JP2011100908A - Printed wiring board, and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a printed wiring board capable of suppressing warpage of the printed wiring board for improving a semiconductor element mounting yield and semiconductor package reliability. <P>SOLUTION: This method of manufacturing a printed wiring board for forming through-holes on a core board of the printed wiring board includes processes of: forming through-holes by emitting laser from one surface side of the core board; and forming other through-holes by emitting laser from the other surface side of the core board. Here, when the number of the through-holes formed by emitting the laser from the one side of the core board and the number of the through-holes formed by emitting the laser from the other surface side of the core board are denoted by A and B, respectively, the ratio of the number A of the through-holes to the number B of the through-holes in the printed wiring board is 0.2-5.0. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a printed wiring board and a semiconductor device.

With the recent demand for higher functionality and lighter, thinner and smaller electronic devices, high-density integration and further high-density mounting of electronic components have progressed. Semiconductor devices used in these electronic devices have been In addition, it is becoming thinner and smaller. (For example, refer to Patent Document 1.)
Due to the miniaturization and higher density of semiconductor devices, higher density is required for printed circuit boards.
In order to respond to this, the through holes arranged in these inner layers for conducting the conduction between the front and back surfaces are similarly increasing in density and diameter. As for the processing of the through hole, since there is a limit to reducing the diameter in the conventional method using a mechanical drill, recently, processing by a laser is applied instead. (For example, refer to Patent Document 2.) When a CO ₂ laser or a UV-YAG laser is used, through-hole processing, which has been limited to a diameter of 100 μm with a mechanical drill, can be performed with a smaller diameter.
In the case of a mechanical drill, if a small diameter machining with a diameter of about 100 μm is performed, the drill blade easily breaks, causing a problem in machining. However, in the case of laser machining, since consumable parts are not used, the machining is performed efficiently. be able to. Furthermore, through-hole processing with a small diameter can be performed, the interval between the through-holes can be narrowed, and as a result, the printed wiring board can be miniaturized.

JP 2003-179350 A JP 2007-227962 A

However, when through holes are formed by laser processing, the through holes have a so-called tapered shape in which the laser irradiation side surface has the maximum diameter and the laser transmission side surface has the minimum diameter.
Then, for example, when the laser is irradiated only from one direction, there is a problem that a difference in opening area between the front and back sides of the printed wiring board is large, and as a result, the warpage of the printed wiring board is increased. In particular, when the thickness of the printed wiring board is reduced, there is a problem that the strength is lowered and the warpage of the printed wiring board is increased.
In addition, the increase in the number of through holes accompanying the increase in density leads to a problem that the opening area is further increased and the warpage of the printed wiring board is further increased.
Furthermore, due to the influence of the warp of the printed wiring board, there is a problem in that a connection failure occurs due to a crack in a solder bump when a semiconductor element is mounted, resulting in a decrease in yield.
Further, in the temperature cycle test after mounting the semiconductor element, there is a problem that a crack due to stress occurs in the solder bump or the semiconductor element itself breaks.
The present invention has been made in view of the above circumstances, and aims to solve the problems in the prior art, and in particular, provides a printed wiring board with small warpage and a highly reliable semiconductor device using the printed wiring board. To do.

The object is achieved by the present invention described in the following items [1] to [5].
[1] A printed wiring board having a tapered through hole, wherein the printed wiring board has a tapered through hole (A) whose diameter decreases from the upper surface to the lower surface of the core substrate, and from the lower surface to the upper surface of the core substrate. A printed wiring board having a tapered through-hole (B) having a smaller diameter opposite to each other, wherein the ratio of the number of the through-holes (A) to the number of the through-holes (B) ((A) / (B)) It is 0.2 or more and 5.0 or less, The printed wiring board characterized by the above-mentioned.
[2] The through hole (A) is a through hole formed by laser irradiation from the upper surface of the core substrate, and the through hole (B) is formed by laser irradiation from the lower surface of the core substrate. The printed wiring board according to item [1], which is a through hole.
[3] The printed wiring board according to [1] or [2], wherein a diameter of a maximum diameter portion in the tapered shape of the through holes (A) and (B) is 10 μm or more and 200 μm or less.
[4] The print according to any one of [1] to [3], wherein the sum of the numbers of the through holes (A) and (B) is 10 to 12,000 on average per 1 cm ^{2 of} the printed wiring board. Wiring board.
[5] The absolute value of the difference between the opening area of the upper surface of the printed wiring board and the opening area of the lower surface is 4.5 mm ² or less per 1 cm ^{2 of} the printed wiring board, according to any one of [1] to [4] The printed wiring board as described.
[6] A semiconductor device comprising a semiconductor element mounted on the printed wiring board according to any one of [1] to [5].

  The printed wiring board according to the present invention has small warpage, and a semiconductor device using the printed wiring board is excellent in reliability.

It is a schematic diagram of the cross section of an example regarding the printed wiring board of this invention. It is sectional drawing which shows an example regarding the manufacturing method of the printed wiring board of this invention. It is sectional drawing which shows an example regarding the manufacturing method of the conventional printed wiring board.

The printed wiring board of the present invention has a tapered through hole (A) whose diameter decreases from the upper surface to the lower surface of the laminate, and a tapered through hole (B) whose diameter decreases from the lower surface to the upper surface of the laminate. A printed wiring board using a core substrate having a circuit formed on a laminated board, the ratio of the number of through holes (A) to the number of through holes (B) (hereinafter referred to as (A) / ( B) is sometimes 0.2 to 5.0, the warpage of the printed wiring board can be reduced, and the semiconductor device using the printed wiring board is excellent in reliability. . In addition, the yield of semiconductor element mounting is good when manufacturing semiconductor devices.
Hereinafter, embodiments of the printed wiring board and the semiconductor device of the present invention will be described in detail. However, it is not limited to these printed wiring boards.

An example of a printed wiring board is schematically shown in FIG.
The printed wiring board can be obtained by alternately forming conductor circuits and insulating layers on the core substrate 1.
Specifically, the laser beam is radiated to a predetermined portion of the laminated plate to form a through hole (A) and a through hole (B), and then a copper plating 3 is applied to the surface of the copper foil 2 to thereby increase the height of the conductor circuit. Is adjusted to a predetermined height, and the conductor circuit 4 having a predetermined circuit pattern is formed by etching, whereby the core substrate 1 can be obtained.
Next, insulating layers 5 are formed on the upper and lower sides of the core substrate 1, via holes 6 are formed in order to provide conduction between the upper and lower sides of the insulating layers, metal plating is formed in the via holes and on the upper surface of the insulating layers, and on the insulating layers. A printed wiring board can be obtained by forming a circuit.
In addition, the metal plating formation in the via hole 6 and the circuit formation on the surface of the insulating layer are performed by forming a metal layer by electroless plating, forming a circuit pattern using a resist, and performing copper plating 3 on the circuit pattern, It can be adjusted to a predetermined height and formed.

  Usually, the conductor circuit formed in the outermost layer of the printed wiring board is covered with a solder resist except for the portion where the electronic component is mounted.

  As the insulating layer, a metal foil such as a copper foil, a resin sheet obtained by laminating a resin layer on a supporting substrate such as a film, or a prepreg can be used.

The core substrate (FIG. 2 (5)) used for the printed wiring board of the present invention has a tapered through hole (a) (FIG. 2 (2)) whose diameter decreases from the upper surface to the lower surface, and from the lower surface to the upper surface. It has a taper-shaped through hole (b) (FIG. 2 (3)) in which the diameter of (A) / (B) is 0.2 or more and 5.0 or less.
The laminated plate 1 used for the core substrate is obtained by laminating two or more metal foils (for example, copper foil 2) and / or a film, or two or more prepregs on the upper and lower surfaces of one prepreg. A metal foil and / or film laminated on the upper and lower surfaces.

  A method for forming a through hole in a laminate is not particularly limited. For example, a method of processing by irradiating a laser beam directly on a metal foil or a film formed on a core substrate surface, and a core substrate surface For example, a method of etching a predetermined portion of the metal foil formed in a predetermined shape into a predetermined shape and irradiating the etched portion with a laser beam may be used.

As shown in FIG. 2 (2) or 2 (3), the through hole has a tapered shape (FIG. 2 (2)) in which the diameter decreases from the upper surface of the core substrate to the lower surface, or the lower surface of the core substrate. It has a tapered shape (FIG. 2 (3)) in which the diameter decreases from the top to the top.

In the tapered shape of the through hole, as shown in FIG. 2, the angles (θ _a , θ _b ) formed by the side surface and the small diameter side surface of the through hole are preferably 60 degrees or more and less than 90 degrees, and more preferably Is 70 degrees or more and less than 90. When it is less than the lower limit, the glass cloth cannot be burnt because the laser irradiation energy is small, and the glass cloth fiber may protrude from the wall surface in the through hole. Originally, it is preferably 90 degrees, but in this case, the laser irradiation energy increases, and fine through-holes cannot be formed. When the laser irradiation energy is large, the resin on the wall surface in the through hole may be carbonized and the insulation reliability may be lowered.
The angle can be arbitrarily determined by the diameter of the maximum diameter portion in the tapered shape of the through hole, the diameter of the minimum diameter portion in the tapered shape, and the thickness of the core substrate.
Further, the diameter of the maximum diameter portion in the tapered shape of the through hole and the diameter of the minimum diameter portion in the tapered shape can be determined by laser conditions and the like described later.

A printed wiring board having a tapered through hole (A) whose diameter decreases from the upper surface to the lower surface of the core substrate and a tapered through hole (B) whose diameter decreases from the lower surface to the upper surface of the core substrate, (A) / (B) is 0.2 to 5.0.
Thereby, by reducing the warpage of the printed wiring board, cracks in the solder bumps at the time of mounting the semiconductor element and poor connection due to the occurrence of cracks in the solder bump and the temperature cycle test after mounting the semiconductor element, Generation of cracks in the K layer or the like can be suppressed, and the reliability of the semiconductor device is improved.
Further, the (A) / (B) is preferably 0.25 or more and 4.0 or less, more preferably 0.3 or more and 3.3 or less. Thereby, the connection reliability at the time of mounting the semiconductor element and the reliability of the semiconductor device in the temperature cycle test after mounting the semiconductor element are improved.
If the above upper limit is exceeded or less than the above lower limit, the amount of warpage of the printed wiring board will increase, resulting in poor connection due to cracks in the solder bumps when mounting the semiconductor element, and the temperature after mounting the semiconductor element. In the cycle test, cracks may occur in solder bumps, the Low-K layer of the semiconductor element, etc., and the reliability of the semiconductor device may be reduced.

The diameter of the maximum diameter portion in the tapered shape of the through holes (A) and (B) is preferably 10 μm or more and 200 μm or less. As a result, the warpage of the printed wiring board can be reduced, and a solder bump or a low-K layer of the semiconductor element can be used in a connection failure due to a crack generated in the solder bump when the semiconductor element is mounted or in a temperature cycle test after the semiconductor element is mounted. The occurrence of cracks can be suppressed, and the reliability of the semiconductor device is improved.
The diameter of the maximum diameter portion in the tapered shape of the through holes (A) and (B) is preferably 20 μm or more and 150 μm or less, and more preferably 30 μm or more and 120 μm or less. Thereby, the said characteristic can be expressed effectively.
When the diameters of the through holes (A) and (B) exceed the upper limit, the resin used in the prepreg is carbonized during laser processing, and the carbide is peeled off by desmear after laser processing, and insulation between the through holes is achieved. If the reliability is reduced or the plating solution may penetrate into the core substrate, the roundness of the through hole will decrease and the shape will become distorted if it is less than the above lower limit value. The protrusion of the inner glass cloth becomes prominent, and the insulation reliability may be reduced.

The sum of the numbers of the through holes (A) and (B) is not particularly limited, but is an average of 10 to 12,000 per 1 cm ^{2 of the} printed wiring board. Preferably, the sum of the numbers of the through holes (A) and (B) is an average of 200 to 1,000 per 1 cm ^{2 of} the printed wiring board. If it is less than the lower limit value, there are few through holes and a printed wiring board adapted to fine wiring may not be manufactured. If it is larger than the upper limit value, the distance between the through holes is narrow, and the inter-wall reliability during long-term moisture absorption decreases. There is a case.
The number of through holes is generally designed from an electrical point of view, and differs depending on the size of the printed wiring board. However, the number of through holes formed per printed wiring board is about 1 cm ² . Convert and calculate.

The absolute value of the difference between the total area of the through holes (A) and the total area of the through holes (B) is 4.5 mm ² or less per 1 cm ^{2 of} the printed wiring board. It is preferable.
Within this range, the warp of the printed wiring board can be reduced.

The minimum interval between the through holes (between (A)-(A), (A)-(B), or (B)-(B)) is preferably 0.05 mm or more. Thereby, the reliability between the walls can be maintained, and fine wiring and high-density mounting can be realized.

Although the thickness of the said laminated board is not specifically limited, It is preferable that they are 0.02 mm or more and 0.40 mm or less. When the value is less than the lower limit, the core substrate is low in strength and difficult to handle, and the printed wiring board warps during circuit formation or semiconductor mounting, resulting in circuit disconnection or poor connection when mounting semiconductor elements. There is. On the other hand, if the value is larger than the upper limit value, through-holes cannot be formed with normal laser irradiation energy and laser irradiation time.
In addition, when the laser is irradiated for a long time, the resin used in the prepreg is carbonized during laser processing, and the carbide is peeled off by desmear after laser processing, and the insulation reliability between through holes is reduced. Infiltration of the plating solution into the substrate may occur.

  After forming a through hole with a laser, various treatments are performed as necessary. For example, a roughening treatment can be applied to the surface of the metal foil, film, or resin layer. Examples of the roughening treatment include bond film treatment (manufactured by Atotech Co., Ltd.), CZ treatment (manufactured by Mec Co., Ltd.), blackening treatment, and the like, and preferably blackening treatment.

The conditions for irradiating the laser are not particularly limited. For example, the pulse width is 3 μsec to 100 μsec, the energy is 5 mJ to 20 mJ, and the number of shots is 1 shot to 10 shots. Preferably, the pulse width is 16 μsec to 100 μsec, the energy is 10 mJ to 20 mJ, and the number of shots is 3 shots to 7 shots.

  The core substrate preferably has an elastic modulus at 25 ° C. of 10 GPa or more and 50 GPa or less. As a result, the amount of warpage of the printed wiring board can be reduced, a connection failure due to the occurrence of a crack in the solder bump, a crack in the solder bump, a low-K layer of the semiconductor element, etc. in a temperature cycle test after mounting the semiconductor element. It is possible to suppress cracks from occurring. The elastic modulus at 25 ° C. of the core substrate is more preferably 15 GPa or more and 45 GPa or less, and particularly preferably 20 GPa or more and 40 GPa or less. As a result, the amount of warpage of the printed wiring board can be effectively reduced, and a solder bump or a low-K layer of the semiconductor element in a connection failure due to the occurrence of a crack in the solder bump or a temperature cycle test after mounting the semiconductor element. The crack which generate | occur | produces etc. can be suppressed.

  The prepreg is not particularly limited as long as it has an appropriate strength. For example, epoxy resin, phenol resin, cyanate resin, triazine resin, bismaleimide resin, polyimide resin, polyamideimide resin, polyphenylene oxide A resin base material (for example, a glass fiber sheet or the like) impregnated with a resin composition containing at least one or more kinds of resins and benzocyclobutene resins and an inorganic filler, and is semi-cured into a plate shape. Can be obtained. In particular, when a prepreg made by impregnating a glass fiber sheet with a resin composition containing an epoxy resin and an inorganic filler and semi-curing is used, the dielectric properties, mechanical and electrical connection reliability under high temperature and high humidity are improved. An excellent printed wiring board can be obtained.

  The laminate is formed by heating and pressing the prepreg. Thereby, the printed wiring board excellent in heat resistance, low expansibility, and a flame retardance can be obtained. When one prepreg is used, the metal foil is overlapped on both the upper and lower surfaces or one surface. Two or more prepregs can be laminated. When two or more prepregs are laminated, a metal foil or film is laminated on the outermost upper and lower surfaces or one surface of the laminated prepreg. Next, a laminate can be obtained by heat-pressing a prepreg and a metal foil or film stacked. Although the temperature to heat is not specifically limited, 120-220 degreeC is preferable.

  Examples of the metal foil used for the laminated plate include copper and / or copper-based alloy, aluminum and / or aluminum-based alloy, silver and / or silver-based alloy, gold and / or gold-based alloy, zinc and / or zinc-based. Examples include alloys, nickel and / or nickel-based alloys, tin and / or tin-based alloys, iron and / or iron-based alloys, and the like.

  The metal foil may be an ultrathin metal foil with a carrier foil. The ultrathin metal foil with a carrier foil is a metal foil obtained by laminating a peelable carrier foil and an ultrathin metal foil. Since an ultrathin metal foil layer can be formed on both sides of a laminate by using an ultrathin metal foil with a carrier foil, for example, when a circuit is formed by a semi-additive method, an ultrathin metal without performing electroless plating By electroplating the foil as a direct power supply layer, the ultrathin copper foil can be flash etched after the circuit is formed.

  Moreover, as a film used for the said laminated board, polyethylene, a polypropylene, a polyethylene terephthalate, a polyimide, a fluorine resin etc. can be mentioned, for example.

The core substrate can be obtained by forming a through hole in the laminated plate and performing circuit processing.
The through-hole forming method uses, for example, a laminate having copper foil on both sides, irradiates a laser at a predetermined position, and provides a through-hole by the manufacturing method of the present invention.
Specifically, the laser beam is irradiated directly to the core substrate copper foil or the conformal method of irradiating the laser to the core substrate where the laser foil has been pre-etched and the surrounding copper foil etched away to form a through hole. There is a direct method for forming through holes.
The method of irradiating the core substrate with the laser is not particularly limited, but a predetermined number of through holes may be formed on the other surface after a predetermined number of through holes are formed on one of the surfaces.
Alternatively, through holes may be formed alternately from the front and back, and some through holes are formed on one side of a predetermined number, and then some through holes are formed on the other side. After forming, it may be repeated to form through holes in some of one side again, and there is no particular problem as long as a predetermined number of through holes can be finally formed.

A method for performing circuit processing is not particularly limited, and examples thereof include a subtractive method and a semi-additive method.
For example, it is possible to form a circuit by etching after forming via holes by a conformal method or a direct method using a laminate having copper foil on both surfaces, and by connecting the upper and lower surfaces by electrolytic plating.
Also, all the copper foils of the laminate having copper foil on both sides are etched, or a laminate having no metal foil is used on the upper and lower surfaces, and after forming through holes, the resin residue (smear) is removed and electroless Conducting the upper and lower surfaces by plating, adjusting the circuit layer height by electrolytic plating, and forming a circuit by etching a predetermined plating portion with a predetermined portion using a resist or the like to obtain a core substrate .

Next, the printed wiring board of the present invention will be described.
A prepreg or a resin sheet is laminated on the core substrate so as to cover the inner layer circuit, and heat-cured to form an insulating layer on the core substrate.
The lamination method is not particularly limited, but a lamination method using a vacuum press, an atmospheric laminator, and a laminator that is heated and pressurized under vacuum is preferable, and a method using a laminator that is heated and pressurized under vacuum is more preferable. It is.
Although the temperature at the time of carrying out heat hardening is not specifically limited, For example, it can be made to harden | cure in the range of 100 degreeC or more and 250 degrees C or less.

Next, a via is provided in the insulating layer using a CO ₂ laser device, and a circuit is formed on the surface of the insulating layer by electrolytic copper plating to achieve conduction with the core substrate.
When an insulating layer is further formed, a prepreg or a resin sheet is laminated as described above, and an insulating layer is provided to form a circuit.
Note that the inner layer circuit portion can be suitably subjected to roughening treatment such as blackening treatment. Further, the through hole portion can be appropriately filled with a conductor paste or a resin paste.

After that, a solder resist is formed on the outermost layer, the connection electrode part is exposed so that a semiconductor element can be mounted by exposure and development, nickel gold plating treatment is performed, and a printed wiring board is obtained by cutting to a predetermined size. it can.
Depending on the design of the printed wiring board, a solder resist is formed on the core substrate, and the connection electrode part is exposed so that a semiconductor element can be mounted by exposure / development. It can also cut | disconnect and can obtain a printed wiring board.

  Next, the semiconductor device of the present invention will be described.

A semiconductor element having solder bumps is mounted on the printed wiring board obtained above, and connection to the printed wiring board is attempted through the solder bumps. A liquid sealing resin is filled between the printed wiring board and the semiconductor element to form a semiconductor device. The solder bump is preferably made of an alloy made of tin, lead, silver, copper, bismuth or the like.
The method for connecting the semiconductor element and the printed wiring board is to align the connection electrode portion on the printed wiring board and the solder bump of the semiconductor element using a flip chip bonder, etc. In addition, the solder bumps are heated to the melting point or higher by using a heating device, and the printed wiring board and the solder bumps are connected by fusion bonding. In order to improve connection reliability, a metal layer having a relatively low melting point, such as a solder paste, may be formed in advance on the connection electrode portion on the printed wiring board. Prior to this bonding step, the connection reliability can be improved by applying flux to the solder bumps and / or the surface layer of the connection electrode portion on the printed wiring board.
The present invention is not necessarily limited to the semiconductor device, but includes a ball grid array (BGA), a chip size package (CSP), a flip chip BGA, etc. that also use the printed wiring board of the present invention. This semiconductor device is particularly excellent in reliability.

EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to this.
Example 1
(1) Preparation of resin varnish 55.4 parts by weight of cresol novolac type epoxy resin (“Epicron N-690”, epoxy equivalent 210, manufactured by Dainippon Ink & Chemicals, Inc.), bisphenol A type epoxy resin (manufactured by Dainippon Ink & Chemicals, Inc.) "Epiclon 850", epoxy equivalent 190) 17.0 parts by weight, bisphenol A type epoxy resin (Dainippon Ink Chemical Co., Ltd. "Epicron 7050", epoxy equivalent 1900) 6.8 parts by weight, dicyandiamide 3.7 parts by weight, To 17.0 parts by weight of 10-benzyl-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 0.1 part by weight of 2-methylimidazole, dimethylformamide was added, and the non-volatile content was 55%. A resin varnish was prepared so that

(2) Production of Prepreg A glass woven fabric (thickness 94 μm, Nittobo, WEA-2116) was impregnated with the resin varnish and dried in a heating furnace at 150 ° C. for 2 minutes to obtain a prepreg.

(3) Manufacture of laminated plate A predetermined number of the prepregs obtained above were stacked, and MT18EX (copper foil thickness 2 μm, carrier foil thickness 18 μm, manufactured by Mitsui Mining & Smelting Co., Ltd.) was stacked on both sides, pressure 4 MPa, temperature 200 ° C. Then, after the carrier foil was peeled off, a 0.4 mm thick laminate having copper foil on both sides was obtained.
The elastic modulus at 25 ° C. of the laminate was 20 GPa.
The elastic modulus was measured by etching the copper foil of the laminated plate to 5 mm × 30 mm and using a dynamic viscoelasticity measuring device (DMA) (Seiko Instruments Inc., DMS6100) at 5 ° C./min. Measurement was performed at a frequency of 10 Hz while raising the temperature.

(4) Manufacture of core substrate Copper foil was removed by etching from predetermined portions of the upper and lower surfaces of the laminate (FIG. 2 (1)).
Next, 333 through-holes (A) were formed by irradiating the portion of the laminated plate from which the copper foil was removed with a CO ₂ laser so that the upper surface had a diameter of 100 μm and the lower surface had a diameter of 72 μm (FIG. 2 ( 2)). Next, the laminated plate was turned over, and a CO ₂ laser was irradiated on the lower surface side of the laminated plate under the same conditions as the upper surface to form 1667 through holes (B) (FIG. 2 (3)). Here, both the through holes (A) and (B) had a taper angle of 88 degrees, and the minimum distance between the through holes was 0.20 mm.
Thereafter, in order to form a circuit, a resist was formed, a circuit was formed by etching, and the resist was removed to obtain a core substrate.
Here, the mask on the CO ₂ laser processing machine side was set to 1.4 mmΦ, and the processing energy was 2.5 mJ, the pulse width was 67 μs, and 10 shots were irradiated.
The core substrate has 2000 through holes in total of the number of through holes (A) and the number of through holes (B) per 50 mm × 50 mm. The ratio of the number of A) ((A) / (B)) was 0.2. There are 80 through holes per 1 cm ^{2 of} printed wiring board.

(5) Manufacture of printed wiring board Resin sheets (ABF GX-13, manufactured by Ajinomoto Fine Techno Co., Ltd.) are laminated on both surfaces of the core substrate, an insulating layer is provided by heat curing, and a carbonic acid laser device is used at a predetermined position. A via was formed.
Next, after electroless plating, a resist was formed, electrolytic copper plating was performed, and etching was performed to form a circuit on the surface of the insulating layer. After that, a solder resist (PSR4000 / AUS308 manufactured by Taiyo Ink Manufacturing Co., Ltd.) is formed on the outermost layer, the connection electrode part is exposed so that a semiconductor element can be mounted by exposure and development, and a nickel gold plating process is performed, and the size is 50 mm × 50 mm. This was cut to obtain a printed wiring board.

(6) Manufacture of Semiconductor Device The printed wiring board was used by cutting a connection electrode portion subjected to nickel gold plating corresponding to a solder bump arrangement of a semiconductor element to a size of 50 mm × 50 mm. A semiconductor element (TEG chip, size 15 mm × 15 mm, thickness 0.8 mm) has a solder bump formed of a eutectic of Sn / Pb composition, and a circuit protective film of the semiconductor element is a positive photosensitive resin (Sumitomo Bakelite). What was formed by company CRC-8300) was used. In assembling the semiconductor device, first, a flux material was uniformly applied to the solder bumps by a transfer method, and then mounted on a printed wiring board by thermocompression bonding using a flip chip bonder device. Next, after solder bumps were melt-bonded in an IR reflow furnace, a liquid sealing resin (manufactured by Sumitomo Bakelite Co., Ltd., CRP-4152S) was filled and the liquid sealing resin was cured to obtain a semiconductor device. The curing condition of the liquid sealing resin was a temperature of 150 ° C. and 120 minutes.

(Example 2)
In the through hole formation of the core substrate of Example 1, 1667 through holes (A) and 333 through holes (B) are formed per 50 mm × 50 mm, and (A) / (B) is 5.0. A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that the above was achieved.

(Example 3)
In the through hole formation of the core substrate of Example 1, 400 through holes (A) and 1600 through holes (B) are formed per 50 mm × 50 mm, and (A) / (B) is 0.25. A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that the above was achieved.

Example 4
In the through hole formation of the core substrate of Example 1, 1600 through holes (A) and 400 through holes (B) are formed per 50 mm × 50 mm, and (A) / (B) is 4.0. A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that the above was achieved.

(Example 5)
In the through hole formation of the core substrate of Example 1, 462 through holes (A) and 1538 through holes (B) are formed per 50 mm × 50 mm, and (A) / (B) is 0.3. A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that the above was achieved.

(Example 6)
In the formation of the through hole of the core substrate of the first embodiment, 1535 through holes (A) and 465 through holes (B) are formed per 50 mm × 50 mm, and (A) / (B) is 3.3. A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that the above was achieved.

(Example 7)
Biphenyl aralkyl type novolak epoxy resin (Nippon Kayaku Co., Ltd., NC-3000) 14.0 parts by weight, resin phenyl varnish raw material, biphenyl dimethylene type phenolic resin (Nippon Kayaku Co., Ltd., GPH-103) 10.8 wt. Parts, 24.6 parts by weight of novolak-type cyanate resin (Lonza Japan Co., Ltd., Primaset PT-30), spherical fused silica (manufactured by Admatechs Co., Ltd., “SO-25R”, average particle size 0.5 μm) 50.4 By adding dimethylformamide to 0.2 parts by weight of a part by weight and a coupling agent (Nihon Unicar Co., Ltd., A187), a resin varnish is prepared so as to have a nonvolatile content concentration of 55%. In the formation, 1000 through holes (A) and 1000 through holes (B) are formed per 50 mm × 50 mm. A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that A) / (B) was 1.0.

(Example 8)
A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except for the above-described steps, except that the through hole forming step in Example 1 was as follows.

In the through hole forming step of the core substrate of the first embodiment, the mask on the CO ₂ laser processing machine side is set to 1 so that the diameter of the upper surface is 100 μm and the diameter of the lower surface is 72 μm in the portion where the copper foil of the laminated board is removed. It was set to 0.1 mmΦ, processing energy was 7.0 mJ, pulse width was 97 μs, and 6 shots were irradiated to form 1000 through holes (A) per 50 mm × 50 mm (FIG. 2 (2)). Next, the laminated plate was turned over, and the bottom surface side of the laminated plate was irradiated with a CO ₂ laser under the same conditions as the upper surface to form 1000 through holes (B) per 50 mm × 50 mm (FIG. 2 (3)).
Here, in the through holes (A) and (B), the taper angle was 83 degrees, and the minimum interval between the through holes was 0.20 mm.
The core substrate has 2000 through holes in total of the number of through holes (A) and the number of through holes (B) per 50 mm × 50 mm, and the ratio of (A) / (B) is 1. 0. The printed wiring board had 80 through holes per 1 cm ² .

Example 9
A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except for the above-described steps, except that the through hole forming step in Example 1 was as follows.

In the through hole forming process of the core substrate of the first embodiment, the mask on the CO ₂ laser processing machine side is set to 1 so that the diameter of the upper surface is 70 μm and the diameter of the lower surface is 43 μm in the portion where the copper foil of the laminated board is removed. 0.1 mmΦ, a processing energy of 7.0 mJ, a pulse width of 97 μs, and 6 shot irradiations were performed to form 1333 through holes (A) and then 2667 through holes (B).
Here, both the through holes (A) and (B) had a taper angle of 88 degrees, and the minimum distance between the through holes was 0.20 mm.
The core substrate has 4000 through holes in total of the number of through holes (A) and the number of through holes (B) per 50 mm × 50 mm, and the ratio of (A) / (B) is 0.00. It was 5. The printed wiring board had 160 through holes per 1 cm ² .

(Comparative Example 1)
In the formation of the through hole of the core substrate of Example 1, a laser was irradiated on the lower surface of the core substrate to form 2000 through holes (B) per 50 mm × 50 mm (only B but no A). A printed wiring board and a semiconductor device were produced in the same manner as in Example 1.
Here, the through hole (B) had a taper angle of 88 degrees, and the minimum distance between the through holes was 0.20 mm.
There are 80 through holes per 1 cm ^{2 of} printed wiring board.

(Comparative Example 2)
A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that in the through hole formation of the core substrate of Example 1, A / B was set to 0.12.
Here, both the through holes (A) and (B) had a taper angle of 88 degrees, and the minimum distance between the through holes was 0.20 mm.
The core substrate has 2000 through-holes including 214 through-holes (A) and 1786 through-holes (B) per 50 mm × 50 mm, and 80 through-holes per 1 cm ^{2 of} the printed wiring board. Has a hole.

(Comparative Example 3)
A printed wiring board and a semiconductor device were produced in the same manner as in Example 1 except that (A) / (B) was set to 8.0 in the formation of through holes in the core substrate of Example 1.
Here, both the through holes (A) and (B) had a taper angle of 88 degrees, and the minimum distance between the through holes was 0.20 mm.
The core substrate has 2000 through holes including 1778 through holes (A) and 222 through holes (B) per 50 mm × 50 mm, and 80 through holes per 1 cm ^{2 of} the printed wiring board. Has a hole.

Evaluation was made by the following methods using the printed wiring boards and semiconductor devices obtained in the examples and comparative examples. The results are shown in Tables 1 and 2.

1. The amount of warpage of the semiconductor device The warpage of the semiconductor package at room temperature was measured using a laser three-dimensional shape measuring machine (Hitachi Technology and Service LS220-MT). The measurement range is 48mm x 48mm, the laser is applied to the BGA surface opposite to the semiconductor element mounting surface, and the distance from the laser head is the difference between the farthest point and the closest point. . Judgment was made as follows.
○: Warpage amount <200 μm
Δ: 200 μm ≦ Warpage amount ≦ 250 μm
×: Warpage amount> 250 μm

2. Reliability The flying device (1116X-YC Hitester: 1116X-YC high tester) after processing the semiconductor device obtained above in Fluorinert for 10 minutes at −55 ° C., 10 minutes at 125 ° C. and 10 minutes at −55 ° C. HIOKI). A 100-point continuity test was conducted, and the disconnected location was examined. Each code is as follows.
○: There was no disconnection.
X: There was a disconnection part.

  As is apparent from Table 1, Examples 1 to 9 can suppress the amount of warpage of the semiconductor package and improve the reliability of the semiconductor package. In Comparative Example 1, since the through hole was formed only from one side, the amount of warpage of the printed wiring board portion of the semiconductor device was increased, and the reliability of the semiconductor device was lowered. In Comparative Examples 2 and 3, since the ratio (A) / (B) was outside the range of 0.2 to 5.0, the amount of warpage of the printed wiring board was increased, and the reliability of the semiconductor device was lowered. .

  According to the present invention, since a printed wiring board with small warpage can be manufactured, it can be suitably used for a printed wiring board that is particularly required to have a small size and high performance, such as an interposer and a semiconductor element and a mother board.

DESCRIPTION OF SYMBOLS 1 Laminated board 2 Copper foil 3 Copper plating 4 Conductor circuit 5 Insulating layer 6 Via hole A Through hole formed by laser irradiation from the surface (A)
B Through hole formed by laser irradiation from the back (B)

Claims (6)

A printed wiring board having a tapered through hole, wherein the printed wiring board has a tapered through hole (A) whose diameter decreases from the upper surface to the lower surface of the core substrate, and a diameter from the lower surface to the upper surface of the core substrate. A printed wiring board having a tapered through-hole (B) that becomes smaller, and the ratio of the number of through-holes (A) to the number of through-holes (B) ((A) / (B)) is 0.2. A printed wiring board characterized by being 5.0 or less.   The through hole (A) is a through hole formed by laser irradiation from the upper surface of the core substrate, and the through hole (B) is a through hole formed by laser irradiation from the lower surface of the core substrate. The printed wiring board according to claim 1. 3. The printed wiring board according to claim 1, wherein a diameter of a maximum diameter portion in the tapered shape of the through holes (A) and (B) is 10 μm or more and 200 μm or less. 4. The printed wiring board according to claim 1, wherein the sum of the numbers of the through holes (A) and (B) is 10 to 12,000 on average per 1 cm ² of the printed wiring board. 5. The printed wiring board according to claim 1, wherein the absolute value of the difference between the opening area of the upper surface of the printed wiring board and the opening area of the lower surface is 4.5 mm ² or less per 1 cm ² of the printed wiring board.   A semiconductor device comprising a semiconductor element mounted on the printed wiring board according to claim 1.

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