OF HIGHER MELTING TEMPERATURES AND TRACES COUPLING ELECTRICAL CONTACTS AT DIFFERING POSITIONS

BACKGROUND

[0001] A printed circuit board (PCB) may be used to provide electrical connections between electronic devices. Components may be soldered to electrical contacts on the PCB, which may couple the components to other components to form an electrical circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Various examples will be described below referring to the following figures:

[0003] Fig. 1 shows an apparatus with a PCB, a high-temperature solder joint, low-temperature solder joint, and a trace in accordance with various examples;

[0004] Fig. 2 shows an apparatus with a PCB, a motherboard, solder, and a trace in accordance with various examples;

[0005] Fig. 3 shows an apparatus with a first interchangeable PCB configuration, a second interchangeable PCB configuration, and a motherboard in accordance with various examples;

[0006] Fig. 4 shows a method of selecting between PCBs and soldering the selected PCB to a motherboard in accordance with various examples; and

[0007] Fig. 5 shows a method of soldering a selected PCB to a motherboard and removing the selected PCB from the motherboard in accordance with various examples.

DETAILED DESCRIPTION

[0008] Solder may be used to couple components to a PCB. Solder may include various metals that may be melted to form a joint between components. The joint may provide an electrical connection between the components as well as a physical connection and physical stability between the components. There may be multiple solder joints to couple the component to the PCB. Other components may be coupled to the PCB with solder. Removing a specific component from the PCB may involve heating up the solder until it melts, allowing removal of the component. In heating up the solder joints for one component, the solder joints for other components may also be heated to their melting point and come loose or be removed from the PCB. Such loosening or removal may be unintentional.

[0009] For a component or groups of components that may be replaced, an additional PCB may be used. The components may be soldered to the additional PCB using a high-temperature solder. The various other components of the PCBs may also be soldered using the high-temperature solder. The two PCBs may be soldered together using a low-temperature solder. By heating the solder joints joining the PCBs to a melting temperature of the low-temperature solder, which is below the melting temperature of the high-temperature solder, the PCBs may be separated without melting the high-temperature solder holding the various components to the PCBs. The additional PCB may thereby be replaced with another PCB. This may allow relatively easy modification or repair of electronic devices in the field by a technician. There may be multiple versions of the additional PCB that provide different routing between electrical contacts, different populations of components, or different functionality. The original PCB may be designed with a common interface that couples to the different versions of the additional PCB. Use of a common underlying PCB and versioning of specific PCBs to couple to the common PCB may reduce costs of design or manufacture.

[0010] Fig. 1 shows an apparatus 100 with a PCB 1 10, a high-temperature solder joint 130, low-temperature solder joint 160, and a trace 180 in accordance with various examples. The high-temperature solder joint 130 has a higher melting temperature than the low-temperature solder joint 160. The PCB 1 10 includes a first surface 1 12 and a second surface 1 14 opposite the first surface 1 12. The PCB 1 10 includes a first electrical contact 120 and a second electrical contact 150. While the electrical contacts 120, 150 are depicted as jutting out from the PCB 1 10 (in order to make them more visible), the electrical contacts 120, 150 may be landing pads or traces on the surface of the PCB 1 10 with minimal rise from the surface of the PCB 1 10, or may be flush or below the surface of the PCB 1 10. The trace 180 is an electrical connection coupling the first electrical contact 120 with the second electrical contact 150. The trace 180 may provide lateral routing from the first electrical contact 120 to the second electrical contact 150 when they are not directly opposite the other on the PCB 1 10.

[0011] In various examples, a chip may be coupled to the first surface 1 12 of the PCB 1 10 via the high-temperature solder joint 130. Additional high- temperature solder joints may be used to couple the chip to the first surface 1 12. Components may also be coupled to the first surface 1 12 or the second surface 1 14 of the PCB 1 10 via additional high-temperature solder joints. An additional PCB may be coupled to the second surface 1 14 of the PCB 1 10 via the low- temperature solder joint 160. Additional low-temperature solder joints may be used to couple the PCB 1 10 to the additional PCB. Components may be coupled to the PCB 1 10 and additional PCB using high-temperature solder joints. The PCB 1 10 may then be coupled to the additional PCB using low-temperature solder joints 160. By using a lower heat to create the low-temperature solder joints 160, the high-temperature solder joints may not be heated to their melting temperature and may thus remain securely in place. The PCB 1 10 could be later removed from the additional PCB by heating the low-temperature solder joints to their melting temperature.

[0012] In various examples, additional traces may couple other electrical contacts on the first surface 1 12 of the PCB 1 10 to electrical contacts on the second surface 1 14 of the PCB 1 10. The relative positioning of the electrical contacts may change from the first surface 1 12 to the second surface 1 14. Some electrical contacts on the first surface 1 12 may be coupled to electrical contacts that are closer to the edge of the PCB 1 10 on the second surface 1 14. Other electrical contacts on the first surface 1 12 may be coupled to electrical contacts that are closer to the middle of the PCB 1 10 on the second surface 1 14. The traces may allow for rerouting of signals in the PCB 1 10. A component, such as a chip, coupled to the first surface 1 12 of the PCB 1 10 may have its signals rerouted to different positions on the second surface 1 14, providing a different footprint for coupling the component to the additional PCB via the PCB 1 10.

[0013] In various examples, the second electrical contact 150 may be part of a peripheral connect interface express (PCIe) bus. The component coupled by solder joint 130 may be a processor with a PCIe interface. The trace 180 may couple the PCIe interface of the processor to the PCIe interface of the second electrical contact 150. The second electrical contact 150 may couple with a PCIe interface on the motherboard via the solder joint 160.

[0014] In various examples, the component may be a processor with a PCIe interface. The PCB 1 10 may split different lanes of the PCIe interface to couple with two different PCIe interfaces via traces on the PCB 1 10, one of which may be trace 180. The PCB 1 10 may be coupled to a motherboard via the solder joint 160. The two different PCIe interfaces may couple to different PCIe interfaces on the motherboard. One of the PCIe interfaces on the motherboard may couple to a solid state drive. The other PCIe interface on the motherboard may couple to a sound card to capture or play sounds. The PCIe interface may couple to a graphics processor or graphics card, a network controller such as for an Ethernet connection, or a PCIe slot that may couple to various input/output devices.

[0015] In various examples, the PCB 1 10 may include a trace to couple one electrical contact on the motherboard with another electrical contact on the motherboard. There may be multiple versions of PCB 1 10, and such traces may couple together contacts to indicate the particular version of the PCB 1 10 coupled to the motherboard. The version of a PCB 1 10 may be indicated by a memory on the PCB 1 10 that may be queried for a version number, or a signal may be provided by the PCB 1 10 to the motherboard to indicate a version. The version of the PCB 1 10 may also be provided to a component soldered to the PCB 1 10, such as a processor.

[0016] In various examples, a chip may be coupled to the PCB 1 10 via the solder joint 130. The chip may be a processor. The PCB 1 10 may translate between a processor interface specific to the chip and a common processor interface to interface with a motherboard. The interface between the PCB 1 10 and the processor may include a first processor interface for accessing the processor. The PCB 1 10 may couple to the motherboard via the solder joint 160. The interface between the PCB 1 10 and the motherboard may include a second processor interface. The first processor interface and second processor interfaces may be different, such as having different footprints or having different signals or signal attributes. The PCB 1 10 may include rerouting and modification of signals to make the processor accessible by the motherboard through the first processor interface and second processor interface. The first processor interface may be specific to a processor manufacturer. The second processor interface may be used by a computer manufacturer or motherboard manufacturer to provide a common processor interface for motherboards. The PCB 1 10 may translate between the common processor interface on the motherboard and the different processor interfaces used by different processor manufacturers. This may enable a motherboard to be used with different processors with different processor interfaces by using a PCB 1 10 designed specifically for that processor interface. Instead of having two different motherboard versions for use with two different processors, one motherboard version may be used which is compatible with two different versions of PCB 1 10 that make different processors accessible by the motherboard.

[0017] Fig. 2 shows an apparatus 200 with a PCB 210, a motherboard 270, solder 230, 260, and a trace 280 in accordance with various examples. The PCB 210 includes a first surface 212 and a second surface 214. The apparatus 200 includes a component 240 soldered to the first surface 212 of the PCB 210 via solder 230. Solder 230 may be high-temperature solder. The second surface 214 of the PCB 210 is coupled to the motherboard 270 via solder 260. Solder 260 may be low-temperature solder. The motherboard 270 may comprise a PCB to provide routing between components placed on the motherboard.

[0018] In various examples, the apparatus 200 may include a computer system. The component 240 may include a processor, and motherboard 270 may include a computer motherboard. The component 240 may include connections for a PCIe interface to communicate with the component 240. The trace 280 may couple the PCIe connections of the component to a PCIe connection on the motherboard 270. This may couple the processor to a PCIe device coupled to the motherboard 270, such as a solid state drive or a sound card.

[0019] Fig. 3 shows an apparatus 300 with a first interchangeable PCB configuration 306, a second interchangeable PCB configuration 308, and a motherboard 370 in accordance with various examples. The first interchangeable PCB configuration 306 and second interchangeable PCB configuration 308 are different versions to connect to the motherboard 370. The motherboard 370 may have one location to receive either the first interchangeable PCB configuration 306 or the second interchangeable PCB configuration 308. The interchangeable PCB configurations 306, 308 may be soldered to the motherboard 370 using a low-temperature solder. This may allow the interchangeable PCB configurations 306, 308 to be removed from the motherboard 370 relatively easily by a technician. The technician may remove the second interchangeable PCB configuration 308 from the motherboard 370 by heating up the solder and then solder the first interchangeable PCB configuration 306 to the motherboard 370. Fig. 3 shows the second interchangeable PCB configuration coupled to the motherboard.

[0020] The first interchangeable PCB configuration 306 includes a PCB 316 and processors 344, 346. The processor 346 is coupled to the PCB 316 via a processor interface 326. The processor 344 is coupled to the PCB 316 via a processor interface 324. The processor interfaces 324, 326 may include various electrical contacts to communicate signals and power with the respective processors 344, 346. The processor interfaces 324, 326 may include power connections, ground connections, PCIe interface connections, memory bus connections, and other signaling connections. The PCB 316 couples to the motherboard 370 via processor interfaces 364, 366. Additional interfaces may exist between the PCB 316 and the motherboard 370. Processor interface 326 may couple to processor interface 366 to allow the motherboard 370 to access processor 346 via processor interfaces 326, 366. Processor interface 324 may couple to processor interface 364 to allow the motherboard 370 to access processor 344 via processor interfaces 324, 364. PCB 316 includes traces 382, 384. Trace 382 provides routing of a signal between processor interface 326 and processor interface 366. The signal may be part of a PCEe bus coupled to processor 346. Trace 384 provides routing of a signal between processor interface 324 and processor interface 364. The signal may be part of a PCIe interface coupled to processor 344.

[0021] The second interchangeable PCB configuration 308 includes a PCB 318 and a processor 348. The processor 348 is coupled to the PCB 318 via a processor interface 328. The PCB 318 couples to the motherboard 370 via processor interface 368 and a connection between trace 388 and trace 386. Additional interfaces or connections between the PCB 318 and the motherboard 370 may exist. Trace 380 provides routing of a signal between processor interface 328 and processor interface 368. The signal may be part of a PCIe interface and be coupled to a PCIe slot 390 on the motherboard 370 via trace 385. Trace 388 may couple a PCIe signal of the processor 348 with a PCIe slot 395 on the motherboard 370 via trace 386. The connection between trace 388 and trace 386 may include low-temperature solder between the PCB 318 and the motherboard 370. Traces 380, 388 may split up lanes of a PCIe interface of the processor 348 to couple to the two PCIe slots 390, 395.

[0022] In various examples, the interchangeable PCB configurations 306, 308 may include different versions of PCBs 316, 318. PCB 316 may be designed to have two processors 344, 346 and couple them to different resources on the motherboard 370, such as the two PCIe slots 390, 395. The processors 344, 346 may also be coupled to different memories on the motherboard 370. Other resources may be shared between the processors 344, 346. PCB 318 may be designed to have one processor 348. As the interchangeable PCB configurations 306, 308 may both be designed to work with the motherboard 370, PCB 318 may connect to the motherboard 370 at electrical contacts that would couple with the two processor interfaces 364, 366 of the first interchangeable PCB configuration. One trace 380 may couple the processor 348 to PCIe slot 390, while another trace 388 may couple the processor 348 to PCIe slot 395. Though the first interchangeable PCB configuration 306 couples the two PCIe slots 390, 395 to different processors 344, 346, the second PCB configuration 308 couples one processor to both PCIe slots 390, 395. The second PCB configuration 308 may couple the processor 348 to memories that would be separately accessed by the different processors of the first PCB configuration 306. This may allow versioning of interchangeable PCB configurations 306, 308 to include different numbers of processors or other resources and reroute signals to make use of resources on the motherboard 370. Instead of PCB 318 being a version of PCB 316 with the processor 344 depopulated, PCB 318 includes different routing of signals than PCB 316 to make PCIe slot 395 accessible by the lower number of processors of the second interchangeable PCB configuration 308.

[0023] In various examples, the processor interfaces 324, 326, 328, 364, 366, 368 may have different specifications. As shown in Fig. 3, the processor interfaces 324, 326, 328, 364, 366, 368 may have A, B, C, and D versions. These processor interface versions may be from different manufacturers or correspond to different processors by one manufacturer. The PCBs 316, 318 may translate between the different processor interfaces 324, 326, 328, 364, 366, 368 to allow for communication between the motherboard 370 and the processors 344, 346, 348. The processor interfaces 364, 366, 368 designated C may be a common processor interface used by the motherboard 370. The processor interfaces 324, 326, 328 may be interfaces used by the specific processors 344, 346, 348. PCB 316 may translate between processor interface 324 and processor interface 364 to allow communication between the processor 344 and the motherboard 370. PCB 316 may also translate between processor interface 326 and processor interface 366 to allow communication between the processor 346 and the motherboard 370. PCB 318 may translate between processor interface 328 and processor interface 368 to allow communication between the processor 348 and the motherboard 370.

[0024] In various examples, the differences between processor interfaces 324, 326, 328, 364, 366, 368 may include different connections, such as one processor using pins, and another using flat or ball contacts. The interface differences may include a difference in pin arrangements, where the two processors provide comparable functionality but are pin-incompatible. The interface differences may include different signaling patterns or even different instruction sets. Versions of the PCB 316, 318 may account for these interface differences to create cross-compatible microprocessor modules using the different processors 344, 346, 348, where the microprocessor modules use a common processor interface 364, 366, 368 to couple to the motherboard 370. The PCB 316, 318 may handle the interface differences by the re-routing of signals on the PCB 316, 318, instead of passing the signals through to the processors 344, 346, 348 through direct vias. The PCB 316, 318 may handle the differences by the inclusion of glue logic that modifies the signaling patterns to match the appropriate processor 344, 346, 348. Some changes may be switching between big endian and little endian representations of data in a data transfer, lane swapping of a PCIe interface, modifying signals to handle timing difference, or translating between edge triggered and level triggered signals. To handle differences in instruction sets, the PCB 316, 318 may include components to translate between different instruction sets. For example, one processor may include a native instruction for adding 1 to a number, in addition to a more general addition instruction for two numbers. Another processor may have the general addition instruction, but not the specific add 1 instruction. If the common processor interface 364, 366, 368 includes the specific add 1 instruction, the version of a PCB 316, 318 for the latter processor could modify the add 1 instruction to use the general addition instruction and supply 1 as the number to be added. Other translations between instruction sets could be performed as well.

[0025] Fig. 4 shows a method 400 of selecting between PCBs and soldering the selected PCB to a motherboard in accordance with various examples. The method 400 includes selecting between a first printed circuit board (PCB) and a second PCB, the first PCB including a chip soldered to the first PCB using a first solder, the second PCB including a second chip soldered to the second PCB using a second solder, the first PCB to implement a first functionality of an interface, the second PCB to implement a second functionality of the interface, the first functionality differing from the second functionality (410). The method 400 includes soldering the selected PCB to a motherboard using a third solder, a melting temperature of the third solder being lower than a melting temperature of the first solder and the second solder (420).

[0026] In various examples, the first PCB and second PCB could correspond to interchangeable PCB configurations, such as those discussed with respect to Fig. 3. The PCBs could implement the functionalities differently by using processors or other components from different manufacturers. The processors or components may use different interfaces from each other. The PCBs could reroute signals and implement glue logic or other functionality to make the processors or components accessible through a common interface. [0027] Fig. 5 shows a method 500 of soldering a selected PCB to a motherboard and removing the selected PCB from the motherboard in accordance with various examples. The method 500 includes selecting between a first printed circuit board (PCB) and a second PCB, the first PCB including a chip soldered to the first PCB using a first solder, the second PCB including a second chip soldered to the second PCB using a second solder, the first PCB to implement a first functionality of an interface, the second PCB to implement a second functionality of the interface, the first functionality differing from the second functionality (510). The method 500 includes soldering the selected PCB to a motherboard using a third solder, a melting temperature of the third solder being lower than a melting temperature of the first solder and the second solder (520). The method 500 includes heating the third solder to a melting temperature of the third solder (530). The method 500 includes removing the selected PCB from the motherboard (540). The method 500 includes soldering a third PCB to the motherboard using a fourth solder, a melting temperature of the fourth solder being lower than melting temperatures of the first solder and the second solder (550).

[0028] In various examples, the PCBs may be interchangeably swapped out with each other. Heating the lower temperature solder between the PCB and the motherboard may allow removal of the PCB from the motherboard without disturbing other components soldered to the PCB or motherboard. Use of low- temperature solder to connect the replacement PCB to the motherboard may enable the repeated removal and replacement of PCBs. The PCB may be swapped out for the same version of PCB, such as when making a repair, or the PCB may be swapped out with a different version of PCB, such as when performing an upgrade or a downgrade.

[0029] In various examples, the PCBs may include additional components beyond the processors. Memory may be included on the PCBs to act as cache memory or random access memory (RAM) for the system. Voltage regulators may be included on the PCBs to modify power provided by the motherboard for use by components on the PCBs or to provide additional power or power regulation. A peripheral control hub (PCH) may be included on the PCBs to interface with a processor and input/output devices.

[0030] In various examples, the PCBs may not have any components soldered to them other than the soldered connection to the motherboard. The PCB versions may provide different routing of signals between electrical contacts of the motherboard, coupling various combinations of devices together.

[0031] The above discussion is meant to be illustrative of the principles and various examples of the present disclosure. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.