Notch design and rocker fixing device for plate stacking

Abstract

A stacked circuit board structure, assembly method, and alignment fixing device are described. In one embodiment, the stacked circuit board structure includes a bottom circuit board and a top circuit board having alignment notches and alignment holes. Alignment of these stacked circuit boards can be achieved using an alignment fixing device including rocker pins that mate with the alignment notches and alignment holes.

Description

Background Technology Technical Field

[0001] The implementation schemes described herein relate to electronic packaging, and more specifically to printed circuit board assemblies.

[0002] Background Information

[0003] Main logic boards (MLBs) are common components in almost all consumer electronics products. With the trend towards smaller products, there is a drive to integrate smaller and thinner dies, packages, and components. There is also a competitive drive to integrate higher density components, resulting in limitations on area, height, or shape. Current MLB assembly may include a stacking process for combining one or more boards and inserters. This is typically accomplished by forming alignment holes through the thickness of one or more boards and inserters, and aligning the alignment holes with corresponding alignment pins of alignment retainers. This may be followed by thermal processes, such as reflowing solder joints to electrically and physically connect the stacked structures. Summary of the Invention

[0004] Various embodiments describe stacked circuit board structures, assembly methods, and alignment and fixing devices for assembling stacked circuit board structures. In one embodiment, the alignment and fixing device includes a support substrate, a first rocker pin in the support substrate, and a second rocker pin in the support substrate. Both the first and second rocker pins may be laterally tilted. The first rocker pin may include a first bump projecting from the back side of the support substrate and a first alignment pin projecting from the top side of the support substrate. Similarly, the second rocker pin may include a second bump projecting from the back side of the support substrate and a second alignment pin projecting from the top side of the support substrate.

[0005] In one embodiment, the method of stacking circuit boards includes placing a bottom circuit board on an alignment fixing device, the alignment fixing device having a first rocker pin extending through a bottom alignment hole of the bottom circuit board and a second rocker pin adjacent to a bottom alignment recess of the bottom circuit board. A top circuit board is then placed on top of the bottom circuit board such that the first rocker pin extends through a top alignment hole of the top circuit board and the second rocker pin is adjacent to a top alignment recess of the top circuit board. Forces can then be applied to the first and second rocker pins to align the top alignment hole with the bottom alignment hole and to align the top alignment recess with the bottom alignment recess.

[0006] In one embodiment, the resulting stacked circuit board structure includes: a bottom circuit board including a bottom alignment notch and a bottom alignment hole; and a top circuit board above the bottom circuit board including a top alignment notch aligned with the bottom alignment notch and a top alignment hole aligned with the bottom alignment hole. Attached Figure Description

[0007] Figure 1 This is an exploded isometric view of a stacked circuit board structure according to one implementation scheme.

[0008] Figure 2 This is a top plan view illustration of an inserter aligned with a bottom circuit board according to one embodiment.

[0009] Figure 3 This is a close-up top plan view of the aligned notch according to one implementation scheme.

[0010] Figure 4 This is a schematic cross-sectional side view of a stacked circuit board structure on an alignment fixing device prior to alignment with a rocker pin, according to one embodiment.

[0011] Figure 5 This is a schematic cross-sectional side view of a stacked circuit board on an alignment fixing device after alignment with a rocker pin, according to one embodiment. Detailed Implementation

[0012] Various embodiments describe stacked circuit board structures, assembly methods, and alignment and fixing devices for assembling stacked circuit board structures. According to one embodiment, the stacked structure may include: a bottom circuit board including a bottom alignment notch and a bottom alignment hole; and a top circuit board above the bottom circuit board including a second notch aligned with the bottom notch and a top alignment hole aligned with the bottom alignment hole. The circuit boards can be aligned by applying force to a rocker pin within the alignment fixing device that engages with the alignment notch and alignment hole.

[0013] In one aspect, it has been observed that conventional circuit board stacking and alignment are achieved by forming at least two alignment holes within the circuit board, which reduces the available area for component placement and electrical wiring. According to various embodiments, alignment notches are formed along the edges of the stacked boards (e.g., printed circuit boards, inserters, etc.) to replace one or more alignment holes. Alignment retainers including rocker pins can be used in assembly, where the rocker pins engage with the notches for precise self-alignment, which can additionally provide reduced pad-to-pad spacing tolerances for the landing pads between stacked boards and a reduced risk of misalignment-related failures such as solder bridging.

[0014] Various embodiments are described with reference to the accompanying drawings. However, certain embodiments may be practiced without one or more of these specific details or in combination with other known methods and constructions. In the following description, numerous specific details such as particular configurations, dimensions, and processes are shown to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques have not been described in particular detail so as not to unnecessarily obscure the embodiments. The phrase "an embodiment" as used throughout the specification means that a particular feature, structure, construction, or characteristic described in connection with an embodiment is included in at least one embodiment. Therefore, the repeated use of the phrase "in an embodiment" throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, construction, or characteristic may be combined in any suitable manner in one or more embodiments.

[0015] As used herein, the terms “above,” “to,” “between,” and “on” can refer to the relative position of a layer with respect to other layers. A layer “above” or “on” another layer, or bonded “to” or “in contact” with another layer, can be in direct contact with other layers or may have one or more interlayers. A layer “between” multiple layers can be in direct contact with those multiple layers or may have one or more interlayers.

[0016] See now Figure 1 An exploded isometric view of a stacked circuit board structure 100 according to one embodiment is provided. Figure 2 This is a top plan view illustration of an inserter aligned with a bottom circuit board according to one embodiment. Figure 3 This is a close-up top plan view of the aligned notch according to one embodiment. For clarity and simplicity, the following discussion is also included. Figures 1 to 3

[0017] As shown in the figure, the stacked circuit board structure 100 may include: a bottom circuit board 102, which includes a bottom alignment notch 104 and a bottom alignment hole 106; and a top circuit board 108 above the bottom circuit board 102. The top circuit board 108 may additionally include a top alignment notch 110 aligned with the bottom alignment notch 104 and a top alignment hole 112 aligned with the bottom alignment hole 106. The top alignment notch 110 may be positioned along an edge 114 of the top circuit board 108 laterally opposite to the top alignment hole 112, but this is not required. Other boards may be arranged in a similar manner.

[0018] According to various embodiments, alignment notches can replace the various alignment holes present in a conventional stacked circuit board arrangement. Fine alignment can be achieved using alignment notches, but each board may include at least one alignment hole for coarse alignment with alignment fixtures.

[0019] According to various embodiments, inserter 116 is coupled to bottom circuit board 102, and top circuit board 108 is coupled to inserter 116. Similarly, inserter may include a central alignment notch 118 and a central alignment hole 120. When aligned and coupled, top alignment notch 110 is additionally aligned with central alignment notch 118 and bottom alignment notch 104, and top alignment hole 112 is aligned with central alignment hole 120 and bottom alignment hole. In some embodiments, top alignment notch 110, central alignment notch 118, and bottom alignment notch 104 are all characterized by the same radius (or other shape), and their side surfaces (S) (see...) Figure 3 Align vertically. Similarly, the side surfaces of the alignment holes can be aligned vertically.

[0020] According to various embodiments, the inserter 116 can be coupled to the bottom circuit board 102 using suitable electrical connections (such as multiple solder points). Similarly, the top circuit board can be coupled to the inserter 116 (or directly to the bottom circuit board) using multiple solder points. The self-aligned assembly methods according to various embodiments facilitate fine alignment and, as in... Figure 2 The fine bonding pads 122 are shown with a spacing (P). For example, the top side of the inserter 116 may have a bonding pad arrangement with a minimum spacing (P) of less than 180 micrometers, such as less than 150 micrometers or less than 125 micrometers. The bottom side of the top board 108 may have a similar bonding pad layout, wherein the bonding pads are combined with solder joints, and the solder can be reflowed after fine alignment. The bottom board and the inserter may similarly utilize a similar bonding pad layout and solder joint bonding.

[0021] The alignment notch can take various shapes depending on the implementation, including being characterized by a radius (e.g., semicircular, but with an arc angle of 180 degrees or less), ellipse, rectangle, U-shape, etc. In one particular implementation, the notch is characterized by a radius. For effective engagement with a rocker pin (which may be cylindrical), the notch can be characterized by an arc angle (θ) of at least 90 degrees. Figures 2 to 3 As shown, the alignment notch can extend a lateral depth (D) into the corresponding circuit board. In some embodiments, the lateral depth can be at least 25% of the radius to effectively mate with the rocker pin. Furthermore, the center point (C1) of the radius of the alignment notch, the point of the maximum depth (d) of the alignment notch, and the center point (C2) of the alignment hole within the corresponding hole can be linearly aligned, such as... Figure 2 As shown by the dashed line in the diagram. This orientation allows for active engagement with the rocker pin and reduces slippage.

[0022] The bottom circuit board 102, according to various embodiments, can be rigid or flexible and can be formed from a variety of suitable printed circuit board (PCB) materials, including FR4, prepreg, polyimide, etc. The electronic components 124 mounted thereon, according to various embodiments, can range from system-on-a-chip (SoC) dies to memory dies, passive components (resistors, capacitors, inductors, etc.), microelectromechanical systems (MEMS), sensors, etc. Various configurations of different electronic components should be understood.

[0023] The top circuit board 108 is also illustrated as including a plurality of electronic components 124 mounted on its top side. Additional electronic components 124 may also optionally be mounted on the bottom side of the top circuit board 108 and facing the bottom circuit board. Similar to the bottom circuit board 102, the top circuit board 108 may be rigid or flexible and is formed of the same material described with respect to the bottom circuit board 102. Similarly, the electronic components 124 may be selected from the same electronic components according to various embodiments and may range from system-on-a-chip (SoC) dies to memory dies, passive components (resistors, capacitors, inductors, etc.), microelectromechanical systems (MEMS), sensors, etc. In a particular embodiment, the top circuit board 108 is a rigid wireless access point (AP) board, while the bottom circuit board 102 is a rigid or flexible radio frequency (RF) board.

[0024] For example, insert 116 may optionally be formed of a material similar to a circuit board, such as FR4 (resin-impregnated braided glass fiber). Therefore, insert 116 can also be considered a wiring substrate or board. Insert 116 can be used to provide electrical wiring between a top circuit board and a bottom circuit board, and / or insert 116 can perform primary mechanical functions. Even when performing primary mechanical functions (such as spacers or thermal matching), insert 116 may be formed of a typical wiring substrate material such as an FR4 board. Insert 116 may also be formed of alternative materials including silicon, organic materials (such as polyimide), etc.

[0025] Now for reference Figures 4 to 5 , Figure 4 This is a schematic cross-sectional side view of a stacked circuit board structure on an alignment fixing device prior to alignment with a rocker pin, according to one embodiment. Figure 5This is a schematic cross-sectional side view of a stacked circuit board on an alignment retainer after alignment with a rocker pin, according to one embodiment. As shown, the alignment retainer 126 may include a support substrate 128, a first rocker pin 130 in the support substrate 128, the first rocker pin 130 including a first bump 132 projecting from a back side 134 of the support substrate 128 and a first alignment pin 136 projecting from a top side 138 of the support substrate 128. The first rocker pin 130 is laterally tiltable within the support substrate 128. A top flange 140 of the first rocker pin 130 may rest within an upper cavity 142 in the support substrate, wherein the body portion of the first rocker pin 130 and the protruding first bump 132 extend from a through-hole 144, which is smaller in size (diameter) than the upper cavity 142. The through-hole 144 may have a width (diameter) slightly larger than the body of the first rocker pin 130 to allow tilting movement of the first rocker pin.

[0026] The alignment and fixing device 126 may additionally include a second rocker pin 150 arranged in the support substrate 128 similarly to the first rocker pin, wherein a second protrusion 152 protrudes from the back side 134 of the support substrate 128 and a second alignment pin 156 protrudes from the top side 138 of the support substrate 128. The second rocker pin 150 is capable of laterally tilting within the support substrate 128. The top flange 160 of the second rocker pin 150 may rest within an upper cavity 162 in the support substrate, wherein the body portion of the second rocker pin 150 and the protruding second protrusion 152 extend from a through-hole 164, which is smaller in size (diameter) than the upper cavity 162. The through-hole 164 may have a width (diameter) slightly larger than the body of the second rocker pin 150 to allow tilting movement of the second rocker pin. It should be understood that although two rocker pins are illustrated, more rocker pins may be included.

[0027] The alignment fixing device 126 may further include a pressure plate 170 adjacent to the back side 134 of the support substrate 128, wherein the pressure plate 170 is vertically movable toward the back side 134 of the support substrate 128 to engage the first protrusion 132 and the second protrusion 152, and to tilt the first protrusion 132 and the second protrusion 152 away from each other and to tilt the first alignment pin 136 and the second alignment pin 136 toward each other. The first alignment pin 136 and the second alignment pin 156 may have a shape that mates with alignment notches in the plates. For example, the two alignment pins may be cylindrical to mate with alignment notches characterized by radius. As shown, the pressure plate 170 may have a tapered side surface 172 that slides along the rounded protrusion of the rocker pin to tilt the corresponding alignment pin of the rocker pin toward the stacked plate arrangement.

[0028] The alignment and fixing device 126, according to various embodiments, can be used to stack and bond multiple boards simultaneously or sequentially. For example, in some embodiments, the alignment and fixing device 126 may first be used to stack inserters 116 onto a bottom board 102, followed by solder reflow to bond the inserters 116 to the bottom board 102. The reflow operation may be performed within the alignment and fixing device 126 or elsewhere. The stacked inserters 116 and bottom board 102 may then be reintroduced into the alignment and fixing device 126, followed by placement of the top board 108, alignment, and reflow. In some embodiments, inserters are not used, or multiple side-by-side local inserters may be utilized.

[0029] In one embodiment, the method of stacking circuit boards includes placing a bottom circuit board 102 on an alignment fixing device 126, wherein a first rocker pin 130 of the alignment fixing device extends through a bottom alignment hole 106 of the bottom circuit board 102, and a second rocker pin 150 is adjacent to a bottom alignment recess 104 of the bottom circuit board 102. A top circuit board 108 is then placed over the bottom circuit board 102 such that the first rocker pin 130 extends through a top alignment hole 112 of the top circuit board 108, and the second rocker pin 150 is adjacent to a top alignment recess 110 of the top circuit board 108. Force can then be applied to the first rocker pin 130 and the second rocker pin 150 to align the top alignment hole 112 with the bottom alignment hole 106 and to align the top alignment recess 110 with the bottom alignment recess 104. In some embodiments, an inserter 116 is already attached to the bottom circuit board 102, and placing the top circuit board 108 over the bottom circuit board 102 includes placing the top circuit board 108 on the inserter 116. According to various embodiments, the force applied to the rocker pin is transmitted as a compressive force to the stacked plates, causing the plates to shift and align with various alignment notches and alignment holes. (See also: Regarding...) Figure 2 The alignment notch center point C1, the alignment notch maximum lateral depth D point, and the alignment hole center point C2 are linearly arranged. After alignment, in one embodiment, multiple solder bumps are reflowed to bond the top circuit board 102 to the inserter 116.

[0030] It should be understood that while the above description and illustrations are for a single alignment hole and a single alignment notch configuration, embodiments are not limited thereto. For example, similar alignment can be achieved using two laterally opposed alignment notches. Furthermore, additional alignment notches may be included.

[0031] When utilizing the various aspects of the embodiments, it will be apparent to those skilled in the art that combinations or variations of the above embodiments are possible for forming stacked circuit board structures. Although the embodiments have been described in language specific to structural features and / or methodological behavior, it should be understood that the appended claims are not necessarily limited to the specific features or behaviors described. Rather, the specific features and behaviors disclosed should be understood as embodiments used for illustrative purposes.

Claims

1. A stacked circuit board structure, the stacked circuit board structure comprising: A bottom circuit board, the bottom circuit board including a bottom alignment notch and a bottom alignment hole; and A top circuit board above the bottom circuit board, the top circuit board including a top alignment notch aligned with the bottom alignment notch and a top alignment hole aligned with the bottom alignment hole.

2. The stacked circuit board structure of claim 1, wherein the top alignment notch is located in the edge of the top circuit board that is laterally opposite to the top alignment hole.

3. The stacked circuit board structure of claim 1, wherein the top alignment notch is characterized by a radius.

4. The stacked circuit board structure of claim 3, wherein the top alignment notch is characterized by an arc of at least 90 degrees.

5. The stacked circuit board structure of claim 3, wherein the top alignment notch extends into the top circuit board with a lateral depth, wherein the lateral depth is at least 25% of the radius.

6. The stacked circuit board structure of claim 5, wherein the center point of the radius of the top alignment notch, the point of the maximum lateral depth of the top alignment notch, and the center point of the top alignment hole are linearly aligned.

7. The stacked circuit board structure of claim 1, further comprising an inserter coupled to the bottom circuit board, the inserter including a central alignment notch and a central alignment hole, wherein the top circuit board is coupled to the inserter, the top alignment notch is aligned with the central alignment notch, and the top alignment hole is aligned with the central alignment hole.

8. The stacked circuit board structure of claim 7, wherein the top alignment notch, the middle alignment notch, and the bottom alignment notch are all characterized by the same radius, and the side surfaces of the top alignment notch, the middle alignment notch, and the bottom alignment notch are vertically aligned.

9. The stacked circuit board structure of claim 7, wherein the top circuit board is bonded to the inserter using a plurality of solder joints.

10. The stacked circuit board of claim 9, wherein the plurality of solder joints are coupled to a plurality of bonding pads of the inserter, the plurality of bonding pads having a minimum spacing of less than 180 micrometers.

11. The stacked circuit boards of claim 1, wherein the top circuit board does not include additional alignment holes.

12. A method for stacking circuit boards, the method comprising: The bottom circuit board is placed on the alignment fixing device, wherein the first rocker pin of the alignment fixing device extends through the bottom alignment hole of the bottom circuit board, and the second rocker pin is adjacent to the bottom alignment notch of the bottom circuit board. The top circuit board is placed above the bottom circuit board such that the first rocker pin extends through the top alignment hole of the top circuit board, and the second rocker pin is adjacent to the top alignment notch of the top circuit board; as well as Force is applied to the first rocker pin and the second rocker pin to align the top alignment hole with the bottom alignment hole and to align the top alignment notch with the bottom alignment notch.

13. The method of claim 12, further comprising an inserter coupled to the bottom circuit board, wherein placing the top circuit board above the bottom circuit board includes placing the top circuit board on the inserter.

14. The method of claim 13, further comprising, after applying the force to the first rocker pin and the second rocker pin, reflowing a plurality of solder bumps to bond the top circuit board to the inserter.

15. The method of claim 12, wherein both the first rocker pin and the second rocker pin transmit compressive force to the top circuit board and the bottom circuit board.

16. The method of claim 15, wherein the center point of the radius of the top alignment notch, the point of the maximum lateral depth of the top alignment notch, and the center point of the top alignment hole are linearly aligned.

17. An alignment and fixing device, the alignment and fixing device comprising: Support substrate; The first rocker pin in the support substrate includes a first protrusion protruding from the back side of the support substrate and a first alignment pin protruding from the top side of the support substrate, and the first rocker pin is capable of tilting laterally. and The second rocker pin in the support substrate includes a second protrusion protruding from the back side of the support substrate and a second alignment pin protruding from the top side of the support substrate, and the second rocker pin is capable of tilting laterally.

18. The alignment and fixing device according to claim 17, further comprising a pressure plate adjacent to the back side of the support substrate, wherein the pressure plate is vertically movable toward the back side of the support substrate.

19. The alignment and fixing device of claim 18, wherein the pressure plate is vertically movable toward the back side of the support substrate to engage the first protrusion and the second protrusion, and tilts the first protrusion and the second protrusion away from each other and tilts the first alignment pin and the second alignment pin toward each other.

20. The alignment fixing device according to claim 19, wherein both the first alignment pin and the second alignment pin are cylindrical.

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