Method of forming electronic component having conformal coating, electronic component, and film precursor of conformal coating

Abstract

The invention provides a method of forming an electronic component having a conformal coating, the method comprising: providing a component preform, the component preform comprising a solder paste between a substrate and an electronic component; providing a film in solid form near the component preform, the film comprising a polymeric material; heating the solder paste to reflow the solder paste, thereby forming a solder joint between the substrate and the electronic component; and heating the film near the component preform to adhere the film to the component preform to form a conformal coating that at least partially coats the electronic component.

Description

[0001] The present invention relates to methods of forming electronic components having conformal coatings and films for use as precursors for conformal coatings of electronic components.

[0002] A conformal coating is a coating that may be formed over a component of an electronic assembly for purposes such as providing a physical layer that protects the assembly from environmental factors such as, for example, humidity, condensation, salt spray, and corrosive gases.

[0003] Conventional methods of forming conformal coatings on electronic components include liquid applied coatings, vacuum applied materials (such as in a batch process), and two-component coatings (such as foams, UV curable compositions, and room temperature vulcanizing (RTV) silicones).

[0004] The most common method of forming a conformal coating on an electronic component involves applying a liquid-coated coating by dipping, spraying, dispensing, or other methods suitable for controlled application of a liquid coating. Such methods may also involve providing a coating precursor in the form of pellets or rods, which is then melted and dispensed onto a substrate or circuit board. Dispensing the molten coating precursor may involve, for example, spraying the molten coating precursor onto the area to be coated. Dipping techniques and brushing techniques are also known. The coating may then be further dried or cured by various methods, including applying heat, applying radiation, chemical reaction, or simple solvent evaporation.

[0005] However, problems with such coating methods may include: dispensing liquid coatings requires additional processing time and equipment and may result in challenges with coverage and thickness uniformity; accuracy of coating placement may be insufficient; curing liquid-applied coatings typically requires additional energy input, which, in addition to being inefficient, can also shorten the life of the coated component; and many materials used for such liquid-applied coatings contain hazardous solvents or other ingredients that can be released into the environment, posing a threat to the user and the environment. In addition, additional pre-coating steps may be required, such as cleaning, masking, or taping to prevent coating of undesirable surfaces.

[0006] For example, US5510138A discloses a similar hot melt conformal coating method. In US5510138A, the conformal coating system is liquid at the high temperature when the coating system is applied to the electronic component. In other words, the hot liquid coating is applied to the substrate at an elevated temperature, wherein the hot liquid coating solidifies as it cools. Optionally, additional cross-linking mechanisms may be incorporated, which may require additional energy input. Therefore, the above-outlined disadvantages of additional processing and energy input may apply.

[0007] US2017 / 0309799A1 relates to a vacuum lamination method for forming a conformal coated article and the associated conformal coated article formed thereby. US 5475379A relates to a solid phase conformal coating suitable for use with electronic devices. WO 95 / 28822A1 relates to a conformal shield and a method for forming the same. US 5102712A relates to a method for conformal coating of a printed circuit board. US 9900988B1 relates to a protective layering method for EMU shielding and thermal management of circuit boards. US 2018 / 0211848A1 relates to electronic products and methods for manufacturing the same. US10568215A relates to PCBA encapsulation by thermoforming. US2003 / 0193113A1 relates to an apparatus and method for protecting electronic circuits. US2020 / 0267844A1 relates to an adhesive circuit patterning method.

[0008] Therefore, there is a need to provide an improved method of forming a conformal coating on an electronic component that is less time and energy intensive, simpler and preferably reduces the number of process steps.

[0009] The present invention seeks to address at least some of the problems associated with the prior art or at least provide a commercially acceptable alternative solution to the prior art.

[0010] The present invention provides a method of forming an electronic component having a conformal coating and a film for use as a precursor for a conformal coating of an electronic component according to the appended claims.

[0011] Specifically, in a first aspect, the present invention provides a method for forming an electronic component with a conformal coating, the method comprising: providing a component preform, the component preform comprising a solder paste located between a substrate and an electronic component; providing a film in a solid form near the component preform, the film comprising a polymer material; heating the solder paste to reflow the solder paste, thereby forming a solder joint between the substrate and the electronic component; and heating the film near the component preform to adhere the film to the component preform, thereby forming a conformal coating that at least partially coats the electronic component.

[0012] Each aspect or embodiment as defined herein may be combined with any other aspect or embodiment unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

[0013] The inventors have surprisingly discovered that electronic components with conformal coatings can be formed by the method of the present invention. In particular, it has been surprisingly discovered that the conformal coating can be provided by providing a film in solid form near a component preform, and heating the film near the component preform to adhere the film to the component preform, thereby forming a conformal coating that at least partially coats the electronic component. In addition, it has been discovered that this method can exhibit certain advantages over conventional methods of forming conformal coatings.

[0014] In particular, this method can surprisingly: avoid the need for additional process steps and equipment requirements (e.g., dispensing, buffering, and curing / drying); utilize existing processes (e.g., reflow profiles); minimize thermal degradation of components / assemblies; improve coverage and uniformity of coatings; and also avoid the need for some pre-coating process steps (such as masking or taping to prevent coating of undesirable surfaces). The present invention eliminates the need to dispense materials in liquid form, for example.

[0015] Furthermore, advantageously, this method can also avoid the use of potentially toxic solvents (since it is not applied in liquid form). This is because the polymeric material films being handled generally have low toxicity. Additionally, placing the film in solid form can be fast and accurate, especially compared to liquid coating methods. This can also eliminate the need for additional steps since existing equipment and similar processes can be used for the reflow profile.

[0016] This approach may also advantageously eliminate the mess and hazardous waste caused by handling liquid products, reduce health and safety requirements, save space required for additional equipment (e.g., hot melt coating applicators), and therefore also reduce energy consumption of the overall process.

[0017] As used herein, the term "electronic assembly" may encompass a system or device that includes one or more electronic components that are electronically connected to each other and configured to perform a function. An electronic assembly is a specialized term known to the skilled person. For example, an electronic assembly may include a printed circuit board (PCB) on which one or more electronic components are mounted.

[0018] As used herein, the term "conformal coating" may generally encompass a thin layer of polymeric material that may cover an electronic component, the thin layer typically conforming to the contours or topography of the electronic component to help physically protect the components and / or substrate of the electronic component from, for example, moisture, dust, chemicals, and / or extreme temperatures. In general, conformal coatings are well known to those skilled in the art.

[0019] As used herein, the term "assembly preform" may encompass a precursor to an electronic assembly, for example, in which one or more electronic components are arranged in their desired positions but in which solder paste has not yet been reflowed.

[0020] As used herein, the term "solder paste" may include, for example, solder powder mixed with flux. Solder paste is well known to the skilled person, and for the purposes of the present invention, the type of solder paste used is not particularly limited. However, preferably, the solder paste is substantially free of rosin or resin, and more preferably, the solder paste is free of rosin or resin. It is also possible to use, for example, sintered powder or solder film instead of solder paste.

[0021] As used herein, the term "substrate" may encompass any object in which electronic components may typically be mounted, such as a PCB. A substrate may typically comprise, for example, an electrically insulating plastic material. Suitable substrates are known to the skilled person.

[0022] As used herein, the term "electronic component" may encompass any basic discrete device or physical entity used to affect electrons or their associated fields in an electronic system. A non-exhaustive list of electronic components includes, for example, resistors, capacitors, light emitting diodes, transistors, field effect transformers (FETs), bottom termination components (BTCs), metal electrode leadless surfaces (MELFs), small outline integrated circuits (SOICs), and quad flat packages (QFPs). However, the type of electronic component is not important for the purposes of the present invention.

[0023] The solder paste is located between the substrate and the electronic component. However, as will be appreciated by the skilled person, the solder paste may not only be located directly between the substrate and the electronic component. For example, the solder paste may also be located around the electronic component.

[0024] As used herein, the term "film" may encompass a layer or sheet, typically a thin layer or sheet (e.g., having a thickness of about 30 μm to about 1 mm (or more)). The film may be flat, i.e., planar, or more typically, have a three-dimensional shape so as to conform to the contours of the component on which the film is placed. The film is in solid form and may substantially retain its shape at room temperature, such as at about 20°C. However, the film may also be flexible. Preferably, the film consists essentially of a polymer material, or more preferably consists of a polymer material. As used herein, the term "consisting essentially of" may encompass the presence of additional specific components, i.e., those components that do not substantially affect the basic properties of the film.

[0025] For example, providing a film in solid form near a component preform may include: providing a film in solid form at or near the expected position of a conformal coating to be formed. For example, the film may be arranged to be opposite (and facing) to the face of the substrate on which the electronic component is arranged, and preferably substantially parallel to, more preferably parallel to the face of the substrate on which the electronic component is arranged. In other words, the film may be provided in solid form near an electronic component and / or a substrate. In this context, the term "nearby" may encompass that the shortest distance between objects is, for example, 0mm to 50mm, preferably 0mm to 20mm, more preferably 0mm to 10mm, even more preferably 0.01mm to 5mm, and more preferably 0.05mm to 2mm. The shortest distance between objects is 0mm and may encompass that objects contact each other. As used herein, the term "in solid form" may encompass that the film is solid when provided near a component preform.

[0026] Once a conformal coating has been formed, polymeric materials can generally exhibit high thermal stability and are also highly electrically insulating.

[0027] As used herein, the term "solder joint" may encompass a solid attachment formed between a substrate and an electronic component, for example, when reflowed solder paste cools.

[0028] As used herein, the term "coating" may encompass directly coating an electronic component (eg, in direct contact with the electronic component) and / or indirectly coating an electronic component (eg, providing a physical barrier between the electronic component and the environment without physically contacting the electronic component).

[0029] Typically, the step of heating the film near the component preform to adhere the film to the component preform may involve: heating the film to soften and / or melt the film, which may then adhere to the component preform while maintaining the desired topographic coverage. In other words, the adhered film may become a conformal coating.

[0030] As will be clear from the description of the invention outlined herein, the step of heating the film near the component preform is performed after the step of providing the film in solid form near the component preform. In other words, the film may be softened or melted, for example, in situ. However, unless otherwise specified, in the broadest embodiment of the present invention, the step of heating the solder paste to reflow the solder paste may be performed at any time after the step of providing the component preform.

[0031] In a preferred embodiment, the film and solder paste are heated simultaneously. Preferably, the solder paste is reflowed after the step of heating the film near the component preform to adhere the film to the component preform. For example, if the reflow temperature of the solder paste is higher than the softening temperature of the film, the simultaneous heating of the film and the solder paste can be compatible with the embodiment in which the solder paste is reflowed after the film is heated near the component preform to adhere the film to the component preform. That is to say, even if the solder paste is heated simultaneously with the film, the solder paste can also be reflowed after the film is heated. More preferably, the solder paste is reflowed while heating the film near the component preform to adhere the film to the component preform. In other words, preferably, the heat from the soldering process is used to melt the film in the appropriate position at the same time. Advantageously, compared with the method of the prior art, such method can provide further improvement to the most extensive embodiment of the present invention. This is because other process steps, i.e. other additional heating steps, can be avoided, for example. Therefore, this method of forming a conformal coating can be very effective. This is because the coating can be applied without first reflowing the solder paste, thereby saving time, energy and cost. In other words, the method may preferably involve a single heating step that may cause reflow of the solder paste to form the solder joints and cause the film to adhere to the component preform to form a conformal coating.

[0032] In an alternative preferred embodiment, heating the solder paste occurs before providing a film in solid form near a component preform (i.e., a component preform on which the solder paste has been reflowed). In other words, in this embodiment, reflowing (or consolidating) the solder paste preferably occurs before providing a film in solid form near a component preform. In other words, in this embodiment, it is preferred to form a solder joint before forming a conformal coating on the component preform (i.e., adhering the film to the component preform). Of course, it should be understood that since the solder paste has been reflowed when providing the film in solid form, it can be said that a film is provided in solid form near a component preform on which the solder paste has been reflowed (i.e., now in the form of an electronic component (i.e., an electronic component provided by heating the solder paste so that the solder paste reflows to form a solder joint between a substrate and an electronic component)). Preferably, heating the solder paste occurs before heating the film near the component preform (or the resulting electronic component, as the case may be). This is possible because, for example, the melting point of the film is usually lower than the melting point of the solder joint. This embodiment may be more preferred when, for example, a "weak" solder is used in order to reduce the risk of "hot tearing" defects in, for example, the solder joint. However, the alternative embodiment as described above may be more preferred because it may require less time and energy input, as described herein.

[0033] In other words, in this alternative preferred embodiment, the present invention provides a method of forming an electronic component having a conformal coating, the method comprising:

[0034] providing an assembly preform including solder paste between a substrate and an electronic component;

[0035] heating the solder paste to reflow the solder paste, thereby forming solder joints between the substrate and the electronic component (i.e., thereby forming an electronic assembly);

[0036] providing a film in solid form adjacent to the component preform (ie, the electronic component) on which the solder paste has been reflowed, the film comprising a polymer material; and

[0037] The film is heated near the component preform (i.e., the electronic component) on which the solder paste has been reflowed to adhere the film to the component preform (i.e., the electronic component) on which the solder paste has been reflowed, thereby forming a conformal coating that at least partially coats the electronic component. The component preform on which the solder paste has been reflowed may cover the electronic component.

[0038] Preferably, providing the film in solid form near the component preform includes: providing the film in solid form and at a non-elevated temperature, preferably at room temperature. As used herein, the term "non-elevated temperature" may encompass heating the film neither intentionally nor purposefully when (initially) providing the film in solid form near the component preform. In other words, the term "elevated" may be relative to room temperature. Therefore, at or during this step of the method, the film may have a temperature of, for example, about 10°C to about 30°C, more preferably about 15°C to about 25°C, more preferably about 20°C. This means that the film can be simply provided in solid form, and no additional heating step is required. This can reduce the complexity of the method and reduce the time, energy and cost requirements for forming a conformal coating.

[0039] Preferably, heating the film near the component preform to adhere the film to the component preform includes: adhering the film to a substrate of the component preform. In other words, the film is preferably adhered to the substrate of the component preform to form a conformal coating. This arrangement can advantageously form a strong conformal coating. Alternatively or additionally, heating the film near the component preform to adhere the film to the component preform may include: adhering the film to an electronic component of the component preform.

[0040] Preferably, the conformal coating at least partially coats the solder joint, and more preferably, the conformal coating completely coats the solder joint.Such conformal coatings can provide the best protection for electronic components.

[0041] Preferably, the conformal coating completely encapsulates the electronic component between the film and the substrate. As used herein, the term "completely encapsulates" may encompass that the electronic component is completely surrounded (directly or indirectly) by the combination of the substrate and the conformal coating (i.e., the adhered film). In other words, the film preferably forms a tent-like shape over the electronic component, wherein the base of the tent-like shape is in contact with the substrate. Thus, the conformal coating also preferably completely encapsulates the solder joints. Such a conformal coating may provide the best protection for the electronic assembly.

[0042] Preferably, heating the solder paste comprises: heating the component preform. In other words, in order to heat the solder paste, it may be necessary to heat the entire component preform. Alternatively, the solder paste may be directly heated. The method of heating the solder paste is not particularly limited, and the method of heating the film is not particularly limited. Heating the component preform may also include: simultaneously heating the film near the component preform.

[0043] Preferably, providing the film in solid form near the component preform comprises: contacting the component preform with the film in solid form, more preferably contacting the substrate of the component preform with the film in solid form. The film may also contact the electronic components of the component preform. Bringing the component preform into direct contact with the film may help adhere the film to the component preform.

[0044] Preferably, heating the film includes: softening and / or at least partially melting the film. Softening and / or at least partially melting the film can help adhere the film to the component preform. Softening and / or at least partially melting the film can also help conform the film to the contour of the component preform so as to obtain a more effective and desired coating. The rheological properties of the molten film can advantageously help keep the film in a desired position on the component preform or electronic component during the heating step, so that the film conforms to the contour of the component preform or electronic component.

[0045] Preferably, the polymer material is a thermoplastic material. Thus, the conformal coating can be heated to allow easy removal of the conformal coating. For example, this can contribute to the recyclability of the electronic assembly.

[0046] Alternatively, the polymer material is preferably a thermosetting material. For example, such materials or plastics can be useful in forming a particularly resilient and resistant conformal coating. Typical thermosetting materials suitable for use in the present invention may include urethane, epoxy, acrylate and silicone parts. Thermosetting materials can be solidified or cured by any suitable method known to the technician (such as, for example, by heat from a reflow curve, moisture from the environment and / or UV radiation). Therefore, the method preferably also includes: curing the polymer material. Curing the polymer material can usually and preferably be performed after forming a conformal coating.

[0047] Preferably, the polymeric material is cross-linkable. Typical cross-linkable polymeric materials suitable for use in the present invention may include urethane, epoxy, acrylate and silicone moieties.

[0048] Preferably, the method does not include reflowing the solder paste prior to the step of heating the film adjacent the component preform. In other words, as described above, the conformal coating is preferably formed prior to or simultaneously with reflowing the solder paste. This can advantageously reduce the number of method steps required to form an electronic component having a conformal coating.

[0049] Preferably, the film is not heated before the step of providing the film in solid form near the component preform. In other words, preferably the film is not heated immediately before the step of providing the film in solid form near the component preform. That is, the film is preferably initially provided in solid form near the component preform in an unheated state. This does not exclude any heating that may be required when manufacturing the film, such as, for example, molding the film into a specific shape or forming a polymer material. Therefore, this can reduce the number of heating steps that may be required in the method compared to, for example, a hot melt coating process.

[0050] Preferably, the film is preformed to be at least partially complementary to the shape of the component preform or (obtained) electronic component. In other words, the film is preferably configured to be at least partially complementary to the shape of the component preform or (obtained) electronic component. The film can be at least partially complementary to the shape of at least a portion (for example, one or more electronic components in the electronic component) of the component preform or (obtained) electronic component. The film can also be fully complementary to the component preform or (obtained) electronic component to be coated. In other words, for example, the film can be shaped (such as in a three-dimensional manner) according to the contour of the component preform or (obtained) electronic component, and cut according to the size of the component preform or (obtained) electronic component. In other words, the film is preferably provided in a 3-dimensional preformed solid form. Advantageously, the amount of polymer material required can therefore be minimized, and excess material can not be wasted. In addition, the preformed film can help to adhere the film more strongly to the component preform or electronic component, because this can provide, for example, a larger contact surface area between the film and the component preform or the electronic component. Additionally, less melting / heating of the film is required because less movement of the film may be required to obtain a conformal coating. Thus, this may save additional time, energy, and cost.

[0051] More preferably, the film is preformed to be at least partially complementary to the shape of the specific electronic component of the component preform or (obtained) electronic component. More preferably, the component preform includes a plurality of electronic components, and the method includes providing a plurality of films, wherein the film is provided in solid form near each electronic component in the electronic component. In other words, the obtained electronic component may include a plurality of conformal coatings, each of which is formed by a separate film, and each film is preformed according to one or more electronic components to be coated. Therefore, a film may be intended to at least partially coat one or more electronic components. This may also enable the amount of required polymer material to be reduced. In addition, for example, this method may enable different polymer material compositions to be used for different films. Therefore, coating requirements (i.e., depending on the sensitivity of the component to moisture or other environmental factors) may be related to the specific electronic component to be coated by the film. This may result in a particularly effective conformal coating produced by an effective method. In other words, the obtained conformal coating may include a sub-coating.

[0052] Preferably, the method further comprises: pre-forming the film by die cutting or molding. Suitable die cutting and molding methods are known to the skilled person.

[0053] Preferably, providing the component preform comprises: printing and / or dispensing solder paste on the substrate. Suitable methods of printing solder paste are known to the skilled person. Preferably, the method further comprises: contacting the electronic component with the solder paste, preferably by a pick and place method. Pick and place methods are known to the skilled person and may involve, for example, picking up the electronic component from one location (e.g. using a pick and place machine or robot) and placing it in another location (such as at a desired location on the solder paste on the substrate) to form the component preform.

[0054] Preferably, providing the film in solid form adjacent the component preform comprises arranging the film by a pick-and-place method. Advantageously, the film may thus be provided in a desired location quickly and efficiently, thereby reducing the time required to form a conformal coating. Arranging the film may comprise positioning the film on or at a desired location on the component preform.

[0055] Preferably, heating the solder paste comprises heating the solder paste to a temperature equal to or higher than the reflow temperature of the solder paste for 1 minute to 5 minutes, such as for 1 minute to 3 minutes. Typical solder paste reflow temperatures may be, for example, about 150°C to about 250°C. When the film and solder paste are heated simultaneously, heating the film and solder paste may comprise, for example, heating the film and solder paste to or higher than the softening temperature of the film for 1 minute to 5 minutes, such as for 1 minute to 3 minutes. Typical softening temperatures of the films of the present invention may be, for example, about 130°C to about 200°C.

[0056] Preferably, the polymer material comprises one or more of polyolefins, polyamides, silicones, urethanes, epoxies and acrylic polymers. Suitable polymer materials are known to the skilled person.

[0057] Preferably, the assembly preform comprises two or more electronic components.

[0058] Preferably, the substrate comprises a printed circuit board. Preferably, the electronic component comprises one or more of the following: a resistor, a capacitor, a light emitting diode, a transistor, a field effect transformer (FET), a bottom termination component (BTC), a metal electrode leadless surface (MELF), a small outline integrated circuit (SOIC), and a quad flat package (QFP). Preferably, the electronic component comprises a QFP.

[0059] In another aspect of the present invention, there is provided an electronic component having a conformal coating formed by the method of any preceding claim.

[0060] In another aspect of the present invention, a film for use as a precursor of a conformal coating of an electronic component is provided, the film comprising a polymer material and being preformed to be at least partially complementary to the shape of a component preform. That is, the film can be preformed to be at least partially complementary to the shape of a component preform of an electronic component, the component preform comprising a solder paste between a substrate and an electronic component. In other words, the component preform can be a precursor of an electronic component, such as a precursor in which one or more electronic components are arranged in their desired positions but in which the solder paste has not yet reflowed, as described herein. In other words, the film can be preformed to be at least partially complementary to the shape of the (obtained) electronic component. The preferred embodiments and associated advantages of the film described herein with respect to the first aspect are equally applicable to the film of this aspect. Such a film can enable the advantages associated with the method described herein to be realized.

[0061] The above detailed description has been provided by way of explanation and illustration and is not intended to limit the scope of the appended claims. Many variations of the preferred embodiments of the invention shown herein will be apparent to those of ordinary skill in the art and are still within the scope of the appended claims and their equivalents.

Claims

1. A method of forming an electronic component having a conformal coating, the method comprising: providing an assembly preform including solder paste between a substrate and an electronic component; providing a film in solid form adjacent to the component preform, the film comprising a polymeric material; heating the solder paste to reflow the solder paste, thereby forming solder joints between the substrate and the electronic component; as well as The film is heated adjacent the component preform to adhere the film to the component preform, thereby forming a conformal coating that at least partially coats the electronic component. The method of claim 1 , wherein the film and the solder paste are heated simultaneously. 3 . The method according to claim 1 , wherein the solder paste is reflowed after heating the film adjacent to the component preform to adhere the film to the component preform.

4. The method of claim 1, wherein heating the solder paste occurs prior to providing a film in solid form adjacent the component preform.

5. The method of any preceding claim, wherein providing a film in solid form adjacent the component preform comprises: The film is provided in solid form and at non-elevated temperature, preferably at room temperature.

6. The method of any preceding claim, wherein heating the film adjacent the component preform to adhere the film to the component preform comprises: The film is adhered to the substrate of the component preform.

7. A method according to any preceding claim, wherein the conformal coating at least partially coats the solder joint.

8. A method according to any preceding claim, wherein the conformal coating completely encapsulates the electronic component between the film and the substrate.

9. The method of any preceding claim, wherein heating the solder paste comprises: The component preform is heated.

10. The method of any preceding claim, wherein providing a film in solid form adjacent the component preform comprises: The component preform is brought into contact with the film in solid form, preferably the substrate of the component preform is brought into contact with the film in solid form.

11. The method of any preceding claim, wherein heating the film comprises: The film is softened and / or at least partially melted.

12. A method according to any preceding claim, wherein the polymer material is a thermoplastic material.

13. The method of any one of claims 1 to 11, wherein the polymer material is a thermosetting material.

14. The method according to claim 13, further comprising: The polymer material is cured.

15. A method according to any preceding claim, wherein the polymeric material is capable of cross-linking.

16. A method according to any one of claims 1 to 3 or claims 5 to 15, wherein the method does not comprise reflowing the solder paste prior to the step of heating the film adjacent the component preform.

17. A method according to any preceding claim, wherein the film is not heated prior to the step of providing the film in solid form adjacent the component preform.

18. A method according to any preceding claim, wherein the film is pre-formed to be at least partially complementary to the shape of the component pre-form.

19. The method of claim 18, wherein the film is preformed to at least partially complement the shape of a particular electronic component of the assembly preform.

20. The method of claim 19, wherein the component preform comprises a plurality of electronic components, and the method comprises: A plurality of films are provided, wherein a film is provided in solid form adjacent each of the electronic components.

21. The method according to any one of claims 18 to 20, wherein the method further comprises: The film is preformed by die cutting or molding.

22. The method of any preceding claim, wherein providing a component preform comprises: The solder paste is printed and / or dispensed on the substrate.

23. The method according to claim 22, further comprising: The electronic component is preferably brought into contact with the solder paste by a pick and place method.

24. The method of any preceding claim, wherein providing a film in solid form adjacent the component preform comprises: The film is arranged by a pick and place method.

25. The method of any preceding claim, wherein heating the solder paste comprises: The solder paste is heated to a temperature equal to or higher than a reflow temperature of the solder paste for 1 minute to 5 minutes.

26. A method according to any preceding claim, wherein the polymer material comprises one or more of polyolefins, polyamides, silicones, urethanes, epoxies and acrylic polymers.

27. A method according to any preceding claim, wherein the component preform comprises two or more electronic components.

28. A method according to any preceding claim, wherein the substrate comprises a printed circuit board.

29. A method according to any preceding claim, wherein the electronic component comprises a quad flat package.

30. An electronic component having a conformal coating, the electronic component formed by the method of any preceding claim.

31. A film for use as a precursor for a conformal coating of an electronic component, the film comprising a polymeric material and being preformed to be at least partially complementary to the shape of the component preform.