Patent Application
20120086110
The present invention relates to an IC package which reduces an electromagnetic noise by using a magnetic body and a conductive board.
Priority is claimed on Japanese Patent Application No. 2009-144282, filed in Jun. 17, 2009, the content of which is incorporated herein by reference.
When an electric device is driven, an electromagnetic field is generated due other electric devices and/or mechanical devices that are simultaneously driven, an electromagnetic interference (EMI) is caused, and a performance of the electric device is deteriorated. In particular, cases are reported with regard to electromagnetic waves which are generated inside a large scale integrated circuit (LSI) based on an SoC (System on a Chip) technology and which are leaked outside and deteriorate functions of a neighboring LSI and electric device, and there has been a demand for a design which reduces unnecessary electromagnetic waves that are generated at an layer which is a level for implementing a chip such as an LSI. Integration by using an SiP (System in a Package) technique is applied to an implementation layer of an IC package to compensate or supplement the limitation on refining the CMOS process, and such integration causes problems because of radiation of unnecessary electromagnetic waves.
On the other hand, there is a possibility in which such electromagnetic waves include secret information, and an electromagnetic wave attack can be conducted to intercept or tap the secret information by measuring the leaked electromagnetic waves. Therefore, from a point of view of security, a technique is necessary which reduces radiation of unnecessary electromagnetic waves from inside of the IC package.
In general, as effective methods for resolving the above-described problems of EMI and security of the electromagnetic waves, a circuit design which reduce strength of the electromagnetic waves around an IC chip and an IC package and a constitution of an IC package which does not leak the electromagnetic waves are used. In one example, electromagnetic shielding techniques have been proposed in that a conductive body used as an electromagnetic shielding and/or an electromagnetic absorber are set to an upside of an IC chip and/or an IC package (for example, see Patent Documents 1-3).
When a conductive body is set to an upside of the IC package which is a source of electromagnetic noise, an electromagnetic field on the IC package is partially or locally reduced. However, there is a possibility of a resonance, and a material which has electromagnetic absorbing characteristics can be loaded. For example, in Patent Document 1, an electromagnetic absorber is used to improve an electromagnetic shielding inside a package. A conductive body and/or a magnetic body are used as such an electromagnetic absorber. A method is also generally used in which an electromagnetic shielding for avoiding leakage of the electromagnetic waves is constituted in a manner in which the conductive body is electrically connected to a printed wiring board on which a high frequency circuit is printed.
Patent Document 2: Japanese Patent Application, First Publication No. H6-112682
In general, an inside of an IC package is constituted by laminating an IC chip in a flat plate shape and an interposer, and electrodes of the IC chip and electrodes of the interposer are connected via bonding wires. These constitutional elements have a steric shape with irregularity. If a conductive layer for improving the electromagnetic shielding is formed at an upper layer on the IC chip and/or the IC package, there is a gap at a side surface of the IC package. There may be a proposal in which a three-dimensional implementation method is used, and in which an electromagnetic shielding structure body is formed by connecting the conductive layer with a ground layer of a package, however, there is a disadvantage because of a complex production process.
An electromagnetic field leaked from a side surface of the IC package generates an electromagnetic field outside the IC package, and there is a possibility of affecting neighboring circuits. Further, such a magnetic field which is radiated has a possibility of causing a trouble on a communication that is conducted at a distant place. In addition, if a measurement probe is arranged closet to the gap of the IC package, it is possible to measure the leaked electromagnetic field and to intercept or tap the secret information.
By using techniques of Patent Documents 1-3, maybe it is possible to avoid a leakage of the electromagnetic waves from inside and an invasion of the electromagnetic waves from outside, however, such constitutions cannot avoid leakage of the electromagnetic waves from the side surface of the IC package.
The present invention is conceived based on the above-described background and has an object to provide an IC package which can prevent the electromagnetic waves from leaking from a side surface of the IC package.
To resolve the above-described problem, for example, an IC package includes: an electric circuit board on which an IC chip is mounted; a first conductive board arranged at a position facing the electric circuit board while the IC chip on the electric circuit board is sandwiched therebetween; and a magnetic body which is arranged on a surface of the first conductive board on a side facing the IC chip, and the magnetic body is arranged at least an end portion of the first conductive board.
In accordance with the present invention, a shielding structure body which is constituted from both a magnetic body and a first conductive board, and therefore, it is possible to constitute a shielding structure body which shields an overall IC package. In particular, the magnetic body which reduces the electromagnetic waves is arranged on at least an end portion, and therefore, if there is a gap on a side surface of the IC package, it is possible to prevent the electromagnetic waves from leaking from such a gap.
Hereinafter, in reference to the drawings, embodiments of the present invention are explained. These embodiments describe aspects of the present invention, are not limitations to the present invention and can be flexibly modified in a scope of a technical idea of the present invention. Further, in the drawings described below, a size and a number of constitutional elements of each constitution are different from a real constitution for an easy understanding of each constitution.
As shown in
The IC chip 10 is arranged on the interposer 11 and is electrically connected to the printed circuit board 20 by using the conductive balls 30 and the wired line 12 (see
The interposer 11 is a printed wiring board on which signal lines (not shown in the drawings) are formed so as to connect the IC chip 10 with the conductive balls 30. The interposer 11 relays an electrical connection between the IC chip 10 and the printed circuit board 20 with different terminal pitch. Further, the interposer 11 has another role of connection between multiple LSI chips when multiple LSI chips are mounted, for example, in SIP.
The wired line 12 is made from materials mainly including, for example, Al and Au, and the wired line 12 performs an electrical connection between external terminals (not shown in the drawings) of the IC chip 10 and signal lines on the interposer 11. In such a manner, the IC chip 10 is electrically connected to the printed circuit board 20 via the wired line 12, the interposer 11 and the conductive balls 30.
The first conductive board 15 is arranged so as to face the interposer 11 while the IC chip 10 on the interposer 11 is sandwiched in between. The first conductive board 15 shields unnecessary electromagnetic waves which are generated by the IC chip 10 and which cause the noise.
The magnetic body 14 is arranged under the first conductive board 15 (on a side facing the IC chip 10). The magnetic body 14 reduces the electromagnetic waves radiated from the IC chip 10. The magnetic body 14 has a relative permeability in a range from 1 to 1000. Further, thickness (length of the shortest edge) of the magnetic body 14 is in a range from 0.1 μm to 1 mm. These values are changed in accordance with a size of each constitutional elements of the IC package and an expected amount of reduced noise. For example, it is possible to apply a ferrite of a Ni-Zn system with high magnetic permeability in a high frequency band to the magnetic body 14. In this embodiment, the magnetic body 14 is arranged so as to substantially cover one surface of the first conductive body.
It should be noted that the magnetic body 14 can be modified so as to be in a plate shape and adhered on the first conductive board 15 or can be directly formed on the first conductive board 15 as a film. If the magnetic body 14 is not conductive, it is possible to obtain an advantage without very closely attaching the first conductive board 15 to the magnetic body 14. In a concrete case, there is no influence if there is a very small gap due to an adherence. This is because reduction can be caused by magnetism of the magnetic body 14. For examples, a spray ferrite-plating method and an aerosol deposition method are film forming methods for forming the magnetic body 14. In particular, in accordance with the spray ferrite-plating method, it is possible to conduct a ferrite-plating operation on a sterical portion. For example, it is possible to form the film of the magnetic body 14 regardless of irregularity on a surface of the first conductive board 15. Further, by using the spray ferrite-plating method, it is possible to form a thin film with a few micro meter thickness, and due to this, it is possible to keep a high magnetic permeability in a high frequency band higher than a gigahertz. When the magnetic body 14 has conductivity, by adhering or very closely arranging the magnetic body 14 on the first conductive board 15 so as to mutually conduct, a current 40b flowing on the first conductive board 15 is decreased due to the resistance of the magnetic body 14, and therefore, it is possible to obtain a further improved advantage.
The sealing member 13 is used as an adherence between the interposer 11 on which the IC chip 10 is mounted, the first conductive board 15 which is arranged at a position facing the interposer 11 and the magnetic body 14. The sealing resin 17 forms an external shape of the IC package 1. It should be noted that it is possible for the sealing resin 17 to have an adherence function of the sealing member 13.
The IC package 1 of this embodiment has a constitution in which the IC chip 10 is mounted on the interposer 11, and an electrical connection between the IC chip 10 and the interposer 11 is provided by a bonding of the wired line 12. Further, the first conductive board 15 shielding the electromagnetic waves is arranged at an upper layer of the IC package 1. Therefore, a gap 19 is formed on a side face of the IC package 1.
Here, when the electromagnetic field with high frequency is generated by the IC chip 10, an electromagnetic wave 40a which is a portion of the electromagnetic components thereof is directed to the magnetic body 14. The magnetic body 14 has a function for reducing the electromagnetic wave 40a, and if the thickness (length of the shortest edge) is thin, it is not possible to sufficiently reduce the electromagnetic wave 40a. In such a case, a portion of the electromagnetic wave 40a passes through the magnetic body 14 and enters close to a central portion of the first conductive board 15.
The portion of the electromagnetic wave 40a entered into the first conductive board 15 generates the current 40b inside the conductive board 15. While flowing along a lengthwise direction of the first conductive board 15, the current 40b is reduced by the magnetic body 14 formed on an overall surface of the first conductive board 15.
On the other hand, electromagnetic wave 40c which is a portion of a magnetic component of an electromagnetic field generated by the IC chip 10 is curved 90 degrees by the first conductive board 15 after entering into the magnetic body 14. The electromagnetic wave 40c which has a path curved by the first conductive board 15 is reduced by the magnetic body formed on an overall surface of the first conductive board 15 while passing through inside of the magnetic body 14 along a lengthwise direction of the first conductive board 15.
Further, an electromagnetic wave 40d which is a portion of a magnetic component of an electromagnetic field generated by the IC chip 10 is curved 90 degrees by the magnetic body 14 before entering into the magnetic body 14. The electromagnetic wave 40d which has a path curved by the first conductive board 15 is reduced by the magnetic body 14 formed on an overall surface of the first conductive board 15 while passing through inside of the magnetic body 14 along a lengthwise direction of the first conductive board 15. Thus, the current 40b and the electromagnetic wave 40c/40d are reduced by the magnetic body 14 formed on an overall surface of the first conductive board 15 while avoiding an leakage from the gap 19 on a side surface of the IC package 1.
In accordance with the IC package 1 of this embodiment, it is possible to avoid leakage of the electromagnetic waves from the gap 19 if there is the gap 19 on a side surface of the IC package 1 because the magnetic body 14 which reduces the electromagnetic waves is formed on an overall surface of the first conductive board 15. Further, it is possible to avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside because the first conductive board 15 which shields the electromagnetic waves is mounted. Thus, it is possible to avoid interception or tapping of the secret information from the leaked electromagnetic waves. Therefore, it is possible to avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside, and it is possible to produce the IC package 1 which is an effective solution to the EMI.
It should be noted that in the IC package 1 of this embodiment, the magnetic body 14 is formed on an overall surface of the first conductive board 15, and end portions of the magnetic body 14 are substantially the same positions as end portions of the first conductive board 15. However, this is not a limitation. For example, it is possible to extend the magnetic body 14 so as to arrange the end portions of the magnetic body 14 outside the signal line on the interposer 11. In accordance with such a constitution, it is possible to reduce the electromagnetic waves generated by the signal lines on the interposer 11.
Further, in the IC package 1 of this embodiment, the first conductive board 15 and the magnetic body 14 are touching each other. However, this is not a limitation. For example, it is possible to have small gaps between the first conductive board 15 and the magnetic body 14. If there are small gaps between the first conductive board 15 and the magnetic body 14, the current 40b inside the first conductive board 15 is reduced by the magnetic body 14 formed on an overall surface of the first conductive board 15 while flowing along a lengthwise direction of the first conductive board 15.
As shown in
Due to the second conductive board 16, the downward (direction opposite to a side on which the magnetic body 14 is mounted) electromagnetic waves from the IC chip 10 are shielded. In other words, the electromagnetic waves generated by the IC chip 10 is shielded by both the first conductive board 15 and the second conductive board 16. In such a case, the electromagnetic waves generated by the IC chip 10 have a strong directivity so as to be directed to the gap 19 on a side surface of the IC package 2. The electromagnetic waves with strong directivity is reduced by the magnetic body formed on an overall surface of the first conductive board 15 while proceeding to the gap 19 on a side surface of the IC package 2.
In accordance with the IC package 2 of this embodiment, the electromagnetic waves generated by the IC chip 10 are shielded by both the first conductive board 15 and the second conductive board 16 and has a strong directivity so as to be directed to the gap 19 on a side surface of the IC package 2. In other words, the electromagnetic waves generated by the IC chip 10 is lead along a lengthwise direction of the magnetic body 14 which is formed on an overall surface of the first conductive board 15 and which reduces the electromagnetic waves. Therefore, it is possible to reliably avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside, and it is possible to produce the IC package 2 which is an effective solution to the EMI.
As shown in
In accordance with the IC package 3 of this embodiment, the electromagnetic waves with strong directivity directed to the gap 19 on a side surface of the IC package 2 generated by the IC chip 10 is reduced by the magnetic bodies 24 arranged along a pair of edges of the first conductive board 15 while proceeding to the gap 19 on a side surface of the IC package 2. As described above, if the electromagnetic waves generated by the IC chip 10 are strongly directed to a specific direction, it is possible to provide the minimum and essential countermeasure for the leakage of the electromagnetic waves by arranging the magnetic bodies 24 to the specific direction. In addition, in this embodiment, there is no magnetic body around the IC chip 10, and therefore, it is possible to reduce influence of the magnetic body 10 on the IC chip 10. Therefore, it is possible to reliably avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside by using the minimum and essential constitution, and it is possible to produce the IC package 3 which is an effective solution to the EMI.
It should be noted that in the IC package 3 of this embodiment, the magnetic bodies 24 are arranged along a pair of edges of the first conductive board 15. However, this is not a limitation. For example, in an area the magnetic bodies 24 are covered by the first conductive board 15 when being seen on a plane, it is possible to arrange the magnetic bodies 24 outside the signal lines on the interposer 11. In accordance with such a constitution, it is possible to reliably reduce the electromagnetic waves generated by the signal lines on the interposer 11.
As shown in
A current 41b which is caused by the electromagnetic field generated by the IC chip 10 and which flows on a surface of and inside the first conductive board 25 is reduced by the magnetic bodies 34 found in a pair of lines along each of two edges of the first conductive board 25 while flowing along a lengthwise direction of the first conductive board 25. Specifically, by embedding the magnetic bodies 34 in the first conductive board 25, the current 41b flows so as to go around the magnetic bodies 34, and a high-frequency impedance around the magnetic bodies 34 is increased. Further, a path along which the current 41b flows is extended because the magnetic bodies 34 is arranged in a pair of lines, and due to this, it is possible to reduce the current 41b more effectively than a case in which the magnetic bodies 34 are arranged in one line.
In accordance with the IC package 4 of this embodiment, the current 41b which is generated by the electromagnetic field caused by the IC chip 10 and which flows inside the first conductive board 25 is reduced by the magnetic bodies 34 arranged in a pair of lines at each of two edges of the first conductive board 25 while flowing along a lengthwise direction of the first conductive board 25. Therefore, it is possible to reliably avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside, and it is possible to produce the IC package 4 which is an effective solution to the EMI.
It should be noted that in the IC package 3 of this embodiment, the magnetic bodies 34 are arranged in a pair of lines along each of two edges of the first conductive board 25. However, this is not a limitation. For example, it is possible to arrange the magnetic bodies 34 in three or four lines. In other words, it is possible to arrange the magnetic bodies 34 in multiple lines along each of two edges of the first conductive board 25.
As shown in
In accordance with the IC package 5 of this embodiment, the electromagnetic waves generated by the wired lines 12 are reduced by the magnetic bodies 24a with comparatively small thickness, and the electromagnetic waves with strong directivity due to the IC chip 10 and the signal line on the interposer 11 are reduced by the magnetic bodies 24b which have a comparatively large thickness. In other words, if the wired lines 12, the IC chip 10 and the interposer 11 are not on the same flat plane (arranged in not even manner), it is possible to reduce the electromagnetic waves by appropriately changing thickness of the magnetic bodies 24a and 24b. Therefore, it is possible to reliably avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside, and it is possible to produce the IC package 5 which is an effective solution to the EMI.
As shown in
In accordance with the IV package 6 of this embodiment, it is possible to reliably avoid leakage of the electromagnetic waves from the gap 19 on all side surfaces of the IC package 6 because the magnetic body 44 is formed in a closed circular state. Therefore, it is possible to reliably avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside, and it is possible to produce the IC package 6 which is an effective solution to the EMI.
As shown in
A current 41b which is caused by the electromagnetic field generated by the IC chip 10 and which flows inside the first conductive board 25 is reduced by the dielectric body 35 and the magnetic bodies 34 formed along each of two edges of the first conductive board 25 while flowing along a lengthwise direction of the first conductive board 25. Specifically, by embedding the magnetic bodies 34 and the dielectric body 35 in the first conductive board 25, the current 41b flows so as to go around the magnetic bodies 34 and the dielectric body 35, and a high-frequency impedance around the magnetic bodies 34 and the dielectric body 35 is increased. Further, a path along which the current 41b flows is extended because the dielectric body 35 and the magnetic bodies 34 are mounted, and due to this, it is possible to reduce the current 41b more effectively than a case in which one line of the magnetic bodies 34 or the dielectric body 35 is mounted.
In accordance with the IC package 7 of this embodiment, the current 41b which is caused by the electromagnetic field generated by the IC chip 10 and which flows inside the first conductive board 25 is reduced by the dielectric body 35 and the magnetic bodies 34 formed along each of two edges of the first conductive board 25 while flowing along a lengthwise direction of the first conductive board 25. Therefore, it is possible to reliably avoid both leakage of the electromagnetic waves generated by the IC chip 10 and invasion of the electromagnetic waves from outside, and it is possible to produce the IC package 7 which is an effective solution to the EMI.
As shown in
In accordance with the IC package 8 of this embodiment, the electromagnetic waves generated by the electric circuit 23 included inside the IC chip 10A are reduced by the magnetic body 14A and the first conductive board 15A arranged and stacked on the IC chip 10A. Therefore, it is possible to reliably avoid both leakage of the electromagnetic waves generated by the electric circuit 23 and invasion of the electromagnetic waves from outside, and it is possible to produce the IC package 8 which is an effective solution to the EMI.
It should be noted that in the IC package 8 of this embodiment, an upside of the IC chip 10B is exposed. However, this is not a limitation. For example, it is possible to stack a magnetic body and a conductive board on the IC chip 10A in the same manner as the IC chip 10A. Therefore, it is possible to reliably avoid the EMI which affects the IC chip 10B and which is caused by the electric circuit 23.
As shown in
In accordance with the IC package 9, it is possible to arrange the magnetic bodies 47 close to the second conductive board 16 while preventing the magnetic bodies 47 from protruding from the first conductive board 45 because a distance between the first conductive board 45 and the second conductive board 16 is comparatively small at the falling portions 46. Therefore, it is possible to reduce the magnetic field close to the second conductive board 16. Further, if a magnetic film is formed on the first conductive board 45, it is difficult to form a thick magnetic film. However, it is possible to reduce the leaked electromagnetic waves without increasing thickness of the magnetic bodies 47 because the falling portions 46 are included in the first conductive board 45.
For example, the present invention can reduce the electromagnetic noise of various electric devices using IC packages.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-144282 | Jun 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP10/04044 | 6/17/2010 | WO | 00 | 12/14/2011 |
