U.S. patent application number 11/522016 was filed with the patent office on 2008-03-20 for electronic component package with emi shielding.
This patent application is currently assigned to Hong Kong Applied Science and Technology Research Institute Company Limited. Invention is credited to Chang-Hwa Chung, Huili Fu, Man-Lung Sham.
Application Number | 20080067650 11/522016 |
Document ID | / |
Family ID | 39187719 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080067650 |
Kind Code |
A1 |
Sham; Man-Lung ; et
al. |
March 20, 2008 |
Electronic component package with EMI shielding
Abstract
An electronic component package having an EMI shielded space is
disclosed. The package comprises a substrate having an electronic
component located on its surface and a conductive enclosure having
a top and downwardly extending sides enclosing the component and
defining a shielded space. A vent opening is provided through the
substrate and is located in the shielded space for venting the
shielded space. A second vent opening may be provided in the top of
the conductive enclosure.
Inventors: |
Sham; Man-Lung; (Hong Kong,
CN) ; Fu; Huili; (Hong Kong, CN) ; Chung;
Chang-Hwa; (Hong Kong, CN) |
Correspondence
Address: |
WELLS ST. JOHN P.S.
601 W. FIRST AVENUE, SUITE 1300
SPOKANE
WA
99201
US
|
Assignee: |
Hong Kong Applied Science and
Technology Research Institute Company Limited
|
Family ID: |
39187719 |
Appl. No.: |
11/522016 |
Filed: |
September 15, 2006 |
Current U.S.
Class: |
257/678 ;
257/E23.004; 257/E23.114; 257/E25.029 |
Current CPC
Class: |
H01L 24/48 20130101;
H01L 2224/48227 20130101; H01L 23/552 20130101; H01L 25/16
20130101; H01L 2924/01004 20130101; H01L 2924/01068 20130101; H01L
2924/181 20130101; H01L 23/3128 20130101; H01L 2924/16152 20130101;
H01L 2924/3025 20130101; H01L 2924/00014 20130101; H01L 2924/14
20130101; H01L 23/315 20130101; H01L 2924/15311 20130101; H01L
2224/48091 20130101; H01L 23/13 20130101; H01L 23/564 20130101;
H01L 2924/00014 20130101; H01L 2924/01078 20130101; H01L 2924/14
20130101; H01L 2224/48091 20130101; H01L 2924/181 20130101; H01L
2924/00014 20130101; H01L 2224/45015 20130101; H01L 2924/207
20130101; H01L 2924/00 20130101; H01L 2924/00014 20130101; H01L
2224/45099 20130101; H01L 2924/00012 20130101; H01L 23/3135
20130101; H01L 2924/1815 20130101 |
Class at
Publication: |
257/678 |
International
Class: |
H01L 23/02 20060101
H01L023/02 |
Claims
1. An electronic component package having an EMI shielded
component, comprising: a substrate having a mounting area for an
electronic component, an electronic component located on the
mounting area, a conductive enclosure having a top and downwardly
extending sides enclosing the mounting area and defining a shielded
space above the mounting area, and a vent opening extending through
the substrate, the opening located in the mounting area for venting
the shielded space.
2. The component package of claim 1 wherein the vent opening
extending through the substrate is a plated via.
3. The component package of claim 1 wherein the component is
covered with an encapsulant and the vent opening extending through
the substrate is not covered with the encapsulant.
4. The component package of claim 1 further including a second vent
opening in the top of the conductive enclosure.
5. The component package of claim 4 wherein the top and sides of
the conductive enclosure do not have any further openings.
6. The component package of claim 4 wherein portions of the
substrate and conductive enclosure are covered with an encapsulant
and the second vent opening is not covered with the
encapsulant.
7. The component package of claim 6 wherein the top of the
conductive enclosure is not covered with the encapsulant.
8. The component package of claim 1 wherein the substrate includes
a ground trace, or other grounding means, and the sides of the
conductive enclosure make contact with the ground trace or
plane.
9. The component package of claim 1 wherein the component is a
semiconductor die.
10. The component package of claim 9 wherein the semiconductor die
is a radio frequency (RF) chip.
11. The component package of claim 1 wherein the conductive
enclosure is adapted to attenuate electromagnetic radiation emitted
by the component.
12. The component package of claim 1 which is a semiconductor chip
package.
13. A method of making an electronic component package, comprising
steps of: providing a substrate having a mounting area for an
electronic component and a vent opening extending through the
substrate adjacent the mounting area, mounting a component on the
mounting area of the substrate, and locating a conductive enclosure
on the substrate to surround the component and the vent
opening.
14. The method of claim 13 wherein before performing the step of
locating a conductive enclosure on the substrate performing a
further step of covering the component with an encapsulant and not
covering the vent opening with the encapsulant.
15. The method of claim 13 wherein locating a conductive enclosure
on the substrate includes providing a conductive enclosure having a
top and downwardly extending sides and a second vent opening in the
top.
16. The method of claim 15 including a further step of covering
portions of the substrate and the conductive enclosure with an
encapsulant and not covering the second vent opening with the
encapsulant.
17. The method of claim 13 wherein mounting a component on the
mounting area includes mounting a semiconductor die on the mounting
area, the die having an active surface, and covering at least the
active surface of the die with an encapsulant.
18. The method of claim 17 wherein covering the active surface of
the die with an encapsulant includes one of an overmolding
procedure, a glob-top procedure or a dam and fill procedure.
19. The method of claim 13 wherein providing a substrate having a
mounting area for an electronic component and a vent opening
includes during a step of preparing the substrate drilling a hole
having a hole wall extending through the substrate and plating the
hole wall.
20. A semiconductor chip package comprising: a substrate having a
surface provided with an electronic circuit, a semiconductor die
mounted on the surface and connected with the electronic circuit, a
shielding enclosure located over the semiconductor die and defining
a shielded space surrounding the semiconductor die, a vent opening
extending through the substrate, the opening located within the
shielded space for venting the shielded space.
21. The semiconductor chip package of claim 20 further including a
second vent opening in the conductive enclosure, and wherein the
surface of the substrate is covered with an encapsulant that
surrounds the shielding enclosure but does not cover the second
vent opening.
Description
BACKGROUND TO THE INVENTION
[0001] 1. Field of the Invention
[0002] The current invention relates to electronic component
packages and to electromagnetic interference (EMI) shielding. More
particularly, the invention relates to electronic component
packages, such as system-in-package modules, with EMI shielding to
isolate a component in the package from electromagnetic
interference, or from causing electromagnetic interference, in
other parts of the package.
[0003] 2. Background Information
[0004] System-in-package (SiP) technology is an integrated module
design that contains one or more IC chips and associated discrete
components for performing an entire electronic circuit function
incorporated into a single encapsulated package. Electromagnetic
interference (EMI), also known as radio frequency interference
(RFI), is caused by electromagnetic radiation emitted by electronic
circuits and components carrying changing electrical signals. EMI
is a major consideration in single package design especially where
EMI sensitive and/or RF components are tightly packed together,
which is becoming increasingly common place with the proliferation
of wireless technologies into a range of small scale electronic
devices.
[0005] The most popular form of shielding within SiP modules is
through use of a shielding lid to enclose the sensitive or EMI
generating component. The component is mounted on an area of a
supporting substrate with a ground trace plane beneath it and a
metal box, or other shaped, lid is mounted over the component to
enclose the component in a conductive enclosure. Metal lids of this
type take up considerable space on the substrate surface and tended
to be not very robust often dislodging from the substrate surface
due to cyclic stress loading on the solder joints holding the lid
to the substrate. This problem is ameliorated to some extent by
overmolding or encapsulation of the package, including the lid, in
resin to protect the package and components from mechanical damage,
shock and moisture. However, the lid must have openings in its top
and sides to facilitate the flow of the encapsulating resin. The
amount and size of these openings is restricted to avoid EMI
leakage, particularly for high frequency operations. The flow of
encapsulating resin is therefore restricted often resulting in air
spaces within the shielding lid. The openings are subsequently
blocked by the resin trapping this air within the lid, which is
hazardous to package reliability during subsequent thermal
excursions and can result in cracking and dislodging of the
shielding lid.
[0006] Accordingly, is an object of the present invention to
provide an electronic component package having EMI shielding for
sensitive electronic or EMI generating components that overcomes or
at least ameliorates the above problems.
SUMMARY OF THE INVENTION
[0007] In view of the forgoing, there is disclosed herein an
electronic component package having EMI shielding, comprising a
substrate having a mounting area for an electronic component, an
electronic component located on the mounting area, a conductive
enclosure having a top and downwardly extending sides enclosing the
mounting area and defining a shielded space above the mounting
area, and a vent opening extending through the substrate, the
opening located in the mounting area for venting the shielded
space.
[0008] Preferably, the vent opening extending through the substrate
is a plated via.
[0009] Preferably, the component is covered with an encapsulant and
the vent opening extending through the substrate is not covered
with the encapsulant.
[0010] Preferably, the component package further includes a second
vent opening in the top of the conductive enclosure.
[0011] Preferably, the top and sides of the conductive enclosure do
not have any further openings.
[0012] Preferably, portions of the substrate and conductive
enclosure are covered with an encapsulant and the second vent
opening is not covered with the encapsulant. More preferably, the
top of the conductive enclosure is not covered with the
encapsulant.
[0013] Preferably, the substrate includes a ground trace or other
grounding means and the sides of the conductive enclosure make
contact with the ground trace or grounding means.
[0014] Preferably, the component is a semiconductor die and in
particular a radio frequency (RF) chip.
[0015] Preferably, the conductive enclosure is adapted to attenuate
electromagnetic radiation emitted by the component.
[0016] Preferably, the component package is a semiconductor chip
package.
[0017] There is also disclosed herein a method of making an
electronic component package, comprising steps of (1) providing a
substrate having a mounting area for an electronic component and a
vent opening extending through the substrate adjacent the mounting
area, (2) mounting a component on the mounting area, and (3)
locating a conductive enclosure on the substrate to surround the
component and the vent opening.
[0018] Preferably various other steps include, but are not limited
to, covering the component, or at least an active part of it, with
an encapsulant and not covering the vent opening with the
encapsulant; and providing a second vent opening in the conductive
enclosure and also covering portions of the substrate and
conductive enclosure with an encapsulant and not covering the
second vent opening with the encapsulant.
[0019] Further aspects of the invention will become apparent from
the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] An exemplary form of the present invention will now be
described by way of example only and with reference to the
accompanying drawings, in which:
[0021] FIG. 1 is a section schematic depiction through an
electronic component package according to a first embodiment of the
invention, and
[0022] FIG. 2 is a section schematic depiction through an
electronic component package according to a second embodiment of
the invention.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0023] In the described exemplary embodiments of the invention an
electronic component package comprises a substrate having an
electronic component located its surface and a conductive enclosure
having a top and downwardly extending sides enclosing the component
and defining a shielded space. A vent opening is provided through
the substrate and opens within the shielded space for venting the
shielded space. A second vent opening may be provided in the top of
the conductive enclosure.
[0024] In the drawings there are depicted two exemplary embodiments
of the invention as practiced in a system-in-package (SiP) package
having both radio frequency (RF) and digital integrated circuit
(IC) chips packaged together on a single substrate. These exemplary
examples are not however intended to limit the scope of use or
functionality of the present invention. Those skilled in the art
will appreciate that aspects of the invention may be practiced in
other types of packaged component arrangements where it is
desirable to isolated one or more component from noise interference
in, or from introducing noise interference into, other parts of the
package. Further, the exemplary embodiment is a single package
having a single support substrate with a Bally Grid Array (BGA) for
interconnection to a system substrate or motherboard. The skilled
artisan will appreciate that the invention applies equally to stack
chip arrangements such as a stacked multi-chip modules (MCMs). A
particular IC chip configuration is also described to illustrate
the invention and this is also not intended to limit the scope of
use or functionality of the invention. Other chip types, components
and/or their combinations may be used with the invention. The
invention applies generally to any sensitive electronic or EMI
generating component that must be isolated within a multi-component
package.
[0025] Referring to FIG. 1, in a first exemplary embodiment of the
present invention an electronic component package 10 comprises a
supporting substrate 11 having a radio frequency (RF) chip 12
mounted in a chip mounting area 13 on a first side of the substrate
in known manner. The supporting substrate 11 is provided with
printed circuits on one or more of its surfaces and bonding pads
for connecting the chip 12 to the printed circuits using bonding
wires 14. The top active surface 15 of the chip 12 is covered with
a plastic resin encapsulant 42 to protect the chip 12 and bonding
wire 14 connections using a known overmolding, glob-top or dam and
fill encapsulation method. The substrate 11 has a ground trace 17,
or other grounding means, surrounding the chip mounting area 13.
The substrate 11 has a plurality of balls of solder 18 arranged in
a grid pattern on its second side forming a Ball Grid Array (BGA)
for mounted and interconnected the package 10 to a system substrate
(not shown). The printed circuits, interconnect vias and other
circuit components not necessary to a proper understanding of the
current invention are not shown for clarity.
[0026] In the exemplary embodiment, the chip 12 and its bonding
wires 14 are covered with a plastic resin encapsulant 42, without
cover the vent opening 30 adjacent the RF chip 12, by using dam and
fill encapsulation method. In this method a dam is first formed by
running a bead of a high-viscosity encapsulant 41 around the RF
chip 12. The dam is then filled with a lower-viscosity filler
encapsulant 42 which flows over the RF chip 12 and bonding wires
14, but is restrained by the dam 41.
[0027] A metallic shielding lid 20 having a top 21 and downwardly
extending sides 22 is located over the chip mounting area 13 to
enclose the RF chip 12. The sides 22 of the shielding lid 20 are
connected with the ground trace 17 of the substrate to ground the
lid 20. The lid forms a shielded space 23 in which the chip 12 is
located for blocking, or at least attenuating, electromagnetic
radiation generated by the RF chip 12. In the first exemplary
embodiment the shielding lid 20 does not have any openings or
apertures in its top 21 or sides 22 and provides an entirely closed
enclosure surrounding the shielded space 23. In order to make the
package more robust the substrate 11 and the shielding lid 20 are
covered in an encapsulating resin 19.
[0028] A vent opening 30 is provided through the substrate 11
adjacent the RF chip 12 from the chip mounting area 13 within the
shielding space 23 to the second side of the substrate. The vent
opening 30 permits venting of the otherwise sealed space 23 to
allow any gases and moisture in the space to escape and to balance
the external and internal pressure of the shielded space 23. To
prevent moisture and other environmental contaminants derogating
the integrity of the substrate 11 by entering the substrate layers
the vent opening 30 is plated on its inside surface. Such a venting
opening 30 is typically, but not essentially, formed as a plated
through-hole (e.g. a via) during substrate manufacturer.
[0029] FIG. 2 shows a second exemplary embodiment of the present
invention. In the drawings like elements have the same reference
numbers. In FIG. 2 the electronic component package 10 comprises a
supporting substrate 11 having a radio frequency (RF) chip 12
mounted in a shielded component mounting area 13 on its first side
in known manner. A second semiconductor chip, such as digital IC
40, is also located on the first side of the substrate. The
supporting substrate 11 is provided with printed circuits on one or
more of its surfaces and bonding pads for connecting the chips 12,
40 to the printed circuits using bonding wires 14. The substrate 11
has a ground trace 17, or other grounding means, surrounding the
shielded component mounting area 13. The substrate 11 has a
plurality of balls of solder 18 arranged in a grid pattern on its
second side forming a Ball Grid Array (BGA) for mounted and
interconnected the package to a system substrate (not shown). The
printed circuits, interconnect vias and other circuit components
not necessary to a proper understanding of the current invention
are not shown for clarity.
[0030] A shielding lid 20 having a top 21 and downwardly extending
sides 22 is located over the shielded component mounting area 13 to
enclose the RF chip 12. The sides 22 of the shielding lid 20 are
connected with the ground trace 17 of the substrate to ground the
lid 20. The lid forms a shielded space 23 in which the chip 12 is
located for blocking, or at least attenuating, electromagnetic
radiation generated by the RF chip 12. A vent opening 30 is also
provided through the substrate 11 adjacent the RF chip 12 from the
shielded component mounting area 13 within the shielding space 23
to the second side of the substrate.
[0031] The chip 12 is covered with a plastic resin encapsulant 42
to protect the chip 12 and bonding wire connections 14 using the
same dam and fill encapsulation method described above for the
first embodiment. To make the package more robust the entire
substrate 11 including digital die 40 and the shielding lid 20 is
covered in an encapsulating resin 43. The height of the shielding
lid 20 and encapsulating resin 43 are controlled so that the top of
the shielding lid 20 is not covered in the encapsulating resin 43.
A second vent opening 44 is provided in the top 21 of the shielding
lid 20 to promote air flow through the shielding space 23 via the
two vent openings 30, 44. This substantially reduces the likelihood
of moisture accumulation inside the shielding lid 20 during the
re-heat process for molding or changes in environmental conditions
or subsequent thermal excursions during storage or service of the
package 10.
[0032] To make the electronic component packages depicted and
described a substrate 11 is first prepared having printed circuits
including a mounting area 13 for an electronic component to be
shielded and a plated through-hole extending through the substrate
adjacent the mounting area 13. The plated through-hole forms the
vent opening 30. The substrate 11 can be prepared using known PCB
manufacturing techniques. The electronic component, in the
exemplary embodiments an RF chip 12, is then mounted to the
substrate and bonding wires 14 connected to the printed circuits.
If needed, the component is covered with an encapsulant using an
overmolding, a glob-top or a dam and fill procedure to protect it
from mechanical damage, shock and moisture. Care must be taken not
to cover the plated through-hole adjacent the mounting area 13.
[0033] After encapsulation of the component the shielding lid 20 is
located on the substrate to surround the component and the plated
through-hole. The sides of the lid are connected to the ground
traces 17 to ground the lid 20. The top of the substrate and lid
are then covered by the further encapsulant.
[0034] For making the package of the second embodiment the
shielding lid is provided with a second vent hole in its top 21
prior being located on the substrate. When covering the top of the
substrate the height of the mould for the encapsulating resin 43 is
controlled so that the top of the shielding lid 20 is not covered
in the encapsulating resin 43.
[0035] For high frequency applications the size of the vent
openings 30, 44 should typically be less that 3 mm, but may be
bigger for lower frequency operations. Electromagnetic waves do not
penetrate very far through holes that have a dimension less than
their wavelength. Most modern electronic devices such as mobile
phones, wireless network adaptors and telecommunications equipment
operate in the Ultra High Frequency (UHF) band from 300 MHz to 3
GHz. This is a wavelength range of 1 meter to 100 millimeters.
[0036] The shielding lid 20 may be made of any suitable material
for blocking, or at least attenuating, electromagnetic radiation
emitting from electronic components carrying changing electrical
signals. For shielding lower frequency components; such as
shielding transforms, inductors and coils; high permeability
materials such as tin plated steel may be used. For shielding high
frequency components; such as RF chips, microprocessors and fast
operating switches; non-ferrous materials such as tin plated
copper, phosphor bronze or beryllium copper may be used.
[0037] It should be appreciated that modifications and/or
alternations obvious to those skilled in the art are not to be
considered as beyond the scope of the present invention. For
example, in the second exemplary embodiment a second vent opening
is provided in the top 21 of the shielding lid 20. Venting of the
shielded space 23 is effective via the vent opening 30 extending
through the substrate 11 so that no openings in the shielding lid
20 are possible. However, one or more vent openings in the top of
the shielding lid 20 are within the scope of the invention although
preferably, to maintain the shielding effectiveness of the lid 20,
fewer openings are desirable. Also, preferably there are no
openings, slots, slits or other apertures in the sides of the lid
20.
[0038] In the exemplary embodiments a RF chip component is used and
it is preferably to protect the chip from mechanical damage, shock
and moisture by covering it in an encapsulant 42. However, the
skilled addressee will appreciate that other components; e.g.
transforms, inductors, coils and fast operating switches; may be
shielded in a package according to the invention that do not
require covering in an encapsulant 42.
* * * * *