JP2006012921A - Multi-layer printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coefficient of linear expansion of a wiring conductor layer and a through conductor and an insulating layer in a multilayer wiring board formed by laminating a wiring conductor layer and a resin insulation layer when the through conductors are stacked one above the other. Due to the difference, stress concentrates around the wiring conductor layer and the through conductor, and the problem of electrical continuity such as peeling of the interface between the wiring conductor layer and the through conductor is eliminated.
A plurality of insulating layers 2 and wiring conductor layers 3 made of resin are alternately laminated, and through conductors 6 in which upper and lower wiring conductor layers 3 are formed in an insulating layer 2 therebetween are provided. In the multilayer wiring board that is electrically connected to each other, the through conductors 6 are arranged in the vertical direction, and the wiring conductor layer 3 formed between the through conductors 6 includes the through conductors. It is characterized by being gradually thinner as it moves away from 6.
[Selection] Figure 1

Description

  The present invention relates to a multilayer wiring board, and more specifically, a package for storing an electronic component such as a package for housing a semiconductor element for housing a semiconductor integrated circuit element, or a probe card for performing an electrical inspection of a semiconductor integrated circuit or the like. The present invention relates to a multilayer wiring board used for, for example.

  2. Description of the Related Art In recent years, in semiconductor integrated circuits, the number of terminals formed on a semiconductor substrate has increased and the pitch of terminals has been reduced due to higher integration of semiconductor elements and an increase in the number of processing signals. As a result, the pitch of the connection terminals of the package for housing the semiconductor element that houses the semiconductor integrated circuit element and the probe of the probe card that performs electrical inspection of the semiconductor integrated circuit is also required.

  In response to this demand for narrow pitches, in the package for housing semiconductor devices, the mounting form of the semiconductor devices is changed from wire bonding connection to flip chip connection, and the probe card is a cantilever type, and needle-like probes are finely latticed. It has changed to something arranged in a shape.

  In addition, the structure of the multilayer wiring board used in the semiconductor element storage package and the probe card is formed by forming a wiring conductor layer obtained by patterning a copper foil on an insulating layer obtained by impregnating and curing an organic resin on a substrate made of glass fiber. Multi-layer consisting of a thin insulating layer and a wiring conductor layer on the top surface of the substrate, which is excellent in narrowing the pitch of the wiring conductor layer and can be arranged in a fine lattice pattern. It is changing to a build-up type multilayer wiring board in which a wiring part is formed.

  Such a build-up type multilayer wiring board is made of a polyimide resin or the like on the upper surface of the board, and an insulating layer formed by applying a resin precursor by a curtain coat method or a spin coat method and then heat-curing, and a copper It consists of metals such as aluminum and aluminum, and has a structure in which wiring conductor layers formed by adopting thin film formation technology such as plating and vapor deposition methods and photolithography technology are alternately stacked in multiple layers .

In addition, these build-up multilayer wiring boards require further narrowing of the wiring conductor layer, and in order to cope with this, further thinning of the wiring conductor layer and narrowing of the through conductors are required. As for through conductors, so-called stacked through conductors, which are formed so that the next through conductor is formed directly above the lower through conductor and are arranged coaxially in the vertical direction, have come to be adopted. Yes.
JP-A-11-163520 Japanese Unexamined Patent Publication No. 11-38044

  However, since the through conductor of the stack structure has a structure in which the through conductors are stacked in two or more stages, the wiring conductor layer and the through conductor are affected by the difference in the linear expansion coefficient between the wiring conductor layer and the through conductor and the insulating layer due to the influence of a thermal load or the like In some cases, stress concentrates on the periphery of the wire, causing problems such as poor electrical continuity such as peeling of the interface between the wiring conductor layer and the through conductor.

  The present invention has been made in view of the problems in the background art as described above, and the object thereof is high environmental connection reliability of the through conductors of the multilayer wiring board, and corresponds to the narrow pitch of the wiring conductor layers. An object of the present invention is to provide a multilayer wiring board that can be used.

  In the multilayer wiring board of the present invention, a plurality of insulating layers made of resin and wiring conductor layers are alternately laminated, and the wiring conductor layers positioned above and below are formed in the insulating layer between them. In the multilayer wiring board that is electrically connected via the through conductors, the through conductors are arranged in the vertical direction, and the wiring conductor layer formed between the through conductors is It is characterized by being gradually thinner as it moves away from the through conductor.

  According to the multilayer wiring board of the present invention, the through conductors are arranged in the vertical direction, and the wiring conductor layer formed by being sandwiched between the through conductors gradually becomes thinner as the distance from the through conductor increases. Therefore, when the insulating layer expands and contracts in the thickness direction under the influence of a thermal load or the like, the wiring conductor layer and the through conductor formed in the insulating layer due to the difference in linear expansion coefficient between the through conductor and the insulating layer It is possible to effectively prevent the occurrence of stress that tends to separate the connection portion between the upper end portion and the wiring conductor layer connected to the upper end portion thereof. That is, even if the insulating layer tries to apply stress in the vertical direction with respect to the wiring conductor layer due to expansion and contraction in the thickness direction of the insulating layer, the stress is distributed in a direction away from the through conductor along the wiring conductor layer that is gradually thinned. As a result, it is possible to effectively relieve the stress that tends to separate the connection portion between the wiring conductor layer and the through conductor.

  Therefore, even in a stack structure in which the through conductors are stacked so as to be continuous in the vertical direction, a very large stress is not applied to the wiring conductor layer, and the environmental conductor connection reliability of the through conductor of the multilayer wiring board is high, A multilayer wiring board that can cope with a narrow pitch of the wiring conductor layer is obtained.

  Hereinafter, a multilayer wiring board of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a multilayer wiring board according to the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part showing a state around a wiring conductor layer in the multilayer wiring board shown in FIG. In these drawings, 1 is a substrate, 2 is an insulating layer, 3 is a wiring conductor layer, 4 is an insulating film layer as a part of the insulating layer 2, 5 is an insulating adhesive layer as a part of the insulating layer 2, 6 is a through conductor, and 7 is a through hole.

  The substrate 1 has a multi-layer wiring portion in which a plurality of insulating film layers 4 are laminated with an insulating adhesive layer 5 therebetween and an insulating layer 2 and a wiring conductor layer 3 are laminated in multiple layers on the upper surface. It functions as a support member for supporting the multilayer wiring portion.

  The substrate 1 is made of an oxide ceramic such as an aluminum oxide sintered body or a mullite sintered body, or a non-oxide type such as an aluminum nitride sintered body or silicon carbide sintered body having an oxide film on the surface. It is formed of an electrically insulating material such as ceramics, a glass epoxy resin obtained by impregnating a glass fiber base material with an epoxy resin, or a glass fiber base material impregnated with a bismaleimide triazine resin.

  When the substrate 1 is formed of, for example, an aluminum oxide sintered body, an appropriate organic solvent or solvent is added to and mixed with raw material powders such as alumina, silica, calcia, and magnesia to form a slurry. A ceramic green sheet (ceramic green sheet) is formed by adopting the doctor blade method and the calender roll method. After that, the ceramic green sheet is appropriately punched into a predetermined shape and at a high temperature (about 1600 ° C). ). Alternatively, a raw material powder is prepared by adding an appropriate organic solvent and solvent to a raw material powder such as alumina, and the raw material powder is formed into a predetermined shape by a press molding machine. Finally, the compact is heated to a high temperature (about 1600 ° C). ). Moreover, when it consists of glass epoxy resins, it manufactures, for example by impregnating the base material which consists of glass fiber with the precursor of an epoxy resin, and thermosetting this epoxy resin precursor at predetermined temperature.

  The substrate 1 is provided with a multilayer wiring portion in which a plurality of insulating layers 2 and wiring conductor layers 3 are laminated in multiple layers on the upper surface thereof. The insulating layer 2 electrically insulates the wiring conductor layer 3 positioned above and below, and the wiring conductor layer 3 functions as a transmission path for transmitting an electrical signal.

  The insulating layer 2 of the multilayer wiring portion is composed of, for example, an insulating film layer 4 and an insulating adhesive layer 5, and the insulating film layer 4 is made of polyimide resin, polyphenylene sulfide resin, wholly aromatic polyester resin, fluororesin, or the like. Consists of. The insulating adhesive layer 5 is made of siloxane-modified polyamideimide resin, siloxane-modified polyimide resin, polyimide resin, bismaleimide triazine resin, or the like.

  The insulating layer 2 is prepared, for example, by first applying an insulating adhesive to an insulating film of about 12.5 to 50 μm to a dry thickness of about 5 to 20 μm using a doctor blade method or the like, and then drying the insulating film layer. 4 are stacked so that the insulating adhesive layer 5 is disposed between the upper surfaces of the substrate 1 and the lower insulating layer 2, and this is heated and pressed using a hot press device and bonded.

  As a combination of the insulating film layer 4 and the insulating adhesive layer 5 used for these, for example, there is a combination in which the insulating film layer 4 is a polyimide resin and the insulating adhesive layer 5 is a siloxane-modified polyamideimide resin. According to this combination, the adhesion between the siloxane-modified polyamideimide resin and the polyimide resin is good and the heat resistance is high, so that the multi-layer wiring board formed by these is resistant to being mounted on a printed board or the like. Good solder heat resistance and the like.

  Further, as a combination having the highest heat resistance, it is preferable to use the insulating film layer 4 as a polyimide resin and the insulating adhesive layer 5 as a thermoplastic polyimide resin. In the case of this combination, the heat resistance is high and the stress due to the difference in linear expansion coefficient for reducing the difference in linear expansion coefficient between the insulating film layer 4 and the insulating adhesive layer 5 can be reduced. As a result, the stress that causes separation at the interface between the wiring conductor layer 3 and the through conductor 6 can be reduced. In addition, since it becomes possible to reduce the overall warpage of the multilayer wiring board, the multilayer wiring can better cope with the narrow pitch of the terminals of the semiconductor integrated circuit element mounted on the surface thereof. It can be a substrate.

  Further, each insulating layer 2 is provided with a wiring conductor layer 3 on the surface, and is provided on the insulating layer 2 in order to electrically connect the wiring conductor layers 3 positioned above and below the insulating layer 2. A through conductor 6 is embedded in the through hole 7. The wiring conductor layer 3 and the through conductor 6 employ a thin film forming technique such as sputtering, vapor deposition, plating, etc., of a metal material such as copper, gold, aluminum, nickel, chromium, molybdenum, titanium, and alloys thereof. Can be formed.

  The through conductors 6 may be formed separately from the wiring conductor layer 3, but it is preferable that these are formed at the same time in that the number of steps can be reduced, and also in terms of reliability of electrical connection between them. It will be good. In addition, when the wiring conductor layer 3 and the through conductor 6 are integrally formed, the wiring conductor layer 3 and the through conductor 6 are mainly formed by using an electrolytic plating method so that each of the wiring conductor layer 3 and the through conductor 6 can be formed to have a desired thickness. It is good to keep.

  Moreover, in the multilayer wiring board of the present invention, the through conductors 6 are arranged so as to be coaxially arranged in the vertical direction, and the wiring conductor layer 3 formed between the through conductors 6 includes the through conductors. As it moves away from 6, it gradually becomes thinner. Thereby, when the insulating layer 2 expands and contracts in the thickness direction under the influence of a thermal load or the like, it is formed in the insulating layer 2 due to the difference in coefficient of linear expansion between the wiring conductor layer 3 and the through conductor 6 and the insulating layer 2. It is possible to effectively prevent the stress that tries to separate the connection portion between the through conductor 6 and the wiring conductor layer 3 connected to the upper end portion thereof. That is, even when the insulating layer 2 tries to apply stress to the wiring conductor layer 3 in the vertical direction by expansion and contraction in the thickness direction of the insulating layer 2, the direction away from the through conductor 6 along the wiring conductor layer 3 that gradually becomes thinner. As a result, it is possible to effectively relieve the stress that tends to separate the connection portion between the wiring conductor layer 3 and the through conductor 6.

  Therefore, even in a stack structure in which the through conductors 6 are stacked so as to be continuous in the vertical direction, a very large stress is not applied to the wiring conductor layer 3, and the environmental connection reliability of the through conductors 6 of the multilayer wiring board is not affected. Therefore, the multilayer wiring board can cope with a narrow pitch of the wiring conductor layer 3.

  As a method for forming the wiring conductor layer 3 and the through conductor 6, for example, first, the through hole 7 for the through conductor 6 is formed on the surface of the insulating layer 2. The through hole 7 is formed by removing the insulating layer 2 at a predetermined position using, for example, a laser. In particular, when the opening diameter of the through hole 7 is small, it is desirable to control the angle of the inner wall surface of the through hole 7 and to form the inner wall surface of the through hole 7 with an ultraviolet laser or the like that is processed smoothly. .

  Next, an underlying conductor layer composed of a diffusion prevention layer (barrier layer) made of chromium, molybdenum, titanium or the like and a copper layer mainly made of copper deposited thereon on the entire upper surface of the insulating layer 2 Is formed by electroless plating or sputtering. Then, a resist pattern is formed on the substrate 1 on which the base conductor layer is formed so as to cover the portion other than the portion that becomes the wiring conductor layer 3 by using a photolithography method, and then the wiring conductor layer 3 and the main conductor layer of the through conductor 6 The part is formed by electrolytic plating. Thereafter, the resist pattern is removed, and the excess base conductor layer covered with the resist pattern is removed by a chemical etching method, a dry etching method, or the like, thereby forming the wiring conductor layer 3.

  For the method of forming the wiring conductor layer 3 connected to the through conductors 6 formed in the respective insulating layers 2 of the present invention and gradually becoming thinner with increasing distance from the through conductors 6, for example, using a laser, a predetermined position After the insulating layer 2 is removed and the through hole 7 is formed, a diffusion prevention layer (barrier layer) made of chromium, molybdenum, titanium or the like and the main layer deposited thereon are formed on the entire surface of the insulating layer 2. A base conductor layer composed of a copper layer made of copper is formed by an electroless plating method, a sputtering method, or the like.

  Next, a resist pattern for forming the wiring conductor layer 3 is formed. At this time, in order to make the wiring conductor layer 3 gradually thinner as the wiring conductor layer 3 is moved away from the through conductor 6, a negative resist is used and an exposure amount for exposing the resist is adjusted (for example, the through hole 7 in a plan view). As the distance from the penetrating conductor 6 decreases, the exposure amount decreases as the distance from the penetrating conductor 6 increases. And the part of the main conductor layer of the penetration conductor 6 and the wiring conductor layer 3 is formed by the electroplating method. Thereafter, by removing the resist pattern and further removing the excessive thin film metal, the wiring conductor layer 3 connected to the through conductor 6 formed in each insulating layer 2 is gradually thinned away from the through conductor 6. can do.

  In addition, the wiring conductor layer 3 manufactured by such a method protrudes from the surface of the insulating layer 2, and the outer peripheral part is in a floating state. Then, in order to use the wiring conductor layer 3 as an internal wiring of the multilayer wiring board, another insulating layer 2 is further laminated and multilayered with the wiring conductor layer 3 protruding. At this time, a part of the insulating layer 2 (insulating adhesive layer 5 in this example) also flows below the protruding wiring conductor layer 3 so that the wiring conductor layer 3 has both upper and lower surfaces as shown in FIG. It becomes a state embedded in the insulating layer 2.

  As described above, the wiring conductor layer 3 formed inside the multilayer wiring board is embedded in the insulating layer 2 on both the upper and lower surfaces, whereby stress generated at the boundary between the insulating layers 2 is applied to the wiring conductor layer 3. Can be effectively prevented, and the connection reliability between the wiring conductor layer 3 and the through conductor 6 can be further improved.

  The main conductor layer of the wiring conductor layer 3 formed on the surface of the insulating layer 2 which is the uppermost layer of the multilayer wiring board is made of a copper layer from the viewpoint of electrical characteristics and connection reliability. In this case, a nickel layer or a gold layer is preferably formed on the main conductor layer from the viewpoint of connection reliability and environmental resistance.

  Thus, according to the multilayer wiring board of the present invention, the wiring conductor layer 3 connected to the upper end portion of the through conductor 6 protruding from the surface of the uppermost insulating layer 2 or to the upper end portion of the protruding through conductor 6. A semiconductor device is formed by mounting a semiconductor integrated circuit and electrically connecting the multilayer wiring board to an external electric circuit.

  Further, according to the multilayer wiring board of the present invention, the probe is placed and fixed in contact with the wiring conductor layer 3 formed on the insulating layer 2 positioned at the uppermost layer, and the multilayer wiring board is electrically connected to an external electric circuit. And by connecting mechanically, it becomes a probe card for carrying out the electrical test | inspection of a semiconductor integrated circuit etc.

  It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above-mentioned example, the insulating layer 2 has a two-layer structure of the insulating film layer 4 and the insulating adhesive layer 5 laminated in multiple layers. You may use what formed the agent layer 5 and laminated | stacked in multiple layers.

It is sectional drawing which shows an example of embodiment of the multilayer wiring board of this invention. FIG. 2 is an enlarged cross-sectional view of a main part showing a state around a wiring conductor layer in the multilayer wiring board of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Insulating layer 3 ... Wiring conductor layer 4 ... Insulating film layer 5 ... Insulating adhesive layer 6 ... Penetration conductor 7 ...・ Through hole

Claims (1)

A plurality of insulating layers and wiring conductor layers made of resin are alternately laminated, and the wiring conductor layers positioned above and below are electrically connected via a through conductor formed in the insulating layer between them. In the multilayer wiring board, the through conductors are arranged in the vertical direction, and the wiring conductor layer formed by being sandwiched between the through conductors gradually moves away from the through conductor. A multilayer wiring board characterized by being thin.

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