Patent ID: 12245382

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

It will be understood that although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element without departing from the scope of the present disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element such as a layer, region, or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element, or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. Likewise, it will be understood that when an element such as a layer, region, or substrate is referred to as being “over” or extending “over” another element, it can be directly over or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly over” or extending “directly over” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.

Relative terms such as “below,” or “above,” or “upper,” or “lower,” or “horizontal,” or “vertical” may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

FIG.1Ais an illustration of a top view of a module100that includes circuit components102on a laminate104. The module100also includes an overmold106disposed on the circuit components102and the laminate104.FIGS.1B and1Care cross-sectional side views of examples of the module100, where both include the overmold106, andFIG.1Cfurther includes a protective shield108disposed on the overmold106. In other aspects, the modules100inFIGS.1B and1Cmay be identical.

A three-dimensional (3D) pattern110formed in an exterior surface112of the overmold106increases the surface area of the overmold106to improve heat dissipation. In the example inFIG.1C, an exterior surface113of the protective shield108disposed on the overmold106also conforms to the 3D pattern110. Increasing the surface area of the module100provides more area from which heat can be dissipated. In this manner, the 3D pattern110can increase a rate of dissipation (from the module100) of heat generated by the circuit components102in the module100.

For example, the module100may be a radio-frequency (RF) front-end module for use in a mobile device (not shown), such as a cellular telephone. In this example, the module100may include various circuit components102for data processing and/or for wirelessly transmitting and receiving signals for different telecommunications interfaces, such as cellular telephone, WiFi, Bluetooth, etc. In such an example, each of the telecommunication interfaces operates at different frequencies, and the transmitted/received signals need to be isolated from each other by transmit (TX) filters and receive (RX) filters, which may be bulk acoustic wave (BAW) or surface acoustic wave (SAW) filters. The signals to be transmitted and received also need to be amplified by respective power amplifiers (PAs). Thus, the circuit components102may include SAW or BAW devices, PAs, complementary metal oxide semiconductor (CMOS) circuits, and other semiconductor devices, for example.

Each of the data processors, TX filters, RX filters, and PAs produce heat during normal operation, causing temperatures in the module100to increase. In situations when multiple circuit components102are generating heat simultaneously, it can be difficult to keep the temperatures of the circuit components from increasing to a level at which there may be a negative impact on performance or even permanent physical damage to the circuit components themselves, causing reduced performance and/or failure. Therefore, measures are needed to help reduce internal temperatures of the module100. As disclosed herein, one such method is to increase the surface area from which heat may be dissipated to the atmosphere, which can increase a rate of heat dissipation. If the rate of heat dissipation can keep up with the rate at which heat is generated internally, the internal temperature of the module100can be successfully managed, increasing the performance and the useful life of an electronic device.

The circuit components102may be semiconductor devices, for example, which are mounted, coupled, and/or disposed on a surface114of the laminate104. The circuit components102may be referred to as surface mount devices (SMDs). The laminate104may be a multi-layer substrate comprising layers115, which may be ground layers or interconnect layers for coupling the circuit components102to each other and also to external circuits, such as circuits mounted on a same circuit board as the module100.

After the circuit components102are disposed on the laminate104, the overmold106, which comprises any of a variety of known mold compounds suitable for the module100, is disposed on the circuit components102and the laminate104. The overmold106may initially be disposed in fluid form and then allowed to solidify. In this manner, the mold compound may encapsulate and protect each of the circuit components and their connections to the laminate104against environmental damage, such as from impact, pressure, vibration, chemicals, water, and humidity, and to improve the dissipation of heat from the circuit components102.

A first side116of the overmold106is disposed on the circuit components102. The exterior surface112is on a second side118(e.g., an upper side inFIG.1B) of the overmold106. The 3D pattern110is formed in the exterior surface112to increase the area of the exterior surface112. In some examples, as inFIG.1B, the exterior surface112may be an exterior of the module100. In other examples, as shown inFIG.1C, the protective shield108may be formed on the 3D pattern110of the exterior surface112. The protective shield108may be formed as a layer of any suitable material providing structural protection and thermal conduction. In some examples, the protective shield108may be an electrically conductive material, such as a metal, that also provides a reduction of electromagnetic interference between circuit components102of the module100and circuits external to the module100. The protective shield108may be disposed onto the exterior surface112by any suitable method, such as by sputtering, chemical vapor deposition (CVD), metal oxide CVD (MOCVD), etc. In this regard, the exterior surface112may be disposed with an approximately constant thickness on the 3D pattern110.

The 3D pattern110may have any suitable shape for increasing the surface area of the exterior surface112on the second side118of the overmold106. In the example inFIGS.1A and1B, the 3D pattern110includes linear ridges122extending in the Y-axis direction with a center-to-center pitch P in the X-axis direction. In this regard, a distance D124between the exterior surface112and the laminate104varies with a thickness of the overmold106. In the X-axis direction, the distance D124increases and decreases in a repetitive manner according to the pitch P. For example, the pitch P may be in the range of 20 to 500 microns (μm). In other examples, the linear ridges122may not have a uniform or constant center-to-center distance.

With or without the protective shield108on the exterior surface112, each of the linear ridges122of the 3D pattern110extends in the Y-axis direction. The linear ridges122each include a ridge portion124that may be planar, having been formed as a planar portion of the exterior surface112of the overmold106(FIG.1B) or being formed by disposed the protective shield108on a planar portion of the exterior surface112.

The linear ridges122also each include channels126, including a side portion128and a bottom portion130. The side portions128of the linear ridges122extend between the ridge portion124and the bottom portion130, which is closer to the laminate104. In this example, the side portion128comprises a surface orthogonal to the surface114of the laminate104and forms at least a portion of a channel126between the ridge portions124. In other examples, the side portions128may not be orthogonal to the laminate104. For example, the side portions128may be at an acute angle to the laminate, or may be concave or convex. A bottom portion130in the channel126closest to the laminate104and the ridge portion124on top of the linear ridges122may be parallel to each other (e.g., and parallel to surface114of the laminate104). Thus, the protective shield108(e.g., a layer of metal) may have a same thickness T108where disposed on the bottom portion130and the ridge portion124. Portions of the protective shield108may have different thicknesses due to, for example, an angle at which the material of the protective shield108is applied to the 3D pattern110.

A width W130of one of the bottom portions130may be in a range of 20 to 250 μm, for example. A height H122of the linear ridges122from the bottom portions130closest to the laminate104to the ridge portions124on top of the linear ridges122may be in the range of 20 to 1000 μm. Thus, an aspect ratio of the linear ridges122, based on a ratio of the width W130of the bottom portions130to the height H122, may be in the range from 1:1 to 1:4. In some examples, the width W130of one of the bottom portions130may be in a range of 20 to 125 μm, and the height H122may be in a range of 20 to 500 μm.

The linear ridges122are formed by one of several possible means for changing a thickness of the overmold106before the protective shield108is disposed on the overmold106. The linear ridges are not formed by merely changing a thickness T108of the protective shield108after it is disposed. That is, the 3D pattern110is determined by modifications to an exterior surface112of the overmold106. The 3D pattern110is formed in the exterior surface112of the overmold106before the protective shield108is applied.

After the overmold106has solidified, for example, the exterior surface112may be planarized, such as by chemical mechanical polishing (CMP) or any suitable method, such as milling, grinding, buffing, chemical etching, etc. In some examples, the 3D pattern110may be formed on the planarized exterior surface112by 3D printing additional overmold106. The linear ridges122shown inFIGS.1A and1Bmay then be cut or formed into the exterior surface112by sawing, etching, or other methods to form the 3D pattern110. Although the 3D pattern110in the example inFIG.1Bincludes only linear ridges122, the 3D pattern is not limited in this regard.

In some examples, in addition to the linear ridges122, the 3D pattern110may also include linear ridges (not shown) running in another direction (e.g., X-axis direction) not parallel to the linear ridges122. In other examples, the 3D pattern may include non-linear ridges with curving or arcing portions, which may include circular ridges (e.g., concentric rings).

The overmold106extends over a length L and a width W of the module100. In some examples, to alleviate a hot spot in a module100, the 3D pattern110may extend over only a portion of the overmold106, which may be less than twenty-five percent (25%) of an area defined by the length L and the width W. In examples where improved heat dissipation is needed for the entire module100, the 3D pattern110may extend over at least 75% of the area A of the protective shield108.

In some examples, a height H122of the ridges122may not be equal in among the ridges122. The height H122is a distance (e.g., in the Z-axis direction) between the ridge portion124and an adjacent one of the bottom portions130. In an example in which channels128are formed by cuts in the protective shield108, some channels128are deeper while all ridge portions124may be at a same distance from the substrate104, wherein a distance from the substrate104to the ridge portions124is based on a maximum acceptable module height. Alternatively, or additionally, some ridge portions may be higher while the distance D124is the same for all bottom portions130. In some examples, the channel is cut such that the distance D124is set to a height of the circuit components102, such that the overmold106has a minimal thickness at the bottom portions130. In examples comprising the protective shield108disposed on the overmold106, the protective shield108may be disposed directly on a circuit component102. In such examples, an absence of overmold between the circuit component102and the protective shield108improves heat dissipation.

In some examples, the channels128are not the entire length L of the module100. In some examples, the channels128may all be a same length, while in other examples the channels128may have different respective lengths, which may be determined by a method of forming the 3D pattern110or may be based on a shape of an area in which the 3D pattern110is formed.

In some examples not shown inFIG.1B, the module100may include circuit components102on both sides of the substrate104. In such examples, the protective shield108may extend over the circuit components102on both sides of the substrate104, and the 3D pattern110may be, with or without the protective shield108, on one side or both sides of the module100.

FIG.2is a flow chart of a method200of fabricating the module100inFIG.1. The method200includes coupling at least one circuit component102to a laminate104(block202) and forming an overmold106on the laminate104and the at least one circuit component102(block204). For example, forming the overmold106on the laminate104further includes disposing the overmold106on the at least one circuit component102and planarizing the overmold106. The method200further includes forming a 3D pattern110in the exterior surface112of the overmold106(block206). For example, forming the 3D pattern110in the exterior surface112of the overmold106may comprise at least one of chemical etching, milling, laser ablation, and 3D printing. Optionally, fabricating the module100may also include forming the protective shield108on the exterior surface112of the overmold106(block208), wherein an exterior surface113of the protective shield108includes the 3D pattern110. Forming the protective shield108may include sputtering a conductive material onto the exterior surface112of the overmold106.

FIG.3is a cross-sectional side view of another example of a module300, including a 3D pattern302formed in an overmold304and a protective shield306disposed on the 3D pattern302having increased surface area for a higher rate of heat dissipation from the module300. The protective shield306comprises a suitable thermally conductive material, such as a metal, which may also be electrically conductive. This illustration is provided merely to show that the 3D pattern302may include ridges308having side portions310that are not orthogonal to planarized portions312of the overmold304. Thus, the ridges308may be formed by methods other than those used to form the linear ridges122inFIG.1B. In another example not shown, the 3D pattern may comprise ridges having a curved profile, such as by chemical etching, for example. The purpose of the 3D pattern is to increase the surface area of the overmold by at least 5%, and in some examples by at least 50%, and is not limited herein to any particular shape or pattern. The 3D pattern may not be a repeating pattern and may be randomly or semi-randomly formed.

FIG.4is an illustration of a perspective view of a circuit board400, which includes a printed circuit board402and at least one module404corresponding to the module100inFIGS.1A-1C. The printed circuit board402may also include additional modules404. As shown inFIGS.1A-1C, the module404includes at least one circuit component102disposed on a laminate104, an overmold106disposed on the at least one circuit component102and the laminate104and may include a protective shield108disposed on an exterior surface112of the overmold106, where both the overmold106and the protective shield108include a 3D pattern110to increase area through which heat may be dissipated from the module100.

With reference toFIG.5, the concepts described above may be implemented in various types of user elements500, such as mobile terminals, smart watches, tablets, computers, navigation devices, access points, and like wireless communication devices that support wireless communications, such as cellular, wireless local area network (WLAN), Bluetooth, and near field communications. User elements500may include modules comprising the 3D pattern110ofFIG.1on an exterior surface. The user elements500will generally include a control system502, a baseband processor504, transmit circuitry506, receive circuitry508, antenna switching circuitry510, multiple antennas512, and user interface circuitry512. In a non-limiting example, the control system502can be a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), as an example. In this regard, the control system502can include at least a microprocessor(s), an embedded memory circuit(s), and a communication bus interface(s). The receive circuitry508receives radio frequency signals via the antennas512and through the antenna switching circuitry510from one or more base stations. A low noise amplifier and a filter of the receive circuitry508cooperate to amplify and remove broadband interference from the received signal for processing. Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams using analog-to-digital converter(s) (ADC).

The baseband processor504processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically comprises demodulation, decoding, and error correction operations, as will be discussed on greater detail below. The baseband processor504is generally implemented in one or more digital signal processors (DSPs) and application-specific integrated circuits (ASICs).

For transmission, the baseband processor504receives digitized data, which may represent voice, data, or control information, from the control system502, which it encodes for transmission. The encoded data is output to the transmit circuitry506, where a digital-to-analog converter(s) (DAC) converts the digitally encoded data into an analog signal and a modulator modulates the analog signal onto a carrier signal that is at a desired transmit frequency or frequencies. A power amplifier will amplify the modulated carrier signal to a level appropriate for transmission, and deliver the modulated carrier signal to the antennas40through the antenna switching circuitry510to the antennas512. The multiple antennas512and the replicated transmit and receive circuitries506,508may provide spatial diversity. Modulation and processing details will be understood by those skilled in the art.

Those skilled in the art will recognize improvements and modifications to the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.