Two-card assembly and how to assemble the two-card assembly

Abstract

To provide a conductive thermal management architecture for electronic modules in a two-card assembly.SOLUTION: A two-card assembly includes a first printed wiring board (PWB) on a first side of the two-card assembly, and a first stiffener secured to the first PWB. The two-card assembly also includes a second PWB on a second side of the two-card assembly, and a second stiffener secured to the second PWB. A center stiffener is disposed between the first stiffener and the second stiffener, and one or more electronic modules are secured to the center stiffener. The center stiffener dissipates heat from the one or more electronic modules.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] Exemplary embodiments relate to the technology of electronic modules, and more particularly, to a thermal transfer management architecture for electronic modules in a two-card assembly. [Background technology]

[0002] In widespread use, electronic components are packaged as electronic modules. The electronic modules are supported by and interconnected with a printed wiring board (PWB). For example, a two-card assembly refers to two PWBs stacked with an electronic module between them. Typically, electronic components mounted directly on the PWB dissipate heat through the PWB. The electronic module dissipates heat from the side opposite the side in contact with the PWB. Summary of the Invention [Problem to be solved by the invention]

[0003] Accordingly, the present invention provides a two-card assembly having an improved heat transfer management architecture, and a method for assembling the same. [Means for solving the problem]

[0004] In one embodiment, a two-card assembly includes a first printed wiring board (PWB) on a first side of the two-card assembly, a first stiffener secured to the first PWB, and a second PWB on a second side of the two-card assembly. The two-card assembly also includes a second stiffener secured to the second PWB, and a central stiffener disposed between the first stiffener and the second stiffener. One or more electronic modules are secured to the central stiffener. The central stiffener dissipates heat from the one or more electronic modules.

[0005] Additionally or alternatively, in this or other embodiments, the wedge lock secures the central stiffener between the first stiffener and the second stiffener based on a compressive force.

[0006] Additionally or alternatively, in this or other embodiments, a first wedgelock mounting rail supports a first set of wedgelocks and a second wedgelock mounting rail supports a second set of wedgelocks.

[0007] Additionally or alternatively, in this or other embodiments, the second stiffener and a first end of the central stiffener form a first wedgelock mounting rail, and the second stiffener and a second end of the central stiffener form a second wedgelock mounting rail.

[0008] Additionally or alternatively, in this or other embodiments, the second stiffener includes a slot in which the central stiffener is disposed.

[0009] Additionally or alternatively, in this or other embodiments, a first stiffener is coupled to the first PWB and a second stiffener is coupled to the second PWB.

[0010] Additionally or alternatively, in this or other embodiments, the material of the first stiffener, the second stiffener, and the central stiffener is an aluminum alloy.

[0011] Additionally or alternatively, in this or other embodiments, the first one or more electronic modules are secured to a first side of the central stiffener and the second one or more electronic modules are secured to a second side of the central stiffener.

[0012] Additionally or alternatively, in this or other embodiments, the first one or more electronic modules are also secured to the first PWB.

[0013] Additionally or alternatively, in this or other embodiments, a second one or more electronic modules are also secured to the second PWB.

[0014] In another embodiment, the method includes securing a first printed wiring board (PWB) to a first stiffener on a first side of the two-card assembly and securing a second PWB to a second stiffener on a second side of the two-card assembly. The method also includes disposing a central stiffener between the first stiffener and the second stiffener. One or more electronic modules are secured to the central stiffener and dissipate heat through the central stiffener.

[0015] Additionally or alternatively, in this or other embodiments, the compressive force is transferred through wedge locks to secure the central stiffener between the first and second stiffeners.

[0016] Additionally or alternatively, in this or other embodiments, the first set of wedge locks are supported on a first wedge lock mounting rail formed from the second stiffener and a first end of the central stiffener, and the second set of wedge locks are supported on a second wedge lock mounting rail formed from the second stiffener and a second end of the central stiffener.

[0017] Additionally or alternatively, in this or other embodiments, disposing the central stiffener includes disposing the central stiffener within a slot within the second stiffener.

[0018] Additionally or alternatively, in this or other embodiments, securing the first PWB to the first stiffener includes bonding the first stiffener to the first PWB, and securing the second PWB to the second stiffener includes bonding the second stiffener to the second PWB.

[0019] Additionally or alternatively, in this or other embodiments, the first stiffener, the second stiffener, and the central stiffener are fabricated from an aluminum alloy.

[0020] Additionally or alternatively, in this or other embodiments, securing the one or more electronic modules to the central stiffener includes securing a first one or more electronic modules to a first side of the central stiffener.

[0021] Additionally or alternatively, in this or other embodiments, the first one or more electronic modules are fixed to the first PWB.

[0022] Additionally or alternatively, in this or other embodiments, securing the one or more electronic modules to the central stiffener includes securing a second one or more electronic modules to a second side of the central stiffener.

[0023] Additionally or alternatively, in this or other embodiments, the second one or more electronic modules are secured to the second PWB.

[0024] The following description should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numbered like. [Brief description of the drawings]

[0025] [Figure 1A] 1 illustrates one side of an exemplary two-card assembly according to one or more embodiments with the top printed wiring board (PWB) visible. [Figure 1B] 1B shows the opposite side of the two-card assembly shown in FIG. 1A with the PWB visible. [Diagram 2] FIG. 2 is a cross-sectional perspective view of an exemplary two-card assembly according to one or more embodiments. [Figure 3A] 1 illustrates the top side of a central stiffener, according to one or more embodiments. [Figure 3B] 1 illustrates the underside of a central stiffener, according to one or more embodiments. [Figure 4A] 1 illustrates an electronic module secured to the top side of a central stiffener, according to one or more embodiments. [Figure 4B] 1 illustrates an electronic module secured to the underside of a central stiffener, according to one or more embodiments. [Diagram 5] FIG. 4B is a cross-sectional view taken along line AA shown in FIG. 4A. [Figure 6]1 illustrates a lower stiffener and a central stiffener according to an illustrative embodiment. [Figure 7] 1 illustrates an upper stiffener in accordance with an illustrative embodiment. [Figure 8A] Shown is the top side of the central stiffener, with the upper stiffener on top and the lower stiffener on the bottom. [Figure 8B] Shown is the underside of the central stiffener, with the upper stiffener underneath and the lower stiffener on top. [Figure 9A] The structure of FIG. 8A is shown with the lower PWB underneath the lower stiffener. [Figure 9B] The structure of FIG. 8B is shown with the upper PWB underneath the upper stiffener. [Figure 10] FIG. 1 illustrates an exploded view of a two-card array according to one or more embodiments. [Figure 11] FIG. 1 is a cross-sectional view of a two-card assembly illustrating heat flow in accordance with one or more embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] A detailed description of one or more embodiments of the disclosed apparatus and methods is presented herein by way of example and not limitation with reference to the drawings.

[0027] As previously mentioned, electronic modules on a PWB dissipate heat from the side opposite the side in contact with the PWB. If the heat dissipating side of the electronic module could be exposed, air cooling would be possible. However, in a two-card assembly, the electronic module is sandwiched between two PWBs. Additionally, in many applications, the two-card assembly is fixed to a chassis. Embodiments of the present invention relate to a thermal conduction management architecture for an electronic module in a two-card assembly. For purposes of illustration, the exemplary electronic module detailed is a half-bridge module. However, the conductive heat transfer facilitated by the architecture detailed herein is equally applicable to other electronic modules that dissipate heat in the same manner as a half-bridge module. Exemplary applications of these embodiments include deep space applications, underwater-based applications, and terrestrial-based applications.

[0028] 1A and 1B show two sides of a two-card assembly 100, according to one or more embodiments. The terms "top" and "bottom" are used for descriptive purposes only and in no way limit the orientation of the two-card assembly 100. FIG. 1A shows one side of the two-card assembly 100 where the top PWB 110a is visible. Holes 115 correspond to optional screw holes for an optional cover for the top PWB 110a. Wedgelocks 120 are also visible in the view of FIG. 1A. These wedgelocks 120 are used to secure the two-card assembly 100 to the inside of the chassis of an electronic box.

[0029] FIG. 1B shows the opposite side of the two-card assembly 100 of FIG. 1A with the lower PWB 110b visible. Like the upper PWB 110a of FIG. 1A, the lower PWB 110b of FIG. 1B is shown with optional holes 115 for an optional cover. Portions of the lower brace 130 and the central brace 140 between the upper PWB 110a and the lower PWB 110b are visible. The central brace 140 may also be referred to as the central portion of the lower brace 130 because it fits into a slot 1010 (FIG. 9) in the central portion of the lower brace 130 shown in FIG. 6. Exemplary non-limiting dimensions of the two-card assembly 100 for a 3 kilowatt (kW) bi-directional direct current DC-DC converter are approximately 15 inches long, approximately 11 inches wide, and approximately 2 inches deep.

[0030] FIG. 2 is a cross-sectional isometric view of an exemplary two-card assembly 100, according to one or more embodiments. The cross-sectional view exposes the components between the upper PWB 110a and the lower PWB 110b. The wedgelocks 120 and wedgelock mounting rails 230 on either side of the two-card assembly 100 are shown. As previously described, the wedgelocks 120 are used to secure the two-card assembly 100 to the chassis of the electronic box. Torque is applied to the wedgelock screws (not shown) to attach the wedgelocks 120 to the chassis. The wedgelock screw torque provides both an axial and vertical force to the wedgelocks 120. The vertical force is transferred to the lower brace 130 and the central brace 140 as a compressive force that ensures that the central brace 140 is held securely in the slot 1010 (FIG. 9) in the center of the lower brace 130. Lower brace 130 is coupled to lower PWB 110b, upper brace 220 is coupled to upper PWB 110a, and central brace 140 sits in slot 1010 (FIG. 9) in the center of lower brace 130 and is held in place only by wedgelocks 120. As a result, central brace 140 is easily removable so that electronic modules 210 attached to central brace 140 can be repaired or replaced.

[0031] The two-card assembly 100 of FIG. 2 includes four electronic modules 210 between the upper PWB 110a and the lower PWB 110b. The exemplary electronic modules 210 include half-bridge modules. For example, the four half-bridge modules shown in FIG. 2 consume a total of 190 watts. Inside each of the half-bridge modules, there are 14 metal oxide semiconductor field effect transistors (MOSFETs) and 13 diodes. Based on the architecture of the two-card assembly 100 according to one or more embodiments, the junction temperature of the MOSFETs and diodes is maintained below a derated junction temperature of 125 degrees Celsius. This can be verified through thermal analysis of the two-card assembly 100. According to alternative embodiments, the electronic modules 210 can be diodes, transistors, magnetics, or DC-DC converters. The two-card assembly 100 according to one or more embodiments not only provides the heat flow required to meet the temperature requirements, but the stiffeners also provide the structural support required to meet the vibration and pyroshock requirements. A structural analysis of the two-card assembly 100 may be used to verify this.

[0032] 3A and 3B detail the central stiffener 140, according to one or more embodiments. FIG. 3A shows the top side 310 of the central stiffener 140. The top side 310 of the central stiffener 140 faces the top PWB 110a of the two-card assembly 100. The top side 310 of the central stiffener 140 houses two electronic modules 210 in the center, as shown in FIG. 4A. Screw holes 315 are shown for fastening the electronic modules 210 to the central stiffener 410. The screw holes 315 correspond to the screws 325 on the opposite side of the central stiffener 140, just as the screws 325 on the top side 310 of the central stiffener 140 correspond to the screw holes 315 on the opposite side, as shown in FIG. 3B.

[0033] FIG. 3B shows the underside 320 of the central stiffener 140. The underside 320 of the central stiffener 140 faces the lower PWB 110b of the two-card assembly 100. The underside 320 of the central stiffener 140 houses two electronic modules 210 at either end, as shown in FIG. 4B. The screws 325 shown in FIG. 3A correspond to the screw holes 315 shown in FIG. 3B, and the screws 325 are used to secure the electronic modules 210 to the underside 320 of the central stiffener 140. The screws 325 shown in FIG. 3B correspond to the screw holes 315 shown in FIG. 3A, and the screws 325 secure the electronic modules 210 to the upper side 310 of the central stiffener 140.

[0034] 4A and 4B show electronic modules 210 secured to each side of the central stiffener 140, according to one or more embodiments. FIG. 4A shows electronic modules 210 secured to the top side 310 of the central stiffener 140. Screw holes 410 shown at the corners of the electronic modules 210 correspond to the screws 325 shown in FIG. 4B to secure the electronic modules 210 to the top side 310 of the central stiffener 140. Screw holes 420 shown in three rows for each of the electronic modules 210 are used to secure each of the electronic modules 210 to the top PWB 110a. As previously mentioned, heat from the electronic modules 210 dissipates to the side opposite to the side secured to the top PWB 110a. That is, heat dissipates from the electronic modules 210 to the surface of the top side 310 of the central stiffener 140. A cross section designated as AA is shown in FIG. 5.

[0035] FIG. 4B shows the electronic module 210 secured to the underside 320 of the central stiffener 140. Screw holes 410 shown in the corners of the electronic module 210 correspond to the screws 325 shown in FIG. 4A and secure the electronic module 210 to the underside 320 of the central stiffener 140. Also shown are screw holes 420 that are used to secure the electronic module 210 to the lower PWB 110b. For the electronic module 210 shown in FIG. 4B, heat dissipates to the side opposite to the side secured to the lower PWB 110b. Thus, heat dissipates from the electronic module 210 to the surface of the underside 320 of the central stiffener 140.

[0036] Figure 5 is a cross-sectional view through AA shown in Figure 4A. The cross-sectional view is through the electronic module 210 secured to the top side 310 of the central stiffener 140. The view shows two screws 325 on the bottom side 320 of the central stiffener 140 that correspond to the screw holes 410 in the electronic module 210.

[0037] Figure 6 shows the lower stiffener 130 and the central stiffener 140, according to one or more embodiments. The perspective view shown in Figure 6 is such that the central stiffener 140 is lowered relative to the slots in the lower stiffener 130, such that the underside 320 of the central stiffener 140 is visible, and the lower stiffener 130 is shown above the central stiffener 140. Thus, the structural support provided by the lower stiffener 130 to the central stiffener 140 in area 610 is visible.

[0038] 7 shows the upper stiffener 220. The upper stiffener 220 is on the opposite side of the central stiffener 140 from the lower stiffener 130 (i.e., the same side as the upper side 310 of the central stiffener 140). The lower stiffener 130, the central stiffener 140, and the upper stiffener 220 may all be made from an aluminum alloy. For example, a 2000, 6000, or 7000 series aluminum alloy may be used.

[0039] 8A and 8B show opposite sides of the structure of the stiffeners 130, 140, 220, in accordance with one or more embodiments. FIG. 8A shows the upper side 310 of the central stiffener 140, with the upper stiffener 220 on top and the lower stiffener 130 on the bottom. The area 810 where the upper stiffener 220 provides support to the central stiffener 140 corresponds to the location of the electronic module 210 on the bottom side 320 of the central stiffener 140. FIG. 8B shows the underside 320 of the central stiffener 140, with the upper stiffener 220 on the bottom and the lower stiffener 130 on top. The area 610 where the lower stiffener 130 supports the central stiffener 140 corresponds to the location of the electronic module 210 on the top side 310 of the central stiffener 140.

[0040] 9A and 9B show the structures of FIG. 8A and 8B for PWB 110b and PWB 110a, respectively. FIG. 9A shows the top side 310 of the central brace 140 with the upper brace 220 on top and the lower brace 130 on bottom, and the lower PWB 110b below the lower brace 130. The wedgelocks 120 are also shown. FIG. 9B shows the underside 320 of the central brace 140 with the upper brace 220 on bottom and the lower brace 130 on top, and the upper PWB 110a below the upper brace 220. The view in FIG. 9B shows that the wedgelock mounting rails 230 are formed at the ends of the lower brace 130 and the central brace 140. As explained with reference to FIG. 4A and 4B, heat from the electronic modules 210 dissipates to the surface of the central brace 140. The central stiffener 140 achieves conductive heat dissipation by transferring heat from the electronic modules 210 on either side of its surface to the wedgelock mounting rails 230. This is described in further detail with reference to FIG.

[0041] FIG. 10 is an exploded view of a two-card assembly 100, according to one or more embodiments. The wedge locks 120 are not shown. The upper PWB 110a is coupled to the upper stiffener 220, and the lower PWB 110b is coupled to the lower stiffener 130 using double-sided adhesive. The central stiffener 140 has a wedge-shaped cross-section, as shown in FIG. 10. The central stiffener 140, with electronic power modules 210 secured to both sides, sits in a wedge-shaped slot 1010 formed in the lower stiffener 130. Thus, once the electronic module 210 is unscrewed from either of the PWBs 110a, 110b to which it is secured, the central stiffener 140 can be lifted out of the slot 1010 for repair or replacement of the electronic module 210, if necessary.

[0042] FIG. 11 is a cross-sectional view of a two-card assembly 100 illustrating heat flow, according to one or more embodiments. According to the exemplary orientation shown in FIG. 11, the downward arrows indicate heat flow from the electronic modules 210 secured to the top side 310 of the central stiffener 140 to the surface of the central stiffener 140. The upward arrows indicate heat flow from the electronic modules 210 secured to the bottom side 320 of the central stiffener 140 to the surface of the central stiffener 140. The heat at the surface of the central stiffener 140 is then conducted outward to the wedgelock mounting rails 230. The temperature of the wedgelock mounting rails 230 can be controlled, for example, by a heat sink (e.g., a convective heat sink, a radiative heat sink, a combination of the two).

[0043] 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 "comprise" and / or "comprising", as 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.

[0044] Although the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for the elements without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope of the present disclosure. Therefore, the present disclosure is not limited to the particular embodiment disclosed as the best mode contemplated for carrying out the disclosure, but the present disclosure is intended to include all embodiments falling within the scope of the claims.

Claims

1. 1. A two-card assembly comprising: a first printed wiring board (PWB) on a first side of the two-card assembly; a first stiffener secured to the first PWB; a second PWB on a second side of the two-card assembly; a second stiffener secured to the second PWB; a central stiffener disposed between the first stiffener and the second stiffener; one or more electronic modules secured to the central stiffener, the central stiffener dissipating heat from the one or more electronic modules; Equipped with A two-card assembly, wherein the central stiffener is disposed within a slot formed within the second stiffener.

2. 10. The two-card assembly of claim 1, further comprising a wedge lock configured to secure the central stiffener between the first stiffener and the second stiffener based on a compressive force.

3. 3. The two-card assembly of claim 2, further comprising a first wedgelock mounting rail configured to support the first set of wedgelocks and a second wedgelock mounting rail configured to support the second set of wedgelocks.

4. 4. The two-card assembly of claim 3, wherein a first end of the second stiffener and the central stiffener form the first wedgelock mounting rail, and a second end of the second stiffener and the central stiffener form the second wedgelock mounting rail.

5. The two-card assembly of claim 1 , wherein the first stiffener is coupled to the first PWB and the second stiffener is coupled to the second PWB.

6. The two-card assembly of claim 1 , wherein the material of the first stiffener, the second stiffener, and the central stiffener is an aluminum alloy.

7. 2. The two-card assembly of claim 1, wherein a first one or more electronic modules are secured to a first side of the central stiffener and a second one or more electronic modules are secured to a second side of the central stiffener.

8. The two-card assembly of claim 7 , wherein the first one or more electronic modules are also secured to the first PWB.

9. The two-card assembly of claim 7 , wherein the second one or more electronic modules are also secured to the second PWB.

10. A method for assembling a two-card assembly, comprising the steps of: Securing a first printed wiring board (PWB) to a first stiffener on a first side of the two-card assembly; Securing a second PWB to a second stiffener on a second side of the two-card assembly; disposing a central stiffener between the first stiffener and the second stiffener; fastening one or more electronic modules to the central stiffener and dissipating heat through the central stiffener; Including, The method, wherein positioning the central stiffener includes positioning the central stiffener within a slot formed within the second stiffener.

11. 11. The method of claim 10, further comprising securing the central stiffener between the first stiffener and the second stiffener using a compressive force transmitted through wedge locks.

12. 12. The method of claim 11, further comprising: supporting a first set of wedgelocks on a first wedgelock mounting rail formed from the second stiffener and a first end of the central stiffener; and supporting a second set of wedgelocks on a second wedgelock mounting rail formed from the second stiffener and a second end of the central stiffener.

13. 11. The method of claim 10, wherein said securing said first PWB to said first stiffener comprises bonding said first stiffener to said first PWB, and said securing said second PWB to said second stiffener comprises bonding said second stiffener to said second PWB.

14. The method of claim 10 , further comprising manufacturing the first stiffener, the second stiffener, and the central stiffener from an aluminum alloy.

15. The method of claim 10 , wherein the securing of the one or more electronic modules to the central stiffener comprises securing a first one or more electronic modules to a first side of the central stiffener.

16. The method of claim 15 , further comprising: securing the first one or more electronic modules to the first PWB.

17. The method of claim 10 , wherein the securing of the one or more electronic modules to the central stiffener includes securing a second one or more electronic modules to a second side of the central stiffener.

18. The method of claim 17 , further comprising: securing the second one or more electronic modules to the second PWB.

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