Patent Description:
As electronic products are developed to be miniaturization, having high density and various functions, the number of components and the number of interconnections in the electronic products have gradually increased, and the physical sizes of the components and the interconnections have become increasingly smaller. Therefore, the system-in-package technology, which integrates electronic systems composed of various active and passive components into a common package, has become a significant trend in the future.

Many printed circuit boards have resonant circuits, and the resonant circuits are configured to form a bandpass filter. The resonant circuit is generally formed by connecting a capacitor and an inductor in parallel. In a high-density printed circuit board, the number of inductors and the number of capacitors are huge. How to integrate the huge numbers of the inductors and capacitors is an important factor affecting miniaturization of the product.

<CIT> discloses a method for manufacturing a board with a built-in electronic element, includes providing a support substrate including a support base and a metal foil, forming a protective film made of a metal material on the metal foil of the support substrate, forming a conductive pattern made of a metal material on the protective film by an additive method, placing an electronic element on the support substrate with the conductive pattern such that a surface of the electronic element where a circuit is formed faces the conductive pattern, covering the electronic element with an insulative resin, etching away the metal foil using a first etching solution such that the protective film is not dissolved by the first etching solution or that the protective film has an etching speed which is slower than an etching speed of the metal foil, and electrically connecting terminals of the electronic element and a part of the conductive pattern.

<CIT> discloses a built-in electronic component-mounted wiring board includes an electronic component having a connecting terminal and being mounted on a support; an insulating layer provided on the support so as to cover at least a portion of the electronic component; an opening provided in the insulating layer so as to expose the connecting terminal of the electronic component; and a connecting portion provided in the opening.

<CIT> discloses an electronic device which includes an electromagnetic shield, can keep down a pro- duction cost, can be made to have a reduced thickness, and has a high degree of freedom in designing a wiring circuit. Further, the present invention provides a method for producing such an electronic device. The electronic device (1A) includes at least one high frequency functional component (<NUM>), an electrically conductive member (<NUM>) which electromagnetically shields the at least one high frequency functional component (<NUM>), and a resin molded body (<NUM>) in which at least part of the high frequency functional component (<NUM>) and at least part of the electrically conductive member (<NUM>) are embedded and fixed.

<CIT> discloses an embedded printed circuit board, including: a first insulating substrate including a first cavity and a second cavity; a first element disposed in the first cavity; an adhesive layer for adhering the first insulating substrate to the first element and including an opening to which the first element is exposed; and an second insulating substrate forming a bonding layer of a lower surface of the first insulating substrate and a bottom surface of the second cavity.

According to a first aspect of the present disclosure, an embedded circuit board is provided and includes: a first outer wiring board, a base board, a second outer wiring board, and an electronic element. The first outer wiring board, the base board, and the second outer wiring board are stacked sequentially. The base board defines at least one groove between the first outer wiring board and the second outer wiring board. A through hole is defined in each of the first outer wiring board, the base board, and the second outer wiring board. The through hole in the first outer wiring board, the through hole in the base board, and the through hole in the second outer wiring board are communicated with each other to serve as a resonant chamber. A minimal distance between a side wall of the at least one groove and a side wall of the through hole adjacent to the at least one groove is in a range of <NUM> to <NUM>. The electronic element is received in the groove. The electronic element is at least one of a mini-microphone, a mini-loudspeaker, an acoustic wave resonator, a microwave resonator, an ultrasonic transducer, a sensor chip, and a digital chip. The resonant chamber includes two adjacent resonant chambers defined by a chamber wall in common. The chamber wall defines a coupling window, and the signals between the two adjacent resonant chambers are coupled through the coupling window. A resonant oscillator is received in each of the two adjacent resonant chambers, a coupling block is received in the coupling window of the chamber wall. An end face is arranged at each of two end portions of the coupling block, and the end face is parallel to a surface of the resonant oscillator; and an electromagnetic field is generated at an outer periphery of the end face of the coupling block, and a direction of the electromagnetic field is the same as a direction of the surface of the resonant oscillator.

According to a second aspect of the present disclosure, a method for manufacturing an embedded circuit board is provided and includes: providing a base board having at least one groove, wherein an electronic element is received in the at least one groove; disposing a first outer wiring board and a second outer wiring board on two opposite sides of the base board; compressing the first outer wiring board, the second outer wiring board, and the base board to fix the first outer wiring board, the second outer wiring board, and the base board; defining a hole in the first outer wiring board, the second outer wiring board, and the base board to obtain at least one through hole in the first outer wiring board, the second outer wiring board, and the base board. The at least one through hole serves as a resonant chamber, and a minimal distance between a side wall of the at least one groove and a side wall of the through hole adjacent to the at least one groove is in a range of <NUM> to <NUM>.

According to the present disclosure, a resonant chamber may be defined by defining a through hole in a first outer wiring board, a base board, and a second outer wiring board. Electronic elements are received in a groove of the base board. In this way, the number of surface elements of the entire printed circuit board may be reduced, such that a miniaturized circuit may be achieved. At the same time, a minimal distance between a side wall of the groove and a side wall of an adjacent though hole may be <NUM> to <NUM>. The resonant wave may be prevented from being transmitted to the electronic elements directly to cause the electronic elements to be loose and fall off, and therefore, the electronic elements received in the groove may not be harmed while defining the through hole.

In order to illustrate technical solutions of embodiments of the present disclosure clearly, accompanying drawings for describing the embodiments will be introduced in brief. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can be acquired based on the provided drawings without any creative work.

Technical solutions of the embodiments of the present disclosure may be clearly and comprehensively described by referring to accompanying figures of the embodiments. Obviously, embodiments to be described are only a part of, but not all of, the embodiments of the present disclosure. Any ordinary skilled person in the art may obtain other embodiments based on the embodiments of the present disclosure without any creative work, and the other embodiments should be included in the scope of the present disclosure.

As shown in <FIG>, the present example, not forming a part of the invention and provided only for better understanding, provides an embedded circuit board <NUM>. The embedded circuit board <NUM> may include: a first outer wiring board <NUM>, a base board <NUM>, and a second outer wiring board <NUM>, which are stacked sequentially.

The first outer wiring board <NUM> may be disposed on an upper surface of the base board <NUM>. The first outer wiring board <NUM> may be a copper layer on the upper surface of the base board <NUM>. The second outer wiring board <NUM> may be disposed on a lower surface of the base board <NUM>. The second outer wiring board <NUM> may be a copper layer on the lower surface of the base board <NUM>.

The base board <NUM> may define at least one though hole <NUM> and at least one groove <NUM>. The groove <NUM> may be defined by depth-control milling. The depth-control milling may refer to a technology of using a milling machine for controlling a depth along a Z direction, and the technology may be limited by accuracy of depth-control milling along the Z direction of the milling machine. A length and a width of the groove <NUM> may be greater than a length and a width of an embedded chip, such that a space of the groove <NUM> may be enough to receive the embedded chip. The groove <NUM> may be in a shape of a regular cube, may be trapezoid, or may be step-shaped. The shape of the groove <NUM> may be determined based on actual needs of a practical work, and will not be limited by the present disclosure. In order to provide intuitive description, the groove <NUM> is shown as cuboid in the present disclosure.

The at least one through hole <NUM> may further be defined in each of the first outer wiring board <NUM> and the second outer wiring board <NUM>. The through hole <NUM> in the first outer wiring board <NUM>, the through hole <NUM> in the base board <NUM>, and the through hole <NUM> in the second outer wiring board <NUM> may communicate with each other to serve as a resonant chamber <NUM>. In the present embodiment, the resonant chamber <NUM> may be squared. In other embodiments, the resonant chamber <NUM> may be L-shaped, circular, U-shaped, or S-shaped.

Further, the embedded circuit board <NUM> may further include an electronic element <NUM>. The electronic element <NUM> may be received in the groove <NUM> of the base board <NUM>. The number of grooves <NUM> may be equal to the number of electronic elements <NUM>. In this situation, one electronic element <NUM> may be received in one groove <NUM>. The number of grooves <NUM> may be different from the number of electronic elements <NUM>. In detail, the number of grooves <NUM> may be less than the number of electronic elements <NUM>. In this situation, two or more electronic elements <NUM> may be received in one groove <NUM>. The electronic element <NUM> may be a device working by physical vibration, such as at least one of, but not limited to: a mini-microphone, a mini-loudspeaker, an acoustic wave resonator, a microwave resonator, an ultrasonic transducer, a sensor chip, a digital chip. The electronic element <NUM> may be a tuning element. The tuning element may adjust a resonance frequency of a resonator corresponding to the resonant chamber <NUM>. The tuning element may be a capacitor and/or an inductor.

Further, a minimal distance between a side wall of the groove <NUM> and a side wall of the through hole <NUM> adjacent to the groove <NUM> may be <NUM> to <NUM>, such as <NUM>, <NUM>, <NUM>, or <NUM>. Preferably, the minimal distance between the side wall of the groove <NUM> and the side wall of the through hole <NUM> may be <NUM> to <NUM>, such as, <NUM>, <NUM>, <NUM>, or <NUM>.

An inner circumferential wall of the resonant chamber <NUM> may be an insulated inner circumferential wall. A function of the resonant chamber <NUM> may be different from that of a metallized through hole. The resonant chamber <NUM> may not be electrically conductive, but may conduct and amplify information such as sound wave vibration, an atmospheric pressure, temperature, and humidity, such that the information may be sensed by the electronic element <NUM> (such as a sensor chip) received in the groove <NUM>. In this way, the information may be converted into an electric signal and displayed in a product, such as a mobile device, a sensor assembly, and so on.

In another example, not forming a part of the invention and provided only for better understanding, as shown in <FIG>, a copper layer <NUM> may be disposed on the inner circumferential wall of the resonant chamber <NUM> to serve as an electrical connection layer.

According to the present embodiment, each of the first outer wiring board <NUM>, the base board <NUM>, and the second outer wiring board <NUM> may define the through hole <NUM>, and the through holes <NUM> may communicate with each other to serve as the resonant chamber <NUM>. The electronic element <NUM> may be received in the groove <NUM> of the base board <NUM>. In this way, the number of elements disposed on a surface of the entire circuit board <NUM> may be reduced, and miniaturization of the circuit board may be achieved. At the same time, the minimal distance between the side wall of the groove <NUM> and the side wall of the through hole <NUM> adjacent to the groove <NUM> may be <NUM> to <NUM>, such that the resonant wave may be prevented from transmitting to the electronic element <NUM> directly, the electronic element <NUM> may be protected from being loose and falling off, and the electronic element <NUM> received in the groove <NUM> may be protected from being harmed while defining the through hole <NUM>. At the same time, a plurality of electronic elements may be received into one same resonant chamber. The circuit board may be highly waterproof and may have a relatively low manufacturing cost.

As shown in <FIG>, two adjacent resonant chambers 110A and 110B may be defined by a chamber wall <NUM> in common. The chamber wall <NUM> may define a coupling window <NUM>. The coupling window <NUM> may be defined to allow signals of the two adjacent resonant chamber 110A and 110B to be coupled. The coupling window <NUM> may be a general inductive coupling structure, or a capacitive coupling structure having a protrusion on a top of the window and a protrusion on a bottom of the window.

In the present embodiment, two adjacent resonant chambers 110A and 110B may be shown for illustration. The two resonant chambers 110A and 110B may be spaced apart from each other by the chamber wall <NUM>. Further, the coupling window <NUM> of the chamber wall <NUM> may extend from a top of the chamber wall <NUM> to a bottom of the chamber wall <NUM>. In this way, a coupling strength may be maximized.

Further, a resonant oscillator (not shown in the figures) may be received in each of the two resonant chambers 110A and 110B, and a coupling block (not shown in the figures) in a certain shape may be received in the coupling window <NUM> of the chamber wall <NUM>. An end face may be arranged at each of two end portions of the coupling block respectively, and the end face may be parallel to a surface of the resonant oscillator. In this way, an electromagnetic field may be generated at a periphery of the end face of the coupling block, and a direction of the electromagnetic field may be the same as a direction of the surface of the resonant oscillator. When the resonant oscillator and the coupling block are close enough, the coupling block may generate sufficient perturbation to the electromagnetic field at an outer side of the surface of the resonant oscillator, such that a coupling effect between the two adjacent resonant chambers 110A and 110B may be improved.

As shown in <FIG>, the base board <NUM> may include a plurality of meltable dielectric layers <NUM> and a plurality of sub-boards <NUM>. The plurality of meltable dielectric layers <NUM> and the plurality of sub-boards <NUM> may be stacked alternately. At least one of the plurality of sub-boards <NUM> may define the groove <NUM>. After the plurality of sub-boards <NUM> and the plurality of meltable dielectric layers <NUM> are compressed, at least a portion of the plurality of meltable dielectric layers <NUM> may flow to a space between the electronic element <NUM> and the side wall of the groove <NUM>.

In detail, each of the plurality of sub-boards <NUM> may be a non-copper core board or a copper clad laminate. Configuring each of the plurality of sub-boards <NUM> to be the non-copper core board is to increase a thickness of the embedded circuit board <NUM>, such that the thickness of the embedded circuit board may be adapted to allow the electronic element <NUM> to be embedded therein. Each of the plurality of sub-boards <NUM> may be the copper clad laminate, and wires may be configured on the copper clad laminate for electrical connection.

Each of the plurality of meltable dielectric layers <NUM> may be disposed between two adjacent ones of the plurality of sub-boards <NUM>. While compressing, at least a portion of the plurality of meltable dielectric layers <NUM> may flow into the space between the electronic element <NUM> and the side wall of the groove <NUM>, and may contact the electronic element <NUM>. In this way, the plurality of sub-boards <NUM> and the electronic element <NUM> may be bonded together.

Material of the plurality of meltable dielectric layers <NUM> may be at least one or a combination of resin and silicone resin glue. In detail, the resin may refer to an organic polymer, which has a softening or melting range after being heated, and tends to flow under an external force during softening. The resin may be solid, semi-solid, and sometimes, liquid at a room temperature. The resin may be an adhesive, such as epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, acrylic resin and so on. The silicone resin glue is a colorless and transparent liquid. The silicone resin glue has certain air permeability and elasticity after curing. The silicone resin glue may have temperature resistance, weather resistance, electrical insulation, physiological inertia, low surface tension and a low surface energy.

Further, as shown in <FIG>, the groove <NUM> may be defined in each of the plurality of sub-boards <NUM> and each of the plurality of meltable dielectric layers <NUM> disposed between adjacent sub-boards <NUM>. That is, the groove <NUM> may be defined to extend through each of the plurality of sub-boards <NUM> and each of the plurality of meltable dielectric layers <NUM> disposed between adjacent sub-boards <NUM>.

Further, as shown in <FIG>, a package <NUM> may be coated on an outer surface of the electronic element <NUM>. After the plurality of sub-boards <NUM> and the plurality of meltable dielectric layers <NUM> are compressed, at least a portion of the plurality of meltable dielectric layers <NUM> may flow to a space between the package <NUM> and the side wall of the groove <NUM>, and may contact the package <NUM>.

Material of the package <NUM> may be the silicone resin glue. The silicone resin glue may be the colorless and transparent liquid, and may have certain air permeability and elasticity after curing. The silicone resin glue may have temperature resistance, weather resistance, electrical insulation, physiological inertia, low surface tension and the low surface energy.

According to the above embodiment, the package <NUM> made of the silicone resin glue may be coated on the outer surface of the electronic element <NUM>. The silicone resin glue may have better performance on transferring heat, conducting heat and dissipating heat. Therefore, the package <NUM> may be resistant to a high temperature have an excellent heat dissipation capability. While the electronic element <NUM> is working, a temperature of the electronic element <NUM> may be increased, and the package <NUM> may dissipate the heat rapidly. At the same time, the package <NUM> made of the silicone resin glue may stably bond with the side walls of the electronic device <NUM> and the groove <NUM>. Therefore, the problem of the electronic element <NUM> falling off and expanding may be solved effectively.

Further, a metal sheet (not shown in the figure) may be disposed inside the package <NUM>. The metal sheet may be configured in the silicone resin glue of the package, an end of the metal sheet may be electrically connected to the electronic element <NUM>, and the other end of the metal sheet may protrude out of the package <NUM> and may be electrically connected to a ground line layer, a signal line layer, or a conductive element <NUM>. The metal sheet may be made of metal only. Material of the metal sheet may include, but is not limited to, copper, copper alloy, aluminum, aluminum alloy, iron, iron alloy, nickel, nickel alloy, gold, gold alloy, silver, silver alloy, platinum group, platinum group alloy, chromium, chromium alloy, magnesium, magnesium alloy, tungsten, tungsten alloy , Molybdenum, molybdenum alloy, lead, lead alloy, tin, tin alloy, indium, indium alloy, zinc, zinc alloy, and so on. In another embodiment, the metal sheet may be made of a metal base block and a conductive graphite sheet. Since thermal resistance of the conductive graphite sheet is lower than that of an ordinary metal and alloy, the conductive graphite sheet can be embedded in the metal base block to make heat conduction faster.

As shown in <FIG>, the conductive element <NUM> may be configured in the base board <NUM> to allow a plurality of layers to be connected. A connection end of the electronic element <NUM> may be electrically connected to the first outer wiring board and/or the second outer wiring board through the conductive via <NUM>.

In detail, a hole may be defined in the base board <NUM>. In the present embodiment, the hole may extend through each of the plurality of sub-boards <NUM> and each of the plurality of meltable dielectric layers <NUM>. A signal layer electrically connected to the sub-boards <NUM> and/or a conductive layer connected to the ground layer may be received in the hole. In this way, the conductive element <NUM> may be obtained. In the present embodiment, the hole may be metallized by electroplating. In detail, in a salt solution containing the metal to be electroplated, the metal of a wall of the hole may be used as a cathode, and cations of the metal to be electroplated in the electroplating solution may be deposited on the metal of the wall of the hole through electrolysis. In this way, a conductive layer may be formed. Metals commonly used for electroplating may include, but are not limited to, titanium, palladium, zinc, cadmium, gold, and brass. Of course, in other embodiments, the metallization of the hole may also be achieved by coating.

Alternatively, one or more components (not shown in the figures) may be configured on a side of the first outer wiring board or a side of the second outer wiring board away from the base board <NUM>. Alternatively, a plurality of components may be configured on the side of the first outer wiring board away from the base board <NUM>, and a plurality of components may be configured on the side of the second outer wiring board away from the base board <NUM>. The plurality of components may be electrically connected to the electronic element <NUM> via the first outer wiring board and/or the second outer wiring board. The components may be one or more of: a microphone chip, a capacitor chip, a resistor chip, a power source component.

According to the present disclosure, electronic elements, such as a digital chip and the like, may be embedded in the base board, whereas components, such as the microphone chip and the like, may still be disposed to the surface of the circuit board and above the through hole <NUM>. In this way, the overall thickness and size of the embedded circuit board <NUM> may be reduced. At the same time, as the electronic elements, such as the digital chip and the like, are disposed inside the base board and completely covered by the base board, the resonant chamber may not affect the digital chip. A better shielding effect may be achieved, external interference, such as noise, received by the electronic elements may be reduced, and performance of the electronic elements may be improved.

The embedded circuit board <NUM> according to the embodiment of the present disclosure may be applied in a mobile device or a sensor assembly.

As shown in <FIG>, a method for manufacturing the embedded circuit board is provided includes following operations.

In an operation S10, a base board having at least one groove may be provided, and an electronic element may be received in the groove.

In other embodiments, the groove and at least one through hole may be defined in the base board firstly, and the electronic element may be received in the groove correspondingly.

In an operation S20, a first outer wiring board and a second outer wiring board may be disposed on two opposite sides of the base board respectively.

In an operation S30, the first outer wiring board, the base board, and the second outer wiring board may be compressed to be fixed.

In an operation S40, a through hole may be defined in each of the first outer wiring board, the base board, and the second outer wiring board, such that the hole may extend through the first outer wiring board, the base board, and the second outer wiring board to serve as the resonant chamber.

In other embodiments, the through hole may be defined in the first outer wiring board, the base board, and the second outer wiring board first, and subsequently, the first outer wiring board, the base board, and the second outer wiring board may be stacked and compressed.

A minimal distance between a side wall of the groove and a side wall of the through hole adjacent to the groove may be <NUM> to <NUM>.

According to the present embodiment, the through hole may be defined in the first outer wiring board, the base board, and the second outer wiring board to serve as the resonant chamber, and the electronic elements may be received in the groove of the base board. In this way, the number of elements disposed on the surface of the entire circuit board may be reduced, and miniaturization of the circuit may be achieved. At the same time, the minimal distance between the side wall of the groove and the side wall of adjacent communicating through holes may be <NUM> to <NUM>. The resonant wave may not be transmitted to the electronic element directly, such that the electronic element may be protected from being loose and falling off, and the electronic element may be protected from being harmed while defining the through hole. Further, a plurality of electronic elements may be embedded into the circuit board, and the plurality of electronic elements may be received in a resonant chamber in common. The circuit board may be highly waterproof and may have a relatively low manufacturing cost.

The present disclosure further provides a mobile terminal including the embedded circuit board <NUM> as mentioned in the above embodiments.

Claim 1:
An embedded circuit board (<NUM>), characterized by comprising:
a first outer wiring board (<NUM>), a base board (<NUM>), and a second outer wiring board (<NUM>), stacking sequentially, wherein
the base board (<NUM>) defines at least one groove (<NUM>) between the first outer wiring board (<NUM>) and the second outer wiring board (<NUM>); a through hole (<NUM>) is defined in each of the first outer wiring board (<NUM>), the base board (<NUM>), and the second outer wiring board (<NUM>), the through hole (<NUM>) in the first outer wiring board (<NUM>), the through hole (<NUM>) in the base board (<NUM>), and the through hole (<NUM>) in the second outer wiring board (<NUM>) are communicated with each other to serve as a resonant chamber (<NUM>); and
a minimal distance between a side wall of the at least one groove (<NUM>) and a side wall of the through hole (<NUM>) adjacent to the at least one groove (<NUM>) is in a range of <NUM> to <NUM>; and
an electronic element (<NUM>), received in the groove (<NUM>), wherein the electronic element (<NUM>) is at least one of a mini-microphone, a mini-loudspeaker, an acoustic wave resonator, a microwave resonator, an ultrasonic transducer, a sensor chip, and a digital chip;
wherein the resonant chamber (<NUM>) comprises two adjacent resonant chambers (110A, 110B) defined by a chamber wall (<NUM>) in common;
the chamber wall (<NUM>) defines a coupling window (<NUM>), and the signals between the two adjacent resonant chambers (110A, 110B) are coupled through the coupling window (<NUM>); and
a resonant oscillator is received in each of the two adjacent resonant chambers (110A, 110B), a coupling block is received in the coupling window (<NUM>) of the chamber wall (<NUM>);
an end face is arranged at each of two end portions of the coupling block, and the end face is parallel to a surface of the resonant oscillator; and
an electromagnetic field is generated at an outer periphery of the end face of the coupling block, and a direction of the electromagnetic field is the same as a direction of the surface of the resonant oscillator.