JP2006148031A - High-frequency plastic package and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic package comprising a multilayered printed wiring board improved in high-frequency signal transmission characteristics and inter-layer connection reliability, and to provide its manufacturing method. <P>SOLUTION: A multilayered printed wiring board 16 comprises: a core substrate 4 comprised of an insulating substrate 1 with copper foils 3a and 3b stuck on its both faces; an insulating layer 6 with copper foil 3c stuck on its one face; conductive coatings 2a-2c with conductor wiring patterns 7a-7c partially formed therein; and a solder resist 8, wherein the core substrate 4 and the insulating layer 6 include non-through holes 5a and 5b of which the upper portions are closed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a package for mounting a semiconductor element, and more particularly, to a high-frequency plastic package including a multilayer printed wiring board in which an insulating layer and a conductive wiring pattern are sequentially stacked while maintaining conduction between layers through a non-through hole. It relates to the manufacturing method.

  In the field of high-frequency packages for mounting semiconductor elements constituting microwave circuits and the like, ceramic materials that have little loss in the high-frequency region and are excellent in heat resistance, mechanical strength, and the like have been used. However, with the downsizing of packages, plastic packages have begun to attract attention in recent years in place of ceramic packages that have a large shrinkage rate and it is difficult to ensure dimensional accuracy.

  In order to enable high-density and fine wiring in high-frequency packages, multilayer printed wiring formed by a manufacturing method (hereinafter referred to as build-up method) in which an insulating layer and a conductive wiring pattern are sequentially stacked by plating or printing. A board is often used. In such a multilayer printed wiring board, a through-hole with a conductive film formed on the inner wall surface is provided in order to establish conduction between the layers, but an opening is formed at the same location in all the conductor wiring patterns. There was a problem of receiving design constraints. Further, when the resin component filled in the through hole remains in the vicinity of the opening on the semiconductor element mounting surface, there is a problem that transmission characteristics are deteriorated.

  In order to cope with such a problem, several inventions and devices have been disclosed. For example, Patent Document 1 discloses a multilayer wiring board having a build-up multilayer wiring layer having excellent electrical characteristics such as high-frequency characteristics and the like, and having a finer and narrower pitch, and the name “multilayer wiring board and manufacturing method thereof” An invention relating to a manufacturing method is disclosed.

Hereinafter, the invention disclosed in Patent Document 1 will be described with reference to FIG. FIG. 3 is a partial longitudinal sectional view of a multilayer wiring board according to the prior art. As shown in FIG. 3, the prior art invention has a wiring layer (55a, 55b, 55c), a three-layer core substrate 52 (52a, 52b, 52c), and one surface of the core substrate 52. In the multilayer wiring substrate 51 in which the build-up wiring layer 53 (53a, 53b) including the insulating layers (59a, 59b) and the wiring layers (58a, 58b) is formed, the core substrate 52 has a plurality of conductive surfaces that are electrically connected to each other. The conductive layer 54 (54a, 54b, 54c) of the wiring layer (58a, 58b) constituting the build-up wiring layer 53 is formed on the surface of the core substrate 52 by vias (57a, 57b). And the thermal expansion coefficient in the XY direction of the core substrate 52 is 2 to 20 ppm, and the core material 52 ′ for the core substrate 52 is made of silicon, ceramics, The insulating layers 59a and 59b of the build-up wiring layer 53 are selected from glass and glass / epoxy composite materials, and are characterized by being a photosensitive resin that can be thermoset at a temperature of 250 ° C. or lower.
According to such a structure, the vias of the multilayer wiring can be made into a stack structure, so that high-density wiring is possible.

Further, Patent Document 2 has a name “manufacturing method of multilayer wiring board”, and the internal circuit is configured with high density by a build-up method in which a plurality of wiring layers are sequentially laminated on a base material via an insulating layer. An invention relating to a method for manufacturing a multilayer wiring board having excellent high-frequency characteristics and pressure resistance is disclosed.
In the invention disclosed in Patent Document 2, after forming a structure in which different wiring layers are conductively connected through a through-hole formed in a base material or an opening formed in an insulating layer, the inside of the opening is formed. The substrate is filled with an insulating material, and the surface of the substrate is flattened by polishing.
According to such a method, it is possible to perform a reliable conductive connection without increasing the amount of conductors, reduce the capacitance between the wiring layers, and increase the insulation resistance. The withstand voltage can be improved. In addition, since the upper insulating layer and the wiring layer can be formed in a flat surface shape, the cross-sectional structure of the substrate can be matched and wiring defects and the like can be prevented.

Furthermore, Patent Document 3 has the name “Plastic Package Manufacturing Method” and relates to a method for manufacturing a plastic package in which a solder resist is filled so that no bubbles remain inside a blind via having a hole on one side of the core substrate. Is disclosed.
In the invention disclosed in Patent Document 3, the surface of the other side of the via hole drilled from the surface of one side of the core substrate in which the copper foil serving as the conductor circuit is pasted on both surfaces of the insulating base material is closed with the copper foil. A first step of printing a photosensitive first solder resist on the opening side of the blind via to be formed; and a second step of vacuum degassing bubbles in the blind via sealed with the first solder resist; And a third step of printing a photosensitive second solder resist on both surfaces of the core substrate and forming a solder resist film having openings on both surfaces by a photolithography method.
According to such a method, bubbles remain in the blind vias, and moisture accumulates, causing the bubbles to rapidly expand due to heating at the time of solder ball connection or board mounting, so-called popcorn phenomenon that destroys the plastic package by steam explosion. Can be avoided.
JP 2004-152915 A JP-A-9-83140 JP 2002-270714 A

  However, in the invention disclosed in Patent Document 1 which is the above-described prior art, since the solder resist is also applied to the periphery of the opening of the semiconductor element mounting surface, there is a problem that transmission characteristics of high frequency signals are deteriorated. It was.

  Moreover, in the invention disclosed in Patent Document 2, it is necessary to polish and flatten the surface of the base material after filling the opening with an insulating material, which increases the number of processes and increases the manufacturing cost. There was a problem. Furthermore, since a copper wiring pattern is formed by plating on a flat-polished insulating material, there is a problem that the interlayer connection reliability is inferior. Further, there is a problem that the substrate is stretched due to a large stress generated during the flat polishing, and the substrate dimensions are changed.

  Furthermore, the invention disclosed in Patent Document 3 has a problem that no effective countermeasure is taken against the phenomenon that the high frequency signal transmission characteristic is hindered by the resin component remaining on the core substrate. It was.

  The present invention has been made in response to such a conventional situation, and includes a build-up multilayer printed wiring board having non-through holes, and has a high frequency signal transmission characteristic and interlayer connection reliability, and its manufacture. It aims to provide a method.

In order to achieve the above object, a high-frequency plastic package according to the first aspect of the present invention is formed on a core substrate in which copper foil is attached to both surfaces of an insulating base, and on the upper surface and the lower surface of the core substrate, respectively. The first and second conductor wiring patterns, the insulating layer laminated on the lower surface of the core substrate via the second conductor wiring pattern and having the copper foil attached to the lower surface, and the copper on the lower surface of the insulating layer The core substrate includes a third conductor wiring pattern formed on the foil and a solder resist covering the third conductor wiring pattern, and the core substrate has a plurality of first non-through holes whose upper portions are closed by copper foil. A semiconductor element is mounted on the upper surface via a copper foil and a first conductor wiring pattern, and the insulating layer has a plurality of second non-through holes closed at the top, and the first and second non-through holes Conductivity formed on the inner wall The first to third conductive wiring pattern by film is characterized in that the electrically connected.
The high-frequency plastic package having the above-described structure has an effect that the opening of the non-through hole is not formed on the semiconductor element mounting surface. Moreover, it has the effect | action that an unnecessary through-hole is not formed in the conductor wiring pattern of an inner layer.

According to a second aspect of the present invention, in the high-frequency plastic package according to the first aspect, a plurality of insulating layers and a third conductor wiring pattern are sequentially laminated on the lower surface of the core substrate, and the plurality of insulating layers are closed at the top. The first to third conductor wiring patterns are electrically connected by the conductive film formed on the inner wall surfaces of the first and second non-through holes. It is characterized by.
The high-frequency plastic package having the above-described structure has the same effect as that of the first aspect of the invention, and has the effect that a multilayered printed wiring board is formed.

According to a third aspect of the present invention, in the method for manufacturing a plastic package for high frequency according to the first or second aspect, a step of forming a core substrate by attaching a copper foil to both surfaces of an insulating base material, and the core Forming a plurality of first non-through holes whose upper portions are closed with copper foil on the substrate, forming a conductive film on both surfaces of the core substrate and the inner wall surface of the first non-through hole, and the core substrate Forming a first and second conductor wiring pattern on the upper and lower conductive films, respectively, and laminating an insulating layer and a copper foil on the lower surface of the core substrate via the second conductor wiring pattern; A step of drilling a plurality of second non-through holes that penetrate through the copper foil and whose upper portion is blocked in this insulating layer, and a conductive film on the inner wall surface of the copper foil and the second non-through hole on the lower surface of the insulating layer Forming a third step on the conductive film of the copper foil on the lower surface of the insulating layer; Forming a conductive wiring pattern, it is characterized in that a step of coating the solder resist third conductive wiring pattern of the bottom layer.
According to the manufacturing method, the high-frequency plastic package according to claim 1 or 2 is realized.

  As described above, in the high-frequency plastic package according to claim 1 of the present invention, the semiconductor element can be mounted also on the first non-through hole closed by the copper foil. Miniaturization is possible. In addition, since the resin component does not remain on the semiconductor element mounting surface of the core substrate, the high-frequency signal transmission characteristics are not hindered. Furthermore, since unnecessary through holes are not formed in other conductor wiring patterns that are not targeted for interlayer connection, there is an effect that restrictions on wiring design are reduced.

  The high-frequency plastic package according to claim 2 of the present invention has the same effect as that of the invention according to claim 1, and the first and second non-through holes have a stacked structure, thereby increasing the wiring height. Density and package size can be reduced.

  According to the method for manufacturing a high-frequency plastic package according to claim 3 of the present invention, the high-frequency plastic package according to claim 1 or 2 can be easily manufactured.

  Examples of the high-frequency plastic package and its manufacturing method according to the best mode of the present invention will be described below (corresponding to claims 1 to 3).

  The high frequency plastic package of the present invention will be described by taking a ball grid array package as an example. FIG. 1 is a longitudinal sectional view schematically showing the structure of a high-frequency plastic package according to an embodiment of the present invention. As shown in FIG. 1, the multilayer printed wiring board 16 constituting the high-frequency plastic package 15 is an insulating substrate 1 made of BT resin (resin mainly composed of bis-maleimide triazine), epoxy resin, polyimide resin, or the like. The core substrate 4 is formed with a plurality of non-through holes 5a having copper foils 3a and 3b attached to both sides thereof and closed at the top by the copper foil 3a, and both inner surfaces of the core substrate 4 and the inner wall surfaces of the non-through holes 5a. The conductive coatings 2a, 2b, such as copper plating, applied on the bottom of the core substrate 4 are laminated via the conductive coating 2b, and a plurality of non-through holes 5b whose upper portions are blocked are formed and the non-through holes 5a are formed. Insulating layer 6 made of a prepreg filling the inside of copper, copper foil 3c laminated on the lower surface of insulating layer 6, conductive film 2c applied to copper foil 3c, and conductive films 2a to 2c, respectively. And body wiring pattern 7 a to 7 c, consisting of a solder resist 8 which covers the conductive wiring pattern 7c to fill the interior of the non-through hole 5b.

  A nickel plating 10 and a gold plating 11 are formed on the conductive film 2 a on the upper side of the multilayer printed wiring board 16, and a semiconductor element 12 is mounted inside a cavity 9 provided at a substantially central portion on the upper surface of the multilayer printed wiring board 16. Yes. Further, the semiconductor element 12 is bonded to the conductor wiring pattern 7 a by a bonding wire 13. Further, a conductor wiring pattern 7c formed with nickel plating 10 and gold plating 11 is exposed from the opening of the solder resist 8 below the multilayer printed wiring board 16, and a plurality of solder balls 14 are formed on the nickel plating 10 and gold plating 11. Are electrically connected to these conductor wiring patterns 7c.

  The high-frequency plastic package 15 configured as described above has an effect that the opening of the non-through hole 5a is not formed on the mounting surface of the semiconductor element 12 of the core substrate 4. In addition, when the through hole is formed, the layer that does not require the path usually becomes a dead space. However, in the case of the present embodiment, for example, the conductor wiring patterns 7a and 7c are formed in the non-through holes 5a and 5b. Since the conductive coatings 2a and 2b respectively formed on the inner wall surfaces are electrically connected, through holes are formed in unnecessary portions with respect to the conductor wiring pattern 7b formed between the core substrate 4 and the insulating layer 6. And no dead space occurs.

Next, the manufacturing method of the high frequency plastic package of this invention is demonstrated. FIG. 2 is a process diagram showing a method for manufacturing a high-frequency plastic package according to an embodiment of the present invention. The components shown in FIG. 1 are denoted by the same reference numerals as those in FIG.
As shown in FIG. 2, in step S <b> 1, copper cores 3 a and 3 b are overlapped on both surfaces of an insulating base material 1 made of BT resin, epoxy resin, polyimide resin or the like, and heated under pressure to form a core substrate 4. Next, in step S2, drilling is performed on the outer periphery, and the core substrate 4 is punched into a predetermined size. Further, in order to improve the laser absorption at the time of laser processing, a roughening process such as etching the surface of the copper foil 3b on the lower surface of the core substrate 4 to about 5 μm is performed in step S3. Next, in step S4, the carbon foil 3b is irradiated with a carbon dioxide laser to form the non-through hole 5a until it reaches the other copper foil 3a. Then, in step S5, the laser processed surface is buffed. In step S6, the resin exudation component remaining on the bottom of the non-through hole 5a is removed by desmear treatment. Desmear is performed using a chemical such as potassium permanganate, but a method of evaporating with a laser device or the like can also be used. In step S7, after applying a catalyst such as palladium to the core substrate 4, electroless copper plating is performed in a strong alkaline bath using formalin as a reducing agent. Further, an electrolytic copper plating film is formed on the surface on which the electroless copper plating has been applied. Thereby, the conductive films 2a and 2b by copper plating are formed on the surfaces of the copper foils 3a and 3b and the inner wall surface of the non-through hole 5a. In step S8, a predetermined mask is formed on the conductive films 2a and 2b formed on the surfaces of the copper foils 3a and 3b by using a photolithography method, and the conductor wiring patterns 7a and 7b are formed by a subtractive method in which an etching process is performed. Form. Note that an additive method using selective plating may be used instead of the subtractive method. In step S9, the lower surface of the core substrate 4 is roughened, and in step S10, the insulating layer 6 and the copper foil 3c are laminated on the lower surface of the core substrate 4 via the conductor wiring pattern 7b. In step S11, drilling is performed at a predetermined location. In step S12, a roughening process is performed on the copper foil 3c on the lower surface of the insulating layer 6 to improve laser absorption during laser processing.

  Next, in step S13, the carbon foil 3c is irradiated with a carbon dioxide laser to form the non-through hole 5b until the conductive film 2b is reached. Then, in step S14, the laser machined surface is buffed, and in step S15, the non-through hole 5b. The resin exudation component remaining on the bottom of the resin is removed by desmear treatment. In step S16, electroless copper plating and electrolytic copper plating are applied to the inner surface of the copper foil 3c and the non-through hole 5b on the lower surface of the insulating layer 6 to form a conductive film 2c by copper plating. In step S17, a conductor wiring pattern 7c is formed on the conductive film 2c formed on the copper foil 3c on the lower surface of the insulating layer 6 by the same method as in step S8. In step S18, the conductor wiring pattern 7c is covered with the solder resist 8. Note that an opening is provided in the solder resist 8, and a part of the conductor wiring pattern 7 a necessary for connecting to the semiconductor element 12 using the bonding wire 13 is exposed from the opening on the upper surface of the core substrate 4. On the lower surface of the core substrate 4, a part of the conductor wiring pattern 7 c on which the nickel plating 10 and the gold plating 11 necessary for connection with the solder ball 14 are applied is exposed from the opening.

  As described above, according to the high-frequency plastic package of this embodiment and the manufacturing method thereof, a high-frequency plastic package that can be designed with high density wiring and can be downsized and has excellent high-frequency signal transmission characteristics can be easily realized. .

  The high-frequency plastic package of the present invention is not limited to the above-described embodiments, and can be variously modified. For example, in FIG. 1, the insides of the non-through holes 5 a and 5 b are filled with the prepreg and the solder resist 8 that are the insulating layers 6, respectively. A structure in which only the conductive coatings 2b, 2c such as copper plating or a conductive paste such as copper paste or silver paste is filled can be employed. The insulating layer 6, the copper foil 3c, and the conductor wiring pattern 2c are not limited to one layer, and may be a plurality of layers. Specifically, in the process described with reference to FIG. 2, steps S9 to S17 are repeated a desired number of times after step S17, so that the semiconductor substrate 12 is not mounted on the lower surface side of the core substrate 4. The multilayer printed wiring board 16 having a structure in which the plurality of insulating layers 6, the copper foil 3c, and the conductor wiring pattern 7c are sequentially laminated is easily realized. In this case, since a high-density wiring design is possible by forming a non-through hole 5b under the non-through hole 5a so as to form a so-called stack structure, the package can be reduced in size. Furthermore, the core substrate 4 may have a structure in which a plurality of conductor wiring patterns are formed.

  The high-frequency plastic package and the manufacturing method thereof according to the present invention can be applied to a high-frequency plastic package that requires good transmission characteristics of high-frequency signals and high interlayer connection reliability.

1 is a longitudinal sectional view schematically showing the structure of a high-frequency plastic package according to an embodiment of the present invention. It is process drawing which shows the manufacturing method of the high frequency plastic package which concerns on embodiment of this invention. It is a partial longitudinal cross-sectional view of the multilayer wiring board based on a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Insulating base material 2a, 2b, 2c ... Conductive film 3a, 3b, 3c ... Copper foil 4 ... Core board 5a, 5b ... Non-through-hole 6 ... Insulating layer 7a, 7b, 7c ... Conductor wiring pattern 8 ... Solder resist DESCRIPTION OF SYMBOLS 9 ... Cavity 10 ... Nickel plating 11 ... Gold plating 12 ... Semiconductor element 13 ... Bonding wire 14 ... Solder ball 15 ... High frequency plastic package 16 ... Multi-layer printed wiring board 51 ... Multi-layer wiring board 52, 52a, 52b, 52c ... Core board 52 '... Core materials 53, 53a, 53b ... Build-up wiring layers 54, 54a, 54b, 54c ... Conducting portions 55a, 55b, 55c ... Wiring layers 56 ... Surface layer patterns 57a, 57b ... Vias 58a, 58b ... Wiring layers 59a 59b ... Insulating layer

Claims (3)

  A core substrate having copper foil attached to both surfaces of an insulating base material, first and second conductor wiring patterns formed on the upper and lower surfaces of the core substrate, respectively, and the second on the lower surface of the core substrate An insulating layer laminated with a copper foil on the lower surface, a third conductor wiring pattern formed on the copper foil on the lower surface of the insulating layer, and the third conductor wiring A solder resist covering the pattern, and the core substrate has a plurality of first non-through holes whose upper portions are closed by copper foil, and the semiconductor element is placed on the upper surface via the copper foil and the first conductor wiring pattern. The insulating layer has a plurality of second non-through holes whose upper portions are blocked, and the first to third conductive films are formed on the inner wall surfaces of the first and second non-through holes. Conductor wiring pattern is electrically connected Frequency plastic package, characterized in that it is.   A plurality of the insulating layers and the third conductor wiring pattern are sequentially stacked on the lower surface of the core substrate, and the plurality of insulating layers have a plurality of the second non-through holes whose upper portions are closed, 2. The high-frequency plastic package according to claim 1, wherein the first to third conductor wiring patterns are electrically connected by a conductive film formed on inner wall surfaces of the first and second non-through holes.   A step of forming a core substrate by attaching copper foil to both surfaces of the insulating base material, a step of drilling a plurality of first non-through holes whose upper portions are closed by copper foil in the core substrate, and the core Forming a conductive film on both surfaces of the substrate and the inner wall surface of the first non-through hole, forming first and second conductive wiring patterns on the conductive film on the upper surface and the lower surface of the core substrate, respectively; A step of laminating an insulating layer and a copper foil on the lower surface of the core substrate via the second conductive wiring pattern, and a plurality of second non-through holes that penetrate the copper foil and have the upper portion closed; Forming a conductive film on the copper foil on the lower surface of the insulating layer and the inner wall surface of the second non-through hole, and a third conductor wiring on the conductive film of the copper foil on the lower surface of the insulating layer A step of forming a pattern and the third conductor wiring pattern in the lowermost layer Method for producing a high-frequency plastic package according to claim 1 or claim 2, characterized in that a step of coating the over resist.