Electronic component and electronic device
To provide an improved solderability for mounting an electronic component onto a circuit board, a package of an electronic component ( 1 ) is formed by bonding together a base ( 3 ) made of glass and a lid ( 2 ). Outer electrodes ( 8 ) and ( 18 ) are formed on a bottom surface of the base ( 3 ), and the outer electrodes ( 8 ) and ( 18 ) are respectively connected to through electrodes ( 7 ) and ( 17 ). The outer electrodes ( 8 ) and ( 18 ) each have a laminated structure of three CrAu layers, that is, from a Cr layer (first layer) to an Au layer (sixth layer). When the outer electrodes ( 8 ) and ( 18 ) are soldered onto a circuit board, the Au layers as the second, fourth, and sixth layers are dissolved into solder, whereas the Cr layers as the third and fifth layers, which hardly form an intermetallic compound with solder, are separated to remain in solder.
1. An electronic component mounted on a circuit board including electrodes thereon, the electronic component comprising:
an electronic element including electrodes; and
a housing case for housing the electronic element in a hollow portion defined inside the housing case, the housing including
via electrodes electrically connected to the electrodes of the electronic element,
the via electrodes extending from an inside of the housing case to an outside of the housing case, and
outer electrodes electrically connected to the via electrodes and attached to the circuit board by a metallic solder,
the outer electrodes on a bottom surface of the housing case,
wherein the outer electrodes comprise:
a first metal layer on the bottom surface of the housing case and connected to the electrodes on the circuit board by the metallic solder;
a second metal layer on a surface of the first metal layer and comprising a solder-soluble metal; and
a third metal layer on a surface of the second metal layer and comprising non-solder-soluble metal in which mobile portions of the third metal are entrained in the metallic solder and increase the shear strength of the connection between the outer electrodes and the electrodes on the circuit board.
2. An electronic component according to claim 1 , wherein the outer electrodes are each formed by further including:
a fourth metal layer on a surface of the third metal layer and comprising a solder-soluble metal; and
a fifth metal layer on a surface of the fourth metal layer and comprising a non-solder-soluble metal.
3. An electronic component according to claim 1 , wherein the outer electrodes each further include an outermost surface layer comprising an anti-oxidation film.
4. An electronic component according to claim 1 , wherein the housing case comprises glass.
5. An electronic component according to claim 1 , wherein the electronic element comprises a crystal resonator.
6. A manufacturing method for an electronic component, comprising:
an electronic element installing step of installing, on a base, an electronic element and via electrodes for wiring to be electrically connected to electrodes of the electronic element;
an enclosing step of bonding a lid to the base on which the electronic element and the via electrodes are installed, to thereby enclose the electronic element in a housing case including the base and the lid; and
an outer electrode forming step of:
forming, on a bottom surface of the housing case, a first metal layer that is to be soldered to;
forming, on a surface of the first metal layer, a second metal layer that is to be dissolved into solder; and
forming, on a surface of the second metal layer, a third metal layer that is to be hardly dissolved into solder, to thereby form an outer electrode.
7. An electronic component mounted on a circuit board, the electronic component comprising:
an electronic element including electrodes;
a housing case for housing the electronic element in a hollow portion defined inside the housing case, the housing case including
via electrodes electrically connected to the electrodes of the electronic element,
the via electrodes extending from an inside of the housing case to an outside of the housing case;
a metal bonding film electrically connected to one of the via electrodes and soldered to electrodes of the circuit board by a metallic solder,
the metal bonding film on a bottom surface of the housing case; and
an anti-oxidation film that on a surface of the metal film for bonding,
wherein the anti-oxidation film includes at least one gold layer having a total thickness of 300 nm or more and 1,000 nm or less so as to substantially prevent, oxidation of the metal bonding film, and
wherein an uppermost surface of the at least one gold layer is bonded to the metal bonding film.
8. An electronic component according to claim 7 , wherein the total thickness of the at least one gold layer is 300 nm or more and 450 nm or less.
9. An electronic component according to claim 7 , wherein the anti-oxidation film includes:
a plurality of the gold layers; and
a predetermined metal layer between the plurality of the gold layers.
10. An electronic component according to claim 9 , wherein the predetermined metal layer comprises a non-solder soluble metal.
11. An electronic component according to claim 7 , wherein the anti-oxidation film includes the at least one gold layer comprising a single layer.
12. An electronic component according to claim 7 , wherein the housing case comprises glass.
13. An electronic component according to claim 7 , wherein the electronic element comprises a crystal resonator.
14. A manufacturing method for an electronic component, comprising:
an electronic element installing step of installing, on a base, an electronic element and via electrodes for wiring to be electrically connected to electrodes of the electronic element;
an enclosing step of bonding a lid to the base on which the electronic element and the via electrodes are installed, to thereby enclose the electronic element in a housing case including the base and the lid;
a metal film for bonding forming step of forming, on a bottom surface of the housing case, a metal film for bonding that is to be soldered to; and
an anti-oxidation film forming step of forming, on a surface of the formed metal film for bonding, an anti-oxidation film that includes at least one gold layer having a total thickness of 300 nm or more and 1,000 nm or less, the at least one gold layer having an uppermost surface bonded to the formed metal film for bonding.