Printed circuit board with healable features

Abstract

A printed circuit board (PCB) for an electronic device assembly, such as a solid-state drive (SSD), comprises at least one solder mask formed of a healable dielectric material and / or conductive traces formed of a healable conductive material. Thus, the solder mask(s) and / or conductive traces can be optionally healed. The healable dielectric material may flow when heated to a recovery temperature. The healable conductive material may flow upon the application of a recovery voltage. Electronic device assemblies are also disclosed, such as methods for healing the solder masks and conductive traces of the PCBs of electronic device assemblies.

Description

Background Technology

[0001] Printed circuit boards (PCBs) of data storage devices typically include soldering masks on each main surface of the PCB. Soldering masks facilitate the electrical coupling of memory devices (e.g., NAND devices), controllers, and other devices to the circuit board. While conventional soldering masks are effective initially, they are prone to physical damage (e.g., scratches, cracks, etc.) that can impair the electronic connections between the circuit board and the memory devices. Any physical damage degrades the performance of the memory devices, reduces their potential lifespan, and ultimately leads to their failure.

[0002] PCBs also include conductive traces that transport electrical signals between devices mounted on the PCBs or otherwise electrically coupled to the PCBs. The conductive traces of PCBs are typically formed of copper, which has low resistivity and high conductivity. Over time and with repeated use, copper conductive traces can be damaged, affecting the performance and reliability of the PCB and the electronic device containing the PCB, and can lead to data errors, communication failures, and device malfunctions.

[0003] Therefore, it would be beneficial for the PCB to include solder masks and / or conductive traces that can be healed. Additionally, it would be beneficial to have a PCB having solder masks and / or conductive traces that can be healed quickly and cost-effectively.

[0004] A printed circuit board (PCB) of the present disclosure includes features that can be healed when damaged. Such a PCB may be designed to be used with one or more memory devices (e.g., one or more NAND devices, etc.) and / or as part of a solid-state drive (SSD). In some examples, the features of the healable PCB may have a configuration that allows them to be optionally healed or restored. In other examples, the PCB may be part of an electronic device (e.g., an SSD, etc.) that can be programmed to heal the features.

[0005] In some examples, the PCB may include a solder mask that can be selectively healed when damaged. The solder mask may include a dielectric material that can be healed when exposed to a sufficient temperature. The dielectric material may be referred to as a "healable dielectric material." The temperature at which the healable dielectric material can be healed may be referred to as a "recovery temperature." The healable dielectric material may include one or more dynamic covalent polymers (DCPs), Diels-Alder (DA) adducts, and / or metal-ligand coordination polymers (e.g., zinc-ligand coordination polymers, etc.). In some examples, the healable dielectric material may include at least one dynamic covalent polymer, at least one DA adduct, and at least one metal-ligand coordination polymer.

[0006] The recovery temperature of such a healable dielectric material is approximately equal to or greater than the operating temperature of the electronic device to which the PCB belongs, but may be sufficiently low to prevent thermal damage to the PCB and / or other devices and features of the electronic device assembly to which the PCB belongs. As an example, the recovery temperature may be below the re-flow temperature of the solder of the electronic device assembly to which the PCB belongs. The healable dielectric material may have a recovery temperature of about 100°C or greater and about 180°C or less. In some examples, the recovery temperature of the healable dielectric material may be in the range of about 100°C to about 150°C or in the range of about 100°C to about 130°C.

[0007] A method for repairing damage to a soldering mask of such a PCB may optionally include a step of detecting damage to the soldering mask. The method may also include a step of applying heat to the damage and then allowing the material of the soldering mask to cool. Heat may be applied specifically to the damaged area of ​​the soldering mask. Alternatively, heat may generally be applied to the entire soldering mask, as well as to the PCB and the electronic device assembly to which the PCB belongs (e.g., SSD, etc.). The soldering mask may be heated to a recovery temperature that allows the material of the soldering mask to be healed without damaging the PCB carrying the soldering mask or any other components or features of the electronic device assembly to which the PCB and the soldering mask belong. For example, the soldering mask may be heated to a temperature in the range of about 100°C to about 130°C, a temperature in the range of about 100°C to about 150°C, a maximum temperature of about 180°C, etc.

[0008] As heat is applied to the soldering mask, hydrogen bonds within the healing dielectric material of the soldering mask may be broken and / or, covalent bonds of DCPs within the healing dielectric material of the soldering mask may be broken and / or, bonds formed by DA reactions within the healing dielectric material of the soldering mask may be broken and / or, or metal-ligand bonds within the healing dielectric material of the soldering mask may be separated. As the healing dielectric material of the soldering mask cools, hydrogen bonds within the healing dielectric material of the soldering mask may be re-established and / or, bonds formed by DA reactions within the healing dielectric material of the soldering mask may be re-established and / or, or metal-ligand bonds within the healing dielectric material of the soldering mask may be re-associated, which can heal damage to the soldering mask.

[0009] In some examples, the PCB may include conductive traces, which may be more simply referred to as "traces" that can be selectively healed or automatically healed if the conductive traces break or otherwise damage. The conductive traces of such a PCB may include polyimide with sufficient silver nanoparticles and copper nanoparticles dispersed throughout the polyimide so that the traces can transmit electrical signals at the operating voltage (e.g., about 3.3 V to about 5 V, etc.) of the electronic device to which the PCB belongs (e.g., SSD, etc.). If such traces break or otherwise damage, the traces can be repaired by exposure to a recovery voltage exceeding the operating voltage (e.g., about 5 V to about 10 V, etc.). Thus, such a material may be referred to as a "healable conductive material."

[0010] A PCB may be part of an electronic device assembly (e.g., an SSD), comprising two or more semiconductor devices, such as a memory device (e.g., a NAND device) and a controller that communicates with each other through traces of the PCB. Each of the semiconductor devices may apply a recovery voltage to a damaged trace. If one of the semiconductor devices is a memory device, the memory device may include a multiplier circuit that increases the operating voltage to a recovery voltage and selectively applies the recovery voltage to a damaged trace.

[0011] A method for repairing a break in a trace or other damage to a trace on a PCB may include the steps of identifying each trace having a break or other damage and applying a repair voltage to the trace to repair the break. The repair voltage (e.g., about 5 V to about 10 V, etc.) may exceed the operating voltage of the electronic device to which the PCB belongs (e.g., about 3.3 V to about 5 V, etc.). As the repair voltage is applied to the break or other damaged trace, a healing conductive material may repair the break or other damage. More specifically, polymers of the healing conductive material and silver nanoparticles and copper nanoparticles may flow across the break or other damage. The application of the repair voltage to the opposite sides of the break or other damage (e.g., from both ends of the trace) may ensure that the repair is properly routed across the break or other damage. For example, the repair voltage may be applied from one side by a controller of the electronic device assembly. In examples where a recovery voltage can be applied to opposite sides of a breakdown or other damage, the recovery voltage can be applied from the other side of the trace by a multiplier circuit of a memory device (e.g., a NAND device, etc.) of an electronic device assembly.

[0012] The features and advantages of various embodiments of the disclosed subject matter, as well as other embodiments of the disclosed subject matter, should be apparent to those skilled in the art through consideration of the following description, the accompanying drawings, and the appended claims. Brief explanation of the drawing

[0013] In the drawings: Figure 1 schematically illustrates a healable solder mask on a printed circuit board (PCB). FIGS. 2 to 5 schematically illustrate a process for repairing damage to a healable soldering mask of FIG. 1. FIGS. 6 to 10 schematically illustrate an electronic device assembly having a PCB containing healable traces. Figure 6 shows a PCB before any of the traces on the PCB were broken or otherwise damaged. FIG. 7 illustrates a PCB having traces that were broken or otherwise damaged. FIG. 8 illustrates the application of a recovery voltage to a broken or otherwise damaged trace from opposite sides of the broken or other damage. FIG. 9 illustrates the application of a recovery voltage from opposite sides of a break or other damage to another break or otherwise damaged trace. Figure 10 illustrates a PCB having recovered traces. Specific details for implementing the invention

[0014] Solder mask damage in SSD manufacturing and assembly can have a significant economic impact. Yield losses resulting from solder mask damage typically range from 2% to 5% of manufactured SSDs. Conventional repair methods are costly and time-consuming. However, there may be situations where an SSD's solder mask is so severely damaged that it cannot be repaired by conventional techniques and must be discarded. Consequently, the total annual loss from repairing and discarding SSDs with failed solder masks can be substantial. This significant financial impact highlights the need for improved solutions that effectively address solder mask damage.

[0015] Traditional methods to improve solder mask durability involved increasing the thickness of the coating or applying additional protective layers. While effective to some extent, these methods can add complexity to manufacturing processes and result in higher manufacturing costs without addressing minor damage repair. Other approaches to improving SSD yields include manual repair techniques and frequent inspections, both of which are labor-intensive and therefore not cost-effective.

[0016] In addition to causing issues during the assembly of SSDs, damage to the solder mask can also become a problem over time, as the solder mask helps protect the PCB, the memory device(s) carried by the PCB, and the electrical connections between the memory device(s) and the PCB. Damage to the solder mask compromises the integrity of the SSD, allows contaminants to come into contact with the SSD's intricate components and features, and can interfere with the communication of electrical signals necessary for the SSD to function properly.

[0017] The ability of an SSD to function reliably over a long period also depends on the integrity of the SSD's conductive paths, including the conductive traces on the SSD's PCB. Conductive traces, typically formed of copper, can degrade over time due to various factors, including physical stress, thermal cycling, and electrical overstress. These and other factors can cause broken or detached conductive traces, leading to data errors, communication failures, and device malfunctions.

[0018] Conventional solutions for repairing damaged conductive traces, such as manual intervention via resoldering or the use of conductive adhesives, are not feasible in highly integrated systems with complex microscale circuits. Additionally, multiple damaged traces located close together pose a risk of accidental short circuits or misconnections when repaired manually, leading to device failure. While some systems include redundant paths to mitigate single-point failures, the use of redundant paths adds design complexity and necessitates an increase in the size of the SSD PCB.

[0019] Referring to FIG. 1, an example of a printed circuit board (PCB) (10) is illustrated. The PCB (10) includes a surface (12) that carries a soldering mask (20). The soldering mask (20) includes a healing material or a healing dielectric material (22). Thus, the soldering mask (20) includes a healing soldering mask. The healing dielectric material (22) of the soldering mask (20) can facilitate the repair of damage to the soldering mask (20) (e.g., scratches on the soldering mask (20), microcracks or cracks within the soldering mask (20)).

[0020] The healing dielectric material (22) may include bonds that can be broken when heated and re-established upon cooling. More specifically, the healing dielectric material (22) may include a base resin, one or more thermoplastic polymers, and at least one heat-activated reversible polymer (HARP) (24), and the HARP (24) may include at least one dynamic covalent polymer (DCP), at least one Diels-Alder (DA) adduct, and / or at least one metal-ligand coordination polymer (e.g., zinc-ligand coordination polymer, etc.).

[0021] The base resin of the healing dielectric material (22) may include a material that is durable, electrically insulating, resistant to moisture, withstands high temperatures, and resists etching by solder flux. Examples of materials suitable for use as a base resin as a solder mask include, but are not limited to, epoxy resins, acrylic resins, polyester resins, etc. The base resin may be a material that has been conventionally used to form solder masks. The use of such a base resin can ensure that the healing dielectric material (22) can be integrated with existing PCB processes and that the solder mask (20) formed from the healing dielectric material (22) is compatible with existing manufacturing processes (e.g., assembly, solder reflow, etc.).

[0022] In addition to the base resin, the healing dielectric material (22) may comprise one or more thermoplastic polymers. One or more thermoplastic polymers may comprise polyurethanes. Polyurethanes are durable and flexible. The properties of polyurethanes can be adjusted by modifying their polyol and isocyanate components. Alternatively or additionally, one or more thermoplastic polymers may comprise polyimides. Polyimides are thermally stable and chemically resistant and can contribute to the mechanical properties of the soldering mask (20) (e.g., strength, toughness, hardness, ductility, brittleness, etc. of the soldering mask (20)).

[0023] In addition to hydrogen bonding within the healable dielectric material (22), HARP(s) (24) of the healable dielectric material (22) (e.g., DCP(s), DA adduct(s), and / or metal-ligand coordination polymer(s), etc.) can impart additional properties (e.g., combinations of additional types, etc.) to the healable dielectric material (22) that enable the healing of physical damage to the healable dielectric material (22) and thus the healing of damage to the solder mask (20) formed by the healable dielectric material (22).

[0024] Hydrogen bonds (26) within the healing dielectric material (22) are non-covalent interactions between negatively charged atoms and molecules. The hydrogen bonds (26) within the healing dielectric material (22) can be reversed or broken by heating the healing dielectric material (22). The hydrogen bonds (26) can be re-established by allowing the healing dielectric material (22) to cool.

[0025] The DCP includes covalent bonds (27) that can be reversed, broken, or reformed under specific conditions. For example, the application of heat to the healable dielectric material (22) can break the covalent bonds (27) of the DCP, while the covalent bonds (27) of the DCP can be formed as the healable dielectric material (22) cools.

[0026] In the DA adduct, a [4+2] cyclization reaction, or DA reaction, occurs between the diene and the dienophil, creating two pi (π) bonds and two sigma (σ) bonds (28) between the diene and the dienophil. The pi bonds and σ bonds (28) can be broken (i.e., retro-DA reaction) by heating the healing dielectric material (22). The pi bonds and σ bonds (28) can be reformed (i.e., DA reaction) by allowing the healing dielectric material (22) to cool.

[0027] The metal-ligand coordination polymer comprises metal-ligand coordination bonds (29), wherein the metal ions (e.g., zinc ions, or Zn) 2+ (etc.) is combined with one or more ligands. Metal-ligand coordination bonds (29) can be broken by heating the healable dielectric material (22). Metal-ligand coordination bonds (29) can be reformed by allowing the healable dielectric material (22) to cool.

[0028] Breaking the bonds (26, 27, 28, 29) within the healable dielectric material (22) may enable at least some components of the healable dielectric material (22) to flow back into the damaged areas of the soldering mask (20). The temperature at which the various bonds (26, 27, 28, 29) within the healable dielectric material (22) may be broken may be the recovery temperature of the healable dielectric material (22). The recovery temperature of the healable dielectric material (22) may be about 180°C or lower. In some examples, the recovery temperature of the healable dielectric material (22) may be in the range of about 100°C to about 150°C or in the range of about 100°C to about 130°C. In some examples, the recovery temperature of the healing dielectric material (22) may be the operating temperature of the PCB (10) covered by the soldering mask (20), which may allow any damage to the soldering mask (20) to self-heal during the operation of the electronic device to which the PCB (10) and the soldering mask (20) belong. When the healing dielectric material (22) is re-flowed into the damaged areas of the soldering mask (20), the healing dielectric material (22) may be allowed to cool. As the healing dielectric material (22) cools, the bonds (26, 27, 28, 29) are reformed to re-establish the integrity of the soldering mask (20) formed by the healing dielectric material (22) and complete the repair of the soldering mask (20).

[0029] In addition to the materials described above, the healing dielectric material (22) may include one or more curing agents. The curing agent(s) may react with the resin to define the strength and other properties (e.g., hardness, ductility, brittleness, etc.) of the healing dielectric material (22) and the soldering mask (20) formed from the healing dielectric material (22).

[0030] The healing dielectric material (22) may also include one or more additives. Non-limiting examples of such additives include fillers, colorants, ultraviolet (UV) absorbers, etc. Fillers can optimize the mechanical properties, thermal resistance, and chemical resistance of the healing dielectric material (22) and the soldering mask (20) formed from the healing dielectric material (22). Colorants can define the color of the healing dielectric material (22) and the soldering mask (20) formed from the healing dielectric material (22). UV absorbers can facilitate the use of UV exposure and chemical development processes, thereby facilitating the formation of soldering masks (20) or other structures from the healing dielectric material (22).

[0031] In a specific but non-limiting example, a healing genomic material (22) can be formulated as follows:

[0032]

[0033] FIGS. 2 to 5 illustrate and describe a healing dielectric material (22) and illustrate a process for repairing damage (23) to a soldering mask (20) formed therefrom.

[0034] In FIG. 2, the soldering mask (20) may be damaged. Some examples of damage (23) to the soldering mask (20) include scratches, microcracks, and cracks. Damage (23) may occur during the assembly of the PCB (10) and the soldering mask (20) and other components (e.g., controllers; memory devices such as NAND devices; etc.), during the handling of the assembly including the PCB (10) and the soldering mask (20) (e.g., during the manufacture of an electronic device, etc.), or after forming the soldering mask (20) on the PCB (10) during the use of the electronic device including the PCB (10) and the soldering mask (20). In some situations, such as during the inspection of the soldering mask (20) immediately after manufacturing or during the inspection of the assembly including the PCB (10) and the soldering mask (20), any damage (23) to the soldering mask (20) may be detected. In other situations, such as during the manufacture or use of an electronic device including a PCB (10) and a soldering mask (20), any damage (23) to the soldering mask (20) may not be detected.

[0035] In FIG. 3, heat may be applied to the soldering mask (20) to repair any damage (23) to the soldering mask (20). Heat may be applied in any suitable manner. For example, heat may be applied by placing the PCB (10) carrying the soldering mask (20) into an oven heated to a suitable temperature. Heat may be applied to intentionally repair damage (23) to the soldering mask (20). Alternatively, heat applied to the soldering mask (20) may automatically, and thus unintentionally, repair damage (23) to the soldering mask (20). For example, heat may be applied to the soldering mask (20) in a reflow oven as part of subsequent processing of the PCB (10) carrying the soldering mask (20); for example, when soldering electrically couples one or more semiconductor devices (e.g., controllers, memory devices, etc.) to the PCB (10). As another example, heat may be applied during the operation of an electronic device including a PCB (10) carrying a soldering mask (20).

[0036] The amount of heat applied to the soldering mask (20) may be the recovery temperature of the healing dielectric material (22) of the soldering mask (20). The recovery temperature may be about 180°C or lower. In some examples, the recovery temperature may be in the range of about 100°C to about 150°C or in the range of about 100°C to about 130°C. In some examples, the recovery temperature may be the operating temperature of the PCB (10) covered by the soldering mask (20), or the temperature of the PCB (10) during normal operation of the electronic device to which the PCB (10) belongs.

[0037] As heat is applied to the soldering mask (20), bonds within the healing dielectric material (22) of the soldering mask (20) may be broken. These bonds may include hydrogen bonds (26), covalent bonds (27) of DCP, π bonds and σ bonds (28) of DA adducts, and / or metal-ligand coordination bonds (29) of metal-ligand coordination polymers. As the bonds are broken, the healing dielectric material (22) may be re-flowed.

[0038] The healing dielectric material (22) may be recirculated to any damage (23) (e.g., scratches, microcracks, cracks, etc.) to the soldering mask (20). When the healing dielectric material (22) is recirculated to any damage (23), heat may be removed from the soldering mask (20) and the healing dielectric material (22), allowing the healing dielectric material (22) to cool. As illustrated in FIG. 4, as the healing dielectric material (22) cools, bonds (26, 27, 28, 29) within the healing dielectric material (22) may be reformed. These bonds may include hydrogen bonds (26), covalent bonds (27) of DCP, π bonds and σ bonds (28) of DA adducts, and / or metal-ligand coordination bonds (29) of metal-ligand coordination polymers. The reformation of bonds within the healing dielectric material (22) can re-establish the complete structural and chemical integrity of the soldering mask (20), as illustrated in FIG. 5.

[0039] The use of a healing dielectric material (22) to form the soldering mask (20) allows damage to the soldering mask (20) to be repaired at any time after the soldering mask (20) has been manufactured, including before assembling the PCB (10) on which the soldering mask (20) has been formed with other devices (e.g., semiconductor devices, such as memory devices, controllers, etc.). For example, PCBs (10) that failed inspection due to damaged soldering masks (20) (e.g., scratches, cracks, etc.) can simply be heated (e.g., placed in an oven, etc.) to repair the damage and then re-inspected. Enabling the salvage of PCBs (10) with damaged soldering masks (20) can improve the overall efficiency of the PCB manufacturing process.

[0040] A soldering mask (20) formed from a healing dielectric material (22) can be repeatedly restored. In some cases, the soldering mask (20) formed from a healing dielectric material (22) may have a restoration temperature applied several times.

[0041] The use of a healing dielectric material (22) to form a soldering mask (20) on a PCB (10) can also maintain the integrity of the soldering mask (20) over time, thereby increasing the durability and lifespan of the PCB (10) and increasing the reliability of the electronic device (e.g., SSD, etc.) in which the PCB (10) is integrated. Thus, the use of a soldering mask (20) formed from a healing dielectric material (22) in an electronic device can reduce the likelihood of requiring expensive repair or replacement.

[0042] Now, referring to FIG. 6, an example of an electronic device assembly (100) comprising a printed circuit board (PCB) (110) having conductive traces is shown, and the conductive traces may also be referred to as traces (130) formed of a healing material or a healing conductive material (132). Thus, the traces (130) include healing conductive traces. The healing conductive material (132) of the traces (130) can facilitate the repair of damage to the traces (130) (e.g., breakage within the traces (130)).

[0043] The healing conductive material (132) may include a high-performance plastic in which conductive particles are dispersed.

[0044] The high-performance plastic of the healing conductive material (132) can be used to define very fine features, such as traces (130) of the PCB (110), by processes suitable for manufacturing PCBs. The inclusion of the high-performance plastic in the healing conductive material (132) can impart greater flexibility to the traces (130) than to conventional copper traces; the increased flexibility can allow the traces (130) to withstand physical impact better than conventional copper traces, and thus increase the potential lifespan of the PCB (110) containing the traces (130) formed from the healing conductive material (132). Additionally, the high-performance plastic of the traces (130) can be highly cross-linked to increase its stability and allow the high-performance plastic to be applied to operating conditions (e.g., temperature changes, relatively high operating temperatures, etc.) to which PCBs typically respond better than to conventional copper traces. In certain examples, the high-performance plastic of the healing conductive material (132) may include polyimide, which can withstand repeated fluctuations in temperature. For example, while conventional PCBs with copper traces may function at an operating temperature of up to about 85°C, a PCB (110) with traces (130) formed from a healing conductive material (132) containing polyimide may function at an operating temperature of up to about 120°C; thus, the use of the healing conductive material (132) to define the traces (130) of the PCB (110) can improve the performance of the PCB (110) in demanding environments compared to the performance of a conventional PCB with copper traces in demanding environments. In some examples, the high-performance plastic (e.g., polyimide, etc.) may account for about 79% to about 90% of the weight of the healing conductive material (132).

[0045] The conductive particles of the healing conductive material (132) may include particles of silver (Ag) and particles of copper (Cu). The particles may include nanoparticles having sizes (e.g., diameters, etc.) of about 20 nm to about 50 nm. The concentration of conductive particles within the healing conductive material (132) may enable the trace (130) formed from the healing conductive material (132) to reliably conduct electrical signals at low voltages, such as the operating voltage of an electronic device assembly (100) including a PCB (110) (e.g., about 3.3 V, about 5 V, etc.). For example, the healing conductive material (132) may have a resistivity comparable to that of resistivity copper, which is about 1.7 × 10⁻⁶. -8 It is Ω·. For example, a healing conductive material (132) is about 5.0×10⁻⁶. -8 It may have a resistivity of Ω·m or less. In non-limiting examples, the conductive particles may constitute about 10% to about 15% of the weight of the healable conductive material (132).

[0046] Optionally, the healable conductive material (132) may include conductive additives, which may further improve the electrical properties of the healable conductive material (132). Conductive additives may enable the healable conductive material (132) to reliably conduct low-voltage electrical signals. Conductive additives may contribute to the ability of the healable conductive material (132) to heal, and thus to the ability of the healable conductive material (132) to repair the breakage of the trace (130). Without limitation, carbon nanotubes and / or graphene may be included in the healable conductive material (132). In more specific examples, the healable conductive material (132) may include both carbon nanotubes and graphene. Much more specifically, carbon nanotubes and graphene may each constitute about 2% to about 3% of the weight of the healable conductive material (132).

[0047] This healing conductive material (132) can be used to form traces (130) having a width of about 500 μm to about 1,000 μm and a thickness of about 20 μm to about 50 μm, compared to traces of conventional PCBs which typically have a width of about 1,000 μm and a thickness of about 35 μm.

[0048] In addition to enabling the design of traces (130) that are potentially thinner than the copper traces of conventional PCBs, the use of a healing conductive material (132) can enable the use of insulating layers that are thinner than the insulating layers of conventional PCBs. For example, while a conventional PCB with copper traces may have insulating layers that are about 50 µm thin, a PCB (110) with traces (130) formed of a healing conductive material (132) may be about 30 µm thin. Furthermore, testing has shown that traces (130) formed of a healing conductive material (132) fail at a rate of only about 1%, in contrast to a 10% failure rate of conventional copper traces, which indicates that a PCB (110) with traces (130) formed of a healing conductive material (132) is much more reliable (e.g., up to about 10 times more reliable) than conventional PCBs with copper traces. Therefore, using a healing conductive material (132) to form the traces (130) can enable the design and manufacture of PCBs (110) that are significantly thinner and substantially more reliable than conventional PCBs having copper traces.

[0049] It has been discovered that such a healing conductive material (132) can flow over a short distance when exposed to an electric field having voltages exceeding the typical operating voltage of electronic devices. For example, the healing conductive material (132) can flow when exposed to a voltage greater than 5V. As a more specific example, the healing conductive material (132) can flow when a voltage greater than 5V to about 10V is applied to it. Applying such voltage to the healing conductive material (132) can heat the healing conductive material (132) (e.g. to a temperature of about 120°C, which is higher than the normal operating temperature of about 60°C to about 85°C), which can cause the healing conductive material (132) to flow. The voltage that causes the healing conductive material (132) to flow may be referred to as the "recovery voltage."

[0050] The application of a recovery voltage to a trace (130) formed of a healing conductive material (132) can cause the healing conductive material (132) to flow across a break (134) (Fig. 7) that is about 10 μm in size in the trace (130). Because the healing conductive material (132) flows, it can bridge the break (134) and thus restore functionality to the trace (130).

[0051] Traces (130) formed of a healing conductive material (132) can be repeatedly restored. In some cases, the traces (130) formed of the healing conductive material (132) can have a restoration voltage applied several times.

[0052] Referring further to FIG. 6, the electronic device assembly (100) may additionally include a first semiconductor device (140) and a second semiconductor device (150) on a PCB (110). Traces (130) may establish electrically conductive links between the first semiconductor device (140) and the second semiconductor device (150), thereby enabling the first semiconductor device (140) and the second semiconductor device (150) to communicate with each other.

[0053] In examples where the electronic device assembly (100) includes an SSD, the first semiconductor device (140) may include a controller. This first semiconductor device (140) may be programmed to control the operation of the electronic device assembly (100) and to enable the electronic device assembly (100) to communicate with other electronic devices. This first semiconductor device (140) may also be for identifying any broken or otherwise damaged traces (130) of the PCB (110); for example, the first semiconductor device (140) may include circuits dedicated and programmed to monitor problems. Additionally, this first semiconductor device (140) may be programmed to apply a recovery voltage to one or more broken or otherwise damaged traces (130). In some examples, while the first semiconductor device (140) applies a recovery voltage to a broken or otherwise damaged trace (130) on one side of the broken (134) or other damage, the first semiconductor device (140) may be further programmed to allow the second semiconductor device (150) to apply a recovery voltage to a broken or otherwise damaged trace (130) from the other side of the broken (134) or other damage.

[0054] The second semiconductor device (150) of the electronic device assembly (100) including the SSD may be a memory device, such as a NAND device. In examples where the second semiconductor device (150) can apply a recovery voltage to a broken or otherwise damaged trace (130), the second semiconductor device (150) may include a multiplier circuit (152). The multiplier circuit may increase or step up a relatively low operating voltage (e.g., about 3.3 V or about 5 V) to a higher recovery voltage (e.g., a voltage in the range of more than 5 V to about 10 V).

[0055] During normal operation, the electronic device assembly (100) (e.g., SSD, etc.) functions as expected, and electrical signals flow through the traces (130) of the PCB (110). A first semiconductor device (140) (e.g., controller, etc.) can monitor the performance of the electronic device assembly (100), including the PCB (110) and its traces (130), to ensure that the electronic device assembly (100) functions optimally (e.g., with optimal read / write speed and data integrity of the second semiconductor device (150) (memory device), without any interference, etc.).

[0056] While the first semiconductor device (140) continues to monitor the performance of the electronic device assembly (100), the first semiconductor device (140) may detect a break (134) or other damage to one or more conductive traces (130) of the PCB (110), as illustrated in FIG. 7. Programming of the first semiconductor device (140), or dedicated monitoring circuits of the first semiconductor device (140), may enable the first semiconductor device (140) to identify a trace (130) that has a break (134) or other damage. In FIG. 7, two traces (130) identified by FIG. 7 as trace (130a) and trace (130b) are broken.

[0057] As illustrated in FIG. 8, if a break (134) or other damage to the trace (130a) is detected, the first semiconductor device (140) may apply a recovery voltage (145) to the trace (130a) on one side of the break (134a) or other damage. Optionally, the first semiconductor device (140) may cause the second semiconductor device (150), or the multiplier circuit (152) of the second semiconductor device (150), to apply a recovery voltage to the trace (130a) on the opposite side of the break (134a) or other damage. The application of a recovery voltage to the trace (130a) from the opposite sides of the break (134a) or other damage can ensure that the healable conductive material (132) flows toward the break (134a) or other damage along the original path of the trace (130a) rather than toward other traces (130a) or conductive features of the PCB (110). Optionally, the PCB (110) may include additional insulators adjacent to the sides and / or bottom of each trace (130) to prevent the healable conductive material (132) of the trace (130) from flowing past the original path of the trace (130) and to prevent the potential creation of electrical issues (e.g., short circuits) between the healable trace (130) of the PCB (110) and other electrical features (e.g., other traces (130), etc.).

[0058] The first semiconductor device (140) can monitor the conductivity of the trace (130a) as the damage (134a) or other damage to the trace (130) is repaired. When the ability of the trace (130a) to conduct electrical signals is restored, the first semiconductor device (140) can terminate the repair process. Additionally, if the repair process continues for a predetermined duration without restoring the ability of the trace (130a) to conduct electrical signals, the first semiconductor device (140) can terminate the repair process and provide an output indicating that the trace (130a) is damaged beyond repair.

[0059] FIG. 9 illustrates the repair of a break (134b) within another trace (130b) of the PCB (110) in the same manner as described with reference to FIG. 8. The repair of the trace (130b) may occur at least partially simultaneously with the repair of the trace (130a) or after the repair of the trace (130a) is completed. Localized electric fields generated by applying a repair voltage across each break may prevent cross-connections from forming between adjacent breaks (134a and 134b).

[0060] FIG. 10 illustrates an electronic device assembly (100) including recovered traces (130a and 130b). If a break (134) or other damage to a trace (130) of a PCB (110) is repaired, normal operation of the electronic device assembly (100) can be resumed.

[0061] Some examples of PCBs may include at least one solder mask (20) formed of a healable dielectric material (22), such as those described with reference to FIG. 1, and traces (130) formed of a healable conductive material (132) of the type described with reference to FIG. 6. Similarly, some examples of electronic device assemblies, such as the electronic device assembly (100) described with reference to FIG. 6, may include a PCB (10, 110) having at least one solder mask (20) formed of a healable dielectric material (22) as described with reference to FIG. 1, and traces (130) formed of a healable conductive material (132) as described with reference to FIG. 6.

[0062] Based on the foregoing, the examples of the present disclosure describe a printed circuit board (PCB), wherein the printed circuit board comprises: a soldering mask comprising a healing dielectric material that flows at a recovery temperature above the operating temperature of an electronic device to which the PCB is to be integrated; and at least one of traces defined as a healing conductive material that flows upon the application of a recovery voltage to one of the traces, wherein the recovery voltage exceeds the operating voltage of the electronic device to which the PCB is to be integrated. In one example, the soldering mask comprises a base resin, at least one thermoplastic resin, and at least one heat-activated reversible polymer (HARP). In one example, the at least one HARP comprises a dynamic covalent polymer (DCP), a Diels-Alder (DA) adduct, and / or a metal-ligand coordination polymer. In one example, the recovery temperature is in the range of 100°C to 130°C. In one example, the healing conductive material comprises a polyimide having silver nanoparticles and copper nanoparticles dispersed throughout the polyimide. In one example, at least one of the silver nanoparticles and the copper nanoparticles has sizes ranging from 20 (nanometer) nm to 50 nm. In one example, the polyimide further comprises at least one of carbon nanotubes and graphene. In one example, the recovery voltage is in the range of 5 volts (V) to 10 V. In one example, the PCB carries a controller and a memory device, and the controller is programmed to monitor the performance of the PCB, detect a breakage on a trace, and apply a recovery voltage to the trace from a first side of the breakage. In one example, the memory device includes a multiplier circuit; the controller is further programmed to cause the multiplier circuit of the memory device to apply a recovery voltage to a trace on a second side of the breakage opposite to the first side of the breakage.

[0063] Examples also describe a method for repairing a break in a trace of a printed circuit board (PCB), the method comprising the steps of: identifying a trace having a break; and repairing the break by applying a repair voltage to the trace, wherein the repair voltage exceeds the operating voltage of an electronic device provided with the PCB. In one example, the step of applying the repair voltage comprises applying a voltage ranging from 5 V to 10 V to the break. In one example, the step of applying the repair voltage comprises applying a repair voltage to the trace from opposite sides of the break. In one example, the step of applying a repair voltage from opposite sides of the break comprises: applying a repair voltage from a first side of the break to a processor communicating with the trace; and applying a repair voltage from a second side of the break. In one example, the step of applying a repair voltage from the second side of the break comprises applying a repair voltage from a multiplier circuit associated with the electronic device.

[0064] Examples also describe a method for repairing damage to a soldering mask on a printed circuit board (PCB), the method comprising: detecting damage to the soldering mask; applying heat to the damage, comprising breaking Diels-Alder bonds in the material of the soldering mask; breaking hydrogen bonds in the material of the soldering mask; and separating metal-ligand bonds in the material of the soldering mask; and allowing the material of the soldering mask to cool, comprising re-establishing Diels-Alder bonds in the material of the soldering mask; re-establishing hydrogen bonds in the material of the soldering mask; and re-associating metal-ligand bonds in the material of the soldering mask. In one example, the step of applying heat to the damage comprises applying heat to the entire soldering mask. In one example, the step of applying heat comprises exposing the soldering mask to a temperature in the range of 100°C to 130°C. In one example, the PCB is included in a data storage device. In one example, the step of applying heat occurs during the operation of the data storage device.

[0065] The descriptions and examples of one or more embodiments provided in this disclosure are not intended to limit or restrict the scope of the disclosure in any way. The embodiments, examples, and details provided in this disclosure are deemed sufficient to convey ownership and to enable others to make and use the best mode of the claimed disclosure.

[0066] The claimed disclosure shall not be construed as being limited to any mode, example, or detail provided in this disclosure. Various features (both structural and methodological), whether depicted and described in combination and separately, are intended to be optionally rearranged, included, or omitted to produce an example having a specific set of features. Although descriptions and examples of this disclosure have been provided, those skilled in the art may conceive variations, modifications, and alternative modes falling within the spirit of broader modes of the general inventive concept embodied in this disclosure, without departing from the broader scope of the claimed disclosure.

[0067] References to elements of the present invention using designations such as “first,” “second,” etc., generally do not limit the quantity or order of such elements. Rather, such designations may be used as a way to distinguish between two or more elements or instances of elements. Accordingly, references to first and second elements do not imply that only two elements may be used or that the first element precedes the second element. Additionally, unless otherwise noted, a set of elements may include one or more elements.

[0068] Terms of the form “at least one of A, B, or C” or “A, B, C, or any combination thereof” used in the specification or claims mean “A or B or C or any combination of these elements.” For example, such terms may include A, B, or C, or A and B, or A and C, or A and B and C, or 2A, or 2B, or 2C, or 2A and B, etc. As an additional example, “at least one of A, B, or C” is intended to cover A, B, C, AB, AC, BC, and ABC, as well as multiples of the same members. Likewise, “at least one of A, B, and C” is intended to cover A, B, C, AB, AC, BC, and ABC, as well as multiples of the same members.

[0069] Similarly, as used herein, a phrase referring to a list of items linked with "and / or" refers to any combination of items. As an example, "A and / or B" is intended to cover A alone, B alone, or A and B together. As another example, "A, B and / or C" is intended to cover A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together.

Claims

Claim 1 A printed circuit board (PCB), comprising: a soldering mask comprising a healing dielectric material that flows at a recovery temperature greater than the operating temperature of an electronic device to which the PCB is to be integrated; and at least one of traces defined from a healing conductive material that flows upon the application of a recovery voltage to one of the traces, wherein the recovery voltage exceeds the operating voltage of the electronic device to which the PCB is to be integrated. Claim 2 In claim 1, the soldering mask comprises a base resin, at least one thermoplastic resin, and at least one heat-activated reversible polymer (HARP), wherein the PCB. Claim 3 In paragraph 2, the at least one HARP comprises a dynamic covalent polymer (DCP), a Diels-Alder (DA) adduct, and / or a metal-ligand coordination polymer, a PCB. Claim 4 In claim 1, the recovery temperature is in the range of 100℃ to 130℃, a PCB. Claim 5 In claim 1, the healing conductive material comprises a polyimide having silver nanoparticles and copper nanoparticles dispersed throughout the polyimide, a PCB. Claim 6 In claim 5, a PCB, wherein at least one of the silver nanoparticles and the copper nanoparticles has sizes in the range of 20 (nanometer) nm to 50 nm. Claim 7 In claim 5, the polyimide further comprises at least one of carbon nanotubes and graphene, a PCB. Claim 8 In paragraph 5, the recovery voltage is in the range of 5 volts (V) to 10 V, PCB. Claim 9 A PCB according to claim 1, comprising a controller and a memory device, wherein the controller is programmed to monitor the performance of the PCB, detect damage to the trace, and apply the recovery voltage to the trace from a first side of the damage. Claim 10 In claim 9, the memory device includes a multiplier circuit; and the controller is additionally programmed so that the multiplier circuit of the memory device applies the recovery voltage to a trace on the second side of the damage opposite to the first side of the damage, the PCB. Claim 11 A method for repairing damage in a trace of a printed circuit board (PCB), comprising: identifying the trace having said damage; and applying a repair voltage to said trace to repair said damage, wherein the repair voltage exceeds the operating voltage of an electronic device provided with said PCB. Claim 12 In claim 11, the step of applying the recovery voltage comprises applying a voltage in the range of 5 V to 10 V to the damage. Claim 13 In claim 11, the step of applying the recovery voltage comprises applying the recovery voltage to the trace from the opposite sides of the damage. Claim 14 In claim 13, the step of applying the recovery voltage from opposite sides of the damage comprises: the step of applying the recovery voltage from a first side of the damage to a processor communicating with a trace; and the step of applying the recovery voltage from a second side of the damage. Claim 15 In claim 14, the step of applying the recovery voltage from the second aspect of the damage comprises the step of applying the recovery voltage from a multiplier circuit associated with the electronic device. Claim 16 A method for repairing damage to a soldering mask on a printed circuit board (PCB), comprising: detecting damage to the soldering mask; applying heat to the damage, comprising breaking Diels-Alder bonds in the material of the soldering mask; breaking hydrogen bonds in the material of the soldering mask; and separating metal-ligand bonds in the material of the soldering mask; and allowing the material of the soldering mask to cool, comprising re-establishing Diels-Alder bonds in the material of the soldering mask; re-establishing hydrogen bonds in the material of the soldering mask; and re-associating metal-ligand bonds in the material of the soldering mask. Claim 17 In claim 16, the step of applying heat to the damage comprises the step of applying heat to the entire soldering mask. Claim 18 In claim 16, the step of applying heat comprises the step of exposing the soldering mask to a temperature in the range of 100°C to 130°C. Claim 19 In paragraph 16, the above PCB is included in a data storage device, a method. Claim 20 In claim 19, the step of applying heat occurs during the operation of the data storage device, a method.

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