Manufacturing and tape transfer method for patterning preforms

Abstract

The invention relates to a manufacturing method for a patterned preform on a transfer tape and such a patterned preform, and the use of a transfer tape as a carrier. The manufacturing method for a patterned preform comprises the steps of: - providing a patterned tape comprising a rigid substrate and a tape, wherein the tape is made of polyimide or polydimethylsiloxane, wherein the rigid substrate is at least partially covered by the tape, and wherein the tape comprises a pattern of recesses; and - at least partially filling the recesses of the patterned tape with an electrically conductive material to obtain the patterned preform. The electrically conductive material comprises a mixture of a first component having a first melting point and a second component having a second melting point, the second melting point being different from the first melting point.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a patterned preform to be used as a transfer tape and to such a patterned preform. The manufacturing method relates to the technical field of conductive materials, such as solder or sintered materials for connecting electronic components. This manufacturing method is particularly suitable for achieving high-precision and fine-pitch applications, wherein there are micrometer, submicrometer, and nanometer-sized gaps between two adjacent printed solder bumps. Background Technology

[0002] In applications such as small and micro LEDs, solder paste printing technology is shifting towards fine-pitch stencil printing, where there is a small gap between two adjacent printed solder bumps. This still relatively small gap, relative to powder size and precision printing, poses a challenge to current stencil solder paste printing technology in order to avoid short circuits in electrical terminals due to bridging of very close adjacent solder bumps. Summary of the Invention

[0003] Therefore, there is a need to provide an improved manufacturing method that, compared to existing technologies, allows for more sophisticated applications with even smaller gap distances.

[0004] The problems of this invention are addressed by the subject matter of the independent claims, wherein further embodiments are incorporated in the dependent claims. It should be noted that the aspects of the invention described below apply to patterned preforms, methods for manufacturing patterned preforms, and belt transfer processes for patterned preforms.

[0005] According to the present invention, a method for manufacturing patterned preforms is provided. The method for manufacturing patterned preforms includes the following steps:

[0006] a) Provides a patterned strip comprising a rigid substrate and a strip, wherein the strip is made of polyimide or polydimethylsiloxane (PDMS), wherein the rigid substrate is at least partially covered by the strip, and wherein the strip includes a pattern of recesses.

[0007] b) The recesses of the patterned polyimide or polydimethylsiloxane strip are at least partially filled with conductive material to obtain a patterned preform.

[0008] The conductive material comprises a mixture of a first component having a first melting point and a second component having a second melting point different from the first melting point.

[0009] The patterned preform obtained through the manufacturing process steps listed above can be used as a patterned transfer tape. In other words, the rigid substrate and tape can serve as a transport carrier for conductive material, which is held by the rigid substrate and tape. The patterned transfer tape then allows the conductive material to be transferred or transported to different locations (e.g., a customer) and further processed or applied to the customer's substrate, as explained below. The patterned preform can be removed and placed in a reversed position (flipped) on an actual substrate (e.g., a substrate provided by the customer for LED attachment), with the conductive material facing the substrate and the tape facing away from the substrate surface. The rigid substrate and tape can be removed such that only the conductive material remains on, for example, the LED substrate, to provide an attachment portion for, for example, an LED component. In other words, the manufacturing method may also include the following steps:

[0010] c) Place the patterned preform on the substrate (e.g., by flipping the patterned preform (transfer tape) in a reverse position).

[0011] d) Remove the rigid substrate and strip, leaving the conductive material portion on the substrate to provide attachment points for electronic components.

[0012] The rigid substrate and / or base can be a semiconductor-grade panel or substrate made of glass or polymer materials, capable of withstanding temperatures, for example, 150°C to 170°C. Glass materials may include SiO2. Polymer materials may include polyamides, PMMS, polyphenylene sulfide (PPS), polyetherimide, polysulfone, liquid crystal polymers, polyetheretherketone, PET, polithiazine, etc.

[0013] The dimensions of the rigid substrate can be, for example, a length and width of 5 mm to 1000 mm and a thickness of 1 mm to 100 mm, preferably a length and width of 5 mm to 500 mm and a thickness of 1 mm to 20 mm.

[0014] The recess can be any type of channel, hole, or opening of any size or shape. The size can be a few millimeters, micrometers, or nanometers. The shape can be spherical, circular, elliptical, angular, rectangular, polygonal, etc. The recesses may all be similar or different. The recess can be an open via, channel, blind hole, or notch. The depth of the recess can be from 1 μm to 1000 μm, preferably from 5 μm to 200 μm, resulting in a printing paste thickness of 10 μm to 100 μm.

[0015] The "filling of recesses" in step b) can be understood as printing, dispensing, or spraying conductive material in paste form into recesses or openings in the tape. The conductive material can also be applied to the recesses as a powder, for example, by dispensing, followed by heating or another compression step to increase the density and adhesion between the powder particles.

[0016] The conductive material disposed in the recess may include solder, sintering paste, or powder material, or may be a solder, sintering paste, or powder material. The conductive material may include solder alloys, metal powders, doped metals, doped metal alloys, conductive binders, etc. The conductive material includes a mixture of a first component and a second component with different melting points. Preferably, both components are solder alloys. In an example, the first component of the conductive material includes a BiSnAg alloy or is a BiSnAg alloy. In an example, the second component of the conductive material includes a SnAgCu alloy or is a SnAgCu alloy. The conductive material may also include heat and / or UV curing agents, binders, solvents, dispersants, rheology modifiers, etc., as one of the first or second components or as additional components.

[0017] The manufacturing method according to the invention is particularly suitable for manufacturing high-precision and fine-pitch applications with inter-pitch distances of micrometer, submicrometer, and nanometer sizes. The inter-pitch distance from the center of a printed dot or square to the nearest adjacent printed dot or square can range from nanometer to micrometer. Preferably, at least some of the inter-pitch distances are less than 30 μm, more preferably less than 20 μm, and more preferably less than 10 μm.

[0018] The manufacturing method according to the invention allows for the production of high-precision and fine-pitch applications, which have extremely small recesses in the strip, thereby resulting in minimal connection points to electronic components to be connected via conductive material. In an example, at least some of the recesses in the strip have a diameter in the range of micrometers to nanometers. Preferably, at least some of the recesses have a width between 10 μm and 100 μm, depending on the customer substrate design, or less than 25 μm, preferably less than 18 μm, and more preferably less than 10 μm.

[0019] In addition, the manufacturing method according to the invention avoids uneven material deposition in the form of conductive materials with different heights and / or compositions, and helps to improve manufacturing throughput and quality.

[0020] Fine-pitch applications manufactured by the method according to the present invention can be small or micro LED applications, semiconductor back-end packaging applications, surface mount interconnect applications, etc.

[0021] In the example, step a) of providing the patterned band also includes the following steps:

[0022] -Provide a rigid base

[0023] - At least partially cover the rigid substrate with a strip, and

[0024] - Provide a pattern for the recessed portion in the strip.

[0025] The tape is preferably made of or comprises polyimide or PDMS. The tape can be applied to a rigid substrate by, for example, mechanical rolling with adhesive. The tape can then be secured to the rigid substrate.

[0026] In the example, step a) of providing the patterned strip also includes providing an intermediate coating between the rigid substrate and the strip. The intermediate coating protects the patterned strip from moisture, dust, chemicals, air pollutants, extreme temperatures, etc. The intermediate coating allows the strip to be easily removed from the rigid substrate. The intermediate coating can be a conformal coating, meaning, for example, a protective coating or polymer film with a thickness of 1 μm to 25 μm, preferably 1 μm to 5 μm, that is "conformal" to the substrate topology. The material composition of the intermediate coating can depend on the rigid substrate material. For a glass panel as a rigid substrate, the coating can be a nitrate or oxide film. For a polymer substrate as a rigid substrate, the coating can be a polymer, such as polyurethane, silicone, acrylic, fluorinated or non-fluorinated parylene (p-xylene), epoxy resin, amorphous fluoropolymers, etc. The intermediate coating can be applied, for example, by spraying, dispensing, or spin coating.

[0027] In another example, step a) of providing the patterned band includes the following steps (not necessarily all of them or in this order):

[0028] -Provide a substrate or silicon wafer.

[0029] - Apply a mask to at least a portion of the substrate.

[0030] - Apply a coating to at least the unmasked portions of the substrate.

[0031] - The coating is hardened by, for example, UV radiation.

[0032] -Remove unwanted parts of the mask.

[0033] - Etch the substrate to receive portions of varying thicknesses, depending on the masking and / or etching of the portion.

[0034] - Cast a film onto the etched substrate, the film preferably being made of or containing polydimethylsiloxane.

[0035] - Remove the etched substrate, leaving a negative shape for the substrate and including recesses of varying thicknesses similar to those obtained through earlier etching.

[0036] - Apply the band to a rigid substrate, such as one made of glass, and

[0037] - By bonding rigid substrates and strips, for example, through plasma or by adhesive films.

[0038] The polyimide or polydimethylsiloxane strip is patterned, and the recessed pattern in the strip can be formed by photolithography, chemical etching (wet and dry), laser cutting, etc.

[0039] In the example, step b) of filling the recesses of the patterned strip with conductive material at least partially also includes a scraping step to remove conductive material (e.g., excess paste) beyond the recesses and / or to flatten the conductive material.

[0040] In the example, the manufacturing method also includes the step of providing an inert film on top of the patterned strip and the filled recesses. The inert film can be laminated onto the patterned strip and the filled recesses by, for example, spraying, gluing, or mechanical rolling. The inert film can be an oxide film, an organic film, a thermoplastic, a sacrificial film, etc. The inert film can protect the patterned preform during processing, especially during transport to the customer. When the inert film is no longer needed and before attachment to the substrate, it can be removed mechanically or otherwise, such as by burning. The thickness of the inert film can range from 1 μm to 2000 μm.

[0041] Step c) is to provide a patterned preform on a substrate. This may include treating or spraying flux onto the substrate and / or the preform to, for example, prevent oxidation and / or improve tack and processability.

[0042] Step c) may include, for example, optical alignment of a patterned preform relative to a substrate. This can be accomplished, for example, by using a reference.

[0043] Step c) may include partial reflow or a first heating to fix the patterned preform (pre) to the substrate. In other words, in this example, there may be an additional step after placing the patterned preform on the substrate in step c). This step may be the first heating step before removing the rigid substrate and strip in step d). The partial reflow or first heating may be in the range of 100°C to 190°C, preferably 150°C to 175°C. The duration may be between 1 minute and 30 minutes.

[0044] In another example, the patterned preform can be (pre)fixed to a substrate using a fixative, which can be applied locally to the preform or substrate, such as glue or solvent droplets.

[0045] Step d) can be understood as removing everything except the conductive material pattern before the electronic component (e.g., an LED component) is attached to the conductive material. Step d) may also include flux treatment or spraying to, for example, prevent oxidation. In other words, the manufacturing method may also include the step of providing flux between the substrate, the patterned preform, and / or the electronic component in or before step d).

[0046] Step d) may also include heating to (pre-)attach the electronic component to the conductive material pattern. Step d) may be followed by soldering, a second heating, or reflow to finally attach the electronic component to the conductive material pattern. The final reflow or second heating may be in the range of 200°C to 300°C, preferably 220°C to 270°C. The duration may be between 1 minute and 20 minutes.

[0047] The conductive material comprises a mixture of a first component and a second component having different melting points. Both the first and second components can be metals, metal alloys, doped metals, or doped metal alloys, or they can be fundamentally different; for example, one component can be a resin, solvent, or dispersant. Preferably, it is a mixture of metals, metal alloys, doped metals, or doped metal alloys, such as solder alloys and / or solder in powder form. The different melting points allow for different heating or reflow steps to achieve different functions. The first component has a first melting point, and the second component has a second melting point. The second melting point can be higher than the first melting point. At the first lower melting point, the second component does not, or at least does not completely react or melt.

[0048] In the example, a first melting point is selected to establish a junction between the conductive material and the substrate. This can be understood as the first component being configured or selected to have a melting point (referred to here as the first melting point) that is configured to establish a junction between the conductive material and the substrate when the patterned preform is subjected to a temperature equal to or higher than the first melting point.

[0049] In this example, the second melting point is selected to form the joint between the conductive material and the electronic component. This can be understood as the second component being selected to have a melting point (referred to here as the second melting point) that is configured to form the joint between the conductive material and the electronic component when the patterned preform is subjected to a temperature equal to or higher than the second melting point.

[0050] In the example, the second melting point is higher than the first melting point.

[0051] In the example, the second melting point is selected to achieve the formation of one or more intermetallic phases at least between the first component and the second component. This can be understood as the second component being selected to have a melting point (referred to herein as the second melting point) that is configured to achieve the formation of one or more intermetallic phases at least between the first component and the second component when the patterned preform is subjected to a temperature equal to or higher than the second melting point.

[0052] In the example, the second melting point is also selected to achieve one or more intermetallic phases between the first component and the electronic component and / or between the second component and the substrate. This can be understood as the second component being selected to have a melting point (referred to herein as the second melting point) configured to achieve the formation of one or more intermetallic phases at least between the first component and the electronic component and / or between the second component and the substrate when the patterned preform is subjected to a temperature equal to or higher than the second melting point.

[0053] In other words, the first melting point is selected to establish a joint between the conductive material and the substrate, and the second melting point is selected to establish a strong connection between the electronic component and the substrate via the conductive material. The first joint can be a weak joint, such as adhesion, or it can be stronger, at least at the boundary of different materials or components, through a first forming of at least one intermetallic phase. The second melting point can be further selected to establish a strong connection between the electronic component and the substrate, for example, through intermetallic phase forming between the metallic components of the conductive material, the substrate, and the electronic component. Joints within the conductive material and / or between the conductive material and the substrate and / or between the conductive material and the electronic component allow rigid substrates and strips to be removed without tearing the conductive material. The joint provides structural integrity.

[0054] In the example, the first component of the conductive material includes or is a BiSnAg alloy. The first low-temperature component of the conductive material may have an alloy composition such as Sn57Bi or Sn56Bi1Ag, for example, with a melting range of 130°C to 150°C. In the example, the second component of the conductive material includes or is a SnAgCu alloy. The second high-temperature component of the conductive material may have an alloy composition such as Sn3Ag0.5Cu (=SAC305), Sn4Ag0.5Cu, Sn1Ag0.5Cu, for example, with a melting range of 215°C to 225°C.

[0055] The conductive material is preferably a mixture or paste of solder alloy or powder. The content of the first low-temperature component can be from 1% to 10% by weight relative to the total paste content, and the content of the second high-temperature component can be from 85% to 95% by weight. An exemplary paste composition can be 1% Sn57Bi1Ag + 87% SAC3O5, which means the total metal content in the paste is 88% by weight.

[0056] The conductive material may include particles from T6 to T9, which means the following particle diameter distribution: T6: 80% of the particles have a diameter between 5 μm and 15 μm, T7: 80% of the particles have a diameter between 2 μm and 11 μm, T8: 80% of the particles have a diameter between 2 μm and 8 μm, and T9: 80% of the particles have a diameter between 1 μm and 4 μm.

[0057] Conductive materials may include other components such as additives, solvents, dispersants, rheology modifiers, etc.

[0058] According to the present invention, a patterned preform is also provided. The patterned preform includes a patterned strip. The patterned strip includes a rigid substrate and a strip. The strip is made of polyimide or polydimethylsiloxane. The rigid substrate is at least partially covered by the strip. The patterned preform also includes a pattern of recesses disposed in the strip. The recesses of the patterned strip are at least partially filled with a conductive material to obtain the patterned preform. The conductive material includes a mixture of a first component having a first melting point and a second component having a second melting point. The second melting point is different from the first melting point.

[0059] The recess can be any kind of channel or opening of any size or shape. The recesses may all be similar or different. The recess can be a through-hole or a blind hole. In the example, at least some of the recesses have a width of less than 25 μm, preferably less than 18 μm.

[0060] In the example, the second melting point is higher than the first melting point. In the example, the first component of the conductive material includes or is a BiSnAg alloy. In the example, the second component of the conductive material includes or is a SnAgCu alloy.

[0061] In the example, the patterned preform also includes an intermediate conformal coating between the rigid substrate and the strip. In the example, the patterned preform also includes an inert sacrificial film on top of the patterned strip and the filled recess.

[0062] Patterned preforms can be used in small or micro LED applications, semiconductor back-end packaging, surface mount interconnects, and more. The width of the patterned preform can vary depending on the customer's substrate design and can range from 1 mm to 1000 mm or even larger.

[0063] It should be understood that the patterned preforms according to the independent claims and the methods for manufacturing the patterned preforms have similar and / or identical preferred embodiments, particularly as defined in the dependent claims. It should be further understood that preferred embodiments of the invention can also be any combination of the dependent claims and the corresponding independent claims.

[0064] These and other aspects of the invention will become apparent from the embodiments described below, and will be illustrated with reference to the embodiments described below. Attached Figure Description

[0065] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings:

[0066] Figures 1 to 5 A schematic diagram illustrating an example of a manufacturing method for patterned preforms.

[0067] Figures 6 to 10 A schematic diagram illustrating an exemplary application of patterned preforms.

[0068] Figures 11 to 16 Show Figures 1 to 3 A schematic diagram of the alternative. Detailed Implementation

[0069] Figures 1 to 10 An embodiment of a method for manufacturing and applying a patterned preform 1 is illustrated schematically and exemplary. The method includes the following steps:

[0070] Figure 1 A rigid substrate 11 is provided. An intermediate coating 15 is provided on the rigid substrate 11. The intermediate coating 15 protects against moisture, chemicals, etc.

[0071] Figure 2 The rigid substrate 11 and the intermediate coating 15 are covered with a tape 12. The tape is preferably made of or includes polyimide or PDMS. The tape 12 is applied to the rigid substrate 11 by, for example, mechanical rolling.

[0072] An inert film 16 is provided on top of the belt 12. The inert film 16 can be an oxide film, thermoplastic, sacrificial film, etc. It can be sprayed onto the belt 12.

[0073] Figure 3 Patterned strip 10 is obtained by providing a pattern of recesses 13 in strip 12 and inert film 16. Recesses 13 are applied here by photolithography. Recesses 13 are blind vias. The size of recesses 13 can be a few micrometers or a few nanometers. Another inert film 16 can be sprayed into the recesses 13 and onto the patterned strip 10.

[0074] Figure 4 The patterned preform 1 is obtained by filling the recesses 13 of the patterned strip 10 with conductive material 14. The filling of the recesses 13 can be accomplished by solder paste printing or by filling the recesses 13 in the strip 12 with conductive material 14 through the spray nozzle 17.

[0075] The conductive material 14 comprises a mixture of a first component and a second component with different melting points. Preferably, both components are solder alloys. The different melting points allow for different heating steps to achieve different functions. The first component of the conductive material 14 is a BiSnAg alloy. The second component of the conductive material 14 is a SnAgCu alloy.

[0076] The conductive material 14 beyond the recess 13 is removed by scraper 18.

[0077] Figure 5An inert film 16 is provided on top of the patterned strip 10 and the filled recess 13. The inert film 16 can be an oxide film, thermoplastic, sacrificial film, etc. It can be sprayed onto the patterned strip 10 and the filled recess 13. The inert film 16 can protect the patterned preform 1 during processing, especially during transportation to the customer.

[0078] The patterned preform 1 obtained through the manufacturing steps listed above is used as a patterned transfer tape, or in other words, as a transport carrier for the conductive material 14, which is held by the rigid substrate 11 and the tape 12. The patterned transfer tape allows the conductive material 14 to be transferred or transported, for example, to a customer, and further processed or applied to the customer's substrate 20, as explained below.

[0079] Figure 6 Substrate 20 is provided here. Substrate 20 is provided by the customer for LED attachment and / or advanced semiconductor packaging applications. Flux, for example to prevent oxidation and / or improve adhesion, may be sprayed onto substrate 20 or onto the surface of a patterned preform.

[0080] Figure 7 The patterned preform 1 is placed on the substrate 20. The patterned preform 1 is removed and placed on the substrate 20 in an inverted position, with the conductive material 14 facing the substrate 20 and the strip 12 facing the environment. The patterned preform 1 can be optically aligned relative to the substrate 20, for example, by a reference.

[0081] The inert film 16 can be removed before the patterned preform is placed on the substrate.

[0082] After the patterned preform 1 is placed on the substrate 20, partial reflow or initial heating may occur. This can be used to pre-fix the patterned preform 1 to the substrate 20 and to facilitate the removal of the rigid substrate 11 and the strip 12 from the conductive material 14. The partial reflow can last for a duration between 1 minute and 30 minutes in the range of 100°C to 190°C.

[0083] This first heat treatment allows the first component (e.g., BiSnAg particles) to melt. This will result in the interconnection of particles of the second component (e.g., SnAgCu), which remains stable as particles after the first heat treatment, and will also cause conductive material to adhere to the substrate. The particles of the second component will... Figure 9 The material is melted during the second heat treatment shown in the figure to form a stronger bond between the first and second components of the conductive material 14 and the substrate.

[0084] Figure 8The rigid substrate 11, strip 12, and all intermediate coatings and inert films are removed, leaving only the conductive material portion on the substrate 20 to provide attachment points for the electronic component 30. This can be understood as removing everything except the pattern of the conductive material 14. Flux treatment may also be used to prevent oxidation.

[0085] Figure 9 The LED component 30 is attached to the conductive material 14.

[0086] A second heating, reflow, or soldering process is applied to attach the electronic component 30 to a conductive material pattern. The reflow can last for a duration between 1 minute and 30 minutes, within the range of 200°C to 300°C.

[0087] The conductive material 14 comprises a mixture of a first component and a second component having different melting points. The first melting point of the conductive material 14 may be selected to establish a junction between the conductive material 14 and the substrate 20, and the second melting point of the conductive material 14 may be selected to establish a junction between the conductive material 14 and the electronic component 30. Such a junction can be understood as the formation of one or more intermetallic phases at least at the boundary between different materials or components. The second melting point may be further selected to establish one or more intermetallic phases at least between the first component and the second component. The second melting point may also be selected to establish one or more intermetallic phases between the first component and the electronic component 30 and / or between the second component and the substrate 20. The formation of the intermetallic phases may also result in a nearly complete mixture and homogeneous composition of the conductive material 14 located between the electronic component and the substrate. The junction within the conductive material 14 and / or between the conductive material 14 and the substrate 20 allows the rigid substrate 11 and the strip 12 to be removed without tearing the conductive material 14.

[0088] Figure 10 A product is obtained having an electronic component 30 having a conductive material 14 fixed to a substrate 20.

[0089] Figures 11 to 16 The above explanation is illustrated schematically and exemplary. Figures 1 to 3 The alternative solution. This alternative solution can be referred to above. Figures 4 to 10 The methods and steps explained.

[0090] Figure 11 A substrate or silicon wafer 41 is provided. The thickness of the silicon wafer 41 may be in the range of 0.5 mm to 1.5 mm. A mask 42, particularly a photomask, is applied to at least a portion of the silicon wafer 41. The mask 42 is aligned with respect to the silicon wafer 41. The thickness of the mask 42 may be in the range of 5 μm to 15 μm. Unmasked portions 44 or openings exist between the masked portions of the silicon wafer 41.

[0091] Figure 12A coating 43, particularly a photoresist coating, is applied at least in the opening between the unmasked portion 44 or the masked portion of the silicon wafer 41.

[0092] Figure 13 Expose the sample to UV light 45 to harden the coating 43. Remove any unwanted portions of the mask before or after exposure to UV light.

[0093] Figure 14 The silicon wafer 41 is etched to obtain a silicon mold substrate 44. A coating protects the area of ​​interest so that the area is not etched. The etched silicon wafer 41 may still have portions with a maximum thickness in the range of 0.5 mm to 1.5 mm, but also portions that are etched and thus reduced in thickness to or in the range of about 5 μm to 75 μm.

[0094] Figure 15 A strip 12 or casting made of polydimethylsiloxane is applied to the etched silicon mold substrate 44. The strip 12 may cover the silicon mold substrate 44 to provide a flat surface, without substantially different thickness in the interlayer.

[0095] Figure 16 Remove the silicon mold substrate 44. The strip 12 is retained and now includes the recess 13 or blind via, which was previously filled by the thickest portion of the silicon wafer 41. The strip 12 is applied to a rigid substrate 11, for example, made of glass. The rigid substrate 11 and the strip 12 are joined. This can be done via plasma or through an adhesive film, etc.

[0096] It should be noted that embodiments of the present invention are described with reference to different subjects. In particular, some embodiments are described with reference to method type claims, while others are described with reference to device type claims. However, those skilled in the art will conclude from the above and below description that, unless otherwise stated, any combination of features relating to different subjects, except for any combination of features belonging to one type of subject, is also considered to be disclosed by this application. However, all features can be combined to provide a synergistic effect greater than the simple sum of the features.

[0097] While the invention has been shown and described in detail in the accompanying drawings and the foregoing description, such illustrations and descriptions should be considered illustrative or exemplary rather than restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and implemented by those skilled in the art in practicing the claimed invention through a study of the drawings, the disclosure, and the dependent claims.

[0098] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are re-referenced in mutually different dependent claims does not imply that a combination of those measures cannot be used advantageously. Any reference numerals in the claims should not be construed as limiting the scope.

[0099] Implementation Plan

[0100] 1. A method for manufacturing a patterned preform (1), comprising the following steps:

[0101] - Provides a patterned strip (10) comprising a rigid substrate (11) and a strip (12), wherein the strip (12) is made of polyimide or polydimethylsiloxane, wherein the rigid substrate (11) is at least partially covered by the strip (12), and wherein the strip (12) includes a pattern of recesses (13); and

[0102] - A patterned preform (1) is obtained by at least partially filling the recesses (13) of the patterned strip (12) with conductive material (14).

[0103] The conductive material (14) comprises a mixture of a first component having a first melting point and a second component having a second melting point, the second melting point being different from the first melting point.

[0104] 2. The manufacturing method according to embodiment 1, wherein the manufacturing method further includes the following steps:

[0105] - Place the patterned preform (1) on the substrate (20), and

[0106] - At least the rigid substrate (11) and the strip (12) are removed, such that the conductive material (14) is partially retained on the substrate (20) to provide an attachment portion for the electronic component (30).

[0107] 3. The manufacturing method according to one of the foregoing embodiments, wherein the first component of the conductive material (14) comprises a BiSnAg alloy or is a BiSnAg alloy.

[0108] 4. The manufacturing method according to one of the foregoing embodiments, wherein the second component of the conductive material (14) comprises or is a SnAgCu alloy.

[0109] 5. The manufacturing method according to any one of embodiments 2 to 4,

[0110] The first melting point is selected to form a junction between the conductive material (14) and the substrate (20).

[0111] The second melting point is higher than the first melting point.

[0112] The second melting point was selected to form the joint between the conductive material (14) and the electronic component (30).

[0113] 6. The method according to the foregoing embodiments, wherein the second melting point is further selected between the first component and the second component, and preferably one or more intermetallic phases are realized between the first component and the electronic component (30) and / or between the second component and the substrate (20).

[0114] 7. The method according to any one of embodiments 2 to 6, wherein the method further comprises the step of providing a flux between the substrate (20) and the patterned preform (1).

[0115] 8. The manufacturing method according to one of the foregoing embodiments, wherein at least some of the recesses (13) in the band (12) have a size in the range of nanometers to micrometers.

[0116] 9. The manufacturing method according to one of the foregoing embodiments, wherein the step of providing the patterned strip (10) includes the following steps:

[0117] - Provide a rigid base (11),

[0118] -The rigid substrate (11) is at least partially covered by the strip (12), and

[0119] - A pattern of recesses (13) is provided in the band (12).

[0120] 10. The manufacturing method according to the foregoing embodiment, wherein the step of providing the patterned strip (10) further includes the step of providing an intermediate coating (15) between the rigid substrate (11) and the strip (12).

[0121] 11. The manufacturing method according to one of the foregoing embodiments, wherein the step of providing the patterned strip (10) further includes the step of forming a pattern of recesses (13) in the strip (12) by chemical etching or laser cutting.

[0122] 12. The manufacturing method according to one of the foregoing embodiments, wherein the manufacturing method further includes a scraping step to remove conductive material (14) beyond the recess (13).

[0123] 13. The manufacturing method according to one of the foregoing embodiments further includes the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

[0124] 14. A patterned preform (1), comprising:

[0125] - A patterned strip (10) comprising a rigid substrate (11) and a strip (12), wherein the strip (12) is made of polyimide or polydimethylsiloxane, wherein the rigid substrate (11) is at least partially covered by the strip (12), and

[0126] - A pattern of recesses (13) provided in the strip (12), wherein the recesses (13) of the patterned strip (10) are at least partially filled with a conductive material (14) to obtain the patterned preform (1).

[0127] The conductive material (14) comprises a mixture of a first component having a first melting point and a second component having a second melting point, the second melting point being different from the first melting point.

[0128] 15. The patterned preform (1) according to the aforementioned embodiment, wherein at least some of the recesses (13) have a width of less than 25 μm, preferably less than 18 μm.

Claims

1. A manufacturing method using a patterned preform (1), comprising the following steps: - Provide a patterned strip (10) comprising a rigid substrate (11) and a strip (12), wherein the strip (12) is made of polyimide or polydimethylsiloxane, wherein the rigid substrate (11) is at least partially covered by the strip (12), and wherein the strip (12) includes a pattern of recesses (13). as well as The patterned preform (1) is obtained by at least partially filling the recess (13) of the strip (12) with a conductive material (14), wherein the conductive material (14) comprises a mixture of a first solder alloy having a first melting point and a second solder alloy having a second melting point different from the first melting point, wherein the first solder alloy of the conductive material (14) comprises a BiSnAg alloy and the second solder alloy of the conductive material (14) comprises a SnAgCu alloy. The first melting point is selected to form a junction between the conductive material (14) and the substrate (20), and the second melting point is selected to form a junction between the conductive material (14) and the electronic component (30). The second melting point is higher than the first melting point. - Place the patterned preform (1) on the substrate (20), - The conductive material (14) and the substrate (20) are bonded by melting the first solder alloy through a first heating process in the range of 100°C to 190°C, and -At least the rigid substrate (11) and the strip (12) are removed, such that the conductive material (14) is partially retained on the substrate (20) to provide an attachment portion for the electronic component (30); - The electronic component (30) is attached to the attachment portion of the substrate by a second heating melting process in the range of 200°C to 300°C.

2. The manufacturing method according to claim 1, wherein the first solder alloy of the conductive material (14) is a BiSnAg alloy, and / or the second solder alloy of the conductive material (14) is a SnAgCu alloy.

3. The manufacturing method according to claim 1, wherein the second melting point is selected to realize one or more intermetallic phases between the first solder alloy and the second solder alloy.

4. The manufacturing method according to claim 2, wherein the second melting point is selected to realize one or more intermetallic phases between the first solder alloy and the second solder alloy.

5. The manufacturing method according to claim 1, wherein the second melting point is selected to realize one or more intermetallic phases between the first solder alloy and the electronic component (30) and / or between the second solder alloy and the substrate (20).

6. The manufacturing method according to claim 2, wherein the second melting point is selected to realize one or more intermetallic phases between the first solder alloy and the electronic component (30) and / or between the second solder alloy and the substrate (20).

7. The manufacturing method according to claim 3, wherein the second melting point is selected to realize one or more intermetallic phases between the first solder alloy and the electronic component (30) and / or between the second solder alloy and the substrate (20).

8. The manufacturing method according to any one of claims 1 to 7, wherein the method further comprises the step of providing a flux between the substrate (20) and the patterned preform (1).

9. The manufacturing method according to any one of claims 1 to 7, wherein at least some of the recesses (13) in the strip (12) have a width of less than 25 micrometers.

10. The manufacturing method according to claim 8, wherein at least some of the recesses (13) in the strip (12) have a width of less than 25 micrometers.

11. The manufacturing method according to any one of claims 1 to 7, wherein the step of providing the patterned strip (10) comprises the following steps: - Provide a rigid base (11), -The rigid substrate (11) is at least partially covered by the strip (12), and - A pattern of recesses (13) is provided in the band (12).

12. The manufacturing method according to claim 8, wherein the step of providing the patterned strip (10) comprises the following steps: - Provide a rigid base (11), -The rigid substrate (11) is at least partially covered by the strip (12), and - A pattern of recesses (13) is provided in the band (12).

13. The manufacturing method according to claim 9, wherein the step of providing the patterned strip (10) comprises the following steps: - Provide a rigid base (11), -The rigid substrate (11) is at least partially covered by the strip (12), and - A pattern of recesses (13) is provided in the band (12).

14. The manufacturing method according to claim 10, wherein the step of providing the patterned strip (10) comprises the following steps: - Provide a rigid base (11), -The rigid substrate (11) is at least partially covered by the strip (12), and - A pattern of recesses (13) is provided in the band (12).

15. The manufacturing method according to any one of claims 1 to 7, wherein the step of providing the patterned strip (10) further comprises the step of providing an intermediate coating (15) between the rigid substrate (11) and the strip (12).

16. The manufacturing method according to claim 8, wherein the step of providing the patterned strip (10) further comprises the step of providing an intermediate coating (15) between the rigid substrate (11) and the strip (12).

17. The manufacturing method according to claim 9, wherein the step of providing the patterned strip (10) further comprises the step of providing an intermediate coating (15) between the rigid substrate (11) and the strip (12).

18. The manufacturing method according to claim 11, wherein the step of providing the patterned strip (10) further comprises the step of providing an intermediate coating (15) between the rigid substrate (11) and the strip (12).

19. The manufacturing method according to claim 14, wherein the step of providing the patterned strip (10) further comprises the step of providing an intermediate coating (15) between the rigid substrate (11) and the strip (12).

20. The manufacturing method according to any one of claims 1 to 7, wherein the step of providing the patterned strip (10) further comprises the step of forming the pattern of the recesses (13) in the strip (12) by chemical etching or laser cutting.

21. The manufacturing method according to claim 8, wherein the step of providing the patterned strip (10) further comprises the step of forming the pattern of the recesses (13) in the strip (12) by chemical etching or laser cutting.

22. The manufacturing method according to claim 9, wherein the step of providing the patterned strip (10) further comprises the step of forming the pattern of the recesses (13) in the strip (12) by chemical etching or laser cutting.

23. The manufacturing method according to claim 10, wherein the step of providing the patterned strip (10) further comprises the step of forming the pattern of the recesses (13) in the strip (12) by chemical etching or laser cutting.

24. The manufacturing method according to claim 11, wherein the step of providing the patterned strip (10) further comprises the step of forming the pattern of the recesses (13) in the strip (12) by chemical etching or laser cutting.

25. The manufacturing method according to claim 15, wherein the step of providing the patterned strip (10) further comprises the step of forming the pattern of the recesses (13) in the strip (12) by chemical etching or laser cutting.

26. The manufacturing method according to claim 19, wherein the step of providing the patterned strip (10) further comprises the step of forming the pattern of the recesses (13) in the strip (12) by chemical etching or laser cutting.

27. The manufacturing method according to any one of claims 1 to 7, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

28. The manufacturing method according to claim 8, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

29. The manufacturing method according to claim 9, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

30. The manufacturing method according to claim 10, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

31. The manufacturing method according to claim 11, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

32. The manufacturing method according to claim 15, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

33. The manufacturing method according to claim 20, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

34. The manufacturing method according to claim 26, wherein the manufacturing method further comprises a scraping step to remove conductive material (14) beyond the recess (13).

35. The manufacturing method according to any one of claims 1 to 7, further comprising the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

36. The manufacturing method according to claim 8 further includes the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

37. The manufacturing method according to claim 9 further includes the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

38. The manufacturing method according to claim 10, further comprising the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

39. The manufacturing method according to claim 11, further comprising the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

40. The manufacturing method according to claim 15 further includes the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

41. The manufacturing method according to claim 20, further comprising the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

42. The manufacturing method according to claim 27 further includes the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

43. The manufacturing method according to claim 34 further includes the step of providing an inert film (16) on top of the patterned strip (10) and the filled recess (13).

44. A patterned preform (1), comprising: - A patterned strip (10) comprising a rigid substrate (11) and a strip (12), wherein the strip (12) is made of polyimide or polydimethylsiloxane, wherein the rigid substrate (11) is at least partially covered by the strip (12), and - A pattern of recesses (13) formed in the strip (12), wherein the recesses (13) of the strip (12) are at least partially filled with a conductive material (14) to obtain the patterned preform (1), wherein the conductive material (14) comprises a mixture of a first solder alloy having a first melting point and a second solder alloy having a second melting point different from the first melting point, wherein the first solder alloy of the conductive material (14) comprises a BiSnAg alloy and the second solder alloy of the conductive material (14) comprises a SnAgCu alloy. The first melting point is selected to achieve a junction between the conductive material (14) and the substrate (20) by first heating in the range of 100°C to 190°C. The second melting point is selected to achieve the formation of a joint between the conductive material (14) and the electronic component (30) by a second heating in the range of 200°C to 300°C, and wherein the second melting point is higher than the first melting point.

45. The patterned preform (1) according to claim 44, wherein the first solder alloy of the conductive material (14) is a BiSnAg alloy, and / or the second solder alloy of the conductive material (14) is a SnAgCu alloy.

46. ​​The patterned preform (1) according to claim 44 or 45, wherein at least some of the recesses (13) have a width of less than 25 μm.

47. The patterned preform (1) according to claim 46, wherein the width is less than 18 μm.

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