JP2002198461A - Plastic package and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic package for forming an external connection terminal pad section by punching a small hole for circulating plating liquid to copper foil that becomes the bottom section of a via hole, stably forming copper plating in the via hole, and at the same time blocking the small hole by the formed copper plating, and to provide the manufacturing method of the plastic package. SOLUTION: In the ball-grid-array type plastic package 10 that has the external connection terminal pad 16 for connecting a solder ball 15 on one surface of a core substrate 13 where the copper foil 12 and 12a that becomes the circuit is applied to both the surfaces of the insulating base 11, the external connection terminal pad 16 includes a section where the small hole 21a formed at the copper foil 12a on one surface of the via hole 17 being provided on the core substrate 13 is blocked by copper plating 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic package having an external connection terminal pad on one side of a core substrate and a method for manufacturing the same, and more particularly, to a via hole formed by closing a through hole of a core substrate with copper plating. The present invention relates to a plastic package having an external connection terminal pad for connecting a solder ball directly below, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become higher in performance and smaller in size, plastic packages for mounting semiconductor devices have increased the number of external connection terminals, mountability of semiconductor devices, lower cost, and heat dissipation. From the viewpoints of characteristics, low impedance, and the like, ball grid array type plastic packages are often used. In the ball grid array type plastic package, the external connection terminal pads for connecting the solder balls were formed at positions away from the via holes by connecting to the via hole conductors. Since it is not possible to suppress an increase in package size due to the development, a method of forming an external connection terminal pad directly on a via hole has been promoted.

In forming the external connection terminal pads on the via holes, a conventional method of filling the inside of the through-type via holes with resin, conductive paste, plating or the like has been adopted. Specifically, filling the via holes with resin,
Form electroless copper plating and electrolytic copper plating on the surface of the resin, fill the via holes with a conductive paste and form electrolytic copper plating directly, directly use special additives or pulse waveform power supply in the via holes There is a method of filling the hole by plating, a method of forming a plating in a via hole in a via hole by a via post method, and the like. However, when the filling is formed by burying the filler in the via hole,
After filling, the opening of the via hole needs to be polished flat, which causes an increase in steps and cost. Also, if the via hole diameter is small and the thickness of the plastic package is small, polishing becomes very difficult, and the thickness is less than 0.1 mm.
When it is less than 15, it becomes almost impossible to polish flat. Therefore, in the case of a small via hole or a thin plastic package, a blind via in which one opening of a conventional through-type via hole is closed is adopted as an effective method.

[0004]

However, the conventional plastic package and the method for manufacturing the same as described above have the following problems to be solved. (1) In a blind via in which one side of the opening of the via hole is closed, it is difficult for the plating solution to be supplied to the bottom of the via hole when copper plating is performed, so that the plating thickness in the via hole is reduced or bubbles are generated in the via hole. Accumulate and no plating is formed. (2) When the aspect ratio (length / diameter) of the via hole becomes large (1.0 or more), the flow of the plating solution in the via hole becomes extremely poor, and the plating thickness becomes thin or the plating is not formed. The copper plating cannot be stably formed in the blind via. The present invention has been made in view of such circumstances, and a hole that allows circulation of a plating solution is formed in a copper foil serving as a bottom portion of a via hole to stabilize copper plating in the via hole. It is an object of the present invention to provide a plastic package in which an external connection terminal pad portion is formed by closing a hole with copper formed at the same time as forming the same and a method of manufacturing the same.

[0005]

According to the present invention, there is provided a plastic package according to the present invention, comprising a core substrate having a circuit board on both sides of an insulative base material and a solder ball connecting surface on one side. In a ball grid array type plastic package having external connection terminal pads, the external connection terminal pads are formed by closing small holes formed in copper foil on one side of via holes provided in a core substrate with copper plating. Includes parts. This allows the plating solution to flow in from the small hole to stably form copper plating in the via hole, and at the same time, close the small hole in the copper foil portion at the bottom of the via hole by copper plating to form a plastic having an external connection terminal pad portion. Package can be provided. Here, the hole diameter of the small hole formed in the copper foil on one side of the via hole is preferably smaller than the diameter of the hole formed through the copper foil and the insulating base material on the other side. Thereby, the small hole of the copper foil is closed by the formed copper plating thickness, and the plastic package having the via hole formed of the non-through hole can be surely provided.

A method of manufacturing a plastic package according to the present invention, which meets the above object, is directed to a ball provided with external connection terminal pads for solder ball connection on one surface of a core substrate having copper foil adhered to both surfaces of an insulating substrate. In the method of manufacturing a grid array type plastic package, a punched hole is formed from the copper foil surface on the other side of the core substrate to penetrate the insulating base material, and is provided on one surface of the core substrate. A step of forming a through hole having a copper foil as a weir and a small hole substantially in the center of the weir, and applying copper plating to the surface and the through hole of the copper foil provided on both sides of the core substrate. Forming a via layer comprising a non-through hole by closing a small hole, and performing a predetermined etching process on the conductive layer provided on one side and the other side of the core substrate to form a conductive layer. Shape pattern And a step, and forming a solder resist film on a predetermined portion of the corresponding to the via hole position on the other hand, except the external connection terminal pads formed on the conductor wiring pattern on the side one side and the other side of. This allows
Since the flow of the plating solution can be improved and copper plating can be stably formed on the inner wall of the through hole, and at the same time, the small hole in the copper foil portion at the bottom of the via hole can be closed by copper plating,
A blind via with a uniform copper thickness can be formed. In addition, since copper plating is performed on through holes having small holes, the plating solution flows from the small holes and the flow of the plating solution is good, and copper plating of a constant thickness is applied to the wall surfaces of the through holes regardless of the aspect ratio. Can be. Here, the diameter of the small hole is preferably not more than twice the thickness of the copper plating applied to the through hole. Thereby, the small hole of the copper foil part at the bottom of the via hole can be reliably closed with the precipitated copper,
External connection terminal pads can be formed on the copper foil portion.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, with reference to the accompanying drawings, embodiments of the present invention will be described for the understanding of the present invention. Here, FIG. 1 is a partially enlarged side sectional view of a plastic package according to an embodiment of the present invention,
FIG. 2 is an explanatory view of a through hole of a core substrate of the plastic package, and FIGS. 3A to 3E are partially enlarged side sectional views illustrating a method of manufacturing a plastic package according to an embodiment of the present invention. .

As shown in FIG. 1, a plastic package 10 according to an embodiment of the present invention is of a ball grid array type, and has a circuit board and a plastic substrate 11 on both sides of a plastic substrate 11 which is an example of an insulating substrate. Copper foil 12, 1
The solder ball 15 exposed from the opening of the solder resist film 14 is formed on one surface of the core substrate 13 to which
An external connection terminal pad 16 for connection is provided. The external connection terminal pads 16 are formed by forming small holes 21a formed in the copper foil 12a on one side of the via holes 17 provided in the core substrate 13 with copper plating 18 made of electroless copper plating and electrolytic copper plating. Includes closed sections.
Also, on the copper plating 18 of the external connection terminal pad 16,
In order to prevent oxidation of the copper plating 18 and the solder ball 1
In order to improve the adhesiveness of No. 5, cover plating 19 made of nickel plating and gold plating is applied. In addition,
On the surface opposite to the surface on which the external connection terminal pads 16 are formed, wire bond pads 20 and the like which are exposed from the opening of the solder resist film 14 and are connected to the semiconductor element by bonding wires are formed. This portion is also provided with a cover plating 19 made of nickel plating and gold plating.

[0009] As shown in FIG.
The hole diameter A of the small hole 21a formed in the core substrate 13a
The hole diameter B of the hole 21b formed in the copper foil 12 and the hole B of the hole 21c formed in the plastic substrate 11 are smaller than the hole diameter B. As a result, the copper plating solution is supplied to the small hole 21a and the hole 2
1b and 21c, the copper flows well through the through-hole 21 formed by the through-hole 21 and copper is deposited on the inner surface of the through-hole 21 to form the copper plating 18, and the small holes 21a of the copper foil 12a are closed by the copper plating 18. You.

Next, a method of manufacturing a plastic package according to an embodiment of the present invention will be described with reference to FIG. First, as shown in FIG. 3 (A), one side or multiple layers of a high heat-resistant BT resin (resin containing bismaileimide triazine as a main component), a polyimide resin, or the like is coated on both surfaces of a plastic substrate 11 with copper. The core substrates 13 are formed by joining the foils 12 and 12a. The thickness of the copper foils 12 and 12a to be attached to the core substrate 13 is usually 10 to 70 μm, and the purity of copper is 99.8% or more.

As shown in FIG. 3 (B), the surface of the copper foil 12 on the other side of the core substrate 13 is etched thinly (about 5 μm) to suppress reflection during laser irradiation and improve laser absorption. Then, the through hole 21 is formed in the core substrate 13 by performing a cycle shot of, for example, once at 18 μsec and four times at 10 μsec from the other surface of the core substrate 13 using a carbon dioxide laser. That is, a hole 21 b is made in the copper foil 12 on the other side of the core substrate 13, and a hole 21 c penetrating the plastic substrate 11 is formed.
The copper foil 12a on one surface of the core substrate 13 is used as a weir 22, and holes 21b and 21 are formed at substantially the center of the weir 22.
A small hole 21a smaller than c is formed. Depending on the adjustment of the laser intensity of the carbon dioxide gas laser, the respective thicknesses of the copper foils 12 and 12a on both sides, and the surface condition of the copper foil 12a, the hole diameter of the small holes 21a can be adjusted to an arbitrary size and the holes can be formed.

As shown in FIG. 3 (C), after a catalyst such as palladium is applied to the core substrate 13 having the through-holes 21 formed of the small holes 21a, the holes 21b and 21c, formalin is used as a reducing agent. Perform electroless copper plating in a strong alkaline bath. As a result, both surface layers of the core substrate 13 are brought into an electrically conductive state via the electroless copper-plated conductor film formed on the inner side surface of the through hole 21. Next, the core substrate 13 on which the electroless copper plating has been performed is disposed as a plating object on the cathode side in a plating bath made of, for example, copper sulfate, pyrophosphoric acid, and the like, and a copper plate is disposed on the anode side, and a voltage is applied. By applying the voltage, metal copper is deposited on the surface layer of the core substrate 13 on which the electroless copper plating is performed and the through-holes 21 to form a film of the electrolytic copper plating. Copper plating 18 made of electroless copper plating and electrolytic copper plating is applied on the surfaces of the copper foils 12 and 12a and the wall surfaces of the through holes 21 to form conductor layers. The small holes 21a are closed by the copper plating 18 to form the via holes 17 formed of non-through holes.

As shown in FIG. 3D, a pattern mask for forming a conductor wiring pattern is aligned with a photoresist film formed on both surfaces of the copper plating 18 on the surface of the core substrate 13, and ultraviolet light exposure is performed. Developing and removing the photoresist film in portions other than the conductor wiring pattern to form an etching resist mask, a ferric chloride solution, a cupric chloride solution, an alkali etchant, a hydrogen peroxide-sulfuric acid system By spraying etchant such as etchant,
The copper plating (electroless copper plating and electrolytic copper plating) 18 and the copper foils 12 and 12a which are not covered with the etching resist mask are etched. After the etching, a stripping solution is sprayed onto the surface of the etching resist mask covering the conductor wiring pattern, and the photoresist is swollen while swelling, thereby peeling and removing to form a conductor wiring pattern 23.

As shown in FIG. 3E, for example, on both sides of the core substrate 13 on which the conductor wiring pattern 23 is formed, for example,
The solder resist film 14 is formed so that the external connection terminal pads 16 for connecting the solder balls, the wire bond pads used for connecting to the semiconductor element with the bonding wires, and the like are exposed from the openings. The solder resist film 14 prevents the solder from adhering and prevents the conductor wiring pattern from being stained, scratched, corroded, and the like. Here, the external connection terminal pads 16 formed on the conductor wiring pattern 23 and exposed from the openings of the solder resist film 14 are formed on the outer surfaces of the copper foil 12a serving as the bottom of the via hole 17 and the copper plating 18 provided on the small holes 21a. Formed on the side. Furthermore,
Cover plating 19 made of nickel plating and gold plating is applied to portions of the copper plating 18 such as the external connection terminal pads 16 and the wire bond pads which are not covered with the solder resist film 14.

The diameter of the small hole 21a formed substantially in the center of the dam 22 of the copper foil 12a is preferably not more than twice the thickness of the copper plating 18 applied to the through hole 21. When the copper plating 18 is performed, since the small holes 21a are opened in the copper foil 12a, the plating solution can flow from the small holes 21a into the through-holes 21 to form copper on the wall surfaces of the through-holes 21. If the hole diameter of the small hole 12a is twice or less, the small hole 21a can be closed by forming it to a desired plating thickness.

When the through hole 21 is formed in the core substrate 13 using a laser as shown in FIG. 3B, the surface of the copper foil 12 on the other side of the core substrate 13 is thinly etched. The laser irradiation is performed after that, but it is not limited to this. The perforation hole 21 is formed by attaching a sheet capable of improving the thermal efficiency of the laser, for example, a laser sheet (trade name) manufactured by Mitsubishi Gas Chemical Co., to the surface of the copper foil 12 on the other side, and then applying the laser. It is also possible to form the through-hole 21 by using. In this case, the copper foil 12
Does not require thinning.

Further, a hole 21b in the copper foil 12 on the other side is formed in advance by etching, and the laser output is reduced so that the copper foil 12 is not damaged. The through-hole 21 can also be formed by a conformal mask method using as a laser mask. Furthermore, in this method, the copper foil 12a on one side may be etched to form the small holes 21a.

[0018]

In the plastic package according to the first and second aspects, the external connection terminal pad closes a small hole formed in the copper foil on one surface of the via hole provided in the core substrate by copper plating. Therefore, copper can be stably formed in the through-hole, and at the same time, the small hole of the copper foil portion at the bottom of the through-hole can be closed by copper plating to form the external connection terminal pad portion. In particular, in the plastic package according to claim 2, the diameter of the small hole formed in the copper foil on one side of the via hole is larger than the diameter of the hole formed through the copper foil on the other side and the insulating base material. Therefore, the small hole can be closed by the thickness of the formed copper, and the via hole composed of the non-through hole can be surely formed.

According to a third aspect of the present invention, there is provided a method of manufacturing a plastic package, wherein a hole is formed from the copper foil surface on the other side of the core substrate to form a through hole penetrating the insulating substrate. Forming a through hole having a copper foil provided on the surface of the weir as a weir, and having a substantially central portion of the weir as a small hole, and the surface of the copper foil provided on both sides of the core substrate and A step of forming a conductor layer by applying copper plating to the through-hole, forming a via hole composed of a non-through-hole by closing the small hole, and a method of forming a predetermined conductor layer on one side and the other side of the core substrate. A step of forming a conductor wiring pattern by performing an etching process, and applying a solder resist film to predetermined portions on one side and the other side except for external connection terminal pads formed on the one side conductor wiring pattern corresponding to via hole positions. Forming process and Because it has, the flow of the plating solution can be good, copper plating can be stably formed on the wall surface of the through hole, and the small hole of the copper foil portion at the bottom of the through hole can be closed with the deposition of copper, A plastic package having an external connection terminal pad portion on a copper foil portion can be manufactured. In particular, in the method of manufacturing a plastic package according to claim 4, the diameter of the small hole is not more than twice the thickness of the copper plating applied to the through hole, so that the thickness of the copper to be deposited is less than the thickness of the copper foil at the bottom of the through hole. Small holes can be reliably closed.

[Brief description of the drawings]

FIG. 1 is a partially enlarged side sectional view of a plastic package according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a through hole in a core substrate of the plastic package.

3A to 3E are partially enlarged side sectional views illustrating a method for manufacturing a plastic package according to an embodiment of the present invention.

[Explanation of symbols]

10: plastic package, 11: plastic substrate, 12, 12a: copper foil, 13: core substrate, 14: solder resist film, 15: solder ball, 16: external connection terminal pad, 17: via hole, 18: copper plating, 19:
Cover plating, 20: Wire bond pad, 21: Through hole, 21a: Small hole, 21b, 21c: Open hole, 22: Weir, 23: Conductor wiring pattern

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/12 Q

Claims (4)

[Claims] 1. A ball grid array type plastic package having an external connection terminal pad for solder ball connection on one surface of a core substrate in which copper foil serving as a circuit substrate is attached to both surfaces of an insulating substrate. A plastic package, wherein the external connection terminal pad includes a portion formed by closing a small hole formed in the copper foil on the one surface of the via hole provided in the core substrate with copper plating. 2. The plastic package according to claim 1, wherein the diameter of the small hole formed in the copper foil on one side of the via hole is formed so as to penetrate through the copper foil on the other side and the insulating base material. A plastic package characterized by being smaller than the diameter of the punched hole. 3. A method of manufacturing a ball grid array type plastic package having an external connection terminal pad for connecting a solder ball on one surface of a core substrate having copper foil adhered to both surfaces of an insulating substrate. Drilled from the copper foil surface on the other side of the substrate, forming a through hole penetrating the insulating base material, the copper foil provided on one surface of the core substrate as a weir, and Forming a through hole having a substantially central portion of the weir portion as a small hole, and forming a conductor layer by applying copper plating to the surface of the copper foil provided on both sides of the core substrate and the through hole. Forming a via hole formed of a non-through hole by closing the small hole, and forming a conductor wiring pattern by performing a predetermined etching process on the conductor layer provided on one side and the other side of the core substrate. And the step of Forming a solder resist film on predetermined portions on one side and the other side except for external connection terminal pads formed on the one side of the conductor wiring pattern corresponding to the rule position. Package manufacturing method. 4. The method of manufacturing a plastic package according to claim 3, wherein the diameter of the small hole is not more than twice the thickness of the copper plating applied to the through hole.