WO2018228724A1 - Method of attaching rigid printed circuit boards on a substrate - Google Patents

Method of attaching rigid printed circuit boards on a substrate Download PDF

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Publication number
WO2018228724A1
WO2018228724A1 PCT/EP2018/025162 EP2018025162W WO2018228724A1 WO 2018228724 A1 WO2018228724 A1 WO 2018228724A1 EP 2018025162 W EP2018025162 W EP 2018025162W WO 2018228724 A1 WO2018228724 A1 WO 2018228724A1
Authority
WO
WIPO (PCT)
Prior art keywords
conducting
adhesive layer
functional group
conducting adhesive
polymer
Prior art date
Application number
PCT/EP2018/025162
Other languages
French (fr)
Inventor
Moazzam ALI
Original Assignee
Saralon Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Saralon Gmbh filed Critical Saralon Gmbh
Publication of WO2018228724A1 publication Critical patent/WO2018228724A1/en

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/36—Assembling printed circuits with other printed circuits
    • H05K3/361—Assembling flexible printed circuits with other printed circuits
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • H05K3/321—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by conductive adhesives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/04—Non-macromolecular additives inorganic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J5/00—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers
    • C09J5/04—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers involving separate application of adhesive ingredients to the different surfaces to be joined
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J5/00—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers
    • C09J5/06—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers involving heating of the applied adhesive
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
    • C09J9/02—Electrically-conducting adhesives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/001—Conductive additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/314—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive layer and/or the carrier being conductive
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H01L2224/8319—Arrangement of the layer connectors prior to mounting
    • H01L2224/83193—Arrangement of the layer connectors prior to mounting wherein the layer connectors are disposed on both the semiconductor or solid-state body and another item or body to be connected to the semiconductor or solid-state body
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/01—Dielectrics
    • H05K2201/0104—Properties and characteristics in general
    • H05K2201/0129—Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/36—Assembling printed circuits with other printed circuits
    • H05K3/368—Assembling printed circuits with other printed circuits parallel to each other

Definitions

  • the present disclosure relates to a method to attach rigid printed circuit board on a substrate, more specifically on a flexible substrate.
  • the present invention relates to a method of attaching a rigid printed circuit board on a substrate, more specifically on a flexible substrate.
  • a first conducting adhesive layer is provided on an electrical contact pad.
  • the electrical contact pad is provided on a bottom surface of the rigid printed circuit board.
  • the first conducting adhesive layer comprises at least one hot melt polymer, at least one first anchoring polymer and at least one conducting particle.
  • the at least one first anchoring polymer comprises at least one first functional group.
  • a second conducting adhesive layer is provided on an electrical conducting layer.
  • the electrical conducting layer is provided on a substrate.
  • the second conducting adhesive layer comprises at least one hot melt polymer, at least one second anchoring polymer and at least one conducting particle.
  • the at least one second anchoring polymer comprises at least one second functional group. After that, at least one of the first conducting adhesive layer and the second conducting adhesive layer is heated up to make the hot melt polymer sticky. In the final step, the first conducting adhesive layer and the second conducting adhesive layer are brought into contact to each other to establish electrical contact between the electrical conducting layer and the electrical contact pad.
  • the strong adhesion between first conducting adhesive layer and the second conducting adhesive layer comes due to the two kinds of chemical interaction involved. First one is the Van der Waals interactions between hot melt polymer chains and the second one is covalent bonds between the first functional group and the second functional group.
  • FIG. 1A is a cross sectional view of a substrate and a rigid printed circuit board, in accordance with an aspect of the present invention.
  • FIG. IB is a cross sectional view of a substrate and a conducting adhesive layer on a rigid printed circuit board, in accordance with an aspect of the present invention.
  • FIG. 1C is a cross sectional view of conducting adhesive layers on a substrate and on a rigid printed circuit board, in accordance with an aspect of the present invention.
  • FIG. ID is a cross sectional view of an attached rigid printed circuit board on a substrate, in accordance with an aspect of the present invention.
  • a carbon-carbon double bond can be called an alkenyl functional group, which may participate in a radical reaction. It is known in literature that a carbon -carbon double bond reacts with a thiol functional group easily and an epoxy functional group reacts with an amine functional group easily.
  • the present invention is about a method to attach a rigid printed circuit board on a substrate.
  • Fig. 1A shows a cross sectional view of a substrate 130. On a top surface 131 of the substrate 130 is provided an electrical conducting layer 140.
  • the substrate 130 can be mechanically flexible or mechanically rigid. In a non-limiting aspect, the substrate 130 is paper, plastic, metal, glass or laminate.
  • the electrical conducting layer 140 can be provided on the substrate 130 by a printing method and by using a conducting ink. In another aspect, the electrical conducting layer 140 can be provided on the substrate 130 by etching out a metal layer from the substrate 130.
  • Fig. 1A also shows a cross sectional view of a rigid printed circuit board 110.
  • At least one electrical contact pad 120 is provided on a bottom surface 111 of the rigid printed circuit board 110.
  • the rigid printed circuit board 110 can further comprise surface mountable devices on a top surface 112.
  • the electrical contact pad 120 is used to electrically connect the rigid printed circuit board 110 to an external circuit.
  • a first conducting adhesive layer 150 is provided on the electrical contact pad 120, as shown in Fig. IB.
  • the first conducting adhesive layer 150 comprises at least one hot melt polymer 151, at least one first anchoring polymer 152 and at least one conducting particle 153.
  • the at least one hot melt polymer 151 is a thermoplastic which becomes sticky and behaves as adhesive after heating it up above a certain temperature. In a non-limiting aspect, this temperature is 50°C.
  • Hot melt thermoplastic adhesives are well known in state-of-the-art. Some of the hot melt polymer 151 are PearlstickTM, PeralbondTM and Estane® from Lubrizol company.
  • the at least one conducting particle 153 is any electrically conducting particle e.g. silver, carbon, copper etc. The purpose of the at least one conducting particle 153 is make the first conducting adhesive layer 150 electrically conducting.
  • the at least one first anchoring polymer 152 comprises at least one first functional group 154.
  • the at least one first functional group 154 is attached to the polymeric chain of the first anchoring polymer 152.
  • the first functional group 154 is selected from the group of epoxy, thiol, acrylate, methacrylate and alkenyl.
  • the first anchoring polymer 152 can be selected, but not limited to, from a group polyaniline, polycarboxylic acid, multiple thiol functional groups containing molecule or polymer, multiple epoxy functional groups containing molecule or polymer, multiple acrylate functional groups containing molecule or polymer, multiple methacrylate functional groups containing molecule or polymer etc.
  • the first conducting adhesive layer 150 is provided on the electrical contact pad 120 by a printing method. It is understood here that after printing a layer, a heating and/or a curing step is needed to convert a wet printed layer into a solid layer.
  • a second conducting adhesive layer 160 is provided on the electrical conducting layer 140, as shown in Fig. 1C.
  • the second conducting adhesive layer 160 comprises at least one hot melt polymer 161, at least one second anchoring polymer 162 and at least one conducting particle 163.
  • the at least one hot melt polymer 161 is a thermoplastic which becomes sticky and behaves as adhesive after heating it up above a certain temperature.
  • the at least one hot melt polymer 151 of the first conducting adhesive layer 150 and the at least one hot melt polymer 161 of the second conducting adhesive layer 160 are the same material.
  • Some of the hot melt polymer 162 is selected from PearlstickTM, PeralbondTM and Estane® from Lubrizol company.
  • the at least one conducting particle 163 is any electrically conducting particle e.g. silver, carbon, copper etc.
  • the purpose of the at least one conducting particle 163 is make the second conducting adhesive layer 160 electrically conducting.
  • the at least one second anchoring polymer 162 comprises at least one second functional group 164.
  • the at least one second functional group 164 is attached to the polymeric chain of the second anchoring polymer 162.
  • the second functional group 164 is selected from a group of epoxy, thiol, acrylate, methacrylate and alkenyl.
  • the second anchoring polymer 162 can be selected, but not limited to, from a group polyaniline, polycarboxylic acid, multiple thiol functional groups containing molecule or polymer, multiple epoxy functional groups containing molecule or polymer, multiple acrylate functional groups containing molecule or polymer, multiple methacrylate functional groups containing molecule or polymer etc.
  • second conducting adhesive layer 160 is provided on the electrical conducting layer 140 by a printing method. It is understood here that after printing a layer, a heating and/or a curing step is needed to convert a wet printed layer into a sold layer.
  • At least one of the second conducting adhesive layer 160 and the first conducting adhesive layer 150 is heated up so that the hot melt polymer 151 and/or 161 becomes sticky.
  • at least one of the second conducting adhesive layer 160 and the first conducting adhesive layer 150 is heated above 100 °C.
  • the second conducting adhesive layer 160 is brought into contact with the first conducting adhesive layer 150, as shown in Fig. ID. It is also possible to first bring the second conducting adhesive layer 160 into contact with the first conducting adhesive layer 150 and then heating both the layers.
  • some of the first functional group 154 makes covalent bonds 170 with some of the second functional group 164. These covalent bonds 170 make the adhesion of the rigid printed circuit board 110 on the substrate 130 very strong.
  • the hot melt polymer 151 and the hot melt polymer 161 makes Van der Waals bonds.
  • the first anchoring polymer 152 and the second anchoring polymer 162 makes covalent bonds 170.
  • the first functional group 154 and the second functional group 164 are selected in such a way that when they come into contact, they react to each other. If first functional group 154 is an epoxy, then the second functional group 164 is selected an amine or a carboxylic acid. If first functional group 154 is an amine or a carboxylic acid, then the second functional group 164 is selected an epoxy. If first functional group 154 is a thiol, then the second functional group 164 is selected from a carbon-carbon double bond based functional group. The carbon- carbon double bond based functional group can be alkenyl, acrylate and methacrylate. If first functional group 154 is selected from a carbon-carbon double bond based functional group, then the second functional group 164 is thiol.

Abstract

A method of attaching a rigid printed circuit board (110) on a flexible substrate (130) is taught. In the first step a first conducting adhesive layer (150) is provided on an electrical contact pad (120) of a rigid printed circuit board (110). The first conducting adhesive layer comprises at least one hot melt polymer, at least one first anchoring polymer and at least one conducting particle. The at least one first anchoring polymer comprises at least one first functional group. In the next step, a second conducting adhesive layer (160) is provided on an electrical conducting layer (140) of a substrate (130). The second conducting adhesive layer comprises at least one hot melt polymer, at least one second anchoring polymer and at least one conducting particle. The at least one second anchoring polymer comprises at least one second functional group. At least one of the first conducting adhesive layer and the second conducting adhesive layer is heated up and then the first conducting adhesive layer and the second conducting adhesive layer are brought into contact to each other to establish electrical contact between the electrical conducting layer and the electrical contact pad.

Description

TITLE
Method of attaching rigid printed circuit boards on a substrate
CROSS-RELATION TO OTHER APPLICATIONS
[0001] None
FIELD OF THE INVENTION
[0002] The present disclosure relates to a method to attach rigid printed circuit board on a substrate, more specifically on a flexible substrate.
BACKGROUND OF THE INVENTION
The demand for flexible electronics has increased substantially. New demands of flexible electronics are coming in the field of use-and-throw low cost electronics, for example smart and intelligent packages. Flexible electronics are produced on on paper or plastic substrate. Printed conducting traces can be provided on a flexible substrate by a printing method and by using a conducting ink. For some applications, flexible circuit board needs to be electrically connected to traditional rigid printed circuit boards. In the state of the art, different methods are used to attached a rigid printed circuit board on a flexible substrate, for example as mentioned in US patent. No. 3,926,360. Another way is to fix bottom electrical contact pads of the rigid printed circuit board on a flexible substrate through epoxy conducting adhesives. But the epoxy conducting adhesives takes more than 5 minutes to cure at a temperature of more than 80°C. From an economical production point this is a slow process. Therefore, there is a need of an economical production method to attach and to electrically connect a rigid printed circuit board on a flexible printed circuit board.
SUMMARY OF THE INVENTION
[0003] The present invention relates to a method of attaching a rigid printed circuit board on a substrate, more specifically on a flexible substrate. In the first step, a first conducting adhesive layer is provided on an electrical contact pad. The electrical contact pad is provided on a bottom surface of the rigid printed circuit board. The first conducting adhesive layer comprises at least one hot melt polymer, at least one first anchoring polymer and at least one conducting particle. The at least one first anchoring polymer comprises at least one first functional group. In the next step, a second conducting adhesive layer is provided on an electrical conducting layer. The electrical conducting layer is provided on a substrate. The second conducting adhesive layer comprises at least one hot melt polymer, at least one second anchoring polymer and at least one conducting particle. The at least one second anchoring polymer comprises at least one second functional group. After that, at least one of the first conducting adhesive layer and the second conducting adhesive layer is heated up to make the hot melt polymer sticky. In the final step, the first conducting adhesive layer and the second conducting adhesive layer are brought into contact to each other to establish electrical contact between the electrical conducting layer and the electrical contact pad. The strong adhesion between first conducting adhesive layer and the second conducting adhesive layer comes due to the two kinds of chemical interaction involved. First one is the Van der Waals interactions between hot melt polymer chains and the second one is covalent bonds between the first functional group and the second functional group.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1A is a cross sectional view of a substrate and a rigid printed circuit board, in accordance with an aspect of the present invention.
[0005] FIG. IB is a cross sectional view of a substrate and a conducting adhesive layer on a rigid printed circuit board, in accordance with an aspect of the present invention.
[0006] FIG. 1C is a cross sectional view of conducting adhesive layers on a substrate and on a rigid printed circuit board, in accordance with an aspect of the present invention.
[0007] FIG. ID is a cross sectional view of an attached rigid printed circuit board on a substrate, in accordance with an aspect of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] The invention will now be described in detail. Drawings and examples are provided for better illustration of the invention. It will be understood that the embodiments and aspects of the invention described herein are only examples and do not limit the protector's scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with the feature of a different aspect or aspects and/or embodiments of the invention.
[0009] The term "functional group" as used in this disclosure refers to a specific group of atoms or bonds within a molecule or a polymer that are responsible for a specific chemical reaction. For example, a carbon-carbon double bond can be called an alkenyl functional group, which may participate in a radical reaction. It is known in literature that a carbon -carbon double bond reacts with a thiol functional group easily and an epoxy functional group reacts with an amine functional group easily.
[00010] The present invention is about a method to attach a rigid printed circuit board on a substrate. Fig. 1A shows a cross sectional view of a substrate 130. On a top surface 131 of the substrate 130 is provided an electrical conducting layer 140. The substrate 130 can be mechanically flexible or mechanically rigid. In a non-limiting aspect, the substrate 130 is paper, plastic, metal, glass or laminate. The electrical conducting layer 140 can be provided on the substrate 130 by a printing method and by using a conducting ink. In another aspect, the electrical conducting layer 140 can be provided on the substrate 130 by etching out a metal layer from the substrate 130. Fig. 1A also shows a cross sectional view of a rigid printed circuit board 110. At least one electrical contact pad 120 is provided on a bottom surface 111 of the rigid printed circuit board 110. The rigid printed circuit board 110 can further comprise surface mountable devices on a top surface 112. Here, the electrical contact pad 120 is used to electrically connect the rigid printed circuit board 110 to an external circuit. A first conducting adhesive layer 150 is provided on the electrical contact pad 120, as shown in Fig. IB. The first conducting adhesive layer 150 comprises at least one hot melt polymer 151, at least one first anchoring polymer 152 and at least one conducting particle 153. The at least one hot melt polymer 151 is a thermoplastic which becomes sticky and behaves as adhesive after heating it up above a certain temperature. In a non-limiting aspect, this temperature is 50°C. Hot melt thermoplastic adhesives are well known in state-of-the-art. Some of the hot melt polymer 151 are Pearlstick™, Peralbond™ and Estane® from Lubrizol company. The at least one conducting particle 153 is any electrically conducting particle e.g. silver, carbon, copper etc. The purpose of the at least one conducting particle 153 is make the first conducting adhesive layer 150 electrically conducting. The at least one first anchoring polymer 152 comprises at least one first functional group 154. The at least one first functional group 154 is attached to the polymeric chain of the first anchoring polymer 152. The first functional group 154 is selected from the group of epoxy, thiol, acrylate, methacrylate and alkenyl. The first anchoring polymer 152 can be selected, but not limited to, from a group polyaniline, polycarboxylic acid, multiple thiol functional groups containing molecule or polymer, multiple epoxy functional groups containing molecule or polymer, multiple acrylate functional groups containing molecule or polymer, multiple methacrylate functional groups containing molecule or polymer etc. In a non-limiting aspect, the first conducting adhesive layer 150 is provided on the electrical contact pad 120 by a printing method. It is understood here that after printing a layer, a heating and/or a curing step is needed to convert a wet printed layer into a solid layer.
[00011] In the next step, a second conducting adhesive layer 160 is provided on the electrical conducting layer 140, as shown in Fig. 1C. The second conducting adhesive layer 160 comprises at least one hot melt polymer 161, at least one second anchoring polymer 162 and at least one conducting particle 163. The at least one hot melt polymer 161 is a thermoplastic which becomes sticky and behaves as adhesive after heating it up above a certain temperature. In an aspect of the invention, the at least one hot melt polymer 151 of the first conducting adhesive layer 150 and the at least one hot melt polymer 161 of the second conducting adhesive layer 160 are the same material. Some of the hot melt polymer 162 is selected from Pearlstick™, Peralbond™ and Estane® from Lubrizol company. The at least one conducting particle 163 is any electrically conducting particle e.g. silver, carbon, copper etc. The purpose of the at least one conducting particle 163 is make the second conducting adhesive layer 160 electrically conducting. The at least one second anchoring polymer 162 comprises at least one second functional group 164. The at least one second functional group 164 is attached to the polymeric chain of the second anchoring polymer 162. The second functional group 164 is selected from a group of epoxy, thiol, acrylate, methacrylate and alkenyl. The second anchoring polymer 162 can be selected, but not limited to, from a group polyaniline, polycarboxylic acid, multiple thiol functional groups containing molecule or polymer, multiple epoxy functional groups containing molecule or polymer, multiple acrylate functional groups containing molecule or polymer, multiple methacrylate functional groups containing molecule or polymer etc. In a non-limiting aspect, second conducting adhesive layer 160 is provided on the electrical conducting layer 140 by a printing method. It is understood here that after printing a layer, a heating and/or a curing step is needed to convert a wet printed layer into a sold layer.
[00012] In the final step, at least one of the second conducting adhesive layer 160 and the first conducting adhesive layer 150 is heated up so that the hot melt polymer 151 and/or 161 becomes sticky. In a preferred embodiment, at least one of the second conducting adhesive layer 160 and the first conducting adhesive layer 150 is heated above 100 °C. After heating, the second conducting adhesive layer 160 is brought into contact with the first conducting adhesive layer 150, as shown in Fig. ID. It is also possible to first bring the second conducting adhesive layer 160 into contact with the first conducting adhesive layer 150 and then heating both the layers. When in contact, some of the first functional group 154 makes covalent bonds 170 with some of the second functional group 164. These covalent bonds 170 make the adhesion of the rigid printed circuit board 110 on the substrate 130 very strong. The hot melt polymer 151 and the hot melt polymer 161 makes Van der Waals bonds. The first anchoring polymer 152 and the second anchoring polymer 162 makes covalent bonds 170.
[00013] The first functional group 154 and the second functional group 164 are selected in such a way that when they come into contact, they react to each other. If first functional group 154 is an epoxy, then the second functional group 164 is selected an amine or a carboxylic acid. If first functional group 154 is an amine or a carboxylic acid, then the second functional group 164 is selected an epoxy. If first functional group 154 is a thiol, then the second functional group 164 is selected from a carbon-carbon double bond based functional group. The carbon- carbon double bond based functional group can be alkenyl, acrylate and methacrylate. If first functional group 154 is selected from a carbon-carbon double bond based functional group, then the second functional group 164 is thiol.

Claims

1. A method of attaching a rigid printed circuit board (110) on a substrate (130), comprising the steps of:
a. providing a first conducting adhesive layer (150) an electrical contact pad (120), the electrical contact pad (120) is provided on a bottom surface (111) of the rigid printed circuit board (110), the first conducting adhesive layer (150) comprises at least one hot melt polymer (151), at least one first anchoring polymer (152) and at least one conducting particle (153), the at least one first anchoring polymer (152) comprises at least one first functional group (154);
b. providing a second conducting adhesive layer (160) on an electrical conducting layer (140), the electrical conducting layer (140) is provided on the substrate (130), the second conducting adhesive layer (160) comprises at least one hot melt polymer (161), at least one second anchoring polymer (162) and at least one conducting particle (163), the at least one second anchoring polymer (162) comprises at least one second functional group (164);
c. heating up at least one of the first conducting adhesive layer (150) and the second conducting adhesive layer (160); and
d. bringing the first conducting adhesive layer (150) and the second conducting adhesive layer (160) into contact to create covalent bonds (170) between some of the at least one first functional group (154) and some of the at least one second functional group (164) and hence to attach the electrical conducting layer (140) to the electrical contact pad (120).
2. The method of claim 1 , wherein the substrate ( 130) is selected from a group of paper, plastic, metal, glass and combinations thereof.
3. The method of claim 1 , wherein the at least one hot melt polymer (151, 161) becomes sticky above 50°C.
4. The method of claim 1, wherein one of the at least one first functional group (154) and the at least one second functional group (164) is an amine and another of the at least one first functional group (154) and the at least one second functional group (164) is an epoxy.
5. The method of claim 1, wherein one of the at least one first functional group (154) and the at least one second functional group (164) is a thiol and another of the at least one first functional group (154) and the at least one second functional group (164) is a carbon-carbon double bond.
PCT/EP2018/025162 2017-06-16 2018-06-15 Method of attaching rigid printed circuit boards on a substrate WO2018228724A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1709587.8 2017-06-16
GB1709587.8A GB2563433A (en) 2017-06-16 2017-06-16 Method of attaching rigid printed circuit boards on a substrate

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WO2018228724A1 true WO2018228724A1 (en) 2018-12-20

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Country Status (2)

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WO (1) WO2018228724A1 (en)

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