Reworking solder components without removing the part

Abstract

A method for forming an electronic device, comprising: soldering pins from components located on a first side of a substrate to plated-through holes in the substrate; and applying solder paste to openings of the plated-through holes on a second side of the substrate opposite the first side on which the components are located. The method may further comprise drawing the solder paste into the pins to provide a rework solder joint joining at least one of the pins to the plated-through holes.

Description

[Background technology]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to solder joints in connectors and electrical devices, and more particularly to reworking solder joints.

[0002] Reflow soldering, using long industrial convection ovens, is one method of soldering surface mount technology (SMT) components to printed circuit boards or PCBs. The temperature of each segment of the oven is adjusted according to the specific thermal requirements of each assembly. Reflow ovens specifically designed for soldering surface mount components can also be used for through-hole components by filling the holes with solder paste and inserting the component leads into the paste. However, wave soldering is the more common method for soldering multi-lead through-hole components to circuit boards designed for surface mount components.

[0003] When used on boards with a mix of SMT and plated through-hole (PTH) components, through-hole reflow, if achievable with specially modified paste stencils, has the potential to eliminate the wave soldering step from the assembly process and reduce assembly costs. Reflow soldering of through-hole components using solder paste in a convection oven process is called intrusive soldering. Summary of the Invention

[0004] In one embodiment, a method for forming an electronic device is provided, the method including soldering pins from components located on a first side of a substrate to plated-through holes (PTHs) in the substrate. The method further includes applying solder paste to openings of the plated-through holes on a second side of the substrate opposite the first side on which the components are located. The method may also include drawing the solder paste into the pins to provide a rework solder joint joining at least one of the pins to the plated-through holes.

[0005] In another embodiment, a method of forming an electrical device is provided, comprising: soldering pins from components located on a first side of a substrate to plated-through holes in the substrate; and applying solder paste to openings of the plated-through holes on a second side of the substrate opposite the first side on which the components are located. The method may further comprise melting the solder paste and using gravity to draw the solder paste into the pins, thereby providing a rework solder joint connecting at least one of the pins to the plated-through holes.

[0006] In yet another embodiment, a method for forming an electronic device is provided, comprising: soldering pins from components located on a first side of a substrate to plated-through holes in the substrate; and applying solder paste to openings of the plated-through holes on a second side of the substrate opposite the first side on which the components are located. The method further comprises melting the solder paste and using a vacuum to draw the solder paste into the pins, thereby providing a rework solder joint connecting at least one of the pins to the plated-through holes. [Brief explanation of the drawings]

[0007] The following detailed description, given by way of example and not intended to limit the disclosure, is best understood in conjunction with the accompanying drawings, in which like reference numerals refer to like elements and parts, and in which:

[0008] [Figure 1] FIG. 1 is a cross-sectional side view of a component soldered to a substrate by penetration solder joining of the pin to a plated-through-hole (PTH) in accordance with one embodiment of the present disclosure, where one of the pins is open, i.e., there is a lack of solder between the component pin and the plated-through-hole (PTH) to provide a secure connection.

[0009] [Figure 2] FIG. 10 is a cross-sectional side view illustrating a component received in a support stiffener such that the ends of the plated through holes opposite the surface closest to the joined component face upward, according to one embodiment of the present disclosure.

[0010] [Figure 3] FIG. 1 is a cross-sectional side view illustrating the placement of a stencil exposing openings to plated through holes (PTHs) according to one embodiment of the present disclosure.

[0011] [Figure 4] FIG. 1 is a cross-sectional side view illustrating the application of solder paste to plated-through holes through a stencil according to one embodiment of the present disclosure.

[0012] [Figure 5] FIG. 5 is a side cross-sectional view showing the structure shown in FIG. 4 with the stencil removed.

[0013] [Figure 6] FIG. 6 is a cross-sectional side view of a component with penetration solder connections to a PCB positioned in a hot gas ball grid array (BGA) rework station with the second application of solder paste shown in FIG. 5 applied in accordance with one embodiment of the present disclosure.

[0014] [Figure 7] FIG. 7 is a side cross-sectional view illustrating a reflow process applied to the structure shown in FIG. 6, in which gravity draws the solder from the second application location shown in FIG. 5 deep into the plated-through holes (PTHs) in accordance with one embodiment of the present disclosure.

[0015] [Figure 8] FIG. 8 is a cross-sectional side view of a reworked solder joint assembly after cooling and removal from the hot gas ball grid array (BGA) rework station shown in FIG. 7 according to one embodiment of the present disclosure.

[0016] [Figure 9] 7 is a cross-sectional side view of another embodiment of the present disclosure, in which a combination of vacuum and gravity is used to rework the solder following the application of FIG. 5 and the removal of the stencil shown in FIG. 6 according to another embodiment of the present disclosure.

[0017] [Figure 10] 10 is a side cross-sectional view illustrating a reflow process applied to the structure shown in FIG. 9, in which the solder is drawn deep into the plated-through holes (PTHs) from the second application location shown in FIG. 5 using a combination of gravity and the application of a vacuum, according to one embodiment of the present disclosure.

[0018] [Figure 11] 11 is a cross-sectional side view of a reworked solder joint assembly after cooling and removal from the hot gas ball grid array (BGA) rework station shown in FIG. 10 according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] Detailed embodiments of the claimed structures and methods are disclosed herein. However, it should be understood that the disclosed embodiments are merely exemplary of the claimed structures and methods, which may be embodied in various forms. Furthermore, each of the multiple examples shown in connection with various embodiments is intended to be illustrative and not limiting. Furthermore, the figures are not necessarily drawn to scale, and some features may be exaggerated to show details of particular components. Therefore, the specific structural and functional details disclosed herein are not intended to be limiting, but merely a representative basis for teaching those skilled in the art how to utilize the disclosed methods and structures in various ways. For purposes of explanation, the terms "above," "below," "right," "left," "vertical," "horizontal," "top," and "bottom," as well as variations thereof, refer to the embodiments of the present disclosure as oriented in the drawing figures. The term "positioned on" means that a first element, such as a first structure, is on a second element, such as a second structure, where an intervening element, such as an interface structure, e.g., an interface layer, may be present between the first and second elements. The term "direct contact" means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediate conductive, insulating, or semiconductive layer at the interface between the two elements.

[0020] The methods and structures described herein provide for reworking penetration solder components without removing the part. Penetration soldering is increasingly being applied for a number of positive reasons. For example, penetration soldering is applicable to solder applications where the physical thickness of raw cards is increasing. Additionally, penetration soldering can provide effective connections to the pin length of plated-through-hole (PTH) components.

[0021] Furthermore, wave soldering is a legacy process that is not cost-effective, and the industry is generally moving away from this technology for a number of reasons. For example, in some instances, the pins for solder connections are shorter than the thickness of the card. In some instances, as thicker cards are used, it may happen that if component pins are short, these components will not be soldered sufficiently and reliably when methods such as wave soldering or solder pot soldering are used.

[0022] Penetration soldering provides a solution to some of the drawbacks mentioned above. "Penetration soldering" is a process in which solder paste for through-hole components is applied using a stencil or syringe that fits over the through-hole components that are inserted and reflow soldered together with surface mount components.

[0023] "Reflow soldering," referred to above as "reflow soldered together," is a process in which solder paste (a sticky mixture of powdered solder and flux) is used to temporarily attach one or several thousand tiny electrical components to their contact pads, and then the entire assembly is exposed to heat (e.g., controlled heat). In response to the heat, the solder paste reflows in its molten state, creating a permanent solder joint. Heating can be accomplished by passing the assembly through a reflow oven under infrared lamps, or (less conventionally) by using a desoldering hot air pen to solder individual joints.

[0024] However, like all soldering methods, penetration soldering has been found to have some drawbacks that can require rework. One common situation that leads to drawbacks in solder joints formed using penetration soldering is that as the dimensions of plated-through-hole (PTH) components decrease, an insufficient amount of solder can be present in the pinhole, resulting in a solder joint with insufficient solder to make a reliable contact. In some instances, a complete "open" can occur without working the contact hole to inject paste. Another drawback results from poor solder wetting of the pin or plated-through-hole (PTH) component.

[0025] When these defects occur, one documented process that can correct the above defects is a rework process that removes the component from the connection. In one example, the rework process involves placing the connector / printed circuit board (PCB) in a ball grid array (BGA) hot gas rework system, where the assembly can undergo global preheating, typically to approximately 120°C. In some examples, a hot gas rework nozzle is positioned and lowered over the pins in the hole component. Localized, hot nitrogen gas is applied until the solder in the plated-through-hole (PTH) melts, and then a worker with pliers pulls out the component. This removes the component from the connection, but this forceful separation can undesirably damage the component. In some examples, the solder can then be removed from the plated-through-hole (PTH) using a solder sucker. The card can then be allowed to cool, after which new solder paste can be applied to the plated-through-hole (PTH). In some examples, a new component can be placed in the plated-through-hole (PTH), forcing the paste down the hole. The assembly can then be returned to the BGA hot gas rework system. Reflow to provide new connections may involve similar steps of preheating and localized heating around the component system with a nozzle. The above process is laborious, potentially damaging to the components involved, and time consuming.

[0026] The methods described herein present a rework process that can be performed on intrusive solder components without removing and / or replacing the components soldered to the board / card. More specifically, the methods described herein can perform the rework step by repacking the solder paste in conjunction with gravity and / or vacuum techniques to accomplish the rework. The methods and structures of the present disclosure will now be described in further detail with reference to Figures 1-11.

[0027] 1 illustrates one embodiment of a component 50 in which solder (denoted by reference numeral 30) is joined to a substrate 55 by penetration solder joining of pin 40 to plated-through hole (PTH) 25. In the embodiment illustrated in FIG. 1, one of the pins 40a is open, meaning there is a lack of solder between pin 40a of component 50 and plated-through hole (PTH) 25 to provide a secure connection.

[0028] In one embodiment, the component 50 may be an integrated circuit (IC) chip 5 solder-bonded to a substrate 55, such as a printed circuit board (PCB). An integrated circuit or monolithic integrated circuit (also called an IC chip or microchip) is a set of electronic circuits on a single, small, flat piece of semiconductor material (or chip). The semiconductor material may be a Group IV semiconductor, such as silicon (Si), or a Group III-V semiconductor material, such as gallium arsenide (GaAs). Multiple field-effect transistors (FETs), such as metal-oxide-semiconductor field-effect transistors (MOSFETs), may be integrated within the chip. Semiconductor device types, such as FETs, may include horizontally oriented devices, vertically oriented devices, fin-type field-effect transistors, and nanowire and / or nanosheet channel-type devices. Any field-effect transistor (FET), such as a gate structure including a channel separating source and drain regions, may be integrated within the chip. The above-mentioned examples of FET types are provided for illustrative purposes only and are not intended to be limiting. It should be noted that regardless of the type of device provided by the component, electrical connections to the component 50 are via the pins 40, 40a. The pins 40, 40a are constructed of a conductive material such as a metal, e.g., copper, and are sized and shaped to engage plated-through holes (PTHs) in the substrate 55.

[0029] In some embodiments, the substrate 55 may be a printed circuit board. A printed circuit board (PCB) includes electrical contact pads and paths that provide electrical signals to the component 50 attached thereto. The printed circuit board (PCB) may be a metal core printed circuit board (MCPB). In some embodiments, other materials, such as FR4, may also be utilized. As described above, the pins 40, 40a of the component 50 are soldered to the plated-through holes (PTHs) 25 of the substrate 55 to provide electrical connection between the substrate 55 and the component 50.

[0030] "Plated through holes" are features that are either milled or drilled into the body of substrate 55 and then plated with a conductive material. For example, the through holes may be plated with conductive copper (Cu). Traces are run between plated through holes (PTHs) 25 to provide electrical connections to other components on the substrate when components such as those identified by reference numeral 50 are soldered in place.

[0031] As mentioned, the solder connection between the pins 40, 40a of the component 50 and the plated-through holes (PTHs) (solder identified by reference numeral 30) may be provided by penetration soldering. Penetration soldering is a process in which a solder paste for a through-hole component is applied using a stencil or syringe that fits over the through-hole component, which is inserted alongside a surface-mount component and reflow-soldered. As used herein, the term "solder" refers to any metal or metal compound or alloy that is melted and then allowed to cool to join two or more metal surfaces together. The solder joint 30 may be composed of a metal suitable for soldering. For example, in some embodiments, the solder 30 may be composed of a eutectic alloy of tin and lead, or may be a lead-free solder composition. In some examples, the solder 30 may be a tin / copper / nickel-based solder, such as Sn-0.7Cu. In another example, the solder 30 may be a lead / tin / silver-based solder such as Pb93-Sn5-Ag2. In yet another example, the solder 30 may be a tin / silver-based solder such as Sn-3.5Ag. In a further example, the solder 30 may be a tin / silver / copper-based solder such as Sn-3.8Ag-0.7Cu. In yet another example, the solder 30 may be a lead / tin-based solder such as Pb980-10Sn. Generally speaking, solders have a melting temperature in the range of 150°C to 300°C.

[0032] 1, one of the pins 40a is open, meaning that there is not enough solder to provide a reliable connection between the pin 40a of the component 50 and the plated through hole (PTH) 25. This condition may be confirmed visually, or electrical testing may be able to determine the presence of an open pin.

[0033] 2 illustrates one embodiment in which a component is received in a support stiffener 60 with the ends of the plated-through holes 25 facing upward, away from the side closest to the joined component 50. The side of the plated-through holes 25 closest to the joined component 50 is referred to as the front side F1 of the board 55. The side of the plated-through holes 25 opposite the front side F1 of the board 55 is referred to as the back side F2 of the board 55. As shown in FIGS. 1 and 2, the solder 30 initially applied by penetration soldering is positioned near the front side F1 of the board 55, opposite the back side F2 of the board 55. However, when the component 50 is soldered to the plated-through holes 25, the openings for engaging the pins 40, 40a in the front side F1 of the board 55 are blocked. FIG. 2 shows the soldered component 50 and substrate 55 assembly positioned on support stiffener 60, which mechanically supports the component and positions the back surface F2 of substrate 55 so that additional solder can be applied and introduced into plated-through holes 25 from the back surface F2 of substrate 55.

[0034] FIG. 3 illustrates one embodiment in which a stencil 63 is installed, exposing openings for the plated-through holes (PTHs) 25. With the components housed in the support stiffener 60, application of the stencil 63 is one step toward applying solder paste 64 from the backside F2 of the substrate 55 to the pins, including, for example, the open pin 40a. The stencil 63 may have holes therethrough for directing the paste through the stencil 63 toward at least the open pin 40a. In some examples, the stencil 63 may have openings corresponding to all of the plated-through holes 25 that engage the pins 40, 40a of the components to be soldered to the substrate 55. The stencil 63 is composed of a solid material that prevents the solder paste 65 from passing through the stencil 63, except for openings corresponding to the intended localized application of the solder paste 65. In some examples, the stencil 63 may be a metal plate. In some examples, the stencil 63 may include adhesive tape. For example, the stencil 63 may comprise a polyamide-based silicone adhesive tape 63. In some embodiments, the stencil 63 may comprise a combination of adhesive tape and a patterned metal plate having openings corresponding to the plated-through holes 25. In some embodiments, the stencil 63 may be constructed entirely from adhesive tape. In further embodiments, instead of utilizing a stencil 63, the solder paste 65 may be applied to the plated-through holes 25 using a syringe.

[0035] 4 illustrates the application of solder paste 65 to plated-through holes 25 via a stencil 63. Solder paste 65 may first be deposited onto stencil 63, for example, by brush, syringe, jet, curtain flow, etc., and then a squeegee 66 may be used to spread and force the solder paste 65 through the openings in stencil 63. A "squeegee" is a tool having a flat, smooth, deformable blade, e.g., rubber, plastic, and / or metal, used to remove or control the flow of material over a substantially flat surface, e.g., stencil 63 (if present).

[0036] "Solder paste" is made from a combination of solder powder and thick flux, which are pre-blended to form a paste. This combination creates a thick material, which allows for easier deposition, typically by printing or depositing with a stencil. In solder reflow applications, the solder paste is heated above its liquidus temperature. This temperature activates the flux and removes oxides from the surfaces of the leads, metal pads, and solder powder, allowing the solder powder to effectively melt and form a solid metal joint.

[0037] The alloy type and particle size of the solder powder in the solder paste 65 determine the time above liquidus, the level of oxide, the strength of the intermetallic bond, the minimum pore size, and the inner diameter of the dispensed print. Fluxes for the solder paste 65 can be made from a combination of ingredients such as rosin, activators, rheological additives, and solvents. The combination of these ingredients determines the subcategory the flux falls into, which in turn affects the rheological properties of the material and the manner in which the flux removes oxides.

[0038] In some embodiments, the alloy components of the solder paste 65 may be composed of various alloys, such as a combination of eutectic (tin and lead) and lead-free, typically SAC305 (tin, silver 3.0, copper 0.5). Alloys composed mostly of tin (Sn) have a low melting point and high tensile and shear strength. Additional metals can be added to further modify the alloy's mechanical properties. For example, lead can lower the overall melting temperature and form strong bonds with other metals, such as copper and aluminum, which are often used for PCB pads or component leads. Lead-free solder alternatives, such as SAC305, composed of tin, silver, and copper, are attractive. Copper lowers the alloy's melting point and aids in wetting of the molten solder, while silver adds mechanical strength but is not as ductile as lead. Additionally, other alloys with different metal and percentage level combinations may exist to improve the quality of the solder joint. Some of these metals include, but are not limited to, antimony, bismuth, indium, and nickel.

[0039] Solder paste flux is a metallurgical material that serves multiple functions and is a component of metal joining and extraction metallurgy. Fluxes serve the functions of stabilizers, flow agents, and / or chemical cleaners. In solder paste, one purpose of flux is to act as a cleaner. Fluxes are reducing agents that prepare the metal surface by removing oxides, debris, and contamination. This prevents oxidation of the metal surface and joining material, preparing the surface and aiding in wetting of the molten metal. The flux in solder paste 65 can be one of a water-soluble flux, a no-clean flux, and a conventional rosin flux.

[0040] Following application of the solder paste 65, the solder paste 65 is forced through the holes in the stencil 63 by a squeegee 66. In the embodiment shown in Figure 4, the solder paste 65 is forced through the openings in the stencil 63 and into the openings of the plated-through holes 25. At this stage in the process flow, the solder paste 65 is proximate the backside F2 of the substrate 55 and is not in direct contact with the pins 40, 40a.

[0041] It should be noted that some embodiments are contemplated in which a syringe is used to apply the solder paste 65 directly to the openings of the plated-through holes 25. In such instances, the stencil 65 and squeegee 66 may be omitted.

[0042] Figure 5 shows the removal of stencil 63 from the structure shown in Figure 4. In some embodiments, excess solder can be removed before or during removal of stencil 63.

[0043] FIG. 6 illustrates one embodiment in which a penetration-solder-connected component 50 to a substrate 55 (e.g., a printed circuit board (PCB)) with a second application of solder paste 65 has been positioned within a hot gas ball grid array (BGA) rework station 70. BGA rework stations 70 are machines that can be used to refinish or repair printed circuit boards (PCBs) having ball grid array (BGA) packaging and surface-mount devices (SMDs). These rework stations allow technicians to remove defective parts, reinstall misplaced parts, or replace any missing parts on the PCB. Generally, BGA rework stations operate by forcing heated gas 76 through a nozzle that is lowered adjacent to the substrate 55. Additionally, in the embodiment illustrated in FIG. 6, the BGA rework station 70 includes a backside heating element 75. The backside heating element 70 can act in combination with the heated gas 76 to increase the temperature of the solder 30, 65.

[0044] For the method of the present disclosure, the substrate 55 and component 50 assembly, with the plated-through holes 25 having been coated a second time with solder paste 65, is placed in a hot air BGA rework machine 70 such that the substrate 55, e.g., a PCB, is upside down, with the intruding component 55 on the bottom and the exposed opening of the plated-through hole (PTH) facing up. More specifically, the backside F2 of the substrate 55 faces up.

[0045] 6, to repair the open pin 40a, the hot air nozzle of the hot air BGA rework machine 70 is aligned with the location of the plated-through hole (PTH) 25 requiring repair. A hot air rework is then applied. For example, nitrogen gas can be used to improve wetting, and the hot air rework temperature is sufficient to melt the solder but does not exceed 240°C. In some embodiments, the hot air rework temperature can range from 200°C to 235°C. The duration of the hot air rework is less than 10 minutes, for example, 7 minutes or less.

[0046] In some embodiments, reflow of the solder paste 65 is induced by aligning a hot air nozzle at the location of the plated through hole needing repair and running a hot air rework recipe.

[0047] Figure 7 illustrates one embodiment of a reflow process applied to the structure shown in Figure 6, where gravity is pulling the solder from the solder paste 65 deep into the plated-through holes (PTHs) 25 from the second application position shown in Figure 5. During reflow, the solder paste 60 melts, and gravity pulls the solder down onto the pins in the plated-through holes 25, contacting the pins 40, 40a. The solder flows onto the pins, electrically connecting the pins 40, 40a to the plated components of the plated-through holes (PTHs), forming reworked solder joints 80.

[0048] 8 shows the assembly with reworked solder joints 80 after cooling and removal from the hot gas ball grid array (BGA) rework station 70 shown in FIG. 7. After reflow, once the assembly has cooled, X-ray locations verifying open defects in the solder, such as pin 40a, have been repaired. More specifically, in some embodiments, the reworked solder joints 80 result in direct contact of the solder paste 65 with the plated sidewalls of the plated through holes 25 and with the pins 40a.

[0049] It should be noted that the embodiment shown in Figures 1-8 represents only one embodiment of the present disclosure. Furthermore, it should be noted that the method described with reference to Figures 1-8 is not intended to be limited to only the steps shown in the provided figures. For example, any number of preliminary, intermediate, and final process steps may be within the scope of the present claims even if not shown in the provided figures. Furthermore, Figures 9-11 illustrate yet another embodiment of the present disclosure in which the solder is drawn into contact with the pins (e.g., open pin 40a) by also applying a vacuum to solder paste 65 during the reflow process.

[0050] The embodiments shown in Figures 9-11 may start with a structure produced by the process flow described above with reference to Figures 1-5. Figure 9 shows another embodiment of a hot gas ball grid assembly (BGA) rework station 70, including a top heating element 76 and a backside heating element 75, as well as a vacuum port 82 through which a vacuum can be applied. Figure 9 illustrates how, following the application of solder paste 65 shown in Figure 5 and the removal of stencil 63 shown in Figure 6, a vacuum is applied, for example, through vacuum port 82 in combination with gravity, to rework the solder. The hot gas ball grid assembly (BGA) rework station 70 shown in Figure 9 is similar to the hot gas ball grid assembly (BGA) rework station 70 shown in Figure 5, except that the rework station 70 shown in Figure 9 includes additional heating elements, a port 82 for applying a vacuum, and a seal 81 for sealing the chamber in which the rework process is performed. The heating elements 75, 76 can act to raise the temperature of the solder 30, 65 for reflow, while the vacuum applied through the vacuum port 82 acts to draw the molten solder deep into the plated through holes 25, thereby bringing the solder paste 65 into contact with the pins 40, 40a (e.g., open pin 40a).

[0051] For the method of the present disclosure, the substrate 55 and component 50 assembly, with the plated-through holes 25 coated a second time with solder paste 65, is placed in a hot air BGA rework machine 70 so that the substrate 55, e.g., a PCB, is upside down, with the intruding component 55 on the bottom and the exposed openings of the plated-through holes (PTHs) facing up. More specifically, the backside F2 of the substrate 55 faces up.

[0052] Continuing with reference to FIG. 9 , to repair the open pin 40a, the hot air nozzle of the hot air BGA rework machine 70 is aligned with the plated-through hole (PTH) 25 requiring repair. Hot air rework is then applied. In some embodiments, the hot air rework may include aligning the head 76 of the upper IR heating element and the head 75 of the lower IR heating element with the plated-through hole 25 requiring repair (e.g., the plated-through hole 25 where the open pin 40a is located). Similar to the embodiment described with reference to FIGS. 1-8 , nitrogen gas may be used to improve wetting, and the hot air rework temperature is sufficient to melt the solder but not exceed 240°C. In some embodiments, the hot air rework temperature may range from 200°C to 235°C. The duration of the hot air rework is less than 10 minutes, such as 7 minutes or less.

[0053] The embodiment shown in FIG. 9 further includes applying a vacuum to draw reflowed solder from the solder paste 65 into direct contact with the pins 40, 40a of the component 50 residing in the plated-through holes 25. In some embodiments, applying a vacuum includes sealing the IR heating element heads 75, 76 to the substrate 55. The sealing of the IR heating element heads 75, 76 to the substrate 55, which may be a PCB substrate, may include a seal, indicated generally by reference numeral 81. The application of the seal 81 may be followed by the application of a vacuum. The space defined by the assembly of the seal 81, the IR heating element heads 75, 76, and the substrate 55 may function as a vacuum chamber. A vacuum chamber is a rigid enclosure from which air and other gases are removed, for example, by a vacuum pump through vacuum port 82. In this manner, a low-pressure environment, commonly referred to as a vacuum, is created within the chamber. For comparison, atmospheric pressure is approximately 760 Torr (1.0132 Pa×10 5 In some embodiments, application of a vacuum through vacuum port 82 provides a pressure between 760 Torr and 25 Torr (1.0132 Pa×10 5 ~3.333×10 3In some embodiments, application of a vacuum through vacuum port 82 creates a low vacuum in the range of 25 to 1×10 -3 Torr (3.333 × 10 3 Pa~1.3332×10 -1 In some embodiments, application of the vacuum creates a medium vacuum in the range of 1×10 -3 Torr ~ 1 × 10 -9 Torr (1.3332 × 10 -1 Pa~1.3332×10 -7 In some embodiments, application of the vacuum creates a high (hard) vacuum in the range of 1×10 -9 ~1×10 -12 Torr (1.3332 × 10 -7 Pa~1.3332×10 -10 An ultra-high vacuum in the range of 1000 Pa is created. Note that the vacuum described above is applied through vacuum port 82 to draw solder paste 60 out of openings in backside F2 of substrate 50 and toward the center of plated-through hole 25.

[0054] During reflow, the solder paste 60 melts, and gravity and vacuum forces pull the solder down onto the pins 40, 40a in the plated-through holes of the substrate 55. Figure 10 illustrates one embodiment of a high temperature and vacuum assisted reflow process applied to the structure shown in Figure 9, where gravity, along with a vacuum applied through vacuum port 82, pulls the solder from the solder paste 65 deep into the plated-through holes (PTHs) 25 from the second application position shown in Figure 5. During reflow, the solder paste 65 melts, and gravity pulls the solder down onto and into contact with the pins 40, 40a in the plated-through holes 25. The flow of the solder to the pins 40, 40a electrically connects the pins 40, 40a to the plated components of the plated-through holes (PTHs), forming reworked solder joints 80.

[0055] 11 shows the assembly with reworked solder joints 80 after cooling and removal from the hot gas ball grid array (BGA) rework station 70 shown in FIG. 7. After reflow, once the assembly has cooled, X-ray locations verifying open defects in the solder, such as pin 40a, have been repaired. More specifically, in some embodiments, the reworked solder joints 80 result in direct contact of the solder paste 65 with the plated sidewalls of the plated through holes 25 and with the pins 40a.

[0056] 1-11 allows the component 50 to remain engaged with the substrate 55, which may be, for example, a printed circuit board (PCB). More specifically, a solder joint 80 may be created to compensate for an open pin 40a resulting from the component 50 engaging the substrate 55 with intrusion solder. The solder joint 80 results from a second application of solder paste 65 to the backside of the plated-through hole 25, and the engagement of the solder paste 65 with the pins 40, 40a may be assisted by high temperature, gravity, and / or vacuum.

[0057] Aspects of the present invention have been described with respect to given example architectures; however, it should be understood that other architectures, structures, substrate materials, and process features and steps may be varied within the scope of aspects of the present invention.

[0058] This embodiment may include a design for an integrated circuit chip, which may be created in a graphical computer programming language and stored in a computer storage medium (such as a disk, tape, physical hard drive, or virtual hard drive, such as in a storage access network). If the designer does not manufacture the chip or the photolithography masks used to manufacture the chip, the designer may transmit the resulting design directly or indirectly to such an entity by physical means (e.g., by providing a copy of the storage medium storing the design) or electronically (e.g., via the Internet). The stored design is then converted into an appropriate format (e.g., GDSII) for the manufacture of photolithography masks, which typically include multiple copies of the chip design to be formed on a wafer. The photolithography masks are utilized to define the areas of the wafer (and / or layers thereon) to be etched or otherwise processed.

[0059] The methods described herein can be used in the manufacture of integrated circuit chips. The resulting integrated circuit chips can be distributed by manufacturers in raw wafer form (i.e., as a single wafer with multiple unpackaged chips), as bare dies, or in packaged form. In the latter case, the chips are mounted in a single-chip package (such as a plastic carrier with leads attached to a motherboard or other higher-level carrier) or in a multi-chip package (such as a ceramic carrier with either surface interconnects or embedded interconnects, or both). In either case, the chips are then integrated with other chips, discrete circuit elements, and / or other signal processing devices as part of either (a) an intermediate product such as a motherboard, or (b) a final product. The final product can be any product containing the integrated circuit chip, ranging from toys and other low-end applications to advanced computer products with displays, keyboards or other input devices, and central processing units.

[0060] It should also be understood that material compounds are described in terms of the elements listed, e.g., SiGe. These compounds may contain different ratios of elements within the compound, e.g., SiGe may contain Si x Ge 1-x where x is less than or equal to 1, etc. Additionally, other elements may be included in the compound and still function according to the present principles. Compounds with additional elements are referred to herein as alloys.

[0061] References herein to "one embodiment" or "an embodiment," as well as other variations thereof, mean that a particular feature, structure, characteristic, etc. described in connection with an embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment," and any other variations thereof, in various places throughout this specification are not necessarily all referring to the same embodiment.

[0062] It should be understood that the use of any of the following: " / ," "and / or," and "at least one of," is intended to encompass the selection of only the first listed alternative (A), or the selection of only the second listed alternative (B), or the selection of both alternatives (A and B), for example, in the case of "A / B," "A and / or B," and "at least one of A and B." As a further example, in the case of "A, B, and / or C" and "at least one of A, B, and C," such language is intended to encompass the selection of only the first listed alternative (A), or the selection of only the second listed alternative (B), or the selection of only the third listed alternative (C), or the selection of only the first and second listed alternatives (A and B), or the selection of only the first and third listed alternatives (A and C), or the selection of only the second and third listed alternatives (B and C), or the selection of all three alternatives (A, B, and C). This can be extended to many of the items listed, as would be readily apparent to one of ordinary skill in this and related arts.

[0063] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit example embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0064] Spatially relative terms such as "beneath," "below," "lower," "above," "upper," and the like are used herein for ease of description and may describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that spatially relative terms are intended to encompass various orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" such other elements or features. Thus, the term "beneath" can encompass both an orientation of above and below. A device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly. Furthermore, when a layer is referred to as being "between" two layers, it will also be understood that it may be the only layer between the two layers, or that one or more intervening layers may also be present.

[0065] While the method and structure for reworking solder components without part removal has been particularly shown and described with respect to preferred embodiments thereof, those skilled in the art will recognize that these and other changes in form and detail may be made therein without departing from the scope of the present disclosure. It is therefore intended that the present disclosure not be limited to the exact form and detail described and illustrated, but fall within the scope of the appended claims.

Claims

1. soldering pins from components located on a first side of the substrate to plated through holes in said substrate; applying solder paste to the openings of the plated-through holes on a second side of the substrate opposite the first side of the substrate on which the component is located; and providing a rework solder joint joining at least one of the pins to the plated-through hole by drawing the solder paste into the pin.

1. A method for forming an electronic device, comprising:

2. 10. The method of claim 1, wherein the step of soldering the pins from the component to the plated-through holes in the substrate uses penetration solder bonding.

3. 2. The method of claim 1, wherein the step of soldering the pin from the component to the plated-through hole of the substrate results in an open pin that is not soldered to the plated-through hole of the substrate.

4. 4. The method of claim 3, wherein the step of providing a rework solder joint solders the open pin by drawing the solder paste into the pin.

5. 5. The method of claim 4, wherein the step of drawing the solder paste comprises reflowing the solder paste by heating the solder paste and allowing gravity to draw the solder paste onto the pins.

6. The method of claim 1 , wherein the step of drawing the solder paste comprises applying a vacuum.

7. The step of applying the solder paste includes: applying a stencil to the second surface of the substrate having openings corresponding to the plated through holes; and forcing the solder paste through the openings in the stencil The method of claim 1 , comprising:

8. The method of claim 7 , wherein the stencil comprises at least one of a metal plate, an adhesive tape, or a combination thereof.

9. soldering pins from components located on a first side of the substrate to plated through holes in said substrate; applying solder paste to the openings of the plated-through holes on a second side of the substrate opposite the first side of the substrate on which the component is located; melting the solder paste; and providing a rework solder joint connecting at least one of the pins to the plated-through hole by using gravity to draw the solder paste into the pin.

1. A method for forming an electronic device, comprising:

10. 10. The method of claim 9, wherein the step of soldering the pins from the component to the plated-through holes in the substrate uses penetration solder bonding.

11. 10. The method of claim 9, wherein the step of soldering the pin from the component to the plated-through hole of the substrate results in an open pin that is not soldered to the plated-through hole of the substrate.

12. 12. The method of claim 11, wherein the step of providing the rework solder joint solders the open pin by drawing the solder paste into the pin.

13. The step of applying the solder paste includes: applying a stencil to the second surface of the substrate having openings corresponding to the plated through holes; and forcing the solder paste through the openings in the stencil 10. The method of claim 9, comprising:

14. The method of claim 13 , wherein the stencil comprises at least one of a metal plate, an adhesive tape, or a combination thereof.

15. soldering pins from components located on a first side of the substrate to plated through holes in said substrate; applying solder paste to the openings of the plated-through holes on a second side of the substrate opposite the first side of the substrate on which the component is located; melting the solder paste; and providing a rework solder joint joining at least one of the pins to the plated-through hole by drawing the solder paste onto the pin with a vacuum.

1. A method for forming an electronic device, comprising:

16. 16. The method of claim 15, wherein the step of soldering the pins from the component to the plated-through holes in the substrate uses penetration solder bonding.

17. 16. The method of claim 15, wherein the step of soldering the pin from the component to the plated-through hole of the substrate results in an open pin that is not soldered to the plated-through hole of the substrate.

18. 16. The method of claim 15, wherein the step of providing the rework solder joint solders the open pin by drawing the solder paste into the pin.

19. The step of applying the solder paste includes: applying a stencil to the second surface of the substrate having openings corresponding to the plated through holes; and forcing the solder paste through the openings in the stencil 20. The method of claim 18, comprising:

20. 20. The method of claim 19, wherein the stencil comprises at least one of a metal plate, an adhesive tape, or a combination thereof.

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