JP5970317B2 - Wiring board and electronic device - Google Patents

Description

  The present invention relates to a wiring board and an electronic device on which electronic components are mounted, for example.

  Conventionally, wiring boards for mounting electronic components such as semiconductor elements, imaging elements, light emitting elements, capacitors, coils, resistors, and vibrators have been known to have an insulating substrate and a conductor electrode including a conductor pattern. ing. A wiring board having such a configuration is disclosed in Patent Document 1, for example.

  For example, a conductor electrode is deposited on an insulating substrate in a predetermined pattern, a main conductor layer made of copper, nickel, etc. is deposited on the upper surface of the conductor electrode, and a coated metal layer made of gold is further deposited. Things are known.

JP-A-8-102580

  In the above-described wiring board, for example, the coating metal layer may not be sufficiently deposited on the outer edge of the main conductor layer, and the outer edge of the main conductor layer may be exposed. When the outer edge of the main conductor layer is exposed in this way, the elements constituting the main conductor layer come into contact with moisture in the atmosphere at the exposed portion of the main conductor layer, and the main conductor layer is corroded and eluted. As a result, the constituent components of the main conductor layer may adhere to the coated metal layer. When the constituent components of the main conductor layer adhere to the coated metal layer in this way, flip chip mounting property, wire bonding mounting property, solder wettability, etc. are lowered, and the electrical and mechanical properties of the electronic component with respect to the conductor electrode are reduced. There have been problems that the reliability of connection is lowered and the yield is lowered when electronic components are mounted.

A wiring board according to one aspect of the present invention includes an insulating substrate, a conductor electrode provided on the insulating substrate, a main conductor layer provided on the conductor electrode, and a main conductor layer so as to cover the main conductor layer. The provided covering metal layer, the main conductor layer has an exposed portion exposed from the covering metal layer, and includes a corrosion preventing layer formed on the exposed portion , the corrosion preventing layer is made of a complex, complex shall be the main component cyanide of elements constituting the main conductor layer.

  According to another aspect of the present invention, an electronic device includes the wiring board having the above-described configuration and an electronic component mounted on the wiring board.

A wiring board according to one aspect of the present invention includes an insulating substrate, a conductor electrode provided on the insulating substrate, a main conductor layer provided on the conductor electrode, and a main conductor layer so as to cover the main conductor layer. The provided covering metal layer, the main conductor layer has an exposed portion exposed from the covering metal layer, and includes a corrosion preventing layer formed on the exposed portion , the corrosion preventing layer is made of a complex, complex shall be the main component cyanide of elements constituting the main conductor layer. Thus, even if the covering metal layer is provided on the main conductor layer so as to cover the main conductor layer and the main conductor layer has an exposed portion exposed from the covering metal layer, the exposed portion of the main conductor layer Since the corrosion prevention layer is formed, the exposed portion of the main conductor layer is difficult to come into contact with moisture in the atmosphere, the main conductor layer is not easily corroded, and the constituent components of the main conductor layer are formed on the coated metal layer. It becomes difficult to adhere, and it is possible to obtain a wiring board with improved reliability of electrical and mechanical connection of the electronic component to the conductor electrode.

  According to another aspect of the present invention, the electronic device includes the wiring board having the above-described configuration, thereby improving the mounting reliability of the electronic component.

(A) is a longitudinal cross-sectional view which shows the wiring board in embodiment of this invention, (b) is a longitudinal cross-sectional view which expands and shows the A section of the wiring board shown by Fig.1 (a). It is a longitudinal cross-sectional view which expands and shows the principal part of the modification of the wiring board in embodiment of this invention.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

  A wiring board according to an embodiment of the present invention will be described with reference to FIGS. The wiring board 1 in this embodiment includes an insulating substrate 2, a conductor electrode 3 provided on the insulating substrate 2, a main conductor layer 4 provided on the conductor electrode 3, a covering metal layer 5, and a corrosion prevention layer. 6 is provided.

  The insulating substrate 2 is mounted with electronic parts such as a semiconductor element, an imaging element, a light emitting element, a sensor element, a capacitor element, a coil, a resistor and a vibrator on the upper surface, for example, an aluminum oxide sintered body, a mullite sintered Body, silicon carbide sintered body, aluminum nitride sintered body, silicon nitride sintered body, glass ceramic sintered body and other electrically insulating ceramics, epoxy resin, polyimide resin, acrylic resin, phenol resin, polyester resin, In addition, a plurality of substantially rectangular insulating layers made of a resin (plastics) such as a fluororesin such as tetrafluoroethylene resin are stacked in a vertical direction. The insulating substrate 2 may be formed of a single layer.

If the insulating substrate 2 is made of, for example, an aluminum oxide sintered body, an organic material suitable for raw material powders such as alumina (Al ₂ O ₃ ), silica (SiO ₂ ), calcia (CaO), and magnesia (MgO) is used. A ceramic green sheet is obtained by adding a solvent and a solvent to form a slurry, and forming this into a sheet by employing a conventionally known doctor blade method or calendar roll method. The sheet is manufactured by performing appropriate punching or laser processing, laminating a plurality of sheets as necessary, and firing at a high temperature (about 1500 to 1800 ° C.).

  Further, when the insulating substrate 2 is made of, for example, a resin, it can be formed by molding by a transfer molding method or an injection molding method using a mold that can be molded into a predetermined shape. Moreover, what impregnated resin to the base material which consists of glass fiber like glass epoxy resin, for example may be used. In this case, it can be formed by impregnating a substrate made of glass fiber with an epoxy resin precursor and thermally curing the epoxy resin precursor at a predetermined temperature.

The insulating substrate 2 is provided with a conductor electrode 3 including a conductor pattern on the upper surface or the lower surface, and includes a through-hole conductor such as a via-hole conductor or a through-hole conductor from the upper surface on which the electronic component is mounted to the lower conductor electrode 3. A wiring conductor is deposited. When the insulating substrate 2 is made of ceramic, the conductor electrode 3 and the wiring conductor are made of metal powder metallization such as tungsten (W), molybdenum (Mo), manganese (Mn), silver (Ag), copper (Cu), The conductor electrode 3 and the conductor paste for the wiring conductor are printed in a predetermined shape on the ceramic green sheet for the insulating substrate 2 by screen printing or the like, and then fired at the same time as the ceramic green sheet to form the insulating substrate 2 at a predetermined position. Is done. Of the internal conductors, the through conductor that penetrates the ceramic green sheet in the thickness direction may be filled with a through hole formed in the ceramic green sheet by printing a conductor paste. Such a conductor paste can be appropriately obtained by adding an appropriate solvent and a binder to a metal powder such as tungsten (W), molybdenum (Mo), manganese (Mn), silver (Ag), copper (Cu), and kneading them. It is produced by adjusting to a proper viscosity. In order to increase the bonding strength with the insulating substrate 2, glass or ceramics may be included.

  The conductor electrode 3 and the wiring conductor are copper (Cu), gold (Au), aluminum (Al), nickel (Ni), chromium (Cr), molybdenum (Mo) when the insulating substrate 2 is made of resin. , Titanium (Ti) and alloys thereof. For example, the copper foil processed into the shape of the wiring conductor is transferred onto a resin sheet made of glass epoxy resin, and the resin sheet on which the copper foil is transferred is laminated and bonded with an adhesive. The through conductor penetrating through the resin sheet in the thickness direction may be formed on the inner surface of the through hole formed in the resin sheet by conductor paste printing or plating, or may be formed by filling the through hole. Further, the metal foil and the metal pillar are formed integrally with the insulating substrate 2 made of resin, or are deposited on the insulating substrate 2 by using a sputtering method, a vapor deposition method, a plating method, or the like.

  A main conductor layer 4 is provided on the conductor electrode 3 provided on the upper surface or the lower surface of the insulating substrate 2. The main conductor layer 4 is preferably one having excellent adhesion to both the conductor electrode 3 and a coated metal layer 5 described later, for example, among metal materials such as copper (Cu), nickel (Ni), iron (Fe), etc. Consists of at least one. As a method of providing the main conductor layer 4, for example, copper (Cu), nickel (Ni), etc. are deposited by using a plating method such as an electrolytic plating method or an electroless plating method, and a sputtering method, a vapor deposition method, or the like is used. Copper (Cu), nickel (Ni), iron (Fe), etc. are deposited.

  A covering metal layer 5 is provided on the main conductor layer 4 so as to cover the main conductor layer 4. The covering metal layer 5 is preferably one that enhances characteristics such as flip chip mounting property, wire bonding mounting property, solder wettability and the like, and suppresses oxidative corrosion of the main conductor layer 4, and is made of a metal material such as gold (Au). Become. As a method for providing the covering metal layer 5, for example, the coating is performed by using a plating method such as an electrolytic plating method or an electroless plating method.

  The main conductor layer 4 has an exposed portion 4a exposed from the coating metal layer 5, and when the exposed portion 4a is located on the side of the main conductor layer 4, a cyan solution used when forming a corrosion prevention layer 6 described later is formed. It is easy to contact the exposed portion 4a, and the corrosion preventing layer 6 is easily formed on the exposed portion 4a of the main conductor layer 4, which is preferable.

  A corrosion prevention layer 6 is formed on the exposed portion 4a. Thus, even if the covering metal layer 5 is provided on the main conductor layer 4 so as to cover the main conductor layer 4 and the main conductor layer 4 has the exposed portion 4 a exposed from the covering metal layer 5, Since the corrosion prevention layer 6 is formed on the exposed portion 4a of the body layer 4, the exposed portion 4a of the main conductor layer 4 is less likely to come into contact with moisture in the atmosphere, and the main conductor layer 4 is less likely to be corroded. The constituent components of the main conductor layer 4 are less likely to adhere to the covering metal layer 5, and the flip chip mounting property, wire bonding mounting property, solder wettability, etc. are not hindered, and the electrical components of the electronic component with respect to the conductor electrode 3 In addition, it is possible to obtain the wiring board 1 with improved mechanical connection reliability.

When the corrosion prevention layer 6 is made of a complex, the complex has a strong binding force, and a complex mainly composed of cyanide of an element constituting the main conductor layer 4 is deposited on the exposed portion 4a of the main conductor layer 4, and the main conductor layer 4 can be prevented from coming into contact with moisture in the atmosphere, the main conductor layer 4 is corroded and hardly eluted, and the constituent components of the main conductor layer 4 are more formed on the coated metal layer 5. Flip chip mounting property, wire bonding mounting property, solder wettability and the like are not hindered, and the reliability of electrical and mechanical connection of the electronic component to the conductor electrode 3 is further improved. It is possible to obtain the wiring board 1 and is preferable.

  Further, when the above-described complex is composed mainly of the cyanide of the element constituting the main conductor layer 4, the complex mainly composed of the cyanide of the element constituting the main conductor layer 4 has a stronger binding force, A complex mainly composed of cyanide of the element constituting the main conductor layer 4 is firmly attached to the exposed portion 4a of the main conductor layer 4, and the exposed portion 4a of the main conductor layer 4 is in contact with moisture in the atmosphere. The main conductor layer 4 is more corroded and less likely to be eluted, and the constituent components of the main conductor layer 4 are less likely to adhere effectively on the coated metal layer 5, Flip chip mounting property, wire bonding mounting property, solder wettability and the like are not effectively hindered, and the wiring substrate 1 in which the reliability of electrical and mechanical connection of the electronic component to the conductor electrode 3 is effectively improved It is possible to get and preferred . In this configuration, when the main conductor layer 4 is made of copper (Cu), a complex mainly composed of copper cyanide is formed as the corrosion prevention layer 6. When the main conductor layer 4 is made of nickel (Ni), a complex mainly composed of nickel cyanide is formed as the corrosion preventing layer 6. When the main conductor layer 4 is made of iron (Fe), a complex mainly composed of iron cyanide is formed as the corrosion prevention layer 6.

  In the above configuration, as shown in FIG. 2, when the main conductor layer 4 is provided on the conductor electrode 3 so as to cover the conductor electrode 3, the conductor electrode 3 extends from the main conductor layer 4. This is preferable because it is difficult to expose and the conductor electrode 3 is less likely to come into contact with moisture or the like in the atmosphere, and the conductor electrode 3 can be prevented from being oxidized or corroded.

  When the conductor electrode 3 and the main conductor layer 4 are made of the same material and are made of at least one of metal materials such as copper (Cu), nickel (Ni), iron (Fe), the conductor electrode 3 is Even when exposed from the main conductor layer 4, when the corrosion prevention layer 6 is formed on the exposed portion 4 a of the main conductor layer 4, the portion of the conductor electrode 3 exposed from the main conductor layer 4 is also exposed to the corrosion prevention layer 6. Thus, the corrosion prevention layer 6 is formed from the exposed portion 4a of the main conductor layer 4 to the portion exposed from the main conductor layer 4 of the conductor electrode 3, so that the main conductor layer 4 can be formed. The exposed portion 4a and the portion of the conductor electrode 3 exposed from the main conductor layer 4 are difficult to come into contact with moisture in the atmosphere, and are exposed from the main conductor layer 4 and the main conductor layer 4 of the conductor electrode 3. It is possible to efficiently prevent corrosion of the location, which is preferable

  Next, the manufacturing method of the wiring board 1 of this embodiment is demonstrated.

The insulating substrate 2 is made of, for example, an aluminum oxide (Al ₂ O ₃ ) -based sintered body, and a conductor electrode 3 including a conductor pattern is provided on the upper surface or the lower surface. When the insulating substrate 2 is made of an aluminum oxide sintered body whose main component is aluminum oxide (Al ₂ O ₃ ), silica (SiO ₂ ), magnesia (MgO) is used as a sintering aid for the Al ₂ O ₃ powder. ) Or calcia (CaO) or the like, and further an appropriate binder, solvent and plasticizer are added, and then the mixture is kneaded to form a slurry. Thereafter, a ceramic green sheet for obtaining a large number of pieces is obtained by a conventionally known molding method such as a doctor blade method.

  Using this ceramic green sheet, the wiring substrate 1 is manufactured by the following steps (1) to (5).

  (1) A punching process using a punching die or a laser at a portion to be a through conductor such as a via-hole conductor or a through-hole conductor.

(2) Including a conductor electrode 3 formed on the upper and lower portions of the insulating substrate 2 and a through-hole conductor such as a via-hole conductor or a through-hole conductor from the upper surface of the insulating substrate 2 to the inside of the insulating substrate 2 and the lower surface. Metal paste printing application process for forming each wiring conductor.

  (3) The process of producing the ceramic green sheet laminated body by laminating | stacking the ceramic green sheet used as each insulating layer.

  (4) A step of firing this ceramic green sheet laminate to obtain a multi-piece substrate having a plurality of insulating substrates 2 each having an upper surface and a lower surface and provided with conductor electrodes 3.

  (5) A method in which a dividing groove is formed along a portion serving as the outer edge of the wiring substrate 1 on the multi-piece substrate obtained by firing, and a method of dividing by dividing along the dividing groove, a slicing method, or the like Thus, it is possible to use a method of cutting along a portion that becomes the outer edge of the wiring board 1. The dividing groove can be formed by cutting the multi-cavity substrate smaller than the thickness of the multi-piece substrate after firing, but the cutter blade can be pressed against the ceramic green sheet laminate for the multi-piece substrate, or the slicing device May be formed by cutting smaller than the thickness of the generated shape.

  In addition, in order to improve the characteristics such as flip chip mounting property, wire bonding mounting property, solder wettability and the like, and to suppress the oxidative corrosion of the main conductor layer 4, the conductive electrode 3 provided on the upper surface or the lower surface of the insulating substrate 2 is used. A copper (Cu) plating layer to be the main conductor layer 4 having a thickness of 0.5 to 10 μm is deposited on the conductor electrode 3, and the thickness of the covering metal layer 5 is 0.1 to cover the copper (Cu) plating layer. A gold (Au) plating layer of 5 to 3 μm is sequentially deposited.

  Further, the insulating substrate 2 having a copper (Cu) plating layer and a gold (Au) plating layer deposited thereon was immersed in a cyan solution such as a potassium cyanide solution, and exposed from the cyan and gold (Au) plating layers of the cyan solution. Copper cyanide which is bonded to copper (Cu) in the exposed portion 4a of the copper (Cu) plating layer and becomes the corrosion prevention layer 6 on the exposed portion 4a of the copper (Cu) plating layer exposed from the gold (Au) plating layer Is formed as a main component. In the case of depositing a nickel (Ni) layer as the main conductor layer 4, the insulating substrate 2 is similarly immersed to expose the nickel (Ni) layer exposed from the cyan and gold (Au) layers of the cyan solution. The nickel (Ni) of the portion 4a is bonded to form a complex containing nickel cyanide as a main component to be the corrosion preventing layer 6 on the exposed portion 4a of the nickel (Ni) layer exposed from the gold (Au) layer. Further, when an iron (Fe) layer is deposited as the main conductor layer 4, the insulating substrate 2 is similarly immersed to expose the iron (Fe) layer exposed from the cyan and gold (Au) layers of the cyan solution. The iron (Fe) of the part 4a is bonded to form a complex containing iron cyanide as a main component as the corrosion prevention layer 6 on the exposed part 4a of the iron (Fe) layer exposed from the gold (Au) layer.

  Electronic components are mounted on the wiring board 1 formed in this way. By mounting an electronic device having electronic parts mounted on the upper surface of the wiring board 1 on the external circuit board, the electronic parts mounted on the wiring board 1 are electrically connected to the external circuit board via the conductor electrode 3 and the wiring conductor. The The electronic component is, for example, a semiconductor element, a CCD type electronic element or a CMOS type imaging element, a light emitting element such as an LED, a chip capacitor, a chip coil, a resistance element, and a vibrator. The electronic component is soldered to the conductor electrode 3 of the wiring substrate 1 by flip chip mounting, wire bonding mounting, solder, or the like, and each electrode of the electronic component is electrically connected by gold bumps, solder, or the like or a bonding wire. In addition, instead of using the above-mentioned gold bump or solder, a connecting member made of conductive resin (anisotropic conductive resin or the like) may be used for electrical connection between each electrode of the electronic component and the plurality of conductor electrodes 3. Good.

The wiring board 1 of the present embodiment has an exposed portion 4a in which the main conductor layer 4 is exposed from the coating metal layer 5, and a corrosion prevention layer 6 is formed on the exposed portion 4a. Thus, even if the covering metal layer 5 is provided on the main conductor layer 4 so as to cover the main conductor layer 4 and the main conductor layer 4 has the exposed portion 4 a exposed from the covering metal layer 5, Since the corrosion prevention layer 6 is formed on the exposed portion 4a of the body layer 4, the exposed portion 4a of the main conductor layer 4 is less likely to come into contact with moisture in the atmosphere, and the main conductor layer 4 is less likely to be corroded. The constituent components of the main conductor layer 4 are less likely to adhere to the covering metal layer 5, and the flip chip mounting property, wire bonding mounting property, solder wettability, etc. are not hindered, and the electrical components of the electronic component with respect to the conductor electrode 3 In addition, it is possible to obtain the wiring board 1 with improved mechanical connection reliability.

  The electronic device of this embodiment is improved in terms of mounting reliability by including the wiring board 1 having the above-described configuration.

DESCRIPTION OF SYMBOLS 1 ... Wiring board 2 ... Insulating board 3 ... Conductor electrode 4 ... Main conductor layer 4a ... Exposed part 5 ... Coated metal layer 6 ... Corrosion prevention layer

Claims (5)

An insulating substrate;
A conductor electrode provided on the insulating substrate;
A main conductor layer provided on the conductor electrode;
A coated metal layer provided on the main conductor layer so as to cover the main conductor layer;
The main conductor layer has an exposed portion exposed from the coated metal layer, and includes a corrosion prevention layer formed on the exposed portion ;
Corrosion-preventing layer is made of complex, the complex is a wiring board, wherein a main component and to Rukoto cyanide of elements constituting the main conductor layer.   The wiring board according to claim 1, wherein the main conductor layer is made of at least one of copper, nickel, and iron.   The wiring board according to claim 1, wherein the covering metal layer is made of gold.   The wiring board according to claim 1, wherein the exposed portion is located on a side portion of the main conductor layer.   An electronic device comprising: the wiring board according to claim 1; and an electronic component mounted on the wiring board.

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