JPH11204940A - Laminated board, bga board and manufacture of laminated board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize linear formation and a small diameter for via conductors. SOLUTION: A copper foil is bonded to one side of a thermosetting insulating resin sheet 27 by hot pressing, and the copper foil is photo-etched to linearly form a pattern of a plurality of via conductors 28. After this, multiple insulating resin sheets 27 are stacked and integrated by vacuum thermocompression. After the laminate of the insulating resin sheets 27 is cut to board sizes, the top and bottom cut surfaces or both sides of a board are polished, thereby forming a laminated board 26. The bonded surface between the individual insulating resin sheets 27 in this laminated board 26 is perpendicular to the board surface. After a core sheet 22 is bonded to the bottom of the laminated board 26, solder resist patterns 29 and 30 are respectively formed on the top of the laminated board 26 and the bottom of the core sheet 22. Then, a solder ball is bonded to the bottom of the core sheet 22, thereby forming a BGA(Ball Grid Array) board 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated substrate, a BGA substrate, and a method for manufacturing a laminated substrate, in which a method for forming a via conductor is improved.

[0002]

2. Description of the Related Art With the recent increase in performance and miniaturization of IC chips, increasing the wiring density and increasing the number of pins of a substrate on which the IC chip is mounted have become important technical issues. Current,
An example of a high-density mounting board that has been put into practical use is a build-up multilayer board. This is, as shown in FIG.
An epoxy-based photosensitive insulating resin layer 12 is formed on both surfaces or one surface of a glass epoxy substrate 11 serving as a core substrate, and a via hole 13 is formed in the photosensitive insulating resin layer 12 by a photo-etching method. Then, the inner conductor pattern 14 and the via conductor 15 are formed, and thereafter, the same steps are sequentially repeated to form a multilayer.

[0003]

In the above build-up multilayer substrate, the via conductor 15 is hollow because the via conductor 15 is formed by copper plating. For this reason, it is impossible to connect the via conductor 15 in a straight line between the layers, and it is necessary to route the wiring pattern for each layer to shift the position of the via conductor 15 to the side.
The miniaturization of the diameter of 3) also has a limit due to the necessity of spreading the plating solution.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and accordingly, it is an object of the present invention to provide a laminated substrate which is capable of linearizing and miniaturizing a via conductor, and which can cope with high density and multi-pin. , A BGA substrate and a method of manufacturing a laminated substrate.

[0005]

In order to achieve the above-mentioned object, the present invention relates to an insulating resin comprising a plurality of insulating resins laminated, wherein a bonding surface between the insulating resins is perpendicular to a substrate surface. Insulating resin is laminated so as to form a via conductor with a wiring pattern formed on one or both sides of each insulating resin (claim 1). In this way, by laminating such that the bonding surface between the insulating resins is perpendicular to the substrate surface, it becomes possible to form a via conductor with the wiring pattern formed on each insulating resin, and a conventional via hole is used. Unlike the via conductor forming method, it is possible to make the via conductor straight and small in diameter.

In this case, a core substrate is joined to the lower surface of the laminated substrate according to the present invention, and solder balls are arranged in line on the lower surface of the core substrate. A BGA (Ball Grid Array) substrate may be formed in which conductors are conducted through through holes formed in the core substrate. In this way, even if the thickness of the insulating resin varies,
The position accuracy of the solder ball can be made accurate by the core substrate.

In the case of manufacturing the laminated substrate of the present invention, after forming a wiring pattern for a via conductor on one or both surfaces of a plurality of insulating resins, the plurality of insulating resins are formed. It is preferable to laminate a resin, cut the resin into a substrate size, and polish the cut surface to form a laminated substrate.
In this way, even if there is a lamination shift between the insulating resins, the substrate surface (cut surface) of the laminated substrate can be reliably flattened. Further, if a large number of laminated substrates are cut from one insulating resin laminated body, it becomes possible to mass-produce the laminated substrates by an extremely easy operation of cutting.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. First, the structure of the BGA substrate 21 will be described with reference to FIGS. Core substrate 22
Is a single-layer or multi-layer substrate formed of, for example, a glass epoxy substrate, a BT (bismaleimide triazine) epoxy substrate, or the like, and a through hole 23 penetrating vertically is formed at a predetermined position thereof. The through-hole conductor 25 and the conductor pattern 24 are formed by electrolytic plating, electrolytic plating, or the like.

On the upper surface of the core substrate 22, the laminated substrate 2
6 are joined by an adhesive, a conductive paste or the like.
The laminated substrate 26 is formed by laminating a plurality of thermosetting insulating resin sheets 27 formed by prepreg or the like by thermocompression bonding.
The joining surface between them is a right angle. Each insulating resin sheet 27
On one side, a pattern of a plurality of via conductors 28 is formed in a straight line by a printed wiring technique. Solder resist patterns 29 and 30 are formed on the upper surface of the laminated substrate 26 and the lower surface of the core substrate 22, respectively. A large number of solder balls (not shown) are joined to the lower surface of the core substrate 22, and each solder ball is electrically connected to the via conductor 28 on the laminated substrate 26 via the through-hole conductor 25 of the core substrate 22. It is connected.

A procedure for manufacturing the BGA substrate 21 configured as described above will be described. First, a copper foil is hot-pressed and joined to one surface of a thermosetting insulating resin sheet 27 (prepreg). This hot pressing is performed, for example, at 130 ° C. for one hour so that the curing of the insulating resin sheet 27 is suppressed halfway. According to the experimental results of the inventor (see FIG. 3), 1
It has been confirmed that the necessary copper foil peel strength (the bonding strength between the copper foil and the insulating resin sheet 27) can be sufficiently ensured by hot pressing at 30 ° C.

After hot pressing, a photosensitive resist is applied to the entire surface of the copper foil with a spin coater, and dried (prebaked) at, for example, 100 ° C. for 7 minutes. Then, only the via conductor pattern forming portion of the photosensitive resist is exposed (3
00mj), immersed in an alkali developing solution for, for example, 1 minute, and developed, and then post-baked at, for example, 120 ° C. for 7 minutes. Thereafter, a portion of the copper foil exposed from the photosensitive resist (that is, a portion other than the via conductor pattern) is removed by etching with an alkaline etchant, and then the photosensitive resist is peeled off with acetone. Thereby, the pattern of the plurality of via conductors 28 is formed in the insulating resin sheet 27 in a straight line.

In the next laminating step, a plurality of insulating resin sheets 27 with via conductors 28 are superposed,
For 8 hours under vacuum, and thermocompression-bonding and unifying the plurality of insulating resin sheets 27 while curing them.

Thereafter, the laminated body of the insulating resin sheet 27 is cut into a substrate size by dicing, and the upper and lower cut surfaces, that is, both surfaces of the substrate are polished to form a laminated substrate 26. Note that the number of the laminated substrates 26 cut from the laminated body of the insulating resin sheets 27 may be one, but may be plural. If a large number of laminated substrates 26 are cut out from the same laminated body of the insulating resin sheets 27, the laminated substrates 26 can be mass-produced by an extremely easy operation of cutting.

On the other hand, a through hole 23 is formed in the core substrate 22 in advance, and a through hole conductor 25 and a conductor pattern 24 are formed by electroless plating, electrolytic plating, or the like.
Then, after bonding the laminated substrate 26 to the upper surface of the core substrate 22 with an adhesive, a conductive paste, or the like, the laminated substrate 26
Are formed on the lower surface of the core substrate 22 and the upper surface of the core substrate 22, respectively. Thereafter, solder balls are bonded to the lower surface of the core substrate 22 to form the BGA substrate 21.
To form

The formation of the through holes 23 in the core substrate 22 may be performed after the core substrate 22 is joined to the laminated substrate 26. In this case, first, the core substrate 22
After the laminated substrate 26 is bonded to the upper surface of the through hole 2 with an adhesive, the through-hole 2 is
Form 3 Thereafter, the through-hole conductor 25 is formed by electroless plating and electrolytic plating, and the through-hole conductor 25 and the via conductor 28 on the side of the laminated substrate 26 are conducted. At this time, a plating film is formed on the entire lower surface of the core substrate 22 simultaneously with the plating of the through holes 23. afterwards,
The plating film is photo-etched to form a conductor pattern.

Thereafter, a photosensitive solder resist is applied to the upper surface of the laminated substrate 26 and the lower surface of the core substrate 22 by printing, for example, to a thickness of, for example, 20 μm.
mj) and after development (sodium carbonate 1%), 1000 mj
UV curing and post baking (150 ° C., 1 hour). After that, pads are formed by performing electroless Ni plating and electroless Au plating, and then solder balls are bonded to the pads on the lower surface of the core substrate 22 to form the BGA substrate 21.

According to the embodiment described above, since the laminated substrate 26 is formed by laminating the insulating resin sheets 27 so that the joining surface between the insulating resin sheets 27 is perpendicular to the substrate surface, the laminated resin substrate 27 is formed on the insulating resin sheet 27. The via conductor 28 can be formed by a wiring pattern, and unlike the conventional via conductor forming method using via holes, the via conductor 28 can be straightened and reduced in diameter, and can be adapted to high density and multi-pin. .

Further, the core substrate 2 is provided on the lower surface of the laminated substrate 26.
Since the BGA substrate 21 is formed by bonding the BGAs 2, even if the thickness of the insulating resin sheet 27 varies, the positional accuracy of the solder balls on the lower surface of the core substrate 22 can be made accurate without being affected by the variation. And contribute to quality improvement. However, when the variation in the lamination thickness of the insulating resin sheet 27 is within the allowable range of the positional accuracy of the solder balls, the solder balls may be directly bonded to the lower surface of the lamination substrate 26 to form a BGA substrate. .

In the above embodiment, the laminated substrate 26 is formed by laminating a plurality of insulating resin sheets 27. However, the insulating resin layers may be formed one by one to build up.

In the above embodiment, all the via conductors 28 are formed in a straight line. However, a part of the via conductor 28 may be bent in accordance with the pitch of the solder balls. Also, the patterning method of the via conductor 28 is not limited to the above-described embodiment, and the via conductor can be patterned using various known printed wiring techniques. In the above embodiment, the via conductor 28 is patterned on one surface of the insulating resin sheet 27, but the via conductor 28 may be patterned on both surfaces of the insulating resin sheet 27.

In addition, the present invention can be implemented with various modifications, such as bonding the laminated substrate 26 to both surfaces of the core substrate 22 and using the laminated substrate 26 for applications other than the BGA substrate.

[0022]

As is apparent from the above description, the laminated substrate of the present invention is formed by laminating each insulating resin such that the bonding surface between the insulating resins is perpendicular to the substrate surface, and Since the via conductor is formed with the formed wiring pattern, the via conductor can be straightened and the diameter can be reduced.
The number of pins can be increased (claim 1).

Further, since the BGA substrate of the present invention is formed by bonding the core substrate to the lower surface of the laminated substrate having the above structure, the BGA substrate is not affected by the variation of the laminated thickness of the insulating resin sheet.
The position accuracy of the solder ball can be improved (claim 2).

In the method for manufacturing a laminated substrate according to the present invention,
Since the laminated body of the insulating resin is cut into a substrate size and the cut surface is polished to form a laminated substrate, it is possible to realize flattening of the substrate surface and improvement of mass productivity. ).

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a structure of a BGA substrate according to an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view schematically showing the structure of a BGA substrate.

FIG. 3 is a view showing an experimental result of measuring a relationship between a temperature and a peel strength when hot pressing a copper foil on an insulating resin sheet.

FIG. 4 is a cross-sectional view schematically showing the structure of a conventional build-up multilayer substrate.

[Explanation of symbols]

21 BGA board, 22 core board, 23 through-hole, 24 conductor pattern, 25 through-hole conductor, 2
6: laminated substrate, 27: insulating resin sheet, 28: via conductor, 29, 30: solder resist pattern.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/12 L

Claims (3)

[Claims] 1. A laminated board comprising a plurality of insulating resins laminated, wherein each insulating resin is laminated such that a bonding surface between the insulating resins is perpendicular to a substrate surface, and one side of each insulating resin or A laminated substrate having via conductors formed by wiring patterns formed on both surfaces. 2. A core substrate is joined to the lower surface of the laminated substrate according to claim 1, and solder balls are arranged in line on the lower surface of the core substrate, and the solder balls and via conductors on the laminated substrate side are connected to each other. A BGA substrate, wherein conduction is made through through holes formed in a core substrate. 3. The method of manufacturing a laminated substrate according to claim 1, wherein after forming a wiring pattern for a via conductor on one or both surfaces of the plurality of insulating resins, the plurality of insulating resins are laminated. A method of manufacturing a laminated substrate, comprising cutting the substrate to a substrate size and polishing the cut surface to form a laminated substrate.