WO2013061500A1

WO2013061500A1 - Flexible wiring board and method for manufacturing same

Info

Publication number: WO2013061500A1
Application number: PCT/JP2012/005238
Authority: WO
Inventors: 典昭関根
Original assignee: 山一電機株式会社
Priority date: 2011-10-24
Filing date: 2012-08-21
Publication date: 2013-05-02
Also published as: JP2013093366A

Abstract

In order to provide a flexible wiring board, which makes it possible to have high-density wiring with high productivity, and a method for manufacturing the flexible wiring board, a flexible wiring board (10) is formed, said flexible wiring board having a plurality of layers of conductor patterns (12, 13) laminated in layers. The first conductor pattern (12) and the second conductor pattern (13) are integrally laminated on a conductor board with an interlayer insulating layer (11) between the first and the second conductor patterns, the layers of the conductor patterns (12, 13) are electrically connected to each other by means of a conductive paste bump (14) that penetrates the interlayer insulating layer (11), and a conductor bump (15) electrically connected to the first conductor pattern (12) is formed by etching the conductor board in contact with the first conductor pattern (12) on the conductor board side, thereby forming the flexible wiring board having the conductor bump (15) protruding from the main surface of the interlayer insulating layer (11), said main surface having the first conductor pattern (12) disposed thereon.

Description

Flexible wiring board and manufacturing method thereof

The present invention relates to a flexible wiring board used as a substrate for semiconductor packages, transmission wiring, circuit wiring, and the like, and a method for manufacturing the same.

For example, flexible wiring boards used in electronic devices such as network devices, servers, and testers require high-speed transmission without impairing their high-frequency characteristics when using high-speed digital signals in the range of several GHz to several tens of GHz. Yes. In mobile electronic devices such as portable devices, for example, as the size and thickness of the mobile electronic devices are reduced, the flexible wiring board is being made to have high density wiring and light weight. In addition, the wiring patterns that become transmission wirings or circuit wirings are miniaturized and the wiring density is increased by multilayering.

In the multi-layer flexible wiring board, conductive members for electrically connecting the wiring pattern layers are formed by plating in via holes, through holes, etc. provided in the interlayer insulator layer. Alternatively, conductive bumps are embedded in interlayer insulating layers and applied to conductive members (for example, see Patent Document 1).

In addition, in order to enable downsizing and higher functionality of electronic equipment, the semiconductor devices mounted on the flexible wiring board are made finer, higher-integrated, faster, or multi-functional (hereinafter referred to as higher performance of semiconductor devices). Say) is remarkable. At the same time, the number of external connection terminals in the semiconductor chip has increased, and for example, BGA (Ball Grid Array) package, LGA (Land Grid Array) package, CSP (Chip Size Package) and the like have been frequently used. In addition, in a flexible wiring board such as an interposer or a film-like board as these package boards, various attempts have been made to increase the density of conductor patterns (see, for example, Patent Documents 2 and 3).

Patent Document 1: Japanese Patent No. 3816038 Patent Document 2: Japanese Patent No. 3378171 Patent Document 3: Japanese Patent Application Laid-Open No. 2005-26491

In the flexible wiring board that is lightened and thinned, the interlayer insulator layer and the wiring layer are thinned with the increase in wiring density, and the flexibility of the base material is increased. In the manufacturing process of flexible wiring boards, this high flexibility leads to a decrease in productivity in the process of laminating and integrating the interlayer insulator layer and the wiring layer or in the process of forming conductive bumps due to the poor handling properties. . Here, it is possible to adopt a handling technique that can handle a highly flexible base material with high accuracy. However, in any case, the manufacturing cost of the flexible wiring board may increase.

Also, as seen in, for example, SiP (System-in-Package) or MCM (Multi-Chip Module), there is a strong demand for a semiconductor package that enables higher-density mounting of semiconductor devices. However, even in a flexible wiring board such as an interposer board used in such a semiconductor package, there is a risk of an increase in manufacturing cost due to the lighter thickness or higher wiring density. In the case of this semiconductor package, a new technology that can cope with high performance of semiconductor devices and enables high-density mounting is also desired.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a flexible wiring board and a method for manufacturing the same that enable high-density wiring with high productivity. And the flexible wiring board which can respond easily to the high performance of a semiconductor device and enables the high-density mounting is provided.

A flexible wiring board according to the present invention is a flexible wiring board in which a plurality of layers of conductor patterns are laminated in multiple layers, and two or more layers of conductor patterns are integrally laminated on a conductor plate with an interlayer insulator layer interposed therebetween. Are electrically connected by conductive paste bumps penetrating the interlayer insulating layer, conductive bumps are formed which are electrically connected to the conductor pattern by etching the conductor plate in contact with the conductor pattern, The conductor bump protrudes from the main surface of the interlayer insulator layer on which the conductor pattern is disposed.

A method for manufacturing a flexible wiring board according to the present invention includes a step of electrically contacting a layer of a first conductor pattern on a surface of a conductor plate, and a conductive paste bump in a predetermined region of the first conductor pattern. A step of forming, and a resin film to be an interlayer insulating layer and a metal foil to be the second conductor pattern are laminated in this order on the conductive paste bump, and heated and pressed to electrically connect the conductive paste bump and the metal foil. A step of patterning the metal foil to form a second conductor pattern, and a step of etching the conductor plate to form a conductor bump electrically connected to the first conductive pattern. .

According to the present invention, it is possible to provide a flexible wiring board and a method for manufacturing the same that enable high density wiring with high productivity. In addition, it is possible to provide a flexible wiring board that can easily cope with high performance of semiconductor devices and enables high-density mounting.

1 is a partially enlarged cross-sectional view illustrating an example of a flexible wiring board according to a first embodiment of the present invention. Sectional drawing according to manufacturing process which shows the manufacturing method of an example of the flexible wiring board concerning the 1st Embodiment of this invention. Sectional drawing according to the manufacturing process following the process of FIG. 2A and 2B show specific examples of the flexible wiring board according to the first embodiment of the present invention, in which FIG. 1A is a plan view of a semiconductor package substrate, and FIG. 2B is an enlarged cross-sectional view taken along line XX in FIG. The partial expanded sectional view which shows an example of the flexible wiring board concerning the 2nd Embodiment of this invention. Sectional drawing according to manufacturing process which shows the manufacturing method of an example of the flexible wiring board concerning the 2nd Embodiment of this invention. Sectional drawing according to manufacturing process following the process of FIG.

Hereinafter, some preferred embodiments of the present invention will be described with reference to the drawings. Here, the drawings are schematic, and ratios of dimensions and the like are different from actual ones.

(First embodiment)
A flexible wiring board according to a first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the flexible wiring board has a conductor bump protruding from its main surface.

This embodiment uses both conductive paste bumps and conductor bumps. The conductor bumps are formed from a metal conductor plate that makes a fragile flexible laminate board rigid and easy to process in the manufacturing process of the flexible wiring board. A conductor plate bump is formed by etching from this conductor plate. That is, the conductor plate functions as a substrate support, as will be described later, and is formed on the conductor bumps to function as connection bumps for connection lands and interlayer insulators.

As shown in FIG. 1, in the flexible wiring board 10 of the example, the 1st conductor pattern 12 and the 2nd conductor pattern 13 are laminated | stacked and arrange | positioned integrally on both surfaces on both sides of the interlayer insulator layer 11. As shown in FIG. Then, the predetermined first conductor pattern 12 and the second conductor pattern 13 are electrically connected through the conductive paste bumps 14. The conductive paste bump 14 provided by this printing is formed so as to penetrate the interlayer insulator layer 11.

Further, the conductor bumps 15 are electrically connected to the predetermined first conductor pattern 12. The conductor bump 15 protrudes from the main surface 11 a of the interlayer insulator layer 11 on which the first conductor pattern 12 is arranged, that is, the main surface of the flexible wiring board 10. The conductor bump 15 is formed by etching a conductive plate, as will be described later in the description of the method for manufacturing the flexible wiring board 10. In the example shown in FIG. 1, the conductive bumps 15 formed by etching are shown to overlap with the conductive paste bumps 14 via the first conductive pattern 12, but in the region where the conductive paste bumps 14 are not provided. One conductor pattern 12 may be connected and protruded.

In the flexible wiring board 10, the conductor bumps 15 are preferably electrically connected to the first conductor pattern 12 via the metal barrier 16, but may be directly connected to the first conductor pattern 12. In addition, it is preferable that a solder resist 17 is formed between the patterns of the second conductor pattern 13. A plating layer 18 is preferably formed on the surfaces of the first conductor pattern 12, the second conductor pattern 13, and the conductor bump 15.

In the flexible wiring board 10, a thermoplastic resin or a thermosetting resin is used as the interlayer insulator layer 11. Among these, a liquid crystal polymer is particularly preferable because it exhibits excellent high-frequency transmission characteristics and flexibility. Here, the liquid crystal polymer is, for example, a multiaxially oriented thermoplastic polymer represented by xidar (trade name, manufactured by Dartco) or Vectra (trade name, manufactured by Clanese). Further, it may be modified by adding and blending another insulating resin. Examples thereof include Bexter FA type, Bexter CT type, and BIAC film.

The first conductor pattern 12 and the second conductor pattern 13 are made of normal copper (Cu) or a copper alloy. The conductive paste bump 14 includes a granular metal material such as silver (Ag), Cu, gold (Au), solder, or the like using a resin as a binder.

The conductor bump 15 is made of a metal material such as Cu or Cu alloy. The metal barrier 16 is made of a metal material such as nickel (Ni) or tin (Sn), and the plating layer 18 is a single layer of Au, Ag, or nickel (Ni), or Ni / Au, Ni / Ag, or the like. It consists of a composite layer.

Next, an example of a method for manufacturing the flexible wiring board according to the first embodiment of the present invention will be described. As shown in FIG. 2A, for example, a conductor plate (eg, Cu plate) 21 having a thickness of 25 μm to 200 μm, a metal barrier layer (eg, Ni layer) 22 having a thickness of about 0.5 μm to 1 μm, and about 10 μm to 50 μm. A clad material having a three-layer structure of a first metal foil (for example, Cu foil) 23 having a thickness of 10 mm is prepared. Here, the conductive plate 21 is preferably thicker than the wiring layer (first conductive pattern) in order to increase the rigidity of the flexible laminate during the manufacturing process.

As shown in FIG. 2B, the first metal foil 23 is in electrical contact with the conductor plate 21 by adopting a clad structure. In order to form the first metal foil 23 in the layer of the first conductor pattern 12, an etching resist 24 having a predetermined pattern is formed on the surface, and an etching resist 25 that covers the entire back side of the conductor plate 21 is formed. Here, these etching resists are formed, for example, by photolithography using a known photosensitive dry film.

Next, the first metal foil 23 is selectively etched using the etching resists 24 and 25 as an etching mask by immersing in an etching solution of a chemical solution such as an ammonia-based alkaline etching solution that selectively dissolves Cu. Here, the metal barrier layer 22 functions as an etching stopper. Then, the etching resists 24 and 25 are removed or dissolved with an alkaline aqueous solution and removed. In this way, the first conductor pattern 12 is formed on the metal barrier layer 22 as shown in FIG.

Next, as shown in FIG. 2D, the conical conductive paste 26 is obtained by repeating screen printing and drying of the conductive paste using, for example, a stainless steel screen plate on the predetermined first conductive pattern 12. Make a bump. Here, the conductive paste is, for example, a mixture of metal particles such as Ag, Au, Cu, Sn, lead (Pb), and carbon and an epoxy resin, a phenol resin, an acrylic resin, or the like.

Next, for example, a resin film 11 having a thickness of about 15 μm to 50 μm and a second metal foil 27 made of, for example, Cu having a thickness of about 10 μm to 50 μm are stacked from above. Thereafter, heat and pressure treatment (heat press) is performed, and as shown in FIG. 2 (e), the conical conductive paste 26 undergoes a composition change along with plastic deformation in which the head is crushed, and the conductive paste bump 14 become. Then, the conductive paste bump 14 is inserted through the interlayer insulator layer 11 and connected to the second metal foil 27. The interlayer insulator layer 11 is made of a thermoplastic resin film such as a liquid crystal polymer, and is bonded to the first conductor pattern 12 and the metal barrier layer 22 by thermocompression bonding.

In the hot press, the atmospheric gas is, for example, in a reduced pressure state, and the heating temperature at that time is a temperature at which the thermoplastic resin film is heat-softened, and in the case of a thermosetting resin film, the temperature is the temperature at which thermosetting is performed. For example, the temperature is set to about 180 ° C. to 230 ° C. The pressurization is, for example, about 30 to 100 kgf / cm ² .

Here, even if the interlayer insulator layer 11 and the first conductor pattern 12 are thinned, the required rigidity and strength can be imparted by the conductor plate 21, so that the handling property of the base material in the manufacturing process of the flexible wiring board is increased. be able to. Therefore, the productivity is improved particularly in the process of forming the conical conductive paste 26 shown in FIGS. 2D and 2E or laminating and integrating by hot pressing.

Next, in the same manner as described in FIG. 2B, an etching resist is applied on both sides to form an etching mask (not shown), and the second metal foil 27 is selectively etched with the same chemical solution as described above. . Then, as shown in FIG. 3A, a second conductor pattern 13 having a required pattern is formed. Further, as shown in FIG. 3B, a solder resist 17 is formed between the patterns of the second conductor patterns 13.

Next, as shown in FIG. 3C, an etching resist 28 having a predetermined pattern is formed on the surface of the conductor plate 21, and an etching resist 29 covering the entire surface of the first conductor pattern 13, the solder resist 17, and the like is formed. To do. These etching resists are formed by, for example, photolithography using a known photosensitive dry film, as described with reference to FIG.

Then, the conductive plate 21 is immersed in a chemical solution for etching, and the conductive plate 21 is selectively wet etched using the etching resists 28 and 29 as an etching mask. Also in this case, the metal barrier layer 22 functions as an etching stopper. This prevents the first conductive pattern from being etched. Thereafter, the etching resists 28 and 29 are removed or dissolved and removed with an alkaline aqueous solution. In this way, a conductor bump 15 as shown in FIG. 3D is formed. The conductor bump 15 has a trapezoidal shape whose cross section is a forward tapered shape.

Next, as shown in FIG. 3E, the exposed metal barrier layer 22 is selectively removed by etching using, for example, a chemical solution that selectively dissolves Ni. Thereafter, a plating layer 18 is formed on the surface of the conductor bump 15, the surface of the first conductor pattern 12, and the surface of the second conductor pattern 13 as shown in FIG. In this way, the flexible wiring board 10 is manufactured.

Next, a specific flexible wiring board having a structure having conductor bumps protruding from the main surface of the board as described above will be described. For example, a flexible wiring substrate 10a as shown in FIG. 4A is an example of a package substrate on which a plurality of semiconductor chips can be mounted, and is used for a BGA package or an LGA package that can easily be multi-pinned. In the flexible wiring board 10a shown in FIG. 4, a predetermined number of die lands 31 are arranged as second conductor patterns on the upper surface thereof. A required number of wire connection lands 32 are formed as second conductor patterns so as to surround each die land 31. These connection lands 32 are formed on one main surface 11a of the flexible wiring board 10a, that is, the lower surface shown in the figure, through the conductive paste bumps 14 penetrating the interlayer insulator layer 11 as shown in FIG. 4B. The conductor bumps 15 are electrically connected.

Note that solder resists 17 and 33 are respectively formed between the die land 31 and the connection land 32 on the upper surface of the flexible wiring board 10a and between the conductor bumps 15 on the lower surface thereof.

In the flexible wiring board 10a, although not shown, the semiconductor chip is attached to the die land 31 with, for example, a conductive paste or an insulating paste. The electrode pads of the respective semiconductor chips are connected to the connection lands 32 by bonding wires. In this manner, these semiconductor chips and bonding wires are resin-sealed, and a plurality of semiconductor chips are mounted on the flexible wiring board 10a with high density.

In addition, as an example of a BGA package or an LGA package that can be easily multi-pinned, there is a flexible wiring board on which a semiconductor chip is flip-chip mounted. As such a flexible wiring board, although not shown, a flexible wiring board 10 having a structure as described in FIG. 1 can be applied. That is, in the flexible wiring board 10 of FIG. 1, the conductor bumps 15 on the lower surface 11a are formed as described with reference to FIG. Then, second conductor patterns 13 (including connection lands) connected to these conductor bumps 15 through the conductive paste bumps 14 are disposed on the upper surface of the flexible wiring board 10. These second conductor patterns 13 have a structure in which they are flip-chip connected to external connection terminals such as electrode pads or solder ball bumps on a semiconductor chip.

In either the bonding wire connection or the flip chip connection, the conductor bump 15 becomes an external connection bump of the semiconductor package substrate, and is used for electrical connection with a mother board such as a printed circuit wiring board. In this flexible wiring board, it is possible to increase the density of the conductor pattern to be the wiring and to make the conductor bump finer and more accurate. For this reason, it becomes easy to cope with miniaturization and high integration of semiconductor devices. Further, high-density mounting of, for example, SiP on a semiconductor device with high performance such as multi-function becomes easy.

Furthermore, as a specific flexible wiring board having a structure having a conductor bump protruding from the main surface of the board, there is a probe board for conducting an electric current inspection of an electronic device such as a semiconductor device or a display device such as an FPD. This flexible wiring board as a probe board is attached to the tip of a probe head attached to a probe card in an energization inspection apparatus (hereinafter also referred to as a prober) for energizing an electronic device. The conductor bump 15 on the lower surface of the flexible wiring board 10 described in FIG. 1 is a probe (contactor) that comes into contact with an external connection terminal of a device under test (hereinafter also referred to as Device under Test; DUT). Function as. Further, the second conductor pattern 13 on the upper surface of the flexible wiring board 10 is appropriately connected to the circuit wiring of the probe card via the probe head.

In recent years, with the improvement in performance of semiconductor devices or the increase in definition of display devices, the terminals for external connection formed on the surface of these devices have become multiterminal and narrow pitched. And the energization inspection of an electronic device is speeded up, and a plurality of DUTs are being inspected simultaneously. Alternatively, as seen in wafer level packages, a large number of external connection terminals are inspected at the same time.

The conventional needle-shaped contact attached to the probe head has a limit in processing accuracy, and it is difficult to cope with a large number of pins and a narrow pitch. On the other hand, the flexible wiring board according to the present embodiment is remarkably improved in dimensional accuracy including the height of the protruding conductor bumps, so that it is very easy to cope with a large number of pins and a narrow pitch. To do. In addition, its reliability is increased. For this reason, the flexible wiring board of the present embodiment is extremely useful as a probe board for electronic devices in which the number of external connection terminals is increased and the pitch is reduced. This energization inspection includes a burn-in test.

The flexible wiring board of the above embodiment can be variously multilayered by build-up. For example, an uncured thermosetting resin is sandwiched between the substrate in the state shown in FIG. 3A described in the method for manufacturing the flexible wiring board 10 and another prepared substrate in FIG. 3E is heated. Laminated and integrated by pressing. In this way, the conductor bump 15 becomes a conductive member that penetrates the thermosetting resin and connects to the second conductor pattern 13. Then, by processing the conductor plate 21 in the state of FIG. 3A into a conductor bump, a flexible wiring board having a wiring layer composed of four layers of conductor patterns and a conductor bump protruding from the main surface of the board is formed.

Alternatively, in FIG. 3E, a conical conductive paste is formed on the predetermined second conductor pattern 13 of the substrate without the solder resist 17, and the substrate in the state of FIG. Laminated and integrated by hot pressing with curable resin in between. Thereafter, the conductor plate 21 in the state of FIG. 3A is processed into a conductor bump. In this way, a flexible wiring board having four-layer wirings that electrically connect the conductive bumps protruding from the main surfaces of the upper and lower surfaces of the substrate and the two-layer conductive paste bumps as conductive members is formed.

In the flexible wiring board of the present embodiment, two or more conductor pattern layers are laminated and integrated with an interlayer insulator layer interposed therebetween, and these conductor pattern layers are electrically connected by conductive paste bumps. A conductor bump connected to the outermost layer of the conductor pattern or the conductive paste bump is formed by etching the conductor plate, and the conductor bump protrudes from the main surface of the flexible wiring board. For this reason, the flexible wiring board according to the present embodiment facilitates miniaturization and high-density mounting of the semiconductor package as described above.

In addition, the flexible wiring board of this embodiment can easily cope with external connection terminals that are multi-terminal and narrow pitched as the performance of a semiconductor device increases or the definition of a display device increases. And in the energization test | inspection of these electronic devices, it becomes very useful as the board | substrate for probes.

Further, when the interlayer insulator layer 11 is made of a liquid crystal polymer, the relative dielectric constant is 3 or less, and the electrostatic tangent is 0.003 or less. The wiring on the flexible wiring board 10 exhibits extremely excellent transmission / conduction characteristics of high-speed digital signals in the range of several GHz to several tens of GHz. For this reason, high-speed mounting and accurate energization inspection that do not degrade the performance of semiconductor devices at high speeds are possible.

In the method for manufacturing a flexible wiring board according to the present embodiment, a conductor plate that finally becomes a conductor bump of the flexible wiring board is used by etching. A very thin resin sheet can be used for processing on the basis of a conductor plate, and even if the base material becomes more flexible as the conductor pattern of the flexible wiring board becomes denser and thinner, its high flexibility It is possible to prevent a decrease in handling property due to the property. Furthermore, the combination of the printed bumps made of conductive paste bumps and the etching bumps on the conductive plate can give the element mounting elasticity even on a thin board such as a flexible circuit board, thereby improving the connection reliability. Further, the productivity in the process of laminating and integrating the interlayer insulator layer and the wiring layer or the process of forming the conductive paste bump is improved, and the cost of the flexible wiring board can be reduced.

(Second Embodiment)
Next, a flexible wiring board according to a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the conductor bump is a conductive member that electrically connects the conductor pattern layers together with the conductive paste bump.

As shown in FIG. 5, the flexible wiring board 20 of the example has four conductor pattern layers. In the inner layer, the first conductor pattern 42 is disposed on the lower surface 41a and the second conductor pattern 43 is disposed on the upper surface 41b with the first insulator layer 41 interposed therebetween, and the predetermined first conductor pattern 42 and second conductor pattern 43 are disposed. Are connected by a conductive paste bump 54. The conductive paste bump 54 penetrates the first insulator layer 41.

In the outer layer of the flexible wiring board 20, the third conductor pattern 45 is disposed on the lower surface with the second insulator layer 44 interposed therebetween, and the fourth conductor pattern 47 is disposed on the upper surface with the third insulator layer 46 interposed therebetween. Has been. The predetermined third conductor pattern 45 is connected to the predetermined first conductor pattern 42 through the first conductor bump 48, and the predetermined fourth conductor pattern 47 is connected to the predetermined second conductor pattern 43 through the second conductor bump 49. is doing. The first conductor bump 48 and the second conductor bump 49 are formed by etching a conductor plate, as will be described later in the description of the method for manufacturing the flexible wiring board 20.

Here, the part 42 a of the predetermined first conductor pattern 42 is electrically connected to the part 47 a of the predetermined fourth conductor pattern 47 through the conductive paste bump 54, the second conductor pattern 43, and the second conductor bump 49. To do. A portion 43 a of the predetermined second conductor pattern 43 is electrically connected to a portion 45 a of the predetermined third conductor pattern 45 through the conductive paste bump 54, the first conductor pattern 42, and the first conductor bump 48. Therefore, the predetermined third conductor pattern 45a and the predetermined fourth conductor pattern 47a are arranged via the first conductor bump 48, the first conductor pattern 42, the conductive paste bump 54, the second conductor pattern 43a, and the second conductor bump 49. Can be connected electrically.

In the flexible wiring board 20, through holes 50 are provided in the first insulator layer 41, the second insulator layer 44, and the third insulator layer 46 as necessary. Then, the inside of the through hole 50 may be made conductive by the conductive body 50a, and the predetermined third conductor pattern 45 and the predetermined fourth conductor pattern 47 may be directly electrically connected. In the example shown in FIG. 5, the conductive body 50 a is formed integrally with the third conductor pattern 45 and the fourth conductor pattern 47.

Next, an example of a method for manufacturing a flexible wiring board according to the second embodiment of the present invention will be described. As shown in FIG. 6A, a plating resist 52 having a required pattern is formed on a first conductor plate (eg, Cu plate) 51 having a thickness of 25 μm to 200 μm, for example. Then, for example, the metal barrier 53 and the first conductor pattern 42 are laminated and formed in an area where the first conductor plate 51 is exposed by electrolytic plating. Here, the metal barrier 53 is made of, for example, a Ni layer or a Sn layer having a thickness of about 0.5 μm to 1 μm, and the first conductor pattern 42 is made of, for example, a Cu layer having a thickness of about 10 μm to 50 μm. Then, the plating resist 52 is stripped or dissolved and removed by an alkaline aqueous solution, and the first conductor pattern 42 is a predetermined region on the main surface of the first conductor plate 51 through the metal barrier 53 as shown in FIG. Formed.

Next, as shown in FIG. 6C, the conical conductive paste 54 is bumped onto the predetermined first conductor pattern 42 in the same manner as described in the first embodiment.

Further, in the same manner as described with reference to FIGS. 6A and 6B, the second conductor pattern 43 is formed in a predetermined region of the main surface of the second conductor plate 55 via the metal barrier 53. Then, as shown in FIG. 6D, the second conductor plate 55 is turned over, and set up and positioned together with a first resin film 56 made of, for example, a liquid crystal polymer having a thickness of about 15 μm to 50 μm.

Next, the first conductor plate 51, the first resin film 56, and the second conductor plate 55 are joined together by thermocompression using a hot press in the same manner as described in the first embodiment. As a result, as shown in FIG. 6E, the conical conductive paste 54 changes its composition along with the plastic deformation that crushes its head, and becomes a conductive paste bump. Further, the first resin film 56 becomes the first insulator layer 41 in which the first conductor pattern 42 and the second conductor pattern 43 are bonded to the both surfaces together with the metal barrier 53 and the conductive paste bumps 54 are inserted therethrough. Here, the predetermined first conductor pattern 42 and the predetermined second conductor pattern 43 are electrically connected through the conductive paste bumps 54.

Here, even if the first insulator layer 41, the first conductor pattern 42, and the second conductor pattern 43 are thinned, the required hardness can be imparted by the first conductor plate 51, so that the base material of the flexible wiring board can be handled. Sexuality can be increased. For this reason, as described in the first embodiment, in particular, in the step of forming the conical conductive paste 54 shown in FIGS. 6C, 6D, and 6E or laminating and integrating by hot pressing, Its productivity is improved.

Next, as described in the first embodiment, the first conductor plate 51 and the second conductor plate 55 are selectively etched by photolithography and wet etching. Then, as shown in FIG. 7A, a first conductor bump 48 and a second conductor bump 49 projecting from the lower surface and the upper surface of the first insulator layer 41 are formed. These conductor bumps have trapezoidal cross sections, and are electrically connected to predetermined first conductor patterns 42 and second conductor patterns 43 through metal barriers 53, respectively. In the etching, the first conductor pattern 42 or the second conductor pattern 43 in the region where the first conductor bump 48 or the second conductor bump 49 is not formed is protected by the metal barrier 53 as an etching stopper.

Next, as shown in FIG. 7B, the thermosetting second resin film 57 and the second resin film 58 in an uncured state are shown in FIG. 7A by a known vacuum laminating method. The first insulator layer 41 is laminated and integrated with each other. In this lamination / integration, a sheet-like support member (not shown) may be used to press the film from both sides. The temperature in this laminate is a predetermined temperature at which the second resin film 57 and the third resin film 58 in an uncured state are cured, and is a temperature lower than the glass transition point or the melting point of the first insulator layer 41. The second resin film 57 and the third resin film 58 are thermosetting resins such as ABFGX-13 (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd. The thickness of these films is about 15 μm to 100 μm.

As shown in FIG. 7C, the second resin film 57 has the first conductor pattern 42 having the first insulator layer 41 and the metal barrier 53 bonded to the upper surface thereof, and the first conductor bumps 48 penetrated. The inserted second insulator layer 44 is obtained. Further, the third resin film 58 is joined to the first conductor layer 41 and the second conductor pattern 43 having the metal barrier 53 on the lower surface thereof to become the third insulator layer 46 through which the second conductor bumps 49 are inserted. .

Next, in the state shown in FIG. 7C, the surfaces of the second insulator layer 44, the third insulator layer 46, etc. are cleaned. Here, mechanical polishing, degreasing, pickling, etc. are performed on the surfaces of the first conductor bump 48 and the second conductor bump 49. Then, if necessary, a through hole 50 penetrating the first insulator layer 41, the second insulator layer 44, and the third insulator layer 46 in a predetermined region is formed by laser processing, for example. Thereafter, a desmear process is performed to clean the exposed surfaces of the first conductor bump 48 and the second conductor bump 49 and the inner wall of the through hole 50.

Next, as shown in FIG. 7D, a metal outer layer 59 that adheres to the surface of the second insulator layer 44, the third insulator layer 46, and the inner wall of the through hole 50, for example, by electroless plating or the like. Form. Here, the thickness of the metal outer layer 59 is set to about 10 μm to 50 μm. Then, by the selective etching of the metal outer layer 59 using photolithography, the third conductor pattern 45 and the fourth conductor pattern 47, which are the outer layers described in FIG. Thereafter, as described in the first embodiment, a plating layer (not shown) is formed on the surface of these outer layers by electroless plating such as Au. In this way, the flexible wiring board 20 as shown in FIG. 5 is manufactured.

In the formation of the first conductor pattern 42 on the first conductor plate 51 or the formation of the second conductor pattern 43 on the second conductor plate 55, the clad having a three-layer structure as described in the first embodiment. Materials can be used. Also in this case, selective etching using photolithography is performed on the metal foil of the clad material.

Further, the first conductor pattern 42 and the first conductor plate 51 may be made of different metal materials. Similarly, the second conductor pattern 43 and the second conductor plate 55 may be made of different metal materials. In these cases, the metal barrier 53 as an etching stopper can be eliminated in the wet etching of the first conductor plate 51 or the second conductor plate 55.

7A, a resin film and a metal foil (copper foil) are laminated in this order from the first conductor bump 48 or the second conductor bump 49 on the substrate in the state of FIG. Here, in order to remove adhesion of oxides and the like on the surface of the conductor bump, the laminated metal foil corresponding to the position of the upper side (bump top) of the conductor bumps 48 and 49 is removed by etching, and then the above-described bump top surface is cleaned. To implement. Subsequent panel copper plating realizes connection with the bump top. The third conductor pattern 45 and the fourth conductor pattern 47 can be formed by patterning the metal foil and the copper plating film. The cleaning and copper plating after the removal of the metal foil on the bump top may be combined with the mechanical polishing and the desmear process after the through-hole drilling.

The flexible wiring board of the second embodiment can be variously multilayered by build-up, as described in the first embodiment. For example, the base material in the state of FIG. 6C is laminated and integrated by hot pressing, for example, with an uncured thermosetting resin sandwiched from the lower surface or the upper surface of the flexible wiring board 20 described in FIG. Then, the first conductor plate 51 is processed into a conductor bump. Thereafter, for example, through the steps of FIGS. 7B, 7C, and 7D, a multilayer flexible wiring board is formed.

In the second embodiment, as described in the first embodiment, in the manufacturing process of the flexible wiring board, a required strength can be imparted to the laminated body by the conductor plate. Productivity etc. improve and the cost reduction is attained.

In addition, since a plurality of wiring layers made of conductive patterns are alternately electrically connected by conductive paste bumps and conductive bumps, a high-density wiring flexible wiring board is manufactured with high reliability of the wiring layers. be able to. This is because the conductive paste bump acts as a buffer for thermal stress caused by thermal expansion or contraction in the manufacturing process of a base material such as an insulator layer, and the conductor bump works to prevent thermal deformation of the material. It is.

Also, it is easy to increase the density of the wiring layer as the interlayer insulating layer and the wiring layer are made thinner. Then, for example, a flexible wiring board having a wiring circuit corresponding to a high frequency reaching the GHz band like a CPU clock of a computer can be easily provided.

As the flexible wiring substrate applied to the semiconductor package substrate or the probe substrate described in the first embodiment, the one having the structure of FIG. 7A can be used in the second embodiment. In the final structure, the first conductor bump 48 and the second conductor bump 49 protruding from the lower surface and the upper surface of the first insulator layer 41 are exposed to cover the first conductor pattern 42 and the second conductor pattern 43. The solder resist is deposited.

Also, the conductive paste bump may be one in which a via hole or a through hole formed in the base material of the flexible wiring board is filled with a conductive paste such as Cu paste.

For convenience, the description uses the terms “upper surface” and “lower surface”. The “upper surface” and the “lower surface” mean that they are in a relationship of front and back, and do not mean spatial top and bottom.

The preferred embodiments of the present invention have been described above, but the above-described embodiments do not limit the present invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

DESCRIPTION OF

SYMBOLS

10, 10a, 20 ... Flexible wiring board, 11 ... Interlayer insulator layer, 11a ... Main surface, 12, 42 ... First conductor pattern, 13, 43 ... Second conductor pattern, 14, 54 ... Conductive paste bump, 15 ... Conductor bump, 16, 53 ... Metal barrier, 17, 33 ... Solder resist, 18 ... Plating layer, 21 ... Conductor plate, 22 ... Metal barrier layer, 23 ... First metal foil, 24, 25, 28, 29 ... Etching Resist, 26, 54 ... conical conductive paste, 27 ... second metal foil, 31 ... die land (conductor pattern), 32 ... connection land (conductor pattern), 41 ... first insulator layer (interlayer insulator layer), 41a ... lower surface (main surface), 41b ... upper surface (main surface), 44 ... second insulator layer (interlayer insulator layer), 45 ... third conductor pattern, 46 ... third insulator layer, 47 ... fourth conductor pattern 48th Conductor bump, 49 ... second conductor bump, 50 ... through hole, 50a ... conductor, 51 ... first conductor plate, 52 ... plating resist, 55 ... second conductor plate, 56 ... first resin film, 57 ... second Resin film, 58 ... third resin film, 59 ... metal outer layer

Claims

In a flexible wiring board in which a plurality of layers of conductor patterns are laminated, two or more layers of conductor patterns are laminated on a conductor plate with an interlayer insulator layer in between, and the layers of the conductor patterns penetrate the interlayer insulation layer Conductive bumps that are electrically connected by conductive paste bumps that are electrically connected to the conductive patterns are formed by etching the conductive plate in contact with the conductive patterns, and the conductive bumps arrange the conductive patterns. A flexible wiring board protruding from the main surface of the interlayer insulator layer.
The flexible wiring board according to claim 1, wherein the conductor plate has a layer thickness greater than that of the conductor pattern layer.
The flexible wiring board according to claim 1, wherein the conductive bump is a bump for external connection of the semiconductor package substrate.
2. The flexible printed circuit board according to claim 1, wherein the flexible printed circuit board is a probe board used for an energization inspection of an electronic device, wherein the conductor bump is a probe bump that contacts an external connection terminal of a subject.
In a flexible wiring board in which a plurality of layers of conductor patterns are laminated, two or more layers of conductor patterns are laminated on a conductor plate with an interlayer insulator layer in between, and the layers of the conductor patterns penetrate the interlayer insulation layer A flexible wiring board characterized in that the conductive paste bump is electrically connected to a conductive bump formed by etching a conductive plate.
6. The flexible wiring board according to claim 5, wherein the layers of the conductive patterns are alternately electrically connected by the conductive paste bumps and the conductive bumps formed by etching a conductive plate. .
Forming a first conductive pattern layer in electrical contact with the surface of the conductive plate;
Forming a conductive paste bump in a predetermined region of the first conductor pattern;
A step of laminating a resin film to be an interlayer insulating layer and a metal foil to be a second conductor pattern in this order from above the conductive paste bump and electrically connecting the conductive paste bump and the metal foil by heating and pressing; ,
Patterning the metal foil to form a second conductor pattern;
Etching the conductive plate to form a conductive bump electrically connected to the first conductive pattern;
The manufacturing method of the flexible wiring board characterized by having.
Forming the first conductor pattern in electrical contact with the surface of the first conductor plate;
Forming a conductive paste bump in a predetermined region of the first conductor pattern;
Forming a second conductor pattern on the surface of the second conductor plate;
Laminating the resin film and the second conductor plate in this order on the conductive paste bump and heating and pressing to connect the conductive paste bump and the second conductor pattern;
Etching the first conductor plate and the second conductor plate into a first conductor bump and a second conductor bump, respectively;
The manufacturing method of the flexible wiring board characterized by having.
The conductor plate and the first conductor pattern layer are made of the same kind of metal, and a metal barrier layer of different metals having different etching characteristics is formed between the conductor plate and the first conductor pattern layer. The manufacturing method of the flexible wiring board of Claim 7.
The first conductor plate and the first conductor pattern layer are made of the same kind of metal, and a metal barrier layer of a different metal having different etching characteristics is formed between the first conductor plate and the first conductor pattern layer,
The second conductor plate and the second conductor pattern layer are made of the same kind of metal, and a metal barrier layer made of a different kind of metal having different etching characteristics is formed between the second conductor plate and the second conductor pattern layer. The method for producing a flexible wiring board according to claim 8.