MICRO POWER CONVERTER AND METHOD OF MANUFACTURING SAME

• US 20070290782A1
• Filed: 06/20/2007
• Published: 12/20/2007
• Est. Priority Date: 06/20/2006
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Device Technology Company Limited (Fuji Electric Systems Company Limited)
• Inventors: USUI, Yoshikiyo, YOKOYAMA, Takeshi
• Granted Patent: US 7,446,639 B2
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: H01F 2017/002 Details of via holes for interconnecting the layers
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01L 2224/32057 in side view
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/83 using a layer connector
• CPC Class Codes: H01L 2224/83385 Shape, e.g. interlocking features
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 23/49805 the leads being also applied on the sidewalls or the bottom of the substrate, e.g. leadless packages for surface mounting
• CPC Class Codes: H01L 23/49822 Multilayer substrates multilayer metallisation on monolayer substrate H01L23/498
• CPC Class Codes: H01L 23/49838 Geometry or layout
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: Y10T 29/49075 : including permanent magnet or core

Abstract

A micro power converter is provided in which magnetic flux passing a route outside of external electrodes and second connection conductors is decreased to reduce noises, and at the same time, adhesiveness of molding resin is preserved to provide excellent humidity resistance.

Claims

1. A micro power converter comprising:

a coil substrate including a coil and external electrodes, a power supply IC chip bonded on a front surface side of the coil substrate, and a resin covering the front surface side of the coil substrate and a front surface side of the power supply IC chip;

wherein the coil substrate has a magnetic insulator substrate, coil conductors formed in inner regions on front and back surfaces of the magnetic insulator substrate, and the external electrodes formed in peripheral regions on the front and back surfaces of the magnetic insulator substrate;

wherein the coil conductors formed in the inner regions on the front and back surfaces of the magnetic insulator substrate are connected by first connection conductors to form the coil and the external electrodes formed on the front and back surfaces of the magnetic insulator substrate are connected by second connection conductors; and

wherein the second connection conductors are surrounded by the magnetic insulator substrate in the front surface side of the magnetic insulator substrate and a side face of the second connection conductor is exposed to an atmosphere in the back surface side of the magnetic insulator substrate.

2. The micro power converter according to claim 1, wherein the magnetic insulator substrate is a ferrite substrate.

3. The micro power converter according to claim 1, wherein the front surface side of the coil substrate and a back surface side of the power supply IC chip are bonded with an insulator adhesive, and pad electrodes formed on a front surface of the power supply IC chip and the external electrodes formed on the front surface side of the coil substrate are electrically connected by bonding wires.

4. The micro power converter according to claim 1, wherein the external electrodes formed on the front surface side of the coil substrate and pad electrodes formed on a back surface side of the power supply IC chip are bonded by stud bumps.

5. A method of manufacturing a micro power converter that includes a magnetic insulator substrate, a power supply IC chip bonded on a front surface side of the magnetic insulator substrate, and a resin covering the front surface side of the magnetic insulator substrate and a front surface side of the power supply IC chip, the method comprising:

(i) (a) forming a plurality of first holes from a front surface side towards an interior of the magnetic insulator substrate, and (b) forming plural pairs of second holes surrounding the first holes and in either side of a straight line that becomes a scribe line, the pair of second holes consisting of two second holes disposed at line symmetric positions with respect to the straight line;

(ii) (a) forming third holes each connecting to each of the first holes from a back surface side of the magnetic insulator substrate at positions projecting the first holes towards interior of the magnetic insulator substrate, and (b) forming fourth holes with a oblong shape each connecting to each of the pairs of the second holes at a place including the positions projecting the pair of the second holes surrounding the third holes from the back surface side towards interior of the magnetic insulator substrate;

(iii) (a) forming coil conductors on front and back surfaces of the magnetic insulator substrate connecting different first holes and different second holes, (b) the forming first connection conductors on side walls of the first holes and third holes connecting the coil conductors formed on the front and back surfaces, (c) forming plural pairs of front side external electrodes on the front surface side of the magnetic insulator substrate, each pair disposed at a place including the second holes, surrounded by the magnetic insulator substrate, off the scribe line and along the scribe line, and positioned in line symmetric with respect to the scribe line, (d) forming back side external electrodes on the back surface side of the magnetic insulator substrate at places including at least a part of the positions projecting the pairs of second holes, and (e) forming second connection conductors on side walls of the second holes and the fourth holes, each second connection conductor connecting the front side external conductor and the back side external conductor;

(iv) connecting the power supply IC chip to the front surface side of the magnetic insulator substrate;

(v) covering the front surface side of the magnetic insulator substrate and front surface side of the power supply IC chip with the resin; and

(vi) cutting the magnetic insulator substrate and the resin along the scribe line positioned between two external electrodes composing a pair on the front side of magnetic insulator substrate.

6. The method according to claim 5, wherein the external electrode is manufactured by forming a seed layer that is formed of a titanium film and a copper film on the titanium film, or of a copper film alone, and then forming a copper film thicker than the copper film of the seed layer, on the seed layer.