Patent Application
20160351526
The present description relates to integrated circuit attachment to an external board or socket and, in particular, to attachment using a local heat source.
Silicon chip components such as CPU's (Central Processing Units), GPU's (Graphics Processing Units), controllers, etc. use an interconnect interface between the pads on a surface of the component and a connection array on an external connector, such as a main circuit board, a test board, or a socket. The connection is typically accomplished by soldering in the case of a BGA (Ball Grid Array) through a socket in the case of an LGA (Land Grid Array). In a test platform environment, the interconnection is sometimes accomplished using a MPI (Metal Particle Interconnect) socket. During production, the component may be connected to several different test fixtures as it moves through different test scenarios before it is finally released. In addition, each circuit board or socket may be reused several times to test different components as the components move through the different test stages.
The different common connection systems provide particular characteristics that work well for different applications. BGA connections in which solder attaches the component are very reliable and provide good high speed signaling performance. However, the soldering is done in a controlled factory setting. Rework of the solder connections requires the controlled factory setting with specialized equipment and training.
LGA connections provide great flexibility. A component may be fitted in a socket at any point of the manufacturing process, and easily replaced in the field. However, the contacts in an LGA socket are prone to damage, rendering an expensive printed circuit board non-functional. In addition, the socket reduces high speed signal performance. The contacts and the paths through the socket add significant impedance and cross talk to the signals. The additional impedance contributes to significant power loss in the contact, thereby lowering power efficiency.
MPI sockets are expensive, and not suited for high volume production. The connections are subject to open contacts, high impedance, and may be unreliable when used for test equipment.
Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements.
As described herein, a direct solder connection can be formed on a circuit board that permits attachment and reattachment of a silicon chip component. The array of contacts may be formed directly on the circuit board. The component is then attached directly to the board with solder. This eliminates the LGA and MPI contacts for higher reliability, serviceability and signal integrity.
A heater is designed into the circuit board to reflow the solder and create a reliable solder joint. The control mechanism for the heater is provided in a reusable, modular device that can be used anywhere. This removes any dependency on factory tools. It also eliminates the expense of integrating the control circuitry integrated into every motherboard.
With the modular heater control circuit, a technician in the factory or field can install or replace a silicon chip component. The modular heater control circuit may be configured to use power from a motherboard or external source to drive the control and to drive the heater elements. The modular device may be configured to provide controlled current to a heater circuit to reflow the solder balls on the socket substrate. Features on the motherboard or a socket may be used to position the silicon chip component for reliable interconnection. When completed, the technician can remove and reuse the modular device.
The component 109, which may be any silicon die or packaged device, is placed over the lands 107 on the circuit board 106. Any of a variety of different alignment features 108 may be attached to the circuit board to guide the component into correct alignment with the lands. In the illustrated example features, in this case alignment corners are provided to allow the component to float and self align to the pads The circuit board may be configured with wiring traces on the circuit board to connect the component through the lands to external components for test or for operation, depending on the implementation. There may also be resistors and other passive devices (not shown) to support the component, power supply lines and other devices attached to the circuit board.
The installation module is in the form of an assembly that includes its own controller board 101 mounted to a power chassis 110 that carries the controller board and other components 146 including the circuitry to control the heating process. The controller board carries active or passive components 146 or both to control the flow of current from the motherboard to heating elements on the motherboard. Pogo pins 102 are mounted to each corner of the chassis and extend through the controller board. In this case four pins are shown but more or fewer may be used or a different alignment system other than pogo pins may be used. The pogo pins interconnect the controller board to electrical connectors 112 on the circuit board. As shown, the electrical connectors are simple copper lands that connect to contacts on the pogo pins, however, any of a variety of other electrical connectors may be used. The pogo pins also serve as alignment pins to align the control module with the alignment features 108 on the circuit board, however, any of a variety of alignment schemes may be used. The pogo pins may be used to receive power from the motherboard and also to supply power to the heater traces. Alternatively, an external connection may be made for one or both of these functions.
A top plate 114 carries a switch 105 to control the operation of the control module. The top plate is mounted over and attached to the power chassis using flexible tabs 126 that snap into slots (not shown) and removable push rivets 103. The push rivets use springs to help lift the packaged device off the board during a removal process. The top plate covers the power chassis and all of the components for safety and to provide a comfortable gripping surface to hold and move the control module. The top cap 122, 124 allows the interposer to be gripped to extract the component when the component is removed.
A mode control switch 105 sets the control module for installation and removal. In this example, the mode control switch has beveled rounded surfaces to engage mating beveled surfaces on the top plate and connect the switch to the top plate. A connection post 122 connected to the power chassis extends through the top plate to also attach to the control switch. In this way, the control switch has a bayonet mount to the top plate and attaches also to the power chassis. This holds the top plate between the power chassis and the switch. The removable push rivets also hold the top plate to the power chassis. Alternatively, the top plate and power chassis may be fastened together in any of a variety of other ways.
Push rivets 116 are attached on each of two sides of the power chassis. The push rivets extend through the power chassis to contact the motherboard. The push rivets have springs 118 to hold a contact plate 110 away from the motherboard during normal use. The push rivets may be pushed down from above against the resistance of the springs to contact the motherboard and be pressed through connection holes 142 that are aligned in position with the push rivets. The push rivets latch into the holes to hold the power chassis in place until firmly pulled away to remove the push pins from the holes. A variety of attachment methods using standoffs, thumbscrews, or other tooled or tool less methods may also be used.
When removing a component, the heater traces may be activated to melt solder of a connection to the motherboard and the push rivet springs may be used to urge the component and the control module 124 up and away from the motherboard. Tabs on the bottom of the power chassis grip the component by the sides so that the component is pulled up by the control module. As shown, there is one push rivets on either of two opposite sides of the power chassis. There are two tabs for holding a component each on opposite side of the power chassis and on adjacent sides from the push rivets. The particular arrangement for the application of extraction forces and gripping features may be adapted to suit different components and different attachment configurations.
The solder may be applied to the motherboard connection grid before the control module is moved into position. With the control module in place, the pogo pins establish an electrical connection from power pads on the motherboard into the control module. The power from the motherboard is provided by the control module to heater traces of the motherboard or an interposer of the motherboard.
The switch 105 of the control module 100 has two positions, remove at 12:00, install at 9:00. The install and remove positions of the switch activate or deactivate the springs that lift the part of the board during removal. The control module may have a variety of different programmed current or temperature cycles that are controlled by the integrated circuit components on the control circuit board. These cycles may be operated autonomously so that the user does not need to monitor the control module during a heating cycle. Alternatively, a simpler on, off switch may be used to control power to the heater traces.
A set of LEDs are used as a control interface for the control module. There is a first LED 130 used for “HOT.” This LED may be activated whenever the heater traces are powered in order to indicate that the system is at a dangerous or high temperature. There is a second LED labeled “SAFE.” This LED may be used to indicate that the control module is in position, connected to the motherboard and the component and that the temperature is safe for user to touch the control module. The third LED is labeled “REFLOW.” This LED may be continuous or flashing to indicate to the user that the soldering operation is in progress, and should not be interrupted in any way. While these three LEDs are sufficient for safe operation of the control module, there may be more or fewer, depending on the particular implementation. Other types of user outputs may be used instead of those shown. A more detailed display system may be used or the system may be configured for a remote display using wireless or wired connections to an operator terminal.
The heat sink 316 has a push pin 318 on at least two sides that connects into respective holes 312 in the motherboard. These are the same holes that were used to hold the control module in place. A thermal grease or other thermally conducing material is applied to the top of the component 309. The heat sink is then pressed against the top of component and the push pins are pressed until bottom pins 314 are pressed through the holes in the motherboard to hold the heat sink in place. The component may then be operated at high speeds and high loads without overheating. Such a heat sink mounting system may be used for test or normal operation purposes.
For a test fixture, after the testing is completed, the heat sink may be removed by pulling up on the push pins. The component may then be removed by reattaching the control module. A similar approach may be used to replace a silicon component in the field. While the heat sink is shown as a metal base with an array of metal heat fins, such as aluminum fins, the heat sink may take any of a variety of passive or active forms. A more precise heat sink, such as a liquid cooling system may be used to control the temperature of the component more precisely.
The heater traces may be embedded into any suitable layer of the interposer, such as layer 2 of the interposer. The heater traces heat the vias in the interposer and, through the vias, heat the pads. The heater traces may be in any of the inner layers of the interposer that is able to heat the vias. In the example of
The process of
The interposer may be soldered to the mother board in a conventional manner. In addition at 504 any other components are soldered to the motherboard. The particular components will depend on the type of board and its intended use. These other components may include voltage regulators, power supplies, or other system components, such as memory, graphics, input/output hubs, and communication interfaces.
At 506, the component item that is to be installed is inserted onto the interposer. This may be done with the aid of the integrated corner alignment features shown, for example, in
At 508 the control module is positioned on the motherboard over the component. This can include aligning the pogo interconnect pins with the electrical connection points on the mother board. It can also include pressing the push rivets into respective holes on the motherboard to secure the push pins and the control module on the board or an alternate attachment method.
At 510, the control module is connected to a power source. This may be done by connecting the motherboard to power so that the control module is powered through the pogo pins, or it may be done by connecting a power source directly to the control module. With power connected, at 512, the operator selects the “install” mode using the mode control.
The control module then initiates a solder reflow cycle at 514. At 516 the control module applies current from the motherboard or another external source to the heater traces of the interposer. The traces heat through resistive heating and this heat propagates from the traces to the connection pads and solder that has been applied either to the interposer or the component.
As the on board controller of the control module energizes the heater elements in the interposer, it also monitors the temperature of the component to ensure that the component is within a temperature range for low temperature solder reflow. The control module regulates the current to the heater traces to maintain a desired temperature. This temperature is selected to be sufficient to reflow the solder without harming the component, the interposer or the connection array.
The particular temperature may be modified to suit different materials, different uses, and different types of connections. As an example, a lower temperature, less robust solder may be used for attachment to a test board because the tests will be run under carefully controlled conditions. For a product shipped to an end user, a more robust, higher temperature solder may be used to withstand the physical stress of shipping and operational temperature changes and also to last the many years desired for the end product. The solder compounds used on the interposer to the motherboard may also affect the choice of solder compound used to connect the interposer to the component. Using a lower temperature solder on the interposer to component joints may allow the lower temperatures solder to reflow without affecting the solder between the interposer and the motherboard.
At 520 a reflow indicator LED blinks. The control module may be fitted with a variety of different control and display systems. In the illustrated example a set of LEDs are used. In such an example, there may be a reflow LED to indicate that a reflow process is underway. When the reflow process ends, then this LED will turn off. Different blinking cycles may be used with all of the LEDs to indicate different levels for each status indication. At 522, the HOT indicator LED illuminates to indicate caution. The HOT indicator may be controlled directly by the measured or monitored temperature or by other conditions.
When the cycle ends, the reflow LED is turned off. The HOT LED may still indicate that the system is too hot to touch and that the solder is still cooling. When the temperature has reached a safe level, then the HOT led extinguishes at 524 and the SAFE LED illuminates at 526 to confirm that the reflow process is over. At this point the component is successfully connected to the interposer and is ready for test or operation depending on the implementation.
At 528 the operator removes the control module by pressing on the pogo pins and pulling the push pins out of their mating holes in the motherboard. At 530 a heat sink may optionally be attached to the component. A particular convenient attachment mechanism is shown in the example of
In the example of
At 556 the control module applies current from the control module to the heater connection terminals of the interposer. The heater connection terminals are coupled to resistive heater traces of the interposer. The heaters heat the solder on the contact pads of the interposer to reflow that solder either to make or break a solder connection. The current may be provided by a connection to the circuit board or from another external source.
At 558 the control module may activate a reflow indicator signal. There may be other signals such as a hot temperature warning, a specific temperature indication, a timer or any other desired signal. A small group of LEDs are shown herein, however, the indicator may be in other forms.
At 560, the control module completes the reflow cycle. As a result, at 562, the current application stops. This may be accompanied by extinguish the reflow indicator signal at 564, indicating a safe temperature or other indications. After the reflow cycle has ended, the control module may be removed. In addition, the component may be removed if the reflow cycle was for removing the component.
Component removal is similar to installation, except that the control module control is set to “remove.” This allows the springs that are coaxial with the pogo pins to exert upward pressure on the component. When the solder has melted enough to release the attachment between the component and the interposer, then the pressure of the springs serves to remove the component from the board.
Starting at 602 the heat sink, if one is present, is removed from the component. At the same time any other accessories or connections are removed from the top of the component. This allows access to the top of the component and at 604 the control module is positioned on the board over the component. As with installation, the pogo pins are connected to the power supply lands of the board and the push rivets are secured to the board.
With the control module attached and in place over the component at 606 the motherboard is connected to power source. The power source may optionally be connected before placing the control module or may simply remain in place.
At 608 an operator begins a remove process with the control module. This may be done in the illustrated example by rotating the selector to the remove mode position on the control module. The control module then initiates a reflow cycle at 610. Similar to installation, for the reflow process, the on board controller energizes the heater elements in the interposer at 612 and also monitors and regulates the temperature for solder reflow at 614.
The reflow indicator blinks at 616 during the process. The HOT LED also illuminates at 618 after the system has become hot from the heater elements. At 620 during the reflow process, in the illustrated example, the pogo pin springs exert an upward pressure on the component as the solder melts in order to remove the component from the board. The control module is physically connected to the component. In
At 622 the reflow LED extinguishes after the component is released or after a timer has elapsed. The HOT LED extinguishes after the reflow cycle is completed and the system has cooled. The SAFE LED illuminates at 624 when the system is safe to touch.
The operator may then remove the control module at 626 and remove the component at 628. This may be done by lifting both off the motherboard as a single assembly. The component may then be released from the control module. The interposer connection array and the component connection array may then be cleaned at 630 of excess solder, rosin, or any other material. For a test system or to repair an operational system, the interposer is prepared for the installation of another component at 632. As an example, a cleaning pad may be installed in the control module, a cleaning cycle initiated. The pad may be used to remove any excess solder and prepare for the installation of a new component. In other cases, the interposer or the component or both may be replaced or discarded. Any preparation of the component or the interposer may be adapted to suit any particular implementation and used of the control module.
As shown the interposer requires very little additional space on the board compared to a surface mount connection. The interposer requires much less space than a socket. This increases flexibility for board designs. The interposer provides a more reliable and efficient connection than an MPI socket. The risk of factory and field damage during assembly or service that is common with LGA sockets is also eliminated.
The control module allows for the last minute configuration of parts, increasing efficiency and minimizing inventory management in a system factory. Additionally, the reworkable nature of the connection to the interposer allows an expensive CPU component to be reclaimed if it is installed on a defective board. The control module is also small and portable. This allows for the component to be replaced, for upgrade or repair on installed systems in the field. The system does not have to be returned to a remote factory or repair facility.
Using power supplied to the motherboard, the control module electrically enables solder reflow between the component and the interposer by providing a constant controlled power to, for example, a BGA (Ball Grid Array) heater. The control module includes circuitry to maintain the heater temperature. The temperature may be set by the motherboard or the temperatures may be set by a control module memory. This heater temperature may be set and changed using the control module at any time during the substrate solder ball reflow process.
The solder is melted under a thermal-balance condition, which is maintained in this example by closed loop control. The closed loop keeps the power delivered to the heater constant, regardless of the heater resistance. The control circuitry also incorporates an enable input 718 that is applied to a comparator 718. The enable comparator compares the enable input to the temperatures set signal and if both are active then the comparator output is provided to the power MOSFET 708. The enable input 718 is set by an external control switch, such as the reflow position of the rotary switch of the control module. The enable input activates the heater by activating the power MOSFET. This allows the control circuitry to regulate the heaters when a package replacement or a solder ball reflow process starts.
When the controlled circuit is enabled, the switching MOSFET turns on and the output capacitor of the RC-filter starts to be charged by the current sensor signal. Once the capacitor voltage crosses an upper hysteretic comparator threshold, set by the TSS, the hysteretic comparator turns the MOSFET off and the RC filter capacitor starts to discharge. As the capacitor voltage crosses a lower hysteretic comparator threshold, the HC turns the MOSFET on. The two thresholds set a temperature range for the reflow process. The MOSFET cycles on and off to maintain the desired heater temperature. After the preset temperature is reached the heater operates in a thermal-balance condition until the package removal or other reflow process is complete and the enable signal gets de-asserted.
Since the low pass filter output signal is proportional to the average current level from the MOSFET, the power generated in the heater, remains unchanged. The power delivered by the MOSFET to the heater is equal to a product of the constant input voltage and the average current consumed by the heater. Because the switching MOSFET dissipates very little power almost all of the power consumed from the input power source is supplied to the heater. In the ON state the voltage across the MOSFET is close to zero. In the OFF state current through the MOSFET is close to zero so the MOSFET dissipates very little power.
A variety of different temperature and current control and regulation systems may be used to provide current to the heater traces. More complex and simpler systems may be used. The example of
The heater may be implemented in any of a variety of different ways.
To generate a required power level in the heater at a lower supply voltage and without using a boost regulator, the heater trace may be divided into N equal sections, which may be controlled jointly or individually, using one or more switches, to provide different temperatures in different heater domains. The resistance of each section may be described as Rt/N, where Rt is the total resistance of the heater trace and N is the number of sections. By connecting all of the heater sections in parallel for joint control, the equivalent heater resistance is N times lower than the resistance of each section. The equivalent heater resistance RtE=Rt/N2.
In
This principle can be shown, for example by comparing a high (V1) voltage level and a low (V2) voltage level and then setting the power to be equal:
P=V
1
2
/R
tE=(N2×V22)/Rt
Accordingly, the same power level achieved at V2 may be achieved at V1/N. As an example to generate 24 W power in an original heater trace with resistance Rt=24Ω, a 24 V voltage source V1 is required. Dividing the heater trace into two equal sections and connecting the two sections in parallel, as shown in
By dividing the heater trace into equal sections and connecting them in parallel, as shown in
The circuit board 904 includes many other features (not shown) to support any of a variety of external components and to connect to power, data, I/O and other devices. The circuit board also includes alignment corners 912 to hold the interposer in position when attaching the interposer and also to help to align alignment pins 910 of a control module 932. In addition to the corners, the circuit board include three pegs 916 that engage three corresponding posts 918 on the control module. The posts are placed over the pegs to hold the control module in place.
The control module 932 has control circuitry 914 and a power connector 924 to receive power from an external supply. This received power may be used to run the control circuitry or to drive the heater traces of the interposer or both. A cover 926 covers the control circuitry and provides a user interface 928.
Analogous to inserting a processor into a socket, during repair or in a manufacturing flow a processor 906 is placed onto the interposer 904. Flux is applied by to the interposer. Alignment features on the interposer align the processor for correct soldering. The installation tool 932 containing the controller 914 is installed onto the board. The reflow cycle is initiated by the operator, and the profile runs, reflowing the processor to the board. The interposer is a part of the main motherboard build and already soldered onto the motherboard, although it could be attached a later time via a rework process. The processor is inserted into the interposer using alignment features by hand, or potentially via installation tool. The control module 932 is positioned on the board. Controller features mate to board features, and secure with screws or any suitable method. The board features may be heat sink mounting standoffs as shown in
Install mode is selected on the control module by software or a mode switch. Reflow is then initiated in response by software or mode switch. During the reflow operation, the reflow indicator 928 blinks, the hot indicator tells the operator to wait, and then the safe indicator illuminates, to indicate that the module can be safely removed.
As the reflow indicator blinks, the control module sends an excitation current through the pogo pins to the heater traces. The heater traces begin to respond to the excitation current. Sensor traces also begin to heat in response to the increasing temperature of the heater traces.
The controller 914 provides a precision current to the sensor traces through others of the pogo pins. The sensor traces are aligned to the heater trace segments to allow for individual control of zones for better flexibility and for compensation of differences in motherboard copper density and layout. The sensor layer of the interposer allows for the accurate temperature measurement and closed loop control of the heater zones.
The controller 914 monitors the voltage, representing sensor trace average temperature, to control the heater current and ensure the proper temperature is attained to meet the solder reflow profile. The controller completes the profile, and manages any controller interface LED indicators 928. The heat sink assembly may be the final installation step.
A power cable connector 956 is coupled to a power supply output 962 of the power module. The power supply output provides the heater drive current. A sensor signal output 958 of the interface module provides the sensor signals to a signal connector 964 of the power module. The signal connector of the interface module may also drive the user interface LEDs 954, and any other functional connections. An external power supply connector 962 of the power module receives an external DC power supply, or AC power supply to power the power module and provide power to feed to the heater traces and any components of the interface module 952. If the external power is AC, then a DC converter may be built into the power module.
With the implementation of
Depending on its applications, computing device 11 may include other components that may or may not be physically and electrically coupled to the board 2. These other components include, but are not limited to, volatile memory (e.g., DRAM) 8, non-volatile memory (e.g., ROM) 9, flash memory (not shown), a graphics processor 12, a digital signal processor (not shown), a crypto processor (not shown), a chipset 14, an antenna 16, a display 18 such as a touchscreen display, a touchscreen controller 20, a battery 22, an audio codec (not shown), a video codec (not shown), a power amplifier 24, a global positioning system (GPS) device 26, a compass 28, an accelerometer (not shown), a gyroscope (not shown), a speaker 30, a camera 32, and a mass storage device (such as hard disk drive) 10, compact disk (CD) (not shown), digital versatile disk (DVD) (not shown), and so forth). These components may be connected to the system board 2, mounted to the system board, or combined with any of the other components.
The communication chip 6 enables wireless and/or wired communications for the transfer of data to and from the computing device 11. The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. The communication chip 6 may implement any of a number of wireless or wired standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, Ethernet derivatives thereof, as well as any other wireless and wired protocols that are designated as 3G, 4G, 5G, and beyond. The computing device 11 may include a plurality of communication chips 6. For instance, a first communication chip 6 may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second communication chip 6 may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.
The processor 4 of the computing device 11 includes an integrated circuit die packaged within the processor 4. In some implementations of the invention, the integrated circuit die of the processor, memory devices, communication devices, or other components include one or more dies that are tested or mounted with an interposer as described herein, if desired. The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.
In various implementations, the computing device 11 may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, the computing device 11 may be any other electronic device that processes data.
Embodiments may be implemented as a part of one or more memory chips, controllers, CPUs (Central Processing Unit), microchips or integrated circuits interconnected using a motherboard, an application specific integrated circuit (ASIC), and/or a field programmable gate array (FPGA).
References to “one embodiment”, “an embodiment”, “example embodiment”, “various embodiments”, etc., indicate that the embodiment(s) of the invention so described may include particular features, structures, or characteristics, but not every embodiment necessarily includes the particular features, structures, or characteristics. Further, some embodiments may have some, all, or none of the features described for other embodiments.
In the following description and claims, the term “coupled” along with its derivatives, may be used. “Coupled” is used to indicate that two or more elements co-operate or interact with each other, but they may or may not have intervening physical or electrical components between them.
As used in the claims, unless otherwise specified, the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common element, merely indicate that different instances of like elements are being referred to, and are not intended to imply that the elements so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.
The following examples pertain to further embodiments. The various features of the different embodiments may be variously combined with some features included and others excluded to suit a variety of different applications. Some embodiments pertain to system having an interposer having a top side to connect to a silicon component and a bottom side to connect to a circuit board, the top side having a plurality of contact pads to electrically connect to the silicon component using solder, a plurality of heater traces in the interposer having connection terminals, and a removable control module to attach over the interposer and silicon component to conduct a current to the heater connection terminals to heat the heater traces, to melt a solder on the contact pads of the interposer and to form a solder joint between the component and the interposer.
Further embodiments include a temperature control circuit of the control module to control the current provided to the heater connection terminals. In further embodiments, the temperature control circuit comprises a comparator to compare a sensed temperature of the interposer to a threshold and to adjust the current to the heater connection terminals based on the comparison. The temperature control circuit comprises a power transistor coupled to the heater traces and wherein the comparator has a second input coupled to a current sensor signal so that the power transistor is switched on when the current sensor signal is below a selected voltage.
Further embodiments include an RC-filter between the current sensor signal and the comparator so that a capacitor of the RC-filter is charged by the current sensor signal and the power transistor is switched off after the RC-filter reaches a selected charge voltage.
In further embodiments the heater traces comprise a serpentine pattern of conductive traces that pass between contact pads of the interposer. The control module further comprises pins to removably physically connect the control module to the circuit board, the pins extending from the control module on at least two opposing sides of the component to connect to the circuit board. The pins connect to the circuit board by extending through and engaging holes formed in the circuit board.
In further embodiments the control module further comprises pogo pins to electrically connect with lands on the circuit board to conduct current from the circuit board to the control module. The control module further comprise pogo pins to electrically connect with lands on the interposer to conduct current from the control module to the heater connection terminals.
In further embodiments the control module further comprises a control switch to cause the control module start a solder reflow process by conducting current to the heater connection terminals. The control module further comprises a display to indicate whether the control module is operating a solder reflow process. The plurality of heater traces are connected in parallel to a single supply voltage.
Some embodiments pertain to a method including receiving a reflow signal at a control module, the control module being attached to a circuit board over a silicon component and over an interposer, the interposer being connected to the circuit board, the interposer having contact pads to electrically connect to pads of the silicon component, initiating a reflow cycle of the control module, applying current from the control module to heater connection terminals of the interposer, the heater connection terminal being coupled to resistive heater traces of the interposer to reflow solder on the contact pads of the interposer, and stopping the application of current upon the completion of the reflow cycle.
Further embodiments include activating a reflow indicator signal upon initiating the reflow cycle. Further embodiments include activating a hot indicator signal after initiating the reflow cycle and activating a safe indicator signal after completing the reflow cycle. In further embodiments applying current comprises applying current from the circuit board to the interposer through the control module. Further embodiments include regulating the applied current to maintain a predetermined reflow temperature of the interposer.
Some embodiment pertain to an apparatus including an electrical connector to receive power from an external supply, an electrical connector to drive heater traces of an interposer to heat solder connections and attach a component to the interposer, an electrical connector to receive thermal sensor signals to determine a temperature of the solder connections, a user interface to receive a command to initiate a solder process and to indicate that the solder process is finished, and a controller to receive the command, to apply the received power to the heater traces in response thereto, to control the applied heater power based on the received thermal sensor signals to drive a solder reflow profile in the solder connections, and to power the user interface to indicate that the solder process is finished.
In further embodiments, the apparatus removably attaches to a printed circuit board to drive the solder reflow process and to press the component against the circuit board.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2014/032280 | 3/29/2014 | WO | 00 |
