder paste layer of Sn: Sb = 95.0: 5.0 was formed in the same manner as described above, and the conductive pins 78 were attached.

(22) Thereafter, the solder paste layer formed in the above step (21) is reflowed at 260 ° C., and is further subjected to flux cleaning, whereby solder bumps and P
A multilayer printed wiring board provided with a GA (Pin Grid Array) was obtained (see FIG. 17).

(Example 3) (18) to (18) in Example 1
A multilayer printed wiring board was manufactured in the same manner as in Example 1 except that the following steps (1) to (4) were performed instead of the step (21). (1) After performing the steps (1) to (17) of Example 1,
A solder paste was applied to the entire surface of the solder resist layer 14 by using a rubber printing squeegee having a hardness of 90 °, and the solder paste was completely filled in the concave solder bump forming openings. The solder paste filled here is
It mainly contains solder having a particle size of 5 to 20 μm, in which Sn: Ag is blended at a weight ratio of 96.5: 3.5, and its viscosity is adjusted to 200 Pa · s. Further, after printing the solder paste, a pressing member made of a fluororesin is pressed against the entire surface of the solder resist layer 14 with a pressing force of 0.5 MPa for 5 seconds, and the solder bump forming openings are completely filled with the solder paste. An opening for forming a solder bump and voids around the opening were removed.

(2) Next, of the solder pastes applied in the above step (1), solder pastes other than the solder paste filled in the openings for forming the solder bumps are first removed using a stainless steel squeegee. After that, the surface of the filled solder paste was flattened by completely removing the surface with a cleaning paper, and the surface of the solder paste was made flush with the surface of the solder resist layer.

(3) A mask having an opening having a diameter of 100 μm is placed on the solder resist layer 14 at a portion facing all the openings for forming solder bumps, and the solder paste is applied by a press-fitting press of a piston type. A solder paste layer was formed by printing. The solder paste filled here mainly contains solder having a particle size of 5 to 20 μm in which Sn: Ag is blended in a weight ratio of 96.5: 3.5, and the viscosity thereof is adjusted to 250 Pa · s. It is.

(4) Thereafter, the solder paste printed in the above steps (1) to (3) is reflowed at 250 ° C., and is further subjected to flux cleaning to obtain a multilayer printed wiring board having solder bumps. (See FIG. 11C).

(Example 4) (19) to (19) in Example 2
A multilayer printed wiring board was manufactured in the same manner as in Example 2 except that the following steps (1) to (4) were performed instead of the step (22). (1) After performing the steps (1) to (18) in Example 2,
A solder paste was applied to the entire surface of the solder resist layer 14 by using a rubber printing squeegee having a hardness of 90 °, and the solder paste was completely filled in the concave solder bump forming openings. The solder paste filled here is
It mainly contains solder having a particle size of 5 to 20 μm, in which Sn: Ag is blended at a weight ratio of 96.5: 3.5, and its viscosity is adjusted to 200 Pa · s. Further, after printing the solder paste, the solder paste layer on the solder resist layer 14 is coated with a 0.3M
By pressing with a pressing force of Pa, the openings for forming solder bumps were completely filled with the solder paste, and voids around the openings for forming solder bumps and the periphery thereof were removed.

(2) Next, of the solder paste applied in the above step (1), the solder paste other than the solder paste filled in the openings for forming the solder bumps is first removed using a stainless steel squeegee. After that, the surface of the filled solder paste was flattened by completely removing the surface with a cleaning paper, and the surface of the solder paste was made flush with the surface of the solder resist layer. Further, the filled solder paste was reflowed at 250 ° C.

(3) Next, a mask having an opening having a diameter of 100 μm is placed on one surface of the solder resist layer 14 at a portion facing all the openings for forming solder bumps, and the solder paste is applied by a press-fitting press of a piston type. A solder paste layer was formed by printing. The solder paste filled here mainly contains solder having a particle size of 5 to 20 μm in which Sn: Ag is blended in a weight ratio of 96.5: 3.5, and the viscosity thereof is adjusted to 250 Pa · s. It is.

On the other side of the solder resist layer 14, a solder paste layer of Sn: Sb = 95.0: 5.0 was formed in the same manner as described above, and the conductive pins 78 were attached.

(4) Thereafter, the solder paste layer formed in the above step (3) is reflowed at 260 ° C., and further, is subjected to flux cleaning, so that the solder bumps and PGA are removed.
(Pin Grid Array) was obtained (see FIG. 17).

(Example 5) (18) to (18) in Example 1
A multilayer printed wiring board was manufactured in the same manner as in Example 1 except that the following steps (1) to (4) were performed instead of the step (21). (1) After performing the steps (1) to (17) of Example 1,
A mask is placed on the solder resist layer 14 and has a hardness of 90.
Use a rubber printing squeegee to print the solder paste, completely fill the concave solder bump opening with solder paste, and place the solder paste on the solder resist layer around the solder bump opening. A layer 1517 was formed (see FIG. 5A). In addition, (1)-of Example 1
An opening for forming a solder bump formed by performing the same process as (17) has a 150 × 10 mm area.
About 5,000 solder bumps are formed at an interval of μm, and a region in which about 5,000 solder bump forming openings are formed becomes a solder bump. In this embodiment, there are a plurality of solder bump areas.

In this step, a mask having a size of about 10 × 10
The one having an opening formed in a portion facing a 15 × 15 mm area that is 5 mm larger per side than a 10 mm solder bump area was used. Therefore, the mask used in the present embodiment has a plurality of openings formed in a portion facing the solder bump area. In addition, the solder paste filled here contains mainly solder having a particle size of 5 to 20 μm in which Sn: Ag is blended in a weight ratio of 96.5: 3.5, and the viscosity thereof is adjusted to 200 Pa · s. It is. further,
After printing the solder paste, a pressing member made of fluororesin is applied on the entire surface of the solder resist layer 14 for 0.5 seconds at 0.5MP.
Pressing was performed with the pressing force of a to completely fill the solder bump forming openings with the solder paste, and also removed the solder bump forming openings and the voids around the openings.

(2) Next, of the solder paste applied in the above step (1), the solder paste other than the solder paste filled in the openings for forming the solder bumps is first removed using a stainless steel squeegee. After that, the surface of the filled solder paste was flattened by completely removing the surface with a cleaning paper, and the surface of the solder paste was made flush with the surface of the solder resist layer.

(3) Next, a mask having an opening of 100 μm in diameter is placed on the solder resist layer 14 at a portion facing all the openings for forming solder bumps, and the solder paste is applied by a press-fitting press of a piston type. A solder paste layer was formed by printing. The solder paste filled here mainly contains solder having a particle size of 5 to 20 μm in which Sn: Ag is blended in a weight ratio of 96.5: 3.5, and the viscosity thereof is adjusted to 250 Pa · s. It is.

(4) Thereafter, the solder paste printed in the above steps (1) to (3) is reflowed at 250 ° C., and is further subjected to flux washing to obtain a multilayer printed wiring board having solder bumps. (See FIG. 11C).

(Example 6) (19) to (19) in Example 2
A multilayer printed wiring board was manufactured in the same manner as in Example 2 except that the following steps (1) to (4) were performed instead of the step (22). (1) After performing the steps (1) to (18) in Example 2,
A mask is placed on the solder resist layer 14 and has a hardness of 90.
Use a rubber printing squeegee to print the solder paste, completely fill the concave solder bump forming openings with the solder paste, and place the solder paste on the solder resist layer around the solder bump forming openings. A layer 1517 was formed (see FIG. 5A). In addition, (1)-of Example 2
An opening for forming a solder bump formed by performing the same process as (18) has a size of 150 mm in an area of 10 × 10 mm.
About 5,000 solder bumps are formed at an interval of μm, and a region in which about 5,000 solder bump forming openings are formed becomes a solder bump. In this embodiment, there are a plurality of solder bump areas.

In this step, a mask having a size of about 10 × 10
The one having an opening formed in a portion facing a 15 × 15 mm area that is 5 mm larger per side than a 10 mm solder bump area was used. Therefore, the mask used in the present embodiment has a plurality of openings formed in a portion facing the solder bump area. The solder paste filled here mainly contains solder having a particle size of 5 to 20 μm in which Sn: Ag is blended at a weight ratio of 96.5: 3.5, and has a viscosity adjusted to 200 Pa · s. It is. further,
After printing the solder paste, the solder resist layer 14 is pressed with a pressing force of 0.3 MPa using a roller made of a fluororesin to completely fill the solder bump forming opening with the solder paste and to form the solder bump forming opening. And voids around it.

(2) Next, of the solder paste applied in the above step (1), the solder paste other than the solder paste filled in the openings for forming the solder bumps is first removed using a stainless steel squeegee. Thereafter, the surface of the filled solder paste was flattened by completely removing the surface using a cleaning paper, and the surface of the solder paste was made flush with the surface of the solder resist layer.
Further, the filled solder paste was reflowed at 250 ° C.

(3) A mask having an opening having a diameter of 100 μm is placed on one surface of the solder resist layer 14 at a portion facing all the openings for forming solder bumps, and the solder paste is applied by a press-fitting press of a piston type. Was printed to form a solder paste layer. The solder paste filled here mainly contains solder having a particle size of 5 to 20 μm in which Sn: Ag is blended in a weight ratio of 96.5: 3.5.
The viscosity was adjusted to 250 Pa · s.

On the other side of the solder resist layer 14, a solder paste layer of Sn: Sb = 95.0: 5.0 was formed in the same manner as described above, and the conductive pins 78 were attached.

(4) After that, the solder paste layer formed in the above step (3) is reflowed at 260 ° C., and further, is subjected to flux cleaning, so that the solder bumps and PGA are removed.
(Pin Grid Array) was obtained (see FIG. 17).

(Example 7) In Example 1, (16)
In step (3), an opening for forming a solder bump having an opening diameter of 100 μm is formed, and in step (18), Sn: Ag is added in a weight ratio of 9.
6.5: Mainly particle size 5 to 20 μm blended at 3.5
A multilayer printed wiring board was manufactured in the same manner as in Example 1 except that the solder paste was filled with a solder paste whose viscosity was adjusted to 250 Pa · s.

(Eighth Embodiment) In the second embodiment, (18)
In step (3), an opening for forming a solder bump having an opening diameter of 100 μm was formed, and in step (19), Sn: Ag was added in a weight ratio of 9.
6.5: Mainly particle size 5 to 20 μm blended at 3.5
A multilayer printed wiring board was manufactured in the same manner as in Example 2, except that the solder paste was filled with a solder paste whose viscosity was adjusted to 250 Pa · s.

Example 9 In Example 3, after forming an opening for forming a solder bump having an opening diameter of 100 μm in the step (1), Sn: Ag was blended in a weight ratio of 96.5: 3.5. A multilayer printed wiring board was manufactured in the same manner as in Example 3, except that the solder paste mainly containing solder having a particle size of 5 to 20 μm and having a viscosity adjusted to 250 Pa · s was filled.

(Embodiment 10) In Embodiment 4, (1)
After forming an opening for forming a solder bump having an opening diameter of 100 μm in the step, Sn: Ag was added in a weight ratio of 96.5: 3.5.
A multilayer printed wiring board was manufactured in the same manner as in Example 4, except that the solder paste mainly containing solder having a particle size of 5 to 20 μm and having a viscosity adjusted to 250 Pa · s was filled.

(Example 11) In Example 5, (1)
After forming an opening for forming a solder bump having an opening diameter of 100 μm in the step, Sn: Ag was added in a weight ratio of 96.5: 3.5.
A multilayer printed wiring board was manufactured in the same manner as in Example 5, except that the solder paste mainly containing solder having a particle size of 5 to 20 μm and having a viscosity adjusted to 250 Pa · s was filled.

(Example 12) In Example 6, (1)
After forming an opening for forming a solder bump having an opening diameter of 100 μm in the step, Sn: Ag was added in a weight ratio of 96.5: 3.5.
A multilayer printed wiring board was produced in the same manner as in Example 6, except that the solder paste mainly containing solder having a particle size of 5 to 20 μm and having a viscosity adjusted to 250 Pa · s was filled.

(Comparative Example 1) (18) to (2) of Example 1
In place of the step 1), 1
A multilayer printed wiring board was manufactured in the same manner as in Example 1, except that a solder paste layer was formed by repeated solder paste printing and solder bumps were formed by reflow. Specifically, the following steps were performed.

That is, a mask having an opening having a diameter of 100 μm was placed on a portion of the solder resist layer on which the solder pads were formed and opposed to all the openings for forming solder bumps. Solder paste was printed on the openings for forming solder bumps, and a solder paste layer for forming solder bumps was formed. Thereafter, the solder paste layer was reflowed at 250 ° C., and further, flux cleaning was performed to obtain a multilayer printed wiring board having solder bumps. In addition, as the solder paste, (1) in Example 1 was used.
The same one used in the step 8) was used.

(Comparative Example 2) (19) to (2) of Example 2
In place of the step 2), 1
A multilayer printed wiring board was manufactured in the same manner as in Example 2 except that a solder paste layer was formed by repeated solder paste printing and solder bumps were formed by reflow. Specifically, the following steps were performed.

That is, a mask having an opening having a diameter of 100 μm was placed on a portion of the solder resist layer on which the solder pads had been formed, opposite to all the openings for forming solder bumps. Solder paste was printed on the openings for forming solder bumps, and a solder paste layer for forming solder bumps was formed. Then, Sn: Sb = 9
A conductive pin is attached to one side of the substrate on which a 5.0: 5.0 solder paste layer is formed.
After reflowing at 60 ° C., flux washing was performed to obtain a multilayer printed wiring board having solder bumps and PGA. The same solder paste as that used in the step (21) of Example 2 was used.

Regarding the multilayer printed wiring boards obtained in Examples 1 to 12 and Comparative Examples 1 and 2, the presence or absence of contamination on the surface of the solder resist layer, the presence or absence of voids in the solder bumps, and the shape and height of the solder bumps were determined. The performance evaluation before and after the observation and the reliability test was performed using the following evaluation methods. Table 1 shows the results
It was shown to.

[0242]Evaluation method  (1) Existence of voids in solder bumps, shape of solder bumps
Height The part of the multilayer printed wiring board where the solder bumps are formed
Is observed with X-rays to evaluate the presence or absence of voids.
Measure the height of the solder bump from the dist layer and observe the shape
did. The shape is hemispherical
Is indicated by ○, and the other is indicated by ×.

(2) Reliability test After leaving for 1000 hours under the condition of 135 ° C. and 85% relative humidity, the following conduction test was performed, and the printed wiring board was cut at the portion where the solder bumps were formed and soldered. The state of the bump was observed.も の indicates that there was no difference from the reliability test, and X indicates that cracks and the like were observed.

(3) Continuity Test After the multilayer printed wiring board was manufactured, a continuity test was performed before and after the above-described reliability test, and the continuity state was evaluated from the results displayed on the monitor. A sample without a short circuit or disconnection was evaluated as ○, and a sample with a short circuit or disconnection was evaluated as ×.

[0245]

[Table 1]

As shown in Table 1, in the multilayer printed wiring boards of Examples 1 to 12, no void was observed in the solder bump, the height and shape of the solder bump were substantially uniform, and the surface of the solder resist layer was Nor was it contaminated with solder paste. Further, there was no short circuit between the solder bumps, and there was no problem in the continuity test before and after the reliability test, and no crack, peeling, etc. were found after the reliability test. Also, when the viscosity of the solder paste to be printed in the second solder paste printing step is sequentially changed in the range of 150 to 350 Pa · s, and the solder bumps are formed using the same method as in the first embodiment, the desired shape is obtained. Could be formed.

On the other hand, in the multilayer printed wiring board of Comparative Example 1, since only a low-viscosity solder paste was printed in one printing step, no void was formed in the solder bumps, but the height was also increased. Compared to No. 1, the variation was large and the shape was not uniform. Further, the surface of the solder resist layer was contaminated with the solder paste. It was presumed that this was because the solder paste wrapped around the back side of the mask during printing. Regarding the continuity test, there was no particular problem after the formation of the solder bumps, but after the reliability test, disconnection and short-circuit occurred. Further, when the cross section of the solder bump at the portion where the disconnection was confirmed was observed, cracking and peeling occurred.

Further, in the multilayer printed wiring board of Comparative Example 2, since only a high-viscosity solder paste was printed in one printing step, the surface of the solder resist layer was hardly contaminated, but the solder bumps were hardly contaminated. Had many voids formed, and the height was more uneven than in Example 2, and the shape was not uniform. Regarding the continuity test, there was no particular problem after the formation of the solder bumps, but after the reliability test, disconnection and short-circuit occurred. Also, when the cross section of the solder bump at the portion where the disconnection was confirmed was observed, it was found that
Many cracks and peeling occurred in comparison with. This was assumed to have been induced by voids in the solder bumps.

[0249]

Since the first to third methods for manufacturing a multilayer printed wiring board of the present invention have the above-described structure, they have a uniform shape and height, have no defects such as voids, and Thus, a solder bump without short-circuit can be formed, and a printed wiring board excellent in connectivity and reliability can be manufactured.

[Brief description of the drawings]

1 (a) to 1 (d) are partial cross-sectional views schematically showing steps (a) to (d) in a first method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 2A and 2B are partial cross-sectional views schematically showing an example of a method of printing a solder paste in the first method of manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 3A to 3D are partial cross-sectional views schematically showing steps (a) to (d) in a second method for manufacturing a multilayer printed wiring board according to the present invention.

FIG. 4A is a plan view schematically showing an example of a multilayer printed wiring board manufactured by the manufacturing method of the third invention, and FIG. 4B is a plan view showing the multilayer printed wiring board shown in FIG. FIG.

FIGS. 5A to 5D are partial cross-sectional views schematically showing steps (a) to (d) in a third method of manufacturing a multilayer printed wiring board according to the present invention.

FIG. 6 is a plan view schematically showing a part of the steps of the method for manufacturing a multilayer printed wiring board according to the third invention.

FIGS. 7A to 7D are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 8A to 8D are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 9A to 9D are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 10A to 10C are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 11A to 11C are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 12A to 12E are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 13A to 13E are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 14A to 14D are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 15A to 15D are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 16A to 16C are cross-sectional views illustrating some of the steps of the method for manufacturing a multilayer printed wiring board according to the present invention.

FIG. 17 is a cross-sectional view schematically showing one example of a multilayer printed wiring board obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 1, 30 Substrate 8, 32 Copper foil 4, 34 Lower conductor circuit 9, 36 Through hole 6, 52 Via hole opening 12, 42 Thin film conductor layer (electroless plating film) 3, 43 Plating resist 13, 44 Electroplating film 2, 50 interlayer resin insulation layer 10, 54 resin filler 58 lid plating layer 14, 70 solder resist layer 17, 76 solder bump 78 conductive pin

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E319 AC01 BB04 BB05 CD29 GG05 5E346 AA02 AA04 AA12 AA15 AA29 AA32 AA43 CC04 CC09 CC10 CC14 CC40 CC52 CC55 DD03 DD13 DD25 EE19 EE20 FF01 FF18 FF23 FF27 GG25 GG19 GG45 HH11

Claims (8)

[Claims] 1. After laminating an interlayer resin insulating layer and a conductive circuit on a substrate on which a conductive circuit is formed, a solder resist layer having a plurality of solder bump forming openings is provided on the uppermost conductive circuit. A method for manufacturing a multilayer printed wiring board, wherein a solder paste is formed by printing a solder paste in the opening for forming a solder bump, the method comprising:
A method for manufacturing a multilayer printed wiring board, comprising performing the step (d). (A) a first solder paste printing step in which solder paste is printed one or more times and a solder paste is filled in a concave solder bump forming opening, and (b) the entire surface of the solder paste layer on the solder resist layer Or a solder paste pressing step of pressing a part of the surface, (c) a solder paste flattening step of flattening the surface of the solder paste filled through the steps (a) and (b), and
(D) A second solder paste printing step in which the solder paste is printed one or more times. 2. In the first solder paste printing step, a solder paste is printed on the solder resist layer after a mask having an opening at a portion opposite to the solder bump forming opening is placed on the solder resist layer. 2. The method for manufacturing a multilayer printed wiring board according to 1. 3. A method according to claim 1, wherein an interlayer resin insulating layer and a conductive circuit are laminated on the substrate on which the conductive circuit is formed, and a solder resist layer having a plurality of solder bump forming openings is provided on the uppermost conductive circuit. A method of manufacturing a multilayer printed wiring board, wherein a solder paste is printed on the solder bump forming opening to form a solder bump, the method comprising:
A method for manufacturing a multilayer printed wiring board, comprising performing the step (d). (A) a first solder paste printing step in which solder paste is applied to the entire surface of the solder resist layer by one or more times of solder paste printing, and the solder paste is filled into openings for forming solder bumps; A solder paste pressing step of pressing the entire surface or a part of the surface of the solder paste layer on the layer, (c) removing the solder paste other than the solder paste filled in the opening for forming the solder bump, and removing the solder paste surface and the solder resist. A solder paste removing step of making the surface of the layer substantially flush with the surface, and (d) a second solder paste printing step of printing the solder paste one or more times. 4. After laminating an interlayer resin insulating layer and a conductor circuit on a substrate on which a conductor circuit is formed, a solder resist layer having a plurality of solder bump forming openings is provided on the uppermost conductor circuit. A method for manufacturing a multilayer printed wiring board, wherein a solder paste is formed by printing a solder paste in the opening for forming a solder bump, the method comprising:
A method for manufacturing a multilayer printed wiring board, comprising performing the step (d). (A) a first solder paste printing step of printing a solder paste at least once in a predetermined area including a plurality of solder bump forming openings on the solder resist layer and filling the solder bump forming openings with the solder paste; (B) a solder paste pressing step of pressing the entire surface or a part of the surface of the solder paste layer on the solder resist layer; (c) removing a solder paste other than the solder paste filled in the opening for forming the solder bump; A solder paste removing step of making the surface of the solder resist layer and the surface of the solder resist layer substantially flush with each other, and (d) a second solder paste printing step of performing one or more solder paste printings. 5. In the first solder paste printing step, after placing a mask having an opening on a portion facing a predetermined region including a plurality of solder bump forming openings on the solder resist layer, Claim 4
3. The method for producing a multilayer printed wiring board according to item 1. 6. In the second solder paste printing step, a solder paste is printed after placing a mask having an opening at a portion facing the solder bump forming opening on the solder resist layer. Any one of 1 to 5
3. The method for producing a multilayer printed wiring board according to item 1. 7. The method according to claim 1, wherein the viscosity of the solder paste printed in the first solder paste printing step is lower than the viscosity of the solder paste printed in the second solder paste printing step. A method for producing the multilayer printed wiring board according to the above. 8. In the first solder paste printing step, in the first solder paste printing, the solder paste is applied to such an extent that only the solder bump forming opening having a recess on the bottom surface is filled with the recess. The method according to any one of claims 1 to 7, wherein the solder paste is applied to the entire surface of the solder resist layer so as to completely fill the concave solder bump forming opening by printing the second solder paste. The method for producing a printed wiring board according to the above.