CN113891549A - Conductive paste, method for producing conductive paste, and circuit board - Google Patents
Conductive paste, method for producing conductive paste, and circuit board Download PDFInfo
- Publication number
- CN113891549A CN113891549A CN202111349553.4A CN202111349553A CN113891549A CN 113891549 A CN113891549 A CN 113891549A CN 202111349553 A CN202111349553 A CN 202111349553A CN 113891549 A CN113891549 A CN 113891549A
- Authority
- CN
- China
- Prior art keywords
- conductive paste
- resin
- circuit board
- raw materials
- alloy powder
- Prior art date
- Legal status (The legal status 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 status listed.)
- Pending
Links
Images
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
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/09—Use of materials for the conductive, e.g. metallic pattern
- H05K1/092—Dispersed materials, e.g. conductive pastes or inks
- H05K1/095—Dispersed materials, e.g. conductive pastes or inks for polymer thick films, i.e. having a permanent organic polymeric binder
-
- 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
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3457—Solder materials or compositions; Methods of application thereof
Abstract
The invention discloses a conductive paste, a preparation method of the conductive paste and a circuit board, wherein the conductive paste is prepared by taking copper powder, alloy powder, thermosetting resin, thermoplastic resin, a curing agent, a dispersing agent and a solvent as raw materials, and the preparation method comprises the steps of uniformly mixing the raw materials and then uniformly rolling and mixing the raw materials on a three-roll machine to obtain the conductive paste with weldability. The conductive paste can be used for welding the surface of a flexible circuit board or a printed circuit board, and has high welding strength and good combination effect; meanwhile, the conductive paste can realize low-temperature curing, has low energy consumption and is suitable for large-scale application.
Description
Technical Field
The present invention relates to a conductive paste, and more particularly, to a conductive paste having solderability, a method for preparing the conductive paste, and a circuit board using the conductive paste.
Background
Conductive pastes are generally used for forming conductor patterns of printed circuit boards, electrodes of electronic components, and the like, and are also called conductive pastes. At present, a conductive layer on the surface of a flexible circuit board is generally formed by printing silver paste, various parts are generally required to be mounted on the conductive circuit, the parts are generally fixed by a conductive bonding agent or are fixed by welding, however, the parts are difficult to repair by using the conductive bonding agent, the silver paste is welded by using a welding technology, the soldering strength is reduced due to the phenomenon of 'eating silver', and the cost of the silver paste is very high.
In chinese patent publication No. CN107615402B, entitled conductive paste, which avoids the phenomenon of "silver eating" during soldering and improves the reliability of soldering at the same time, a conductive paste made of flake silver-coated copper powder is used. However, the silver-coated copper powder has high cost and is not beneficial to large-scale industrial application.
Disclosure of Invention
The invention aims to provide a solderable conductive paste, a preparation method of the conductive paste and a circuit board, which can improve the soldering strength and the bonding effect of the conductive paste on electronic parts on the surfaces of electronic products such as the circuit board and the like, and can realize low-temperature curing so as to reduce the cost.
In order to achieve the purpose, the invention provides the following technical scheme: the conductive paste is prepared from the following raw materials in parts by weight:
preferably, the particle size of the copper powder is 1-20 microns.
Preferably, the alloy powder is an alloy powder containing tin, the grain diameter is 5-30 microns, the alloy powder comprises an alloy formed by tin and any one or more of metals such as lead, bismuth, cadmium, indium, copper, silver and the like, and the grain diameter of the alloy powder is 5-30 microns.
Preferably, the thermosetting resin is selected from one or a combination of any of epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, bismaleimide resin and cyanate resin.
Preferably, the thermoplastic resin is selected from one or a combination of any of polyurethane, polyether, polyamide and polyacrylic resin.
Preferably, the curing agent is an imidazole curing agent;
preferably, the dispersant is a carboxylic acid type graft dispersant, and the dispersant with the structure forms chemical bond combination with the metal surface, has good binding force and has the effect of preventing copper powder from being oxidized.
Preferably, the solvent is a high boiling point solvent with a boiling point of about 200 ℃ and good compatibility with resin, such as ethyl carbitol, or ethylene glycol monobutyl ether, terpineol and the like.
The invention also provides a preparation method of the conductive paste, which comprises the steps of weighing the raw materials according to the weight parts of the raw materials of the conductive paste, uniformly mixing the raw materials, and then uniformly rolling and mixing the raw materials on a three-roll machine to obtain the weldable conductive paste.
The invention also provides a Flexible Printed Circuit Board (FPCB), wherein the conductive paste is printed on the surface of the flexible printed circuit board, and when the flexible printed circuit board is prepared, the prepared weldable conductive paste is screen-printed on the surface of the flexible printed circuit board and is put into an oven for curing, the curing temperature is 150 ℃, the curing time is 1 hour, and parts are welded on the cured conductive paste by adopting soldering tin.
Likewise, the invention also provides a Printed Circuit Board (PCB), wherein the surface of the PCB is printed with the conductive paste.
According to the invention, thermosetting resin and thermoplastic resin are added into the conductive paste, and the thermosetting resin can reduce the displacement of the conductive paste and keep the dimensional stability and welding strength; the soldering temperature is about 260 ℃ in the welding process, the temperature reaches the glass transition temperature of the thermoplastic resin and generates deformation, so that copper powder and alloy powder in the resin cannot be completely coated by the resin, the addition of the alloy powder can reduce the welding temperature melting point, so that part of the copper powder and the alloy powder can be directly combined with molten soldering tin at the temperature, the copper powder and the molten soldering tin form Cu-Sn alloy, the alloy powder and the molten soldering tin are mixed and melted together, the temperature is reduced after welding, the conductive paste and the soldering tin are re-solidified, the thermoplastic resin recovers deformation again, the area part of the original thermoplastic resin is occupied by the Cu-Sn alloy, the alloy powder and the molten soldering tin, a new alloy system is formed, and the welding strength and stability are further improved.
Compared with the prior art, the invention has the beneficial effects that:
(1) the conductive paste can realize low-temperature curing, has low energy consumption and low cost, and can be applied in large scale;
(2) the conductive paste can realize the welding on the surface of a circuit board, particularly a flexible circuit board, and has high welding strength and good combination effect.
(3) The particle size of the copper powder selected by the invention is 1-20 microns, the particle size of the copper powder is less than 1 micron, and the copper powder is easy to oxidize and not easy to disperse. The particle size of the copper powder is larger than 20 microns, and the leveling property of the circuit is poor during printing.
(4) The grain diameter of the alloy powder selected by the invention is 5-30 microns, the grain diameter of the alloy powder is less than 5 microns, the oxidation is easy to occur, and the grain diameter is more than 30 microns, so that the printing of a circuit is not facilitated. The alloy powder may have a melting point above 140 ℃ and does not melt, or melts, during the solidification process. At the same time, the temperature should be lower than 250 ℃ to ensure preheating and melting in the welding process.
Drawings
FIG. 1 is a scanning image under an electron microscope of a cross-section of a conductive paste in example 1 of the present invention.
Detailed Description
The invention will be further described with reference to examples of embodiments shown in the drawings to which the invention is attached. However, the present invention is not limited to the following examples. The implementation conditions adopted in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not mentioned are conventional conditions in the industry. The technical features of the embodiments of the present invention may be combined with each other as long as they do not conflict with each other.
The invention discloses a conductive paste which is prepared from the following raw materials in parts by weight 100:
the following table shows the ratios of the raw material components selected in examples 1 to 4 of the present invention and comparative examples 1 to 3, respectively, and the results of the performance test of the conductive paste of each example are shown in table two. From the data in tables one and two, it can be seen that if the plastic resin is not heated, the volume resistivity is low because the thermosetting resin can promote the powder particles to approach each other and form more conductive paths. But at the same time, because of no thermoplastic resin, the resin on the surface of the powder can not deform in the soldering process, and the solder paste can not directly contact with the powder to form firm alloy connection, so that the welding strength is obviously reduced.
However, as shown in comparative examples 2 and 3, when the amount of the thermoplastic resin was excessively increased, there was some increase in the weld strength, but not much. The reason is considered that the soldering strength depends on the condition that tin is alloyed with copper, and the increase of the thermoplastic resin increases the contact area of tin and copper, but the influence degree is limited. With the negative effect that the volume resistivity will increase.
Table one example 1 to example 4 and the raw material components in each ratio
Table two examples 1 to 4 and the results of the performance test of each comparative example
The preparation method of the conductive paste disclosed by the invention comprises the following steps of:
weighing the raw materials according to the proportion of the formula of the conductive paste with weldability, uniformly mixing the raw materials, and then rolling and uniformly mixing the raw materials on a three-roller machine to obtain the conductive paste with weldability.
The flexible circuit board of the invention is carried out according to the following steps:
the solderable conductive paste obtained by the above preparation is screen-printed on the surface of a flexible circuit board and is put into an oven for curing, wherein the curing temperature is 150 ℃ and the curing time is 1 hour. And soldering the parts on the cured conductive paste by using soldering tin.
The test method comprises the following steps:
(1) welding strength: the paste is screen-printed on the surface of a glass substrate, heated and cured at 150 ℃, an SMT original piece is spot-welded by an electric soldering iron, and then the thrust of the SMT original piece is tested by a Dage push-pull tester.
(2) Volume resistivity: after printing the paste on a glass substrate, curing at 150 ℃, testing the resistance R at two ends of the printed circuit by a four-terminal method, testing the thickness t and the length l, the width w of the printed circuit, and calculating the volume resistivity of the printed circuit by using a formula rho-R l w/t.
After soldering, the solder and the cured conductive paste were cut into a cross section and observed under an electron microscope. As shown in fig. 1, the solder portion and the paste contact interface are seen, and after soldering, the tin alloy and the alloy in the copper paste fuse with each other and surround the copper powder, and the melted solder and the tin alloy in the resin fuse with each other as a whole to form a tight bond.
The present invention has been described in detail in order to enable those skilled in the art to understand the invention and to practice it, and it is not intended to limit the scope of the invention, and all equivalent changes and modifications made according to the spirit of the present invention should be covered by the present invention.
Claims (10)
1. The conductive paste is characterized by comprising the following raw materials in parts by weight:
2. the conductive paste of claim 1, wherein: the particle size of the copper powder is 1-20 microns.
3. The conductive paste of claim 1, wherein: the alloy powder is tin-containing alloy powder with the grain diameter of 5-30 microns, and comprises an alloy formed by tin and any one or more of lead, bismuth, cadmium, indium, copper and silver, and the grain diameter of the alloy powder is 5-30 microns.
4. The conductive paste of claim 1, wherein: the thermosetting resin is one or a composition of any more of epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, bismaleimide resin and cyanate resin.
5. The conductive paste of claim 1, wherein: the thermoplastic resin is selected from one or a combination of any of polyurethane, polyether, polyamide and polyacrylic resin.
6. The conductive paste of claim 1, wherein: the curing agent is an imidazole curing agent, and the dispersing agent is a carboxylic acid type grafting dispersing agent.
7. The conductive paste of claim 1, wherein: the solvent is selected from ethyl carbitol, ethylene glycol monobutyl ether or terpineol and is a high-boiling point solvent with good compatibility with resin.
8. A method for preparing a conductive paste, characterized in that raw materials are weighed according to the components of any one of claims 1 to 7, and the raw materials are uniformly mixed and then uniformly rolled and mixed on a three-roll mill to obtain a solderable conductive paste.
9. A flexible circuit board, characterized in that: the surface of the flexible circuit board is printed with the conductive paste of claims 1-7.
10. A printed circuit board, characterized by: the surface of the printed circuit board is printed with the conductive paste according to claims 1 to 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111349553.4A CN113891549A (en) | 2021-11-15 | 2021-11-15 | Conductive paste, method for producing conductive paste, and circuit board |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111349553.4A CN113891549A (en) | 2021-11-15 | 2021-11-15 | Conductive paste, method for producing conductive paste, and circuit board |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113891549A true CN113891549A (en) | 2022-01-04 |
Family
ID=79018126
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111349553.4A Pending CN113891549A (en) | 2021-11-15 | 2021-11-15 | Conductive paste, method for producing conductive paste, and circuit board |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113891549A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07331126A (en) * | 1994-06-14 | 1995-12-19 | Lion Corp | Coating composition |
| CN101341557A (en) * | 2005-12-22 | 2009-01-07 | 纳美仕有限公司 | Thermosetting conductive paste and multilayer ceramic component having external electrode which is formed by using such thermosetting conductive paste |
| CN101431140A (en) * | 2007-01-30 | 2009-05-13 | 大自达系统电子株式会社 | Heat conductive paste, light emitting diode substrate using the same and manufacturing method thereof |
| CN105513668A (en) * | 2016-01-25 | 2016-04-20 | 深圳市思迈科新材料有限公司 | Conductive silver paste for nano-silver film low-temperature setting and preparation method thereof |
-
2021
- 2021-11-15 CN CN202111349553.4A patent/CN113891549A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07331126A (en) * | 1994-06-14 | 1995-12-19 | Lion Corp | Coating composition |
| CN101341557A (en) * | 2005-12-22 | 2009-01-07 | 纳美仕有限公司 | Thermosetting conductive paste and multilayer ceramic component having external electrode which is formed by using such thermosetting conductive paste |
| CN101431140A (en) * | 2007-01-30 | 2009-05-13 | 大自达系统电子株式会社 | Heat conductive paste, light emitting diode substrate using the same and manufacturing method thereof |
| CN105513668A (en) * | 2016-01-25 | 2016-04-20 | 深圳市思迈科新材料有限公司 | Conductive silver paste for nano-silver film low-temperature setting and preparation method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4667455B2 (en) | Conductive filler and solder material | |
| KR101086358B1 (en) | conductive paste | |
| US5958590A (en) | Dendritic powder materials for high conductivity paste applications | |
| US6238599B1 (en) | High conductivity, high strength, lead-free, low cost, electrically conducting materials and applications | |
| US5837119A (en) | Methods of fabricating dendritic powder materials for high conductivity paste applications | |
| US7022266B1 (en) | Printable compositions, and their application to dielectric surfaces used in the manufacture of printed circuit boards | |
| EP0933010B1 (en) | Printable compositions, and their application to dielectric surfaces used in the manufacture of printed circuit boards | |
| JP2003211289A (en) | Electrically conductive joining material, method of joining by using the same and electronic device | |
| JP4507750B2 (en) | Conductive paste | |
| JPH0321659A (en) | Electroconductive copper composition | |
| JP2965815B2 (en) | Solderable conductive paste for film formation | |
| JPH10279902A (en) | Electroconductive adhesive | |
| JPH10279903A (en) | Electroconductive adhesive | |
| CN113891549A (en) | Conductive paste, method for producing conductive paste, and circuit board | |
| EP0818061B1 (en) | Process for producing electrically conductive connecting structures | |
| CN110970151B (en) | High-weldability anti-warping thick film conductor slurry for stainless steel base material and preparation method thereof | |
| JP2004167569A (en) | Lead-free solder paste composition and soldering method | |
| JPH10265748A (en) | Electroconductive adhesives | |
| Melton | Alternatives of lead bearing solder alloys | |
| JP4089368B2 (en) | Conductive paste | |
| Yim et al. | Conduction path formation mechanism of solderable polymer composites with low-melting-point alloy/high-melting-point alloy mixed filler | |
| CN103480978A (en) | Environmentally-friendly lead-free anti-electrode-stripping solder wire | |
| WO2024070628A1 (en) | Bonded structure, method for producing same, conductive member for solder bonding, and structure for solder bonding | |
| KR102355781B1 (en) | self-assembled conductive bonding compound for LED chip bonding having excellent self-assembly, LED chip-circuit board bonding module comprising the same and manufacturing method thereof | |
| JPH11209716A (en) | Electroconductive adhesive |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |