Patent Application
20210060676
The present application claims the benefit of European Patent Application No. EP19193946.1, filed Aug. 27, 2019, entitled “SOLDERING ASSEMBLY, METHOD AND USE.” The entirety of European Patent Application No. EP19193946.1 is expressly incorporated herein by reference.
The present disclosure relates to a soldering assembly and a method of manufacturing a soldering assembly. In particular, but not exclusively, the present disclosure relates to a soldering assembly including a nozzle.
Selective soldering can be used in many soldering applications, for example soldering components of a Printed Circuit Board (PCB). Selective soldering can, in general, be differentiated into two methods: multi-wave dip soldering and point-to-point soldering.
In multi-wave dip soldering processes, typically a large solder pot, or soldering assembly 100 is used (as shown in
In point-to-point soldering processes, typically a small solder pot, or soldering assembly 200 (as shown in
Lead-free solders are very corrosive (due to the presence of Ag—Silver—and high operation temperatures). As such, components that have contact with the liquidus solder, for example the inner parts of the nozzle can be subject to corrosion/erosion. Stainless steel nozzles, in particular, are susceptible to corrosion.
In addition, current methods of manufacturing the soldering components are limited with regards to the nozzle geometry that can be produced. This can lead to sub-optimal nozzles. For example, for multi-wave dip soldering nozzles, the nozzle and screen are currently manufactured separately, which leads to a fragile screen.
It would be advantageous to produce a nozzle that helps overcome the above described problems.
According to a first aspect of the present disclosure there is provided a soldering assembly comprising:
at least one nozzle for directing solder during a soldering operation, the at least one nozzle comprising:
an inlet for receiving a supply of solder;
an outlet for dispensing solder therefrom; and
at least one channel fluidly coupling the inlet to the outlet;
wherein the at least one nozzle comprises a plurality of stacked layers of stainless steel or titanium, provided so as to at least partially define the at least one channel, and
wherein the at least one nozzle is at least partially diffusion coated with chromium carbide so as to protect the stacked layers from corrosion.
Suitably, the stacked layers are deposited during an additive manufacturing, or 3D printing, process.
Suitably, the at least one nozzle further comprises a de-bridging screen formed integrally therewith.
Suitably, the soldering assembly further comprises a nozzle plate.
Suitably, the soldering assembly further comprises a conduit configured to project a de-bridging fluid to an area proximate to the outlet of the nozzle, wherein the conduit comprises a plurality of stacked layers of material.
Suitably, the material is stainless steel or titanium.
Suitably, the soldering assembly further comprises a shield assembly, the shield assembly comprising:
Suitably, the nozzle has at least one guiding portion configured to guide solder dispensed from the outlet.
Suitably, the nozzle includes at least two releasably connected parts.
According to a second aspect of the present disclosure there is provided a system for soldering a component, comprising
According to a third aspect of the present disclosure there is provided, a method of manufacturing a soldering assembly, the method comprising:
Suitably, the method further comprises forming a de-bridging screen in the nozzle during the additive manufacturing process.
Suitably, the method further comprises depositing layers of material in an additive manufacturing, or 3D printing, process to construct a conduit configured to project a de-bridging fluid to an area proximate to the outlet of the nozzle.
Suitably, the method further comprises:
Suitably, the material is stainless steel or titanium.
According to a fourth aspect of the present disclosure there is provided, use of an assembly in a soldering process, the assembly comprising at least one nozzle, the at least one nozzle being formed through the deposition of layers of stainless steel or titanium in an additive manufacturing process and the diffusion coating of the at least one nozzle with chromium carbide so as to protect the deposited layers from corrosion.
Suitably, the assembly is the soldering assembly according to the first aspect of the disclosure.
According to a fifth aspect of the present disclosure there is provided an assembly for de-bridging a soldered connection (or preventing the de-bridging of a soldered component), the assembly comprising
Certain embodiments of the disclosure provide the advantage that a soldering assembly is provided including a nozzle that can be produced more efficiently (for example through use of less material) compared to known nozzles.
Certain embodiments of the disclosure provide the advantage that a soldering assembly is provided including a nozzle that can be produced with additional functionality compared to known nozzles.
Certain embodiments of the disclosure provide the advantage that a soldering assembly is provided including a nozzle that has an increased lifetime compared to some known nozzles, in particular those used in combination with lead-free solder.
Certain embodiments of the disclosure provide the advantage that a method of manufacturing a soldering assembly is provided that allows assemblies with both an increased functionality and increased lifetime to be produced.
As used herein, when referring to ‘solder’ in use within a nozzle, it is to be understood that the solder is in a liquid state.
Embodiments of the disclosure are further described hereinafter with reference to the accompanying drawings, in which:
In the drawings like reference numerals refer to like parts.
In its most general form, a soldering assembly is disclosed including at least one nozzle for directing solder during a soldering operation. The soldering assembly may be a soldering assembly for use in multi-wave soldering process (typically including more than one nozzle) or point-to-point soldering processes (typically including a single nozzle).
The nozzle (or nozzles when referring to a multi-wave soldering assembly) of the present disclosure include an inlet for receiving a supply of solder, an outlet for dispensing solder therefrom and at least one channel fluidly coupling the inlet to the outlet.
The nozzle includes a plurality of stacked layers of stainless steel or titanium, provided so as to at least partially define the at least one channel. In this example, the stacked layers are deposited during an additive manufacturing, or 3D printing, process. That is, during construction, successive layers of stainless steel or titanium are deposited to build up the nozzle structure, including the bounding walls of the at least one channel.
As an example of an additive manufacturing or 3D printing process, a thin layer (for example, of 20 to 100 microns thickness) of metal powder (for example stainless steel or titanium) is laid down on top of a build-plate. The powder is melted or welded together in predetermined positions, for example by a laser or welding means. The predetermined positions may be defined by a 3D CAD model, for example. The build-plate is lowered by a distance substantially corresponding to the thickness of the thin layer and these steps are repeated. Once the required number of layers have been added, the non-melted/welded powder is removed to reveal the component inside. The component may be heat treated to improve the mechanical properties or post-processed (for example turning, milling, tumbling or shot peening).
The construction of a nozzle in this way allows different shapes and models to be produced that would generally not be possible with milling, drilling or casting processes. As such, nozzles with improved functionality may be produced. In addition, the use of materials within the printed nozzles may be more efficient.
Previously, it would have been expected that a 3D printed component, such as the nozzle of this disclosure, would have a rough surface (as a result of the addition of successive layers). As such, there would be an expectation that the roughened surface of the nozzle (in particular, the surface defining the channel) may affect the nozzles ability to produce a consistent, laminar flow of solder. However, surprisingly, this has found to not be an issue for the 3D printed nozzle.
The nozzle is at least partially diffusion coated with chromium carbide so as to protect the stacked layers from corrosion, for example from corrosive solder. The process of diffusion coating with chromium carbide is sometimes referred to as inchromizing (for example, hard inchromizing). In other words, the nozzle are at least partially hard inchromized.
In general, diffusion coating is a diffusion process where a layer of a material, for example a ceramic material is applied to a metal surface. In an inchromizing process, ceramic chromium carbide (CRxCy), for example in the form of a powder, is applied to the metal surface. In this example, the chromium carbide powder is brought into contact with the stainless steel or titanium and heated to approximately 850° C. for several hours (ranging from about 2 hours to 60 hours depending on the nozzle size). The resulting diffusion layer may have a thickness of from about 5 μm to about 25 μm. After treatment, the surface is extremely hard, densely structured and resistant to wear.
An advantage of diffusion coating over other coating methods is that bonding issues between the base material and the surface layer are reduced. In addition, diffusion coating with chromium carbide provides improved corrosion resistance over other types of protective corrosion coatings.
In some examples, the entire surface of the nozzle is diffusion coated. However, in other examples only portions of the surface of the nozzle that may come into contact with the solder are coated (for example the defining walls of the channel and portions of the exterior surface over which the solder may flow).
The expected roughened surface of the 3D printed component may have also led to doubts as to the effects of inchromizing of a 3D printed component on the microstructure of the printed nozzle. In other words, manufacturers may have been detracted from treating the nozzle in this way over concerns for the effectiveness of the corrosion resistance of the nozzle. However, surprisingly, the applicant has found that inchromizing the nozzle provides comparable results to a non-3D printed nozzle.
For example, it has been found that inchromizing the surface of the nozzle in this way makes the nozzle non-wettable, which helps extend the lifetime of nozzle. For example, the lifetime of an inchromized nozzle may be greater than 5 years in comparison to a wettable nozzle (for example made of carbon steel), which may only have a lifetime of approximately 2 weeks.
For a soldering assembly for use in multi-wave soldering process, according to the present disclosure, the assembly may include a nozzle plate, from which the nozzle (or nozzles) extend. In some examples, the nozzle plate may be 3D printed as described above, for example using stainless steel or titanium. In some areas of the nozzle plate, in particular those which have contact with solder, the nozzle plate may be inchromized in the same manner as the nozzle.
The nozzle of the multi-wave soldering assembly may include a de-bridging screen. The de-bridging screen extends at least partially over the outlet of the nozzle.
In such an example, the de-bridging screen may be formed integrally with the nozzle. That is the de-bridging screen may be formed as part of the nozzle itself. For example, the de-bridging screen may be defined by stacked layers of stainless steel or titanium, the stacked layers being deposited during the same additive manufacturing process as the nozzle itself. By providing the de-bridging screen as an integral component of the nozzle (i.e. by providing the nozzle and de-bridging screen as part of a single-piece component) the structural integrity of the de-bridging screen is improved. That is, de-bridging screens provided separately from the nozzle (and then attached/coupled thereto) can be very fragile. This fragility is reduced by providing the screen integrally with the nozzle. In other words, the structural integrity of the screen may be increased by printing the screen as an integral part of the nozzle.
During a soldering process, the nozzle 402 is arranged such that solder flows in a generally upward direction towards, and subsequently from, the nozzle outlet 406.
As the solder is dispensed from the nozzle outlet 406, the solder flows over an over-flow section of the nozzle 402 before flowing in a generally downwardly direction along (or adjacent to) an exterior surface of the nozzle (i.e. due to gravity). In general, the connector pin to be soldered is dragged through or dipped into the flowing solder after the solder has flowed at least partially over the over-flow section.
As used herein, it is to be understood that an ‘over-flow section’ is a section of the outlet over which solder flows as the solder ‘over-flows’ from the nozzle outlet. The over-flow section may be an edge (for example a peripheral edge of the outlet), a section of the edge, or a surface connected to the edge.
In this example, the exterior surface of the nozzle includes at least one guiding portion configured to guide solder dispensed from the outlet 406. The guiding portion may be a channel, groove, flat guiding surface or similar.
In this example, the nozzle includes a body portion 470. The body portion is surrounded by a side wall portion 472. At the junction between the body portion 470 and the raised wall portion 472 is defined a first guiding portion, channel 480 configured to guide solder dispensed from the outlet 406. The channel 480 extends around an exterior surface of the nozzle 402 and guides the over-flowing liquid solder back into the supply of liquid solder (i.e. a solder pot or reservoir). In other words, the channel portion 480 is configured to function as a gutter, positioned around body portion 470 of the nozzle 402 to guide the solder smoothly back to the solder supply.
The solder may, for example, be guided back to the solder supply through an opening 482 in the side wall portion 472 of the channel portion 480.
The body portion 470 and side wall portion 472 are integral parts of the nozzle 402. That is, the channel 480 is defined by stacked layers of stainless steel or titanium being deposited during the additive manufacturing process of the nozzle 402 itself. The use of 3D printing to produce the nozzle 402 allows the straightforward inclusion of such channels/gutters within the exterior surface of the nozzle. In addition, 3D printing enables more specific, or complex, gutter geometry to be included in the nozzle, which may help ensure laminar flow of the liquid solder. This allows smooth flow of solder back into solder pot and hence reduces splattering of solder which may result in solder balls on the bottom side of the assembly.
In this example, the nozzle 402 includes a second guiding portion, guiding surface 484. In this example the guiding surface 484 is a flat section on the body portion 470 that extends longitudinally along the exterior of the nozzle 402. In this example, the guiding surface 484 is longitudinally aligned with (i.e. extends downwardly from) the over-flow edge 486. As such, as the solder flows over the over-flow edge 486, the solder may flow downwardly along the guiding surface back to the solder supply.
In this example, the soldering assembly 400 further includes a shield assembly 410, including a shield 412, configured to at least partially surround the nozzle 402. In particular, the shield 412 is configured to at least partially surround the sides (i.e. the side wall portion 472) of the nozzle 402, allowing the nozzle to extend through the bore, or hollowed interior, of the shield 412. In this example, the shield 412 has a hollow, truncated cone profile. However, in other examples the shield 412 may have other profiles, for example cylindrical.
In use, the shield 412 is configured to contain splattering of solder from the nozzle 402 and help guide solder from the nozzle 402 back to the solder supply.
The shield 412 may be manufactured in any suitable manner (for example, through machining or casting). However, in this example the shield 412 may itself include a plurality of stacked layers deposited during an additive manufacturing, or 3D printing, process. The stacked layers may be stainless steel or titanium, for example.
In this example, as illustrated in
In this example, the shield assembly 410 further includes a conduit 414 configured to project, emit or dispense a de-bridging fluid. In this example, the conduit 414 has a first end configured to be coupled to a supply of de-bridging fluid, for example an inert gas stream such as nitrogen. The conduit 414 has a second end positioned proximate to the nozzle outlet 406. In use, the de-bridging fluid is supplied from the fluid supply through the conduit 414 and projected as a stream or jet of de-bridging fluid from the second end of the conduit 414. The supply of de-bridging fluid may be continuous or intermittent (for example, corresponding to the soldering of connector pins). In some examples, the temperature and/or velocity of the stream of de-bridging fluid are adjustable.
The conduit 414 is configured to project the de-bridging fluid to an area proximate to the outlet 406 of the nozzle 402. That is, the jet or stream of de-bridging fluid is directed or angled towards an area proximate to the outlet 406 of the nozzle 402. In doing so, the jet or stream of de-bridging fluid is projected towards components recently soldered by the over-flowing stream of solder dispensed from the outlet. For example, when the soldering assembly is being used to solder connector pins on a PCB, as the connector pins emerge from the over-flowing stream of solder, the connector pins are impinged by the de-bridging fluid. In this example, in use, the conduit 414 is pointed/angled so as to direct the jet or stream of de-bridging fluid in the opposite direction to the relative movement between the PCB and the nozzle.
As the de-bridging fluid impinges the soldered components, bridging between adjacent soldered components (for example, adjacent connector pins within a row of connector pins, soldered in succession) is reduced, or prevented. That is, when the overflowing solder bridges adjacent connector pins, it may become unstable, with this instability being corrected by the impinging de-bridging fluid. In addition, the use of a hot gas (for example nitrogen at a temperature of more than about 230 degrees Celsius, corresponding generally to liquidus temperature of solder) as the de-bridging fluid improves thermal solderability.
In this example, the second end of the conduit is substantially flattened. That is, the conduit 414 has a generally tubular profile, with the second tubular end being flattened to provide a more concentrated flow therefrom.
In this example the conduit 414 is a 3D printed component. In other words, the conduit 414 includes a plurality of stacked layers deposited during an additive manufacturing, or 3D printing, process. The stacked layers may be stainless steel or titanium, for example.
In this example, the conduit is supported by the shield 412, the second end of the conduit extending above the upper portion of the shield 412. In other words, in use, the second end of the conduit 412 extends above the top of the shield 412 and projects towards the nozzle outlet. The shield 412 helps provide an inert environment in the solder area. That is, the de-bridging fluid is blown in the solder-pot and will escape along the nozzle. The shield reduces the oxygen level and avoids oxidation during soldering and helps promote the solder wetting.
In this example, the conduit 414 is integrally formed with the shield 412. That is, the shield 412 and the conduit 414 are defined by stacked layers (for example of stainless steel or titanium) deposited during the same additive manufacturing process. By 3D printing the conduit 414 as part of the shield 412, the space required for the de-bridging unit is reduced. That is, the conduit 414, supported by the shield 412, replaces a much larger nitrogen unit (SDC), which would include a separate bracket for supporting the conduit.
In addition, the 3D printed conduit 414 makes it easier to maintain the temperature of the de-bridging fluid above the liquidus temperature of the solder to make de-bridging possible. In particular, previous SDC designs were larger (for example including a separate mounting bracket) and hence included a larger mass of metal. Due to the high mass of metal, the heat in the SDC was at least partially dispersed prior to reaching the conduit (or the end of the conduit). 3D printing the conduit 414, allows different designs to be implemented (for example a conduit with a flattened end and/or a conduit integrated within the shield) that doesn't absorb so much heat.
The heater can therefore have lower setpoints to achieve the required nitrogen temperature.
The nozzles described above are configured for use in a system for soldering a component, the system further including a supply of liquid solder, a pump apparatus, configured to pump solder from the solder supply to the nozzle (or more specifically to the outlet of the nozzle). The system may, for example, be of a type known in the art, for example a Vitrionics Soltec ZEVAm (for a point-to-point soldering process) or a Vitrionics Soltec ZEVAv (for a multi-wave soldering process). The system may be used to solder PCBs.
Various modifications to the detailed designs as described above are possible. For example, the entire soldering assembly may be 3D printed and then diffusion coated. That is, the soldering assembly may include a plurality of stacked layers of stainless steel or titanium, provided so as to at least partially define the at least one channel, the soldering assembly being at least partially diffusion coated with chromium carbide so as to protect the stacked layers from corrosion. In other examples, components of the soldering assembly that, generally, do not contact solder, may instead be 3D printed with stainless steel or titanium without coating.
In some examples, components of the soldering assembly, for example the nozzle, may be formed of two releasably connected parts. For example, the nozzle may include two or more sub-components, that couple together in use, but between uses can be de-coupled or separated to allow for maintenance. For example, the nozzle may include top and bottom portions that couple axially, or two or more side portions that couple longitudinally.
It would be understood that when referring to stainless steel in the examples above, any suitable grade of stainless steel may be used, for example A316 stainless steel.
It will be clear to a person skilled in the art that features described in relation to any of the embodiments described above can be applicable interchangeably between the different embodiments. The embodiments described above are examples to illustrate various features of the disclosure.
Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the disclosure are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The disclosure is not restricted to the details of any foregoing embodiments. The disclosure extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19193946.1 | Aug 2019 | EP | regional |
