JP2013004919A - Printed wiring board and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board having a solder resist layer which has an opening shape in which an excellent solder bump can be formed, and to provide a manufacturing method therefor.SOLUTION: The printed wiring board has: an interlayer insulating layer; a conductive pattern formed on the interlayer insulating layer; a solder resist layer that is provided on the interlayer insulating layer and the conductive pattern, and has an opening part from which at least one part of the conductive pattern is exposed; and a solder bump which is formed in the inner part of the opening part. The shape of the opening part is a teardrop shape in plan view or an n-angled shape (n≥3) in plan view.

Description

The present invention relates to a printed wiring board and a manufacturing method thereof.

In general, in a printed wiring board, a conductor pattern and an interlayer insulating layer are sequentially laminated on a substrate, and then a solder resist layer is formed on the outermost layer in order to protect these conductor circuits. When forming the solder bump, a part of the solder resist layer is opened for connection with the conductor circuit, and the solder bump forming pad is exposed. Thereafter, flux is applied to the opening and a solder ball is supplied, and then reflow is performed to form a solder bump.

In recent years, with the demand for electronic component miniaturization, it has been required to reduce the thickness of the entire printed wiring board. Further, in order to ensure contact with the printed wiring board, it is necessary to increase the height of the solder bumps compared to the thickness of the solder resist layer, and the thickness of the solder resist layer is becoming thinner.
Furthermore, in order to respond to the demands for downsizing electronic components, the distance between solder bumps on the printed wiring board connected to the IC chip is reduced as the wiring of the IC chip becomes higher and the wiring width becomes narrower. It is coming. In response to this, it is required that the interval between the solder bump forming pads be narrowed, and thus the opening of the solder resist layer be reduced. In response to this, Patent Document 1 discloses a technique for forming a minute opening with a laser inside a solder resist layer.

JP-A-2005-57298

However, when the solder resist layer is made thinner and the opening of the solder resist layer is made smaller, when the solder ball is supplied by applying flux to the opening of the solder resist layer, the inner wall of the opening and the above The distance between the side surfaces of the solder balls is extremely small. In such a printed wiring board, a space for flux to escape is not ensured during reflow, and the solder ball is in a floating state. As a result, the contact area between the solder ball and the solder bump forming pad is reduced, and there is a possibility that the solder bump is not properly formed.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a printed wiring board having an opening shape capable of forming a good solder bump on a solder resist layer and a method for manufacturing the same. .

In order to achieve the above object, a printed wiring board according to claim 1 is provided on an interlayer insulating layer, a conductor pattern formed on the interlayer insulating layer, the interlayer insulating layer, and the conductor pattern. A printed wiring board having a solder resist layer having an opening exposing at least a part of the conductor pattern and a solder bump formed inside the opening, wherein the shape of the opening is a plane It is a visual tear drop shape or a planar view n-corner shape (n ≧ 3).

When solder bumps are formed by reflow, for example, using solder balls at the openings of the printed wiring board having such a shape, the solder balls melt in the openings and the flux is gasified after liquefaction, Its volume expands. However, the opening is configured in a plan view teardrop shape or a plan view n-corner shape (n ≧ 3).
In this case, an escape path for the liquefied or gasified flux is secured, and the flux can easily escape to the outside (for example, the surface of the solder ball) via the escape path without lifting the solder ball or blowing off the solder ball. It is speculated that it can be done. Therefore, the contact area between the solder ball melted at the time of reflow and the solder bump forming pad is increased, and the molten solder ball is solidified in a state where the molten solder ball is securely in contact with the solder bump forming pad. As a result, the solder bump is appropriately formed on the solder bump forming pad without moving the solder ball from the opening.
For example, when solder bumps are formed by screen printing, the solder self-alignment performance is exhibited and the solder bumps can be appropriately formed on the pads.

In the printed wiring board according to claim 2, the shape of the opening has a protruding portion protruding in a predetermined direction, and the protruding portion protrudes in a direction different from the most adjacent opening.
As a result, it is presumed that a space between the solder bump forming pads is secured, and it is possible to prevent the solder ball from flowing in the direction of the protruding portion and causing a short circuit.

In the printed wiring board according to claim 3, the solder bump is formed using a solder ball.
When solder bumps are formed using solder balls, it is possible to easily form solder bumps having a uniform height.

In the printed wiring board according to claim 4, when the solder ball is mounted in the opening, the narrowest space between the surface of the solder ball and the inner wall of the opening is on the same plane as the upper surface of the solder resist layer. The gap is 4 μm or more.
If the narrowest gap between the surface of the solder ball and the inner wall of the opening on the same plane as the upper surface of the solder resist layer is 4 μm or more, the gap serves as a flux escape path during reflow. It is possible to easily escape through the gap. As a result, the solder balls are solidified in a state where they are securely in contact with the solder bump forming pads, and the solder bumps can be appropriately formed on the solder bump forming pads.
If the gap is less than 4 μm, a sufficient flux escape path is not ensured during reflow, and the flux may remain between the solder balls and the solder pads. As a result, the contact area between the solder ball and the solder bump forming pad cannot be increased, and it becomes difficult to appropriately form the solder bump on the solder bump forming pad.

In the printed wiring board according to claim 5, the length of the longest opening diameter of the opening in plan view is 110 to 150% of the diameter of the solder ball.
When the length of the longest opening diameter of the opening in plan view is 110 to 150% of the diameter of the solder ball, a sufficient distance is secured between the inner wall of the opening and the side surface of the solder ball. Therefore, the flux can easily escape to the outside during reflow. As a result, the solder balls are solidified in a state where they are securely in contact with the solder bump forming pads, and the solder bumps can be appropriately formed on the solder bump forming pads.
When the length of the longest opening diameter of the opening in plan view is less than 110% of the diameter of the solder ball, the distance between the inner wall of the opening and the side surface of the solder ball is narrow, and reflow At this time, a sufficient escape path for the flux is not secured, and the flux may remain between the solder ball and the solder pad. As a result, the contact area between the solder ball and the solder bump forming pad cannot be increased, and it becomes difficult to appropriately form the solder bump on the solder bump forming pad.
When the length of the longest opening diameter of the opening in plan view exceeds 150% of the diameter of the solder ball, the volume of the opening becomes excessively large, and the height of the solder bump to be formed is sufficiently increased. It becomes difficult to ensure.

In the printed wiring board according to claim 6, the thickness of the solder resist layer is 15 to 40% of the length of the longest opening diameter of the opening in plan view.
Since the thickness of the solder resist layer relative to the size of the solder ball to be used can be sufficiently secured when the thickness of the solder resist layer is 15 to 40% of the length of the opening diameter in plan view, reflow Sometimes the solder ball is difficult to move out of the opening, and the missing bump can be prevented.
If the thickness of the solder resist layer is less than 15% of the length of the opening diameter in plan view, the solder resist layer is too thin with respect to the size of the solder ball to be used, and the solder ball is reflowed. Becomes easier to move out of the opening and missing bumps are more likely to occur.
When the thickness of the solder resist layer exceeds 40% of the length of the opening diameter in plan view, the thickness of the solder resist layer becomes thick and the volume of the opening becomes excessively large. It is difficult to ensure sufficient thickness.

In the printed wiring board according to claim 7, the projecting portion in plan view has a corner portion configured by a curve.
If the contour of the corner of the protruding portion is configured by a curve, the temperature of the printed wiring board rises and thermal stress at the corner is easily relieved even when thermal stress is generated. As a result, it is possible to suppress the cracks starting from such corners from being formed on the solder bumps.

9. The printed wiring board according to claim 8, wherein the opening is formed around a solder ball housing portion for housing the solder ball, and a flux outflow portion from which flux flows out during reflow. And have.
When solder bumps are formed by reflow using solder balls in the openings of the printed wiring board having such a structure, the solder balls are melted in the openings and the flux is gasified after liquefaction. It is assumed that the volume expands. However, since the opening is composed of a solder ball housing portion and a flux outflow portion, the flux outflow portion becomes a escape route for the gasified flux and easily escapes to the outside via the flux outflow portion. Can do. Therefore, the contact area between the solder ball melted during reflow and the solder bump forming pad is increased, and the solder ball is solidified in a state where the solder ball is securely in contact with the solder bump forming pad. As a result, it is possible to appropriately form solder bumps on the solder bump forming pads.

In the printed wiring board according to claim 9, the flux outflow portion is the protruding portion.
Therefore, it is possible to easily escape the flux to the outside via the protruding portion.

The method for manufacturing a printed wiring board according to claim 10, wherein the interlayer insulating layer, the conductor pattern formed on the interlayer insulating layer, the interlayer insulating layer and the conductor pattern are provided on the conductor pattern. A solder resist layer having an opening that exposes at least a part thereof, and a solder bump formed inside the opening, and the shape of the opening is a teardrop shape in plan view or an n-square shape in plan view (n ≧ 3) A method of manufacturing a printed wiring board, wherein the step of forming the interlayer insulating layer, the step of forming the conductor pattern on the interlayer insulating layer, the layer insulating layer and the conductor pattern And forming a solder resist layer having an opening exposing at least a part of the conductor pattern, and applying a flux to the inside of the opening to form a solder ball. After feeding, characterized in that it comprises a step of forming a solder bump performs a reflow.

In the method for manufacturing a printed wiring board according to the tenth aspect, the same effect as in the first aspect can be obtained.

It is sectional drawing which shows typically the printed wiring board of 1st embodiment of this invention. (A) is a top view which shows typically a planar view tear drop-shaped opening part in the printed wiring board which concerns on 1st embodiment of this invention, (b) is a planar view tier shown to (a). It is a top view which shows typically the soldering resist layer which has a drop-shaped opening part, (c) is AA sectional view taken on the line AA of the planar-view tear drop-shaped opening part shown to (a). (A)-(d) is sectional drawing which shows typically the manufacturing method of the printed wiring board which concerns on 1st embodiment of this invention. (A)-(d) is sectional drawing which shows typically the manufacturing method of the printed wiring board which concerns on 1st embodiment of this invention. (A)-(d) is sectional drawing which shows typically the manufacturing method of the printed wiring board which concerns on 1st embodiment of this invention. (A)-(d) is sectional drawing which shows typically the manufacturing method of the printed wiring board which concerns on 1st embodiment of this invention. (A) And (b) is sectional drawing which shows typically the manufacturing method of the printed wiring board which concerns on 1st embodiment of this invention. (A) is a top view which shows typically a planar view square-shaped opening part in the printed wiring board which concerns on 2nd embodiment of this invention, (b) is a planar view square shape shown to (a). It is a top view which shows typically the soldering resist layer which has this opening part. In the printed wiring board concerning a third embodiment of the present invention, it is a top view showing typically a plane view hexagonal opening. In the printed wiring board concerning a first embodiment of the present invention, it is a top view showing typically an opening of shapes other than tear-drop shape in a plane view.

Hereinafter, embodiments of the present invention will be specifically described. However, the present invention is not limited to the following embodiments, and can be applied with appropriate modifications without departing from the scope of the present invention.

(First embodiment)
Hereinafter, a first embodiment which is an embodiment of a printed wiring board and a manufacturing method thereof according to the present invention will be described.

First, the printed wiring board which concerns on 1st embodiment of this invention is demonstrated.
The printed wiring board according to the present embodiment is provided with an interlayer insulating layer, a conductor pattern formed on the interlayer insulating layer, the interlayer insulating layer and the conductor pattern, and at least a part of the conductor pattern. A printed wiring board having a solder resist layer having an opening exposing the solder and a solder bump formed inside the opening, wherein the shape of the opening is a teardrop shape in plan view And

FIG. 1 is a cross-sectional view schematically showing the printed wiring board of the first embodiment.
In the printed wiring board 10 of the first embodiment shown in FIG. 1, the conductor pattern 12 and the lower interlayer insulating layer 20 are formed on both surfaces of the insulating substrate 11. The conductor patterns 12 formed on both surfaces of the insulating substrate 11 are electrically connected by through-hole conductors 16a.
A conductor pattern 24 is formed on the lower interlayer insulating layer 20. The conductor pattern 24 and the conductor pattern 12 formed on the insulating substrate 11 are connected via a via conductor 22 inside the lower interlayer insulating layer 20. An interlayer insulating layer 30 is formed on the lower interlayer insulating layer 20 and the conductor pattern 24. A conductor pattern 34 is formed on the interlayer insulating layer 30. The conductor pattern 34 and the conductor pattern 24 are connected via a via conductor 32 inside the interlayer insulating layer 30. A solder resist layer 40 having an opening is disposed on the interlayer insulating layer 30 and the conductor pattern 34.
Further, a solder bump forming pad 34a is formed in a portion of the conductor pattern 34 exposed from the opening of the solder resist layer 40, and a solder bump 46 is formed on the solder bump forming pad 34a. In the solder bump forming pad 34a, for example, a Ni plating layer, a Pd plating layer, and a gold plating layer are formed on a conductor pattern 34 made of a material such as copper, and a solder bump 46 is formed thereon. Yes.
Here, the solder bumps 46 are preferably formed using solder balls.

In the present embodiment, the shape of the opening of the solder resist layer 40 is a teardrop shape in plan view.
Therefore, the shape of the planar view teardrop shape will be specifically described.

FIG. 2A is a plan view schematically showing an opening having a teardrop shape in plan view in the printed wiring board according to the first embodiment of the present invention, and FIG. 2B is a plan view of FIG. It is a top view which shows typically the soldering resist layer which has a planar-view teardrop-shaped opening part to show, FIG.2 (c) is the sectional view on the AA line of the planar-view teardrop-shaped opening part shown to (a) FIG. 2A and 2B show the shape of the boundary between the upper surface of the solder resist layer and the opening.

As shown in FIG. 2A, the plan view tear-drop shape refers to a shape including a circular portion 202 and a protruding portion 201 protruding outward from the circular portion 202. Note that the circular portion 202 includes an elliptical shape.
The protrusion 201 has a substantially triangular shape obtained by adding the semicircular portion 202a of the circular portion 202 to the protrusion 201.
Here, as for the protrusion part 201, it is desirable that the outline of the corner | angular part 204 is comprised from the curve.
Further, it is desirable that the protruding portion 201 protrudes in a predetermined direction, and it is more preferable that the protruding portion 201 protrudes in a direction different from the most adjacent opening as shown in FIG.

The length of the longest opening diameter of the teardrop-shaped opening (indicated by a double arrow X1 in FIG. 2A) is preferably 110 to 150% of the diameter of the solder ball.
Further, the thickness of the solder resist layer is desirably 15 to 40% of the length of the longest opening diameter (indicated by a double-headed arrow X1 in FIG. 2A) of the opening portion having a teardrop shape in plan view. .

As shown in FIG. 2 (c), the teardrop-shaped opening in plan view is formed around the solder ball housing portion for accommodating the solder ball and the solder ball housing portion, and the flux flows out during reflow. It is desirable to have an outflow part.
Here, it can be considered that the solder ball housing portion for housing the solder ball 203 corresponds to the circular portion 202 and the flux outflow portion corresponds to the protruding portion 201 in the opening having a teardrop shape in plan view.

The narrowest gap between the surface of the solder ball and the inner wall of the opening on the same plane as the upper surface of the solder resist layer when the solder ball is mounted on the opening having a teardrop shape in plan view (FIG. 2C) Among them, indicated by a double arrow Y1) is preferably 4 μm or more, and more preferably 4 μm or more and 10 μm or less.
With such a shape and size, the gap becomes an escape route for the flux during reflow, so that the flux can easily escape through the gap. As a result, the solder ball and the solder pad come into reliable contact.

In this embodiment, as a material constituting the solder resist composition, for example, a material containing a resin such as polyphenylene ether resin, polyolefin resin, fluororesin, thermoplastic elastomer, epoxy resin, polyimide resin, and inorganic filler is used. Can be mentioned.
Moreover, as a material which comprises the soldering resist composition other than the above, for example, (meth) acrylate of novolak type epoxy resin, imidazole curing agent, bifunctional (meth) acrylic acid ester monomer, molecular weight of about 500 to 5000 ( Examples thereof include a paste-like fluid containing a polymer of a (meth) acrylic acid ester, a thermosetting resin composed of a bisphenol type epoxy resin, a photosensitive monomer such as a polyvalent acrylic monomer, a glycol ether solvent, and the like.
Moreover, when forming the layer of a soldering resist composition, you may press-bond the film which consists of the said soldering resist composition, and may form the layer of a soldering resist composition.
Moreover, the thickness of a soldering resist layer is 10-20 micrometers, and the diameter (maximum diameter) of an opening part is 45-60 micrometers.

Next, the manufacturing method of the printed wiring board which concerns on 1st embodiment of this invention is demonstrated in order of a process.
3 (a) to (d), FIGS. 4 (a) to (d), FIGS. 5 (a) to (d), FIGS. 6 (a) to (d), FIGS. 1 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to a first embodiment of the present invention.

(1) First, as shown in FIG. 3A, an insulating substrate 11 is prepared. The insulating substrate is not particularly limited, and examples thereof include a glass epoxy substrate, a bismaleimide-triazine (BT) resin substrate, a copper clad laminate, a resin substrate such as an RCC substrate, a ceramic substrate such as an aluminum nitride substrate, and a silicon substrate. Can be mentioned. FIG. 3A shows a copper clad laminate having a copper foil 110.

(2) Next, as shown in FIG. 3 (b), a through hole 16 is formed in the central portion of the insulating substrate 11 using a drill.
The through hole 16 can also be formed using a laser. In this case, the through holes 16 are formed by irradiating laser from both surfaces of the insulating substrate 11.

(3) Next, the insulating substrate 11 is impregnated with an electroless plating solution to form an electroless plating film 122 on the surface of the insulating substrate 11 and the inner walls of the through holes 16. Subsequently, the insulating substrate 11 is impregnated with an electrolytic plating solution to form an electrolytic plating film 124 on the surface of the insulating substrate and the inner wall of the through hole 16.

In this step, a through-hole conductor 16a for connecting the conductor patterns 12 'sandwiching the insulating substrate 11 is simultaneously formed in the through-hole 16 (see FIG. 3C).
Further, after forming the conductor pattern, the insulating substrate 11 is immersed in a blackening bath (oxidation bath) and roughened to form a roughened surface on the conductor pattern 12 'and the through-hole conductor 16a. (See FIG. 3D). Here, the roughened surface is formed by the blackening reduction treatment, but the roughened surface can also be provided by etching or electroless plating.

(4) Next, printing is performed in which a filler containing an epoxy resin and an inorganic filler is applied to both surfaces of the insulating substrate 11 using a printing machine. The printing is preferably performed by a vacuum printing method performed in a reduced pressure atmosphere or a vacuum atmosphere.
By the above printing, the through hole 16 is filled with a filler, and then heat drying is performed. That is, by this process, the filler layer 15 is formed inside the through hole 16 (see FIG. 4A).
The filler preferably contains a leveling agent or the like in addition to the resin and the inorganic filler.

(5) Further, electroless plating and electrolytic plating are performed to form a plating film 126 on the insulating substrate 11 (see FIG. 4B).

(6) Thereafter, an etching resist 128 is formed on the plating films 126 on both sides (see FIG. 4C), and the conductor pattern 12 is formed on both sides of the substrate by etching (see FIG. 4D). .

(7) Next, the insulating substrate 11 on which the conductor pattern 12 is formed is washed with water and dried. Subsequently, an etching solution is sprayed on both surfaces of the insulating substrate 11 to spray the surface of the conductor pattern 12 and the surface of the cover plating 120 of the through hole 16, thereby forming the surface of the conductor pattern 12 and the through hole 16. The surface of the lid plating 120 is roughened.
This etching can be performed, for example, by immersing or spraying in an etching solution composed of a cupric complex and an organic acid salt, hydrogen peroxide and sulfuric acid.

(8) Next, a thermosetting resin sheet is vacuum-bonded and laminated on both surfaces of the insulating substrate 11 that has undergone the above-described steps while being heated to a temperature of 50 to 150 ° C. to provide a lower interlayer insulating layer 20 (FIG. 5 ( a)).

(9) Next, opening processing by laser processing, exposure, development processing, or the like is performed to provide a via conductor opening 220 in the lower interlayer insulating layer 20 (see FIG. 5B). After providing the via conductor opening 220, it is preferable to perform a desmear process.

(10) Next, the surface of the lower interlayer insulating layer 20 is roughened using a permanganic acid solution (see FIG. 5C). Thereafter, electroless plating is performed to form, for example, an electroless plating film 222 on the surface of the lower interlayer insulating layer 20 (see FIG. 5D).

(11) A pattern of plating resist 70 is formed on both surfaces of the substrate after the above processing (see FIG. 6A), and electrolytic plating is performed to form an electrolytic plating film 224 (see FIG. 6B). ).
By the formation of the electrolytic plating film 224, the thickness of the portion that becomes the conductor pattern 24 and the filling of the plating that becomes the portion of the via conductor 22 are performed in the steps described later.

(12) Next, after the plating resist 70 is peeled and removed, the electroless plating film 222 existing under the plating resist 70 is dissolved and removed by etching to form a conductor pattern 24 (such as an electrolytic copper plating film 224). A via conductor 22 is formed (see FIG. 6C).

(13) Subsequently, the steps (6) to (12) are repeated to further form the interlayer insulating layer 30 and the conductor pattern 24 (including the via conductor 32) (see FIG. 6D).

A part or all of the outermost conductor pattern 34 of the conductor pattern 24 formed through such a process becomes a solder bump forming pad 34a. Therefore, by forming the outermost conductor pattern 34, the solder bump forming pad 34a is simultaneously formed.

(14) Next, the solder resist layer 40 is formed on both surfaces of the substrate on which the interlayer insulating layer 30 and the conductor pattern 24 (including the via conductor 32) are formed, and solder bumps are formed on the solder resist layer 40. An opening 420 is formed (see FIG. 7A).
Specifically, a solder resist composition is applied on the interlayer insulating layer 30 including the outermost conductor pattern 34 by a roll coater method or the like, and subjected to an opening treatment by laser treatment, exposure, development treatment, etc., and a curing treatment or the like. To form a solder resist layer 40 having an opening at a predetermined position.

(15) Subsequently, the Ni plating layer 422 and the gold plating layer 424 are formed in the opening 420 to form the solder bump forming pad 34a (see FIG. 7B).

(16) Finally, a solder ball is mounted on the opening 420 of the solder resist layer 40 and solder bumps 46 are formed by reflowing at a predetermined temperature to complete the printed wiring board 10 (see FIG. 1). At this time, since the solder bump forming pad 34a has a teardrop shape in plan view, the solder bump 46 is appropriately formed on the solder bump forming pad 34a without moving the solder ball from the opening of the solder resist layer 40. It is formed.

Hereinafter, effects of the printed wiring board and the printed wiring board manufacturing method according to the first embodiment of the present invention will be listed.

(1) In the printed wiring board according to the first embodiment of the present invention, the shape of the opening formed on the solder resist layer is a teardrop shape in plan view.
When solder bumps are formed by reflow, for example, using solder balls at the openings of the printed wiring board having such a shape, the solder balls melt in the openings and the flux is gasified after liquefaction, Its volume expands. However, the opening has a teardrop shape in plan view.
In this case, an escape path for the liquefied or gasified flux is secured, and the flux can easily escape to the outside (for example, the surface of the solder ball) via the escape path without lifting the solder ball or blowing off the solder ball. It is speculated that it can be done. Therefore, the contact area between the solder ball melted at the time of reflow and the solder bump forming pad is increased, and the molten solder ball is solidified in a state where the molten solder ball is securely in contact with the solder bump forming pad. As a result, the solder bump is appropriately formed on the solder bump forming pad without moving the solder ball from the opening.
For example, when solder bumps are formed by screen printing, the solder self-alignment performance is exhibited and the solder bumps can be appropriately formed on the pads.

(2) In the printed wiring board according to the first embodiment of the present invention, the shape of the opening has a protruding portion protruding in a predetermined direction, and the protruding portion is different from the most adjacent opening. Sticks out. As a result, it is presumed that a space between the solder bump forming pads is secured, and it is possible to prevent the solder ball from flowing in the direction of the protruding portion and causing a short circuit.

(3) In the printed wiring board according to the first embodiment of the present invention, the solder bump is formed using a solder ball. As a result, it is possible to easily form solder bumps having a uniform height.

(4) In the printed wiring board according to the first embodiment of the present invention, when the solder ball is mounted in the opening, the surface of the solder ball and the inner wall of the opening are flush with the upper surface of the solder resist layer. The narrowest gap between them is 4 μm or more. As a result, at the time of reflow, the gap becomes an escape route for the flux, so that the flux can easily escape through the gap. Therefore, it is possible to solidify the solder balls in a state where they are securely in contact with the solder bump forming pads, and to appropriately form the solder bumps on the solder bump forming pads.

(5) The length of the longest opening diameter of the opening in plan view is 110 to 150% of the diameter of the solder ball. As a result, a sufficient distance between the inner wall of the opening and the side surface of the solder ball is secured, so that the flux can easily escape to the outside during reflow. Therefore, it is possible to solidify the solder balls in a state where they are securely in contact with the solder bump forming pads, and to appropriately form the solder bumps on the solder bump forming pads.

(6) In the printed wiring board according to the first embodiment of the present invention, the thickness of the solder resist layer is 15 to 40% of the length of the longest opening diameter of the opening in plan view. As a result, the thickness of the solder resist layer with respect to the size of the solder ball to be used can be sufficiently secured, so that it is difficult for the solder ball to move out of the opening during reflow, and missing bumps can be prevented.

(7) In the printed wiring board according to the first embodiment of the present invention, the projecting portion in plan view has a contour of a corner portion formed by a curve. As a result, even when the temperature of the printed wiring board rises and thermal stress is generated, the thermal stress at the corners is easily relaxed. As a result, it is possible to suppress the cracks starting from such corners from being formed on the solder bumps.

(8) In the method for manufacturing a printed wiring board according to the first embodiment of the present invention, the same effect as in the first aspect can be obtained.

(Second embodiment)
Hereinafter, a second embodiment which is an embodiment of the printed wiring board and the manufacturing method thereof of the present invention will be described.

First, the printed wiring board which concerns on 2nd embodiment of this invention is demonstrated.
The printed wiring board according to the present embodiment is provided with an interlayer insulating layer, a conductor pattern formed on the interlayer insulating layer, the interlayer insulating layer and the conductor pattern, and at least a part of the conductor pattern. A printed wiring board having a solder resist layer having an opening that exposes and a solder bump formed inside the opening, wherein the shape of the opening is a square shape in plan view To do.

FIG. 8A is a plan view schematically showing an opening having a square shape in plan view in the printed wiring board according to the second embodiment of the present invention, and FIG. 8B is shown in FIG. It is a top view which shows typically the soldering resist layer which has a square-shaped opening part by planar view. 8A and 8B show the shape of the boundary between the upper surface of the solder resist layer and the opening.

The printed wiring board according to the second embodiment of the present invention is the same as the printed wiring board according to the first embodiment except that the shape of the opening of the solder resist layer to be formed is a square shape in plan view.
Therefore, only the quadrangular shape in plan view will be specifically described, and description of other parts will be omitted.

The regular square includes an inscribed circle that is inscribed in each side of the regular square, and the opening of the solder resist layer 40 has a circular portion 302 and a circular portion 302 as shown in FIG. It can be considered that it consists of four projecting portions 301a to 301d projecting outward.
Here, as for protrusion part 301a-301d, it is desirable for the outline of corner | angular part 304a-304d to be comprised from the curve.
The protrusions 301a to 301d preferably protrude in a predetermined direction, and more preferably protrude in a direction different from the most adjacent opening as shown in FIG.

Also in this embodiment, the same operational effects as the operational effects (1) to (8) described in the first embodiment of the present invention can be exhibited.

(Third embodiment)
Hereinafter, a third embodiment which is an embodiment of the printed wiring board and the manufacturing method thereof of the present invention will be described.

First, a printed wiring board according to a third embodiment of the present invention will be described.
The printed wiring board according to the present embodiment is provided with an interlayer insulating layer, a conductor pattern formed on the interlayer insulating layer, the interlayer insulating layer and the conductor pattern, and at least a part of the conductor pattern. A printed wiring board having a solder resist layer having an opening that exposes a solder bump and a solder bump formed inside the opening, wherein the shape of the opening is a hexagonal shape in plan view. To do.

FIG. 9 is a plan view schematically showing a hexagonal opening in a plan view in the printed wiring board according to the third embodiment of the present invention. In FIG. 9, the shape of the boundary between the upper surface of the solder resist layer and the opening is shown.

The printed wiring board according to the third embodiment of the present invention is the same as the printed wiring board according to the first embodiment except that the shape of the opening of the solder resist layer to be formed is a hexagonal shape in plan view.
Therefore, only the hexagonal shape in plan view will be specifically described, and description of other parts will be omitted.

The regular hexagon includes an inscribed circle inscribed in each side of the regular hexagon, and the opening of the solder resist layer 40 is also outward from the circular portion 402 and the circular portion 402 as shown in FIG. It can be considered that it consists of six projecting portions 401a to 401f protruding to the surface.
Here, as for protrusion part 401a-401f, it is desirable for the outline of corner | angular part 404a-404f to be comprised from the curve.

Also in this embodiment, the same operational effects as the operational effects (1) to (8) described in the first embodiment of the present invention can be exhibited.

(Other embodiments)
In the first embodiment of the present invention described above, as an example of the opening formed in the solder resist layer 40, the opening in the shape of a teardrop in the plan view including the circular portion 202 and the protruding portion 201 protruding outward from the circular portion. However, it is not limited to these. For example, as shown in FIG. 10, the shape may include a circular portion 502 having a relatively large diameter and a projecting portion 501 formed of a circular having a relatively small diameter. The circular portion 502 and the circular projecting portion 501 include an elliptical shape.

In the second embodiment and the third embodiment of the present invention described above, as an example of an opening having an n-square shape (n ≧ 3) in plan view formed in the solder resist layer 40, a square shape in plan view or a hexagonal shape in plan view. Although the opening is formed, it is not limited to these, and may be, for example, a triangular shape in plan view, a pentagonal shape in plan view, or the like.

In the embodiment described above, the roughened surface is formed on the conductor pattern 12 ′, the through-hole conductor 16a, and the lower interlayer insulating layer 20, but either the conductor pattern 12 ′, the through-hole conductor 16a, or the lower interlayer insulating layer 20 is used. One or more roughened surfaces may be formed, or no roughened surface may be formed in any of them.

In the embodiment described above, the Ni plating layer 422 and the thickness gold plating layer 424 are formed in the opening 420, but the total number of the coating layers is not limited to two, and may be one. Three or more layers may be used.
A plurality of plating layers may be formed in the opening 420 by sequentially plating Ni, Pd, and Au.

When the openings of the lower interlayer insulating layer, the upper interlayer insulating layer and the solder resist layer are formed by laser processing, examples of the laser used for the laser processing include a carbon dioxide laser, an ultraviolet laser, and an excimer laser. It is done.

DESCRIPTION OF SYMBOLS 10 Printed wiring board 12 Conductor pattern 12 'Conductor pattern 20 Lower interlayer insulation layer 24 Conductor pattern 30 Interlayer insulation layer 34 Conductor pattern 34a Solder bump formation pad 40 Solder resist layer 46 Solder bump 420 Opening 201, 301a-301d, 401a- 401f, 501 Protruding portion 202, 302, 402, 502 Circular portion 203, 303, 403 Solder ball 204, 304a to 304d, 404a to 404f Corner portion

Claims (10)

An interlayer insulation layer;
A conductor pattern formed on the interlayer insulating layer;
A solder resist layer provided on the interlayer insulating layer and the conductor pattern, and having an opening that exposes at least a part of the conductor pattern;
A printed wiring board having a solder bump formed inside the opening,
The shape of the opening is a teardrop shape in plan view or an n-corner shape in plan view (n ≧ 3). The printed wiring board according to claim 1, wherein the shape of the opening has a protruding portion protruding in a predetermined direction, and the protruding portion protrudes in a direction different from the most adjacent opening. The printed wiring board according to claim 1, wherein the solder bump is formed using a solder ball. The narrowest gap between the surface of the solder ball and the inner wall of the opening on the same plane as the upper surface of the solder resist layer when the solder ball is mounted in the opening is 4 μm or more. The printed wiring board as described. The printed wiring board according to claim 3, wherein a length of the longest opening diameter of the opening in a plan view is 110 to 150% of a diameter of the solder ball. 2. The printed wiring board according to claim 1, wherein a thickness of the solder resist layer is 15 to 40% of a length of the longest opening diameter of the opening in a plan view. The printed wiring board according to claim 1, wherein the projecting portion in plan view has a corner portion configured by a curve. 4. The printed wiring according to claim 3, wherein the opening includes a solder ball housing portion that houses the solder ball, and a flux outflow portion that is formed around the solder ball housing portion and from which flux flows out during reflow. Board. The printed wiring board according to claim 8, wherein the flux outflow portion is the protruding portion. An interlayer insulation layer;
A conductor pattern formed on the interlayer insulating layer;
A solder resist layer provided on the interlayer insulating layer and the conductor pattern, and having an opening that exposes at least a part of the conductor pattern;
Consisting of solder bumps formed inside the opening,
A method of manufacturing a printed wiring board in which the shape of the opening is a plan view teardrop shape or a plan view n-corner shape (n ≧ 3),
Forming the interlayer insulating layer;
Forming the conductor pattern on the interlayer insulating layer;
Forming a solder resist layer having an opening exposing at least a part of the conductor pattern on the interlayer insulating layer and the conductor pattern;
A method of manufacturing a printed wiring board, comprising: applying flux inside the opening and supplying solder balls; and reflowing to form solder bumps.

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