Coated solder paste stencil and the method of producing thereof
The coated solder paste stencil with silicone and fluoroelastomer coatings on its surface and aperture walls addresses solder bridging and adhesion issues, ensuring precise deposition and reduced maintenance, achieving a 110-degree water contact angle for enhanced manufacturing efficiency.
Patent Information
- Authority / Receiving Office
- AU · AU
- Patent Type
- Applications
- Current Assignee / Owner
- ULTRACORE (PENANG) SDN BHD
- Filing Date
- 2024-12-16
- Publication Date
- 2026-07-23
AI Technical Summary
Conventional solder paste stencils lack coatings on their surface and aperture walls, leading to solder bridging, residue, and reduced release capability, necessitating frequent cleaning and maintenance, and existing coatings do not achieve optimal hydrophobic properties.
A coated solder paste stencil with coatings on its surface and aperture walls, using materials like silicone, titanium, or fluoroelastomer, applied via physical vapor deposition to achieve a high contact angle and prevent solder paste adhesion.
The solution ensures precise solder paste deposition, reduces downtime, and enhances manufacturing efficiency by minimizing adhesion and clogging, achieving a water contact angle of at least 110 degrees for superior hydrophobicity.
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Abstract
Description
TECHNICAL FIELD OF THE INVENTION Embodiments of the present invention relate to the field of electronics 5 manufacturing or surface mount technology (SMT) and, more specifically, to solder paste stencils with coatings on their surface and aperture wall, as well as a manufacturing method for producing them. These stencils are essential tools used in the assembly of electronic circuit boards. They facilitate the precise application of solder paste onto circuit board surfaces 10 through apertures, enabling the attachment of surface-mounted components during the manufacturing process. BACKGROUND OF THE INVENTION In the field of electronics manufacturing or surface mount technology (SMT), the solder paste stencil plays a pivotal role in the production of high- 15 quality printed circuit boards (PCBs). Traditionally, solder paste stencils have been employed to precisely deposit solder paste onto PCBs, enabling the solder to form reliable electrical connections during the reflow soldering process. However, the conventional solder paste stencils have exhibited 20 significant drawbacks that hindered their performance and reliability. One prominent drawback pertains to the absence of coatings on the stencil's 2024278432 16 Dec 2024 surface and aperture walls. Without such coatings, solder paste tends to adhere to the stencil's outer and inner surfaces, causing solder bridging on the stencil’s surfaces and clogging within the apertures and leading to residue solder paste sticking to the outer surface and inner surfaces. This 5 undesirable phenomenon not only disrupts the uniformity of solder paste deposition but also reduces the solder paste release capability of the stencil, of which necessitates frequent stencil cleaning and maintenance, thereby increasing manufacturing downtime and costs. Furthermore, as technology in electronics manufacturing has 10 advanced, some prior art solutions attempted to address these issues by introducing coatings and hydrophobic surface treatments. While these innovations demonstrated progress, they fell short in achieving the desired level of effectiveness. In particular, the contact angle of these coatings remained notably low, leading to persistent wetting issues. These 15 innovations often used materials that were not suitable or sufficient for creating a truly hydrophobic surface with a high contact angle. Additionally, the methods employed for coating were not optimized for achieving the desired hydrophobic properties. As a result, the solder paste stencil's ability to consistently deliver precise solder deposits and maintain high production 20 yields remained compromised. Thus, it is evident that a need exists for an improved solder paste stencil solution that not only incorporates coatings on both the stencil's surface and aperture walls but also ensures an optimal contact angle to 2024278432 16 Dec 2024 prevent wetting issues. Such an innovation would alleviate the problems associated with prior art, resulting in enhanced solder paste stencil performance, reduced downtime, and improved manufacturing efficiency. SUMMARY OF THE INVENTION 5 Accordingly, it is the primary aim of the present invention to provide an improved solder paste stencil and associated manufacturing process that address the deficiencies of prior art solutions. It is yet another objective of the present invention to provide a solder paste stencil with coatings on its surface and aperture walls. 10 It is yet another objective of the present invention to provide coatings on solder paste stencil with hydrophobic surface with a high contact angle to prevent wetting issues. It is yet another objective of the present invention to provide a solder paste stencil which is able to minimize solder paste adhesion to the stencil's 15 inner and outer surfaces. It is yet another objective of the present invention to provide a solder paste stencil which is able to enhance the precision and uniformity of solder paste deposition. 2024278432 16 Dec 2024 It is yet another objective of the present invention to provide a solder paste stencil which is able to reduce the need for frequent stencil cleaning and maintenance. Additional objects of the invention will become apparent with an 5 understanding of the following detailed description of the invention or upon employment of the invention in actual practice. According to the preferred embodiment of the present invention the following is provided: A coated solder paste stencil, comprising: 10 a substrate defining a plurality of solder apertures, characterized in that at least one outer surface of said substrate is coated with at least a coating material; each aperture wall of each of the plurality of solder apertures is 15 coated with at least a coating material; wherein said coating material includes but not limited to silicone, titanium, fluoroelastomer, or the like, or any combination thereof. According to another preferred embodiment of the present invention the following is provided: 2024278432 16 Dec 2024 A method for manufacturing a coated solder paste stencil, comprising the steps of: forming a substrate that defines a plurality of solder apertures; depositing at least a coating material on the substrate; 5 characterized in that said coating material is silicone, titanium, or fluoroelastomer, or any combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS Other aspect of the present invention and their advantages will be 10 discerned after studying the Detailed Description in conjunction with the accompanying drawings in which: FIG. 1-A illustrates an exemplary front perspective view of a coated solder paste stencil according to the preferred embodiment of the present invention. 15 FIG. 1-B illustrates an exemplary back perspective view of a coated solder paste stencil according to the preferred embodiment of the present invention. 2024278432 16 Dec 2024 FIG. 1-C illustrates an exemplary enlarged view of a coated solder paste stencil depicting the solder apertures according to the preferred embodiment of the present invention. FIG. 2-A illustrates an exemplary flow chart of a method for 5 producing a coated solder paste stencil according to the preferred embodiment of the present invention. FIG. 2-B illustrates an exemplary flow chart of sub-steps according to the method for producing a coated solder paste stencil in FIG. 2-A. FIG. 3 illustrates an exemplary flow chart of a method for producing 10 a coated solder paste stencil according to another embodiment of the present invention. FIG. 4-A illustrates an exemplary flow chart of a method for producing a coated solder paste stencil according to another embodiment of the present invention. 15 FIG. 4-B illustrates an exemplary flow chart of a method for producing a coated solder paste stencil according to another embodiment of the present invention. FIG 5 depicts a water contact angle diagram showcasing the hydrophobic properties of the coated solder paste stencil, as produced 20 using the method outlined in the embodiments of this present invention. 2024278432 16 Dec 2024 FIG. 6 illustrates an exemplary flow chart of a method for producing a coated solder paste stencil according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE DRAWINGS 5 In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by the person having ordinary skill in the art that the invention may be practised without these specific details. In other instances, well known methods, procedures and / or components have 10 not been described in detail so as not to obscure the invention. The invention will be more clearly understood from the following description of the embodiments thereof, given by way of example only with reference to the accompanying drawings, which are not drawn to scale. As used in this disclosure and the appended claims herein, the 15 singular forms "a", "an", and "the" include plural referents unless the context clearly dictates or denotes otherwise. Throughout the disclosure and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to 20 exclude, for example, other components, integers or steps. “Exemplary” 2024278432 16 Dec 2024 means “an example of” and is not intended to convey an indication of a preferred or ideal embodiment, “such as” is not used in a restrictive sense, but for explanatory purposes. The embodiments of the present invention are focused on a coated 5 solder paste stencil (1), which is an essential component in the electronics manufacturing industry, particularly in the assembly of printed circuit boards (PCBs). They play a crucial role in the application of solder paste onto PCBs, which is a fundamental step in surface mount technology (SMT) assembly processes. The primary purpose of a solder paste stencil (1) is to 10 precisely deposit solder paste onto specific areas of a PCB where electronic components (such as resistors, capacitors, and integrated circuits) will be mounted. Solder paste acts as a temporary adhesive that holds components in place during the soldering process. This invention presents a solder paste stencil with unique features designed to enhance its performance and 15 reliability. The coated solder paste stencil (1) according to the present invention includes framed stencils and frameless stencils. Framed stencils are attached to a frame, providing rigidity and stability during the solder paste application process. Frameless stencils do not have a frame and are 20 generally attached to a universal carrier, which can be more cost-effective for some applications. 2024278432 16 Dec 2024 The coated solder paste stencil (1) according to the present invention comprises a substrate (3) which defines a multitude of solder apertures or openings (5). The substrate (3), is preferably constructed from materials known for their durability and suitability for stencil fabrication and 5 materials that can withstand repeated use and the harsh conditions of the soldering process. These materials can include but not limited to stainless steel, nickel, glass, or combinations thereof, providing a sturdy foundation for the stencil's functionality. The solder apertures (5) are strategically positioned to align with specific locations on a PCB where solder paste 10 needs to be applied. These apertures (5) must be accurately positioned and have precise dimensions to ensure that the solder paste is deposited with high accuracy. The solder apertures (5) within the stencil (1) can be produced using a precision manufacturing process known as electroforming. This method ensures accurate dimensions and consistent 15 aperture shapes, which are crucial for achieving precise solder paste application on PCBs. The term "substrate" as utilized throughout this document encompasses a broad range of materials, including but not limited to base materials, support structures, platforms, films, foils, or similar components, 20 and may also involve combinations thereof. This inclusive definition ensures the flexibility to incorporate various materials and configurations within the scope of the term "substrate”. 2024278432 16 Dec 2024 FIGS. 1-A, 1-B and 1-C respectively show the front perspective view, back perspective view and enlarged view of an exemplary framed solder paste stencil (1), representing one embodiment of the present invention. The coated solder paster stencil (1) comprising said substrate (3) defining a 5 plurality of solder apertures or openings (5). Said substrate (3) is encircled or held in place by at least an interlaced or interwoven structure (7), preferably a mesh. The interlaced or interwoven structure (7) is then framed within a metal structure (9), typically made of aluminium. The coated solder paste stencil (1) according to the present invention 10 further comprises at least a coating material that reduces the wetting of solder paste, wherein said coating material is coated, applied, deposited or formed onto the surface of the substrate (3). Ideally, this coating material is extended to cover the inner wall (51) of each individual aperture (5), as well as at least one external surface (3a, 3b) of the substrate (3). This ensures that 15 solder paste does not adhere to the aperture walls (51) during the application process, preventing clogs and inaccuracies in solder paste placement. Within this context, the external surface (3a, 3b) of the substrate comprises two distinct surfaces, a top (3a) and a bottom surface (3b). wherein the top surface (3a) is the surface where the solder paste is 20 deposited onto, and the bottom surface (3b) is the area where solder paste flows out and deposited on intended surface or the surface in close contact with the intended object. The top surface (3a) is designated for depositing solder paste, and the bottom surface, where the solder paste flows out and adheres to the intended surface or makes close contact with the targeted 2024278432 16 Dec 2024 object. This arrangement ensures precise deposition and efficient flow of solder paste during the assembly process. Accordingly, it stands as a pivotal requirement for the solder apertures (5) to be coated with said coating material, primarily to ensure the 5 seamless flow of solder paste. The core purpose of the coating material is to minimize or altogether prevent or reduce the solder paste from adhering excessively or spreading across surfaces, a phenomenon commonly known as wetting. Hence, this coating material serves the critical function of preventing the solder paste from adhering and clogging within these 10 apertures (5), thereby guaranteeing a continuous, uninterrupted and efficient transfer of solder paste onto the desired surface or object. Additionally, the application of this coating material on the bottom surface (3b) is even more preferable as it diminishes the wetting of solder paste upon flow, preventing it from adhering to this surface (3b). This particular 15 treatment significantly reduces the tendency of solder paste to adhere upon its flow, mitigating any bonding to the bottom surface (3b). As a result, this coating facilitates an uninterrupted and optimal deposition of solder paste onto the intended surface, ensuring an appropriate and controlled amount of solder paste application. 20 While there's a consideration that the top surface (3a) could be coated with the mentioned material, it's not deemed necessary or recommended due to the coating's typical effect in reducing solder paste wetting. During the solder paste deposition process, automated machinery controls the 2024278432 16 Dec 2024 precise amount of paste applied onto the top surface of the substrate (3). Consequently, this deposited solder paste must smoothly flow through the apertures (5) to reach its intended target. Coating the top surface (3a) is discouraged to ensure the unimpeded flow of solder paste into the 5 apertures (5). If the top surface (3a) were coated, the reduced wetting effect might cause the solder paste to disperse or leak from the top surface (3a), potentially impacting the overall operational efficiency. According to the preferred embodiment of the present invention, the coating material is carefully selected to optimize the stencil's performance. 10 Said coating is typically a PVD (physical vapor deposition) coating comprising materials including but not limited to, silicone, titanium, fluoroelastomer, or any anti-fouling material or any combination thereof. Nevertheless, the choice of coating materials is not limited to specific options and may include other materials or other suitable vapor deposition 15 materials known in the art that offer similar benefits. This flexibility allows for adaptation to specific manufacturing requirements and materials availability. Ideally, the optimized coating for this invention combines silicone, titanium, and fluoroelastomer for enhanced efficacy. To achieve the desired coating on both the substrate's outer surfaces 20 (3a, 3b) and aperture walls (51), a specific deposition method is employed. In this case, the coating material is applied using the physical vapor deposition (PVD) technique, ensuring uniform and precise coverage, which is essential for optimal stencil performance. The PVD technique refers to a 2024278432 16 Dec 2024 variety of thin film deposition techniques that vaporize a solid material in a vacuum environment and deposit the solid material on substrate (3) as a pure material. FIG. 2-A illustrates an exemplary flow chart of a method (100) for manufacturing, producing, or preparing a coated solder paste 5 stencil (1), representing another preferred embodiment of this present invention. While the subsequent description of the method (100) for producing a coated solder paste stencil may initially employ "a" rather than "the" as an antecedent, it's imperative to note that the essence, objective, and purpose of 10 the features of the solder paste stencil (1) remain consistent with the aforementioned context. The method (100) of manufacturing said coated solder paste stencil (1) comprising the steps of forming a substrate (3) that defines a plurality of solder apertures (5) (110), achieved through methods including but not 15 limited to electroforming, etching, cutting, stamping, 3D printing, electro discharge machining, or the like, or any combination thereof; and depositing at least a coating material on the substrate (3) (130), wherein the coating material reduces the wetting of solder paste relative to the surfaces (3a, 3b, 51). This deposition involves applying the coating to the inner walls (51) of 20 each solder aperture (5) as well as at least one of its outer surfaces (3a, 3b). The coating material comprises various elements, including silicone, titanium, fluoroelastomer, or any suitable vapor deposition materials, any combinations thereof. Further illustrated in FIG. 2-B, the process of 2024278432 16 Dec 2024 depositing at least a coating material onto the substrate (3) (130) involves multiple sub-steps. Initially, the substrate (3) undergoes sputtering with silicone and / or titanium materials (131), creating a nano coating of film on the substrate surfaces. The process may then be followed by the subsequent 5 sputtering or evaporation of an anti-fouling material or fluoroelastomer material onto the substrate (3) (133), resulting in the creation of a coating composed of silicone and / or titanium, and fluoroelastomer. Turning attention to FIG. 3, displaying an illustrative flowchart outlining an alternative embodiment of this invention's method (100). Before 10 applying the specialized coating material, the substrate (3) undergoes a pretreatment step to prepare its surface. This pre-treatment involves cleaning the substrate with isopropyl alcohol (120), ensuring the surface is free from contaminants, and promoting effective adhesion of the coating material. Referring now to FIG. 4-A, presenting an illustrative flowchart that 15 outlines another alternative embodiment of the method (100) within this invention. This method (100) expands to comprise additional steps following the step of forming a substrate (3) defining multiple solder apertures (110) and preceding the step of deposition of the coating material onto the substrate (3) (130). These supplementary steps involve subjecting 20 the substrate (3) within a chamber (121), of which is equipped with coating bodies of silicone material, titanium material and fluoroelastomer material; subjecting the chamber into a vacuum state (123); and ejecting or 2024278432 16 Dec 2024 introducing fluid into the chamber (125), wherein said fluid includes but not limited to argon, oxygen, or the combination thereof. FIG. 4-B presents another illustrative flowchart that outlines another alternative embodiment of the method (100) within this invention, wherein 5 the supplementary steps (121, 123, 125) in FIG. 4-A are conducted following the step of cleaning the substrate with isopropyl alcohol (120), but preceding the step of deposition of the coating material onto the substrate (3) (130). It should be noted or considered that while the method describes the application of silicone and / or titanium material preceding the anti-fouling 10 material or fluoroelastomer material, the sequence can be altered. Alternatively, the anti-fouling material or fluoroelastomer material can be subjected to sputtering or evaporation before the application of silicone and / or titanium material. Through the method's embodiments, a coated solder paste stencil (1) 15 is formed or produced. It's crucial to emphasize the chemical reactions occurring in this coating process. During the PVD coating process, the collision of electrons with argon atoms from argon gas generates argon ions. These argon ions subsequently interact with the silicone and / or titanium material, producing silicone and / or titanium atoms / ions that adhere to the 20 substrate surfaces (3a, 3b, 51). Following this, the fluoroelastomer material undergoes either sputtering or evaporation, transitioning into a gaseous 2024278432 16 Dec 2024 state before depositing onto the substrate surfaces (3a, 3b, 51). This sequence culminates in the creation of a coating layer on the substrate (3). The silicone and / or titainium material, and / or anti fouling or fluoroelastomer material, or the combination thereof plays a pivotal role in 5 establishing a substantial hydrophobic and oleophobic effect. Particularly, the anti-fouling or fluroelastomer material contain active ingredient which can form a nano film with high hydrophobicity or oleophobicity. Illustrated in FIG. 5 is a diagram depicting the water contact angle resulting from the coating technique employed in the methods (100) of this present invention. 10 It's a universally accepted industry standard that a water contact angle below 90 degrees signifies potential wetting issues, while higher angles indicate a heightened degree of hydrophobicity. As per the figure, the methodology outlined in this invention consistently yields a water contact angle that surpasses the significant benchmark of 110 degrees, specifically 15 achieving an outstanding 115-degree and above measurement, which signifies a superior hydrophobicity. Through extensive and repetitive testing, this method consistently delivers a water contact angle that maintains a threshold of at least 110 degrees without ever dropping below this crucial level. This sustained level of performance underscores the 20 pioneering nature of this breakthrough within the industry, as achieving water contact angles no less than 110 degrees or in other words, equal or beyond 110 degrees, of which represents an unprecedented feat, not previously accomplished by any existing methodologies. 2024278432 16 Dec 2024 In accordance to another embodiment of the present invention as illustrated in FIG. 6, the method (100) of producing the coated solder paste stencil may further comprise a post-coating step, wherein the coated solder paste stencil (1) undergoes cleaning with isopropyl alcohol (150), ensuring 5 the surface is free from contaminants, and promoting effective adhesion of the coating material. While the present invention has been shown and described herein in what are considered to be the preferred embodiments thereof, illustrating the results and advantages over the prior art obtained through the present 10 invention, the invention is not limited to those specific embodiments. Thus, the forms of the invention shown and described herein are to be taken as illustrative only and other embodiments may be selected without departing from the scope of the present invention, as set forth in the claims appended hereto. The scope of the invention encompasses numerous alternatives, 15 modifications and the equivalents. Of necessity, there are many alternative ways of configuring and implementing the invention to suit particular installations and environments while providing biological outcomes of differing design.
Claims
1. A coated solder paste stencil (1), comprising:a substrate (3) defining a plurality of solder apertures (5), characterized in thatat least one outer surface (3a, 3b) of said substrate (3) is coated with at least a coating material;each aperture wall (51) of each of the plurality of solder apertures (5) is coated with at least a coating material;wherein said coating material is a combination of silicone, titanium, and fluoroelastomer.
2. The coated solder paste stencil (1) as claimed in Claim 1, wherein the substrate (3) is made of stainless steel, nickel, or glass or the like, or any combination thereof.
3. The coated solder paste stencil (1) as claimed in claim 1 or 2, wherein the coating material is deposited with physical vapor deposition (PVD).
4. The coated solder paste stencil (1) as claimed in any one of the preceding claims, further comprising an interwoven structure (7) that surrounds and secures the substrate (3), with this interwoven structure (5) then being framed by a metal structure (9).2024278432 24 Jun 20265. The coated solder paste stencil (1) as claimed in any one of the preceding claims, wherein said substrate (3) is pre-treated with isopropyl alcohol before the coating material is deposited.
6. The coated solder paste stencil (1) as claimed in any one of the preceding claims, exhibits a water contact angle of no less than 110 degrees.
7. A method (100) for producing a coated solder paste stencil (1), comprising the steps of:i. forming a substrate (3) that defines a plurality of solder apertures (5) (110);ii. depositing at least a coating material to the substrate (3) (130);characterized in thatwherein said coating material is a combination of silicone, titanium, and fluoroelastomer.
8. The method (100) for producing a coated solder paste stencil (1) according to Claim 7, wherein the coating material is applied to the solder apertures (5) of the substrate (3) and at least one outer surface (3a, 3b) of the substrate (3).
9. The method (100) for producing a coated solder paste stencil (1) according to Claim 7 or 8, wherein the step of depositing at least a coating material on the substrate (3) (130) comprising the following sub-steps:2024278432 24 Jun 2026a. the substrate (3) undergoes sputtering with silicone and / or titanium materials (131);b. sputtering or evaporation of fluoroelastomer material onto the substrate (3) (133).
10. The method (100) for producing a coated solder paste stencil (1) according to any of the Claims 7 to 9, comprising a pre-treatment step of cleaning the substrate (3) with isopropyl alcohol (120), wherein this step is done before the step of depositing at least a coating material on the substrate (3) (130).
11. The method (100) for producing a coated solder paste stencil (1) according to Claim 10, further comprising the following steps take place between the step of pretreatment step of cleaning the substrate (3) with isopropyl alcohol (120) and preceding the step of depositing at least a coating material on the substrate (3) (130):I. subjecting the substrate (3) within a chamber (121);II. subjecting the chamber into a vacuum state (123); andIII. ejecting or introducing fluid into the chamber (125), wherein said fluid includes but not limited to argon, oxygen, or the combination thereof.
12. The method (100) for producing a coated solder paste stencil (1) according to any one of Claims 7 to 11, wherein the coated solder paste stencil (1) exhibits a water contact angle of no less than 110 degrees.2024278432 24 Jun 202613. The method (100) for producing a coated solder paste stencil (1) according to any one of Claims 7 to 11, the step of depositing at least a coating material onto the substrate (3) (130) utilize physical vapor deposition (PVD) method.
14. The method (100) for producing a coated solder paste stencil (1) according to any one of Claims 7 to 11, further comprising a post-coating step of cleaning the coated solder paste stencil (1) with isopropyl alcohol (150), whereby this step is done after the step of depositing at least a coating material to the substrate (3) (130).