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A method and process for rapid prototyping of flexible circuits

Release time: 12/10/2018

Background technology:

Droplet jet printing technology is a new technology that has attracted much attention in recent years. By combining droplet injection technology with computer technology, printed circuit information can be directly printed on flexible substrates according to CAD documents, and a complete conductive line can be formed, thus solving the problem that the production methods of flexible conductive lines are not perfect. The preparation process is complex and the cost of production is high.

In the existing technology, a rapid prototyping method using flexible inkjet printing technology to prepare flexible conductive lines has been reported. The method is to use droplet injection system to deposit two conductive ink on non-conductive substrates, and two kinds of ink to react to produce conductive lines, of which two solutions are metal compounds, such as gold, silver and nickel. Copper, palladium, platinum, etc., one is the precursor solution (such as hydrazine hydrate, ascorbic acid, etc.), the oxidation-reduction method is used to obtain the metallic monomer. In order to obtain high conductivity flexible circuits, the concentration of silver nitrate solution is higher, which leads to the increase of the conductive line system and the excessive concentration of silver nitrate solution. The liquid will produce precipitation at the nozzle orifice, blocking the nozzle, affecting the stability of the droplet spray deposition system, making the accuracy of the formed conductive line worse.

flexible circuit

Technology realization elements:

The purpose of the invention is to provide a flexible circuit rapid prototyping method, which solves the problem of reducing the electrical conductivity of the flexible conducting line by increasing the concentration of silver nitrate solution in the preparation process of the existing flexible circuit, resulting in the deterioration of the accuracy of the conductive line.

The invention relates to a flexible circuit rapid prototyping method adopting a technical proposal, which comprises the following steps:

Step 1, the preparation of ink a.

The proper amount of ascorbic acid is dissolved in deionized water and added with dispersant, stirring evenly, and the precursor solution is obtained. After filtering the precursor solution and obtaining filtrate, the ink a is obtained.

Step 2, the preparation of ink B.

Step 2.1, the appropriate amount of silver nitrate is dissolved in deionized water and stirred evenly to obtain silver nitrate solution.

Step 2.2, filtration of silver nitrate solution in step 2.1 to obtain filtrate;

Step 2.3, add proper amount of nano silver thread to filtrate of step 2.2, disperse it completely by ultrasonic oscillating instrument, filter the solution again, get ink B and reserve.

Step 3, take ink a of appropriate steps 1 and ink B of step 2, and insert two test tube A and test tube B embedded in the droplet injection system respectively.

Step 4, the droplet injection system of operation step 3 first prints the ink a on the treated flexible substrate, and then prints the ink B by ink a path, printing 20-30min, and solidifying the flexible circuit.

The invention also features that the dispersant in step 1 is polyvinylpyrrolidone, and the mass ratio of ascorbic acid to polyvinylpyrrolidone is 7-8:1, of which the concentration of ascorbic acid is 25%w/v to 35%w/v, and the concentration of polyvinylpyrrolidone is 2%w/v ~ 6%w/v.

In step 2, the mass ratio of silver nitrate to silver nanowires is 24-26:1, and the concentration of silver nitrate solution is 41.8%w/v ~ 58.6%w/v.

Step 1, step 2.1 and step 2.2 filter operation: use the slow filter paper with an aperture of 1~3 m for the first time. After filtration, the filtrate is then filtered through a double-layer and a slow filter paper with an aperture of 1~3 m.

The size of the silver nanowires in step 2.3 is 8-12 m, the diameter is 90-110nm, and the dispersion time is 25-35min.

In step 3, the diameters of test tube A and test tube B are all 100 to 150 m m.

The flexible substrate in step 4 is a fabric with 100% cotton content treated with cationic fatty amide.

The curing temperature in step 4 is 15-25 C.

The invention has the beneficial effect that: a flexible circuit rapid prototyping method is formed by adding silver nanowires and reductant in the silver salt solution to form flexible conductive lines, and adding nano silver wire in the solution can effectively reduce the concentration of silver nitrate solution, reduce the sedimentation at the nozzle test tube, and prevent the blocking nozzle test tube. At the same time, adding nanoscale silver wire can form a continuous network conductive path in the deposited lines, and change the point contact between the microparticles into line and point contact, which effectively improves the conductivity of the flexible circuit, shortens the preparation period of the flexible conductive circuit of silver, and overcomes the poor electrical conductivity of the existing flexible circuit and the electricity in the manufacturing process. The problem of uneven distribution of resistance and high resistivity is of great practical value.

Technical summary

The invention discloses a flexible circuit rapid prototyping method, which is formed by dissolving the target reducing agent into deionized water and adding dispersant, forming a precursor solution, filtering the ink a, melting silver nitrate into deionized water, filtering, and then adding silver nanowires into the silver salt solution, and completely dispersing it with an ultrasonic oscillating instrument. In silver salt solution, the ink B is filtered again, and ink a and ink B are printed on a flexible substrate in turn, and then a flexible circuit is formed after being solidified and solidified. The invention realizes the silver silver solution adding nano silver wire and reducing agent to react and deposit and form flexible circuit. Adding nano silver wire in the solution can reduce the deposition at the nozzle mouth of the nozzle, change the point contact between the micro particles into line and point contact, effectively improve the conductive characteristics of the flexible circuit, and shorten the preparation period of the flexible conductive circuit of silver greatly. The utility model overcomes the problems of poor electrical conductivity of existing flexible circuits, uneven distribution of resistance and excessive resistivity in the manufacturing process, and has very good practical value.