U.S. patent application number 15/495405 was filed with the patent office on 2017-10-26 for mechanically-compliant and electrically and thermally conductive leadframes for component-on-package circuits.
The applicant listed for this patent is LINEAR TECHNOLOGY CORPORATION. Invention is credited to Frederick E. BEVILLE, John David BRAZZLE, David A. PRUITT.
Application Number | 20170311447 15/495405 |
Document ID | / |
Family ID | 58610047 |
Filed Date | 2017-10-26 |
United States Patent
Application |
20170311447 |
Kind Code |
A1 |
BRAZZLE; John David ; et
al. |
October 26, 2017 |
MECHANICALLY-COMPLIANT AND ELECTRICALLY AND THERMALLY CONDUCTIVE
LEADFRAMES FOR COMPONENT-ON-PACKAGE CIRCUITS
Abstract
A component-on-package circuit may include a component for an
electrical circuit and a circuit module attached to the component.
The circuit module may have circuitry and at least one leadframe
which connects the circuitry to the component both electrically and
thermally. The leadframe may have a high degree of both electrical
and thermal conductivity and a non-planar shape that provides
spring-like cushioning of force applied to the component in the
direction of the circuit module. A method of making a
component-on-package circuit may include attaching a component for
an electrical circuit to a circuit module. The circuit module may
have circuitry and at least one leadframe which connects the
circuitry to the component after the attachment both electrically
and thermally. The leadframe may have a high degree of both
electrical and thermal conductivity and a non-planar shape that
provides a spring-like cushioning of force applied to the component
in the direction of the circuit module. The circuit module may be
encapsulated in molding material after the circuit module has been
attached to the component, without encapsulation the component at
the same time.
Inventors: |
BRAZZLE; John David; (Tracy,
CA) ; BEVILLE; Frederick E.; (San Jose, CA) ;
PRUITT; David A.; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LINEAR TECHNOLOGY CORPORATION |
Milpitas |
CA |
US |
|
|
Family ID: |
58610047 |
Appl. No.: |
15/495405 |
Filed: |
April 24, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62327875 |
Apr 26, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 2201/10515
20130101; H05K 1/181 20130101; H05K 3/284 20130101; H05K 2203/1316
20130101; H01L 23/50 20130101; H05K 2201/1003 20130101; H05K 1/0203
20130101; H05K 2201/10522 20130101; H05K 2201/10553 20130101; H05K
2201/10757 20130101; H05K 3/3426 20130101; H01L 23/49811
20130101 |
International
Class: |
H05K 1/18 20060101
H05K001/18; H05K 3/34 20060101 H05K003/34; H05K 1/02 20060101
H05K001/02; H05K 3/28 20060101 H05K003/28 |
Claims
1. A component-on-package circuit comprising: a component for an
electrical circuit; and a circuit module attached to the component,
the circuit module having: circuitry; and at least one leadframe
which connects the circuitry to the component both electrically and
thermally, the leadframe having a high degree of both electrical
and thermal conductivity and a non-planar shape that provides
spring-like cushioning of force applied to the component in the
direction of the circuit module.
2. The component-on-package circuit of claim 1 wherein the
leadframe has at least one foot electrically connected to the
circuitry.
3. The component-on-package circuit of claim 2 wherein the
leadframe has at least two distinct feet.
4. The component-on-package circuit of claim 1 wherein the
leadframe has at least one top surface electrically and thermally
connected to the component.
5. The component-on-package circuit of claim 4 wherein the
leadframe has at least two, separated top surfaces that are each
attached to the component.
6. The component-on-package circuit of claim 1 wherein the
leadframe has: at least one foot electrically connected to the
circuitry; at least one top surface electrically and thermally
connected to the component; and at least one step between the foot
and the top surface.
7. The component-on-package circuit of claim 6 wherein the
leadframe has at least two distinct steps.
8. The component-on-package circuit of claim 7 wherein the at least
two distinct steps are at different elevations between the at least
one foot and the at least one top surface.
9. The component-on-package circuit of claim 7 wherein the at least
two distinct steps are at the same elevation.
10. The component-on-package circuit of claim 1 wherein: the
circuit module has a second leadframe that connects the circuitry
to the component both electrically and thermally; and the second
leadframe has a high degree of both electrical and thermal
conductivity and a non-planner shape that provides spring-like
cushioning of force applied to the component in the direction of
the circuit module.
11. The component-on-package circuit of claim 1 wherein: the
circuit module, including the leadframe, is encapsulated in molding
material; and the leadframe has a top surface that is not covered
by the molding material.
12. The component-on-package circuit of claim 11 wherein the
component is not also encapsulated by the molding material.
13. The component-on-package circuit of claim 1 wherein the
component is a passive component.
14. The component-on-package circuit of claim 13 wherein the
passive component is an inductor.
15. A method of making a component-on-package circuit comprising:
attaching a component for an electrical circuit to a circuit
module, the circuit module having circuitry and at least one
leadframe which connects the circuitry to the component after the
attachment both electrically and thermally, the leadframe having a
high degree of both electrical and thermal conductivity and a
non-planar shape that provides spring-like cushioning of force
applied to the component in the direction of the circuit module;
and encapsulating the circuit module in molding material after the
circuit module has been attached to the component, without
encapsulation the component at the same time.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims priority to U.S.
provisional patent application 62/327,875, entitled
"MECHANICALLY-COMPLIANT AND ELECTRICALLY AND THERMALLY CONDUCTIVE
LEADFRAMES FOR COMPONENT-ON-PACKAGE CIRCUITS," filed Apr. 26, 2016,
attorney docket number 081318-1003. The entire content of this
application is incorporated herein by reference.
BACKGROUND
Technical Field
[0002] This disclosure relates to high power density
systems-in-packages (SIPs) or modules, packages that require low
impedance, and packages with high thermal performance requirements.
This disclosure also relates to module packages with high
power/high current applications that require large externally
mounted components and/or improved heat dissipation.
Description of Related Art
[0003] The desire for SIPs to have increased power and current
capabilities, while at the same time minimizing their footprint
within a system board design, can present a multitude of design
constraints and limitations on the designer and module package
engineer.
[0004] Higher power components may require a large amount of board
space and may have a large thermal mass. Large inductors, for
example, can be integrated into an SIP, but size limitations of the
molded package may prevent the use of larger and more power-capable
components. Due to their size, these large components may not be
able to be enclosed within the SIP. They may also require
attachments on the system board as near to the SIP as possible to
minimize loss or noise in the circuit. For this reason, a package
design and assembly methodology may need to integrate larger high
power external active and passive components with the molded SIP,
while maintaining minimal impact to real estate on the board.
[0005] Additionally, higher power packages and components may
dissipate larger amounts of heat into their surroundings, primarily
into the system board, distributing heat into adjacent packages and
components. This may affect overall system efficiency and
reliability. These high power packages may require high current
pathways that may exceed the heat and current carrying capacity of
package substrates and system boards, without the use of additional
metal layers, solid metal vias, and costly heat sink apparatus. For
this additional demand on the high power module package, a
technology may be needed that provides a highly conductive thermal
and electrical pathway within the SIP package body that is not
dependent upon limitations of substrate and system board
architectures.
SUMMARY
[0006] A component-on-package circuit may include a component for
an electrical circuit and a circuit module attached to the
component. The circuit module may have circuitry and at least one
leadframe which connects the circuitry to the component both
electrically and thermally. The leadframe may have a high degree of
both electrical and thermal conductivity and a non-planar shape
that provides spring-like cushioning of force applied to the
component in the direction of the circuit module.
[0007] A method of making a component-on-package circuit may
include attaching a component for an electrical circuit to a
circuit module. The circuit module may have circuitry and at least
one leadframe which connects the circuitry to the component after
the attachment both electrically and thermally. The leadframe may
have a high degree of both electrical and thermal conductivity and
a non-planar shape that provides a spring-like cushioning of force
applied to the component in the direction of the circuit module.
The circuit module may be encapsulated in molding material after
the circuit module has been attached to the component, without
encapsulation the component at the same time.
[0008] These, as well as other components, steps, features,
objects, benefits, and advantages, will now become clear from a
review of the following detailed description of illustrative
embodiments, the accompanying drawings, and the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0009] The drawings are of illustrative embodiments. They do not
illustrate all embodiments. Other embodiments may be used in
addition or instead. Details that may be apparent or unnecessary
may be omitted to save space or for more effective illustration.
Some embodiments may be practiced with additional components or
steps and/or without all of the components or steps that are
illustrated. When the same numeral appears in different drawings,
it refers to the same or like components or steps.
[0010] FIGS. 1A and 1B illustrate an external view of an example of
a partially assembled (FIG. 1A) and fully assembled (FIG. 1B)
components-on-package (CoP) device.
[0011] FIG. 2 illustrates internal construction details of an
example of a CoP module package with internal leadframes forming
electrical and/or thermal pathways for an externally attached
component.
[0012] FIGS. 3A and 3B illustrate an external view of an example of
a partially assembled (FIG. 3A) and fully assembled (FIG. 3B)
multiple components-on-package (mCoP) device.
[0013] FIG. 4 illustrates internal construction details of another
example of an mCoP module package that may have one or more
internal leadframes that may form electrical and/or thermal
pathways to one or more externally attached component
connections.
[0014] FIG. 5 illustrates an external view of another example of a
multiple components-on-package (mCoP) device with four separate
components that may be attached to the top of a mCoP module
package.
[0015] FIG. 6 illustrates internal construction details of another
example of an mCoP module package with mechanically compliant
internal leadframes that may form electrical and/or thermal
pathways for externally attached component connections.
[0016] FIG. 7 illustrates an external view of another example of a
multiple components-on-package (mCoP) device that may have multiple
active and/or passive components attached to the top of a module
package.
[0017] FIG. 8 illustrates internal construction details of another
example of an mCoP module package that may have internal leadframes
forming electrical and/or thermal pathways for externally attached
component connections.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0018] Illustrative embodiments are now described. Other
embodiments may be used in addition or instead. Details that may be
apparent or unnecessary may be omitted to save space or for a more
effective presentation. Some embodiments may be practiced with
additional components or steps and/or without all of the components
or steps that are described.
[0019] Disclosed is a package design and assembly methodology that
may integrate mechanically compliant through-mold conductive
leadframes for thermal and/or electrical interconnection of large
high power externally attached active and passive components.
[0020] Active and/or passive components may be attached to the top
of molded and/or unmolded SIPs and modules with full electrical
functionality by use of internal leadframes embedded within the
module package. These externally mounted components may combine
with highly conductive leadframes to provide additional thermal
pathways for dissipation of heat and may enhance thermal
characteristics and improve power efficiency.
[0021] The highly conductive leadframes may be mechanically
compliant and spring-like. Their spring-like action may absorb
compressive forces placed on the externally mounted components in
the direction of the module during or after assembly and/or may
redirect these forces away from the substrate, internal components,
and/or exposed component pads.
[0022] Electrical and/or thermal pathways may be provided by use of
a mechanically compliant leadframe. The leadframe may extend from
within the molded module substrate contact through the mold
compound to make contact with internal components. The leadframe
may extend through to the top of the module to form a contact pad
for connection to top mounted active or passive components.
[0023] FIGS. 1A and 1B illustrate an external view of an example of
a partially assembled (FIG. 1A) and fully assembled (FIG. 1B)
components-on-package (CoP) device. A component 102 may be an
inductor or other type of passive or active component or a set of
components attached to a top of a CoP module package 100. The CoP
module package 100 may be a fully molded electrical circuit and may
be constructed with internal leadframes to form one or more exposed
metal pads 101 for electrical and/or thermal connection to the
externally mounted component 102. The component 102 may be
electrically, thermally, and/or mechanically attached to the
package.
[0024] The component 102 may have two contact terminals and may be
electrically, thermally, and/or mechanically attached to the top of
the module package. Electrical connection from the module to the
component may be provided by an internal leadframe that may be
embedded within the module package during a plastic molding
process.
[0025] FIG. 2 illustrates internal construction details of an
example of a CoP module package with internal leadframes 103
forming electrical and/or thermal pathways for an externally
attached component 104. The example may be the same as the example
shown in FIG. 1. The leadframes 103 may each be a mechanically
compliant through-mold leadframe that completes the electrical
circuit from a substrate up to the component 104 and may provide
additional thermal and electrical connections 105 for internal
components, such as a quad flat no-lead (QFN) package with exposed
pad. One or more of the leadframes may also contain one or more
openings 106 that may each be round, oval, rectangular, or any
other shape. The openings 106 may improve plastic mold compound
flow during the molding process and/or mold compound
interlocking.
[0026] The internal leadframes 103 that are illustrated in FIG. 2
may each form a solderable contact region at the top surface of the
module following the mold process. They may also each provide a
high current electrical connection from the externally attached
component 104 down through the mold compound to connect to the
electrical circuit.
[0027] This leadframe electrical circuit connection may be soldered
down to the module substrate and may also be connected to multiple
internal components. This electrical pathway may provide a thermal
pathway for heat to escape the module package.
[0028] The component 104 may be affixed to the top of the module by
use of solder and/or epoxy attach materials using a post-mold SMT
assembly process. Adhesive or other type of attaching material may
be used to attach the body of the component to the plastic body of
the module for additional mechanical stability.
[0029] The solder and epoxy materials used to attach the component
may be electrically and/or thermally conductive to provide a high
current (e.g., >50 amps) and a highly thermally conductive
connection (e.g., >25 watts per meter per degree celsius) to the
molded SIP. The attachment process and materials may combine to
provide hold down strength and heat working characteristics
sufficient to survive high temperature thermal cycling during
operation and reliability testing.
[0030] The component 104 or multiple components may be passive
and/or active. Their number may depend on the number of through
mold connections provided by the leadframe design.
[0031] FIGS. 3A and 3B and FIG. 5 show examples of multiple
components-on-package (mCoP) devices that may include multiple
passive components that are electrically and/or thermally attached
to the top of the fully molded SIP or Module.
[0032] FIGS. 3A and 3B illustrate an external view of an example of
a partially assembled (FIG. 3A) and fully assembled (FIG. 3B)
multiple components-on-package (mCoP) device. Attached external
components 202 may each be an inductor and/or other type of
component or components which may be attached to the top of a mCoP
module package 200. The mCoP module package 200 may be a full
molded electrical circuit with internal leadframes that form one or
more exposed pads 201 for electrical and/or thermal connection to
the external components 202. The external components may be
electrically, thermally, and/or mechanically attached to the module
package 200.
[0033] FIG. 4 illustrates internal construction details of another
example of an mCoP module package that may have one or more
internal leadframes 203 that may form electrical and/or thermal
pathways to one or more externally attached component connections
204. The example may be the same as the example shown in FIGS. 3A
and 3B. One or more mechanically compliant through-mold leadframes
206 may complete the electrical circuit from the substrate up to
each of the component connections 204 and may provide additional
thermal and/or electrical connections 205 to internal components,
such as to a QFN. The one or more of the leadframes 206 may also
contain one or more openings 206 that may each be circular, oval,
rectangular, or any other shape. The opening 206 may improve
plastic mold compound flow during the molding process and/or
improve mold compound interlocking.
[0034] FIG. 5 illustrates an external view of another example of a
multiple components-on-package (mCoP) device with four separate
components 302 that may be attached to the top of a mCoP module
package 300. The mCoP Module package 300 may be a full molded
electrical circuit with internal leadframes that form exposed pads
301 for electrical and/or thermal connection to all of the external
components 302. All of the external components 302 may be
electrically, thermally, and/or mechanically attached to the
package through the leadframes. A different number of components
may be used instead.
[0035] FIG. 6 illustrates internal construction details of another
example of an mCoP module package with mechanically compliant
internal leadframes 303 that may form electrical and/or thermal
pathways for externally attached component connections 304. The
example may be the same as the example shown in FIG. 5. The
mechanically compliant through-mold leadframes may complete the
electrical circuit from the substrate up to the components and may
provide additional thermal and/or electrical connections 305 for
internal components. One or more of the leadframes may also contain
openings 306 that may be circular, oval, rectangular or any other
shape. These openings 306 may improve plastic mold compound flow
during the molding process and/or mold compound interlocking.
[0036] The leadframes employed (FIGS. 4 and 6) may provide
electrical and/or thermal pathways for each attached component and
may have openings that may assist in the assembly process by
enhancing mold flow during the plastic molding process and/or
providing additional mechanical stability by mold locking of the
leadframe within the molded structure. The leadframe design may
also provide for isolated and individual connection of all
component leads for full functionality of each component, as
required by the function of the electrical circuits within the
module package.
[0037] FIG. 7 illustrates an external view of another example of a
multiple components-on-package (mCoP) device 400 that may have
multiple active and/or passive components 402 attached to the top
of a module package 400. The mCoP Module package 400 may be a fully
molded electrical circuit with internal leadframes that form
exposed pads 401 for electrical and/or thermal connections to one
or more externally attached components 402.
[0038] FIG. 8 illustrates internal construction details of another
example of an mCoP module package that may have internal leadframes
403 forming electrical and/or thermal pathways for externally
attached component connections 404. The example may be the same as
the example shown in FIG. 7. Mechanically compliant through-mold
leadframes 406 may complete the electrical circuit from the
substrate up to the component and may provide additional thermal
and/or electrical connections for internal components 405. One or
more of the leadframes 406 may contain openings 406 that may each
be circular, oval, rectangular or any other shape. These openings
406 may improve plastic mold compound flow during the molding
process and/or mold compound interlocking.
[0039] FIGS. 7 and 8 show an example of an mCoP device with
multiple active and/or passive components attached to the top
surface of the module package. This device may require more complex
leadframe designs and/or post-mold processing and/or post-mold
machining, but may provide all the same functional characteristics
as previously disclosed herein.
[0040] Additional machining and/or etching of the leadframe can be
performed once the leadframe is embedded within the mold compound
in case further electrical isolation is required for proper circuit
operation of the mCoP. This machining may include both additive and
subtractive modification to the imbedded/attached leadframe by
means of mechanical and electrical means. For example, a milling
machine, laser machining, chemical etching, and/or sawing the
leadframe may be used to obtain isolated and/or routed connections
for externally mounted components.
[0041] The mechanically compliant internal leadframes that have
been described may provide electrically and/or thermally conductive
pathways that distribute between the internal components and
circuit within the module and the attached external components.
Angular bends may be at precise locations and may act to decouple
and redistribute any downward force due to assembly and mold
packing pressures that might otherwise damage the substrate and/or
attached components. The openings in the leadframe may be circular,
oval, rectangular, or any other shape and may facilitate mold
locking, mold flow, and/or minimize mold voids and/or prevent large
areas of delamination.
[0042] The leadframe may also have a multiplicity of areas along
the length on each side containing thinned regions, typically half
the thickness being removed by machining and/or etching. These
half-etch features may be provided at specific locations to further
reduce the chance of delamination during subsequent reflows and
other reliability related concerns.
[0043] The components, steps, features, objects, benefits, and
advantages that have been discussed are merely illustrative. None
of them, nor the discussions relating to them, are intended to
limit the scope of protection in any way. Numerous other
embodiments are also contemplated. These include embodiments that
have fewer, additional, and/or different components, steps,
features, objects, benefits, and/or advantages. These also include
embodiments in which the components and/or steps are arranged
and/or ordered differently.
[0044] For example, internal leadframes could be used to
redistribute electrical signals within the module package,
effectively providing an additional signal layer between
components. These internal leadframes would not necessarily require
exposure to the top surface of the package. These leadframes could
be considered to be intermediate conductive layers that could act
to bridge electrical signals from components at one side of the
package and extend over many internal components to make high
current connections to other components at the other side of the
package. Leadframes forming internal connections from the backside
of flip chip silicon die to other internal components would be one
example. Connecting vertical FET's together and to the substrate
would be another. Another example would be a leadframe spanning the
entire distance of the package length to provide electrical and
thermal connections for any number of components.
[0045] Internal leadframes that are exposed and/or revealed for
surface connection of components can also form connections to
external heat sinking materials, such as a heatsink, thermal pipes,
and/or other electrically and/or thermally conductive materials.
Connections such as these may further enhance heat dissipation from
within the package and potentially allow for operation at higher
power densities and currents.
[0046] Variations of what have been described may include a variety
of attach methods to the substrate, internal components, and/or
external components. These methods may include but are not limited
to epoxy, solder, and/or any adhesive that is either conductive or
non-conductive to heat and/or electricity. Furthermore, the
internal leadframe may include any multiple of leadframes and/or
structures that may form conductive pathways for relevant operation
of the package. Leadframe structures may connect/attach to
interposers, clips, metallic stand-offs, and/or any variation of
material structure capable of providing a conductive pathway for
heat and/or electricity. Externally mounted/attached components may
include but are not limited to passive components, active
components, and/or any variation of thermally and/or electrically
conductive material to include heat sinking devices, heat pipes,
intercoolers, and/or externally attached Peltier and/or energy
harvesting and control devices.
[0047] Unless otherwise stated, all measurements, values, ratings,
positions, magnitudes, sizes, and other specifications that are set
forth in this specification, including in the claims that follow,
are approximate, not exact. They are intended to have a reasonable
range that is consistent with the functions to which they relate
and with what is customary in the art to which they pertain.
[0048] All articles, patents, patent applications, and other
publications that have been cited in this disclosure are
incorporated herein by reference.
[0049] The phrase "means for" when used in a claim is intended to
and should be interpreted to embrace the corresponding structures
and materials that have been described and their equivalents.
Similarly, the phrase "step for" when used in a claim is intended
to and should be interpreted to embrace the corresponding acts that
have been described and their equivalents. The absence of these
phrases from a claim means that the claim is not intended to and
should not be interpreted to be limited to these corresponding
structures, materials, or acts, or to their equivalents.
[0050] The scope of protection is limited solely by the claims that
now follow. That scope is intended and should be interpreted to be
as broad as is consistent with the ordinary meaning of the language
that is used in the claims when interpreted in light of this
specification and the prosecution history that follows, except
where specific meanings have been set forth, and to encompass all
structural and functional equivalents.
[0051] Relational terms such as "first" and "second" and the like
may be used solely to distinguish one entity or action from
another, without necessarily requiring or implying any actual
relationship or order between them. The terms "comprises,"
"comprising," and any other variation thereof when used in
connection with a list of elements in the specification or claims
are intended to indicate that the list is not exclusive and that
other elements may be included. Similarly, an element proceeded by
an "a" or an "an" does not, without further constraints, preclude
the existence of additional elements of the identical type.
[0052] None of the claims are intended to embrace subject matter
that fails to satisfy the requirement of Sections 101, 102, or 103
of the Patent Act, nor should they be interpreted in such a way.
Any unintended coverage of such subject matter is hereby
disclaimed. Except as just stated in this paragraph, nothing that
has been stated or illustrated is intended or should be interpreted
to cause a dedication of any component, step, feature, object,
benefit, advantage, or equivalent to the public, regardless of
whether it is or is not recited in the claims.
[0053] The abstract is provided to help the reader quickly
ascertain the nature of the technical disclosure. It is submitted
with the understanding that it will not be used to interpret or
limit the scope or meaning of the claims. In addition, various
features in the foregoing detailed description are grouped together
in various embodiments to streamline the disclosure. This method of
disclosure should not be interpreted as requiring claimed
embodiments to require more features than are expressly recited in
each claim. Rather, as the following claims reflect, inventive
subject matter lies in less than all features of a single disclosed
embodiment. Thus, the following claims are hereby incorporated into
the detailed description, with each claim standing on its own as
separately claimed subject matter.
* * * * *