RU2151475C1 - Method for manufacturing of printed circuit boards - Google Patents

Abstract

FIELD: manufacturing of radio electronic equipment. SUBSTANCE: method involves drilling holes in dielectric blank, preparation of its surface, simultaneous deposition of copper layer of required height onto dielectric base and holes walls from gas phase using decomposition of first group carbonyl metal vapor, for example, Cu₂(CO)₆; CuCO; Cu(CO)₂; Cu(CO)₃, or others from group, depending on their chemical properties. Operation proceeds in vacuum under pressure of 0.1 torr or in hydrogen, nitrogen or argon. Said gases are used as carriers and are driven from vaporizer into reactor, which contains blanks of printed circuit boards. Deposition process involves sequence of operations: evaporation of primary first group carbonyl metal, which is heated to respective temperature, feeding vapors to heated blanks of printed circuit boards, which temperature provides thermal dissociation of vapors, absorption-desorption events on blanks of printed circuit boards, production of nuclei and development of coating until it reaches required height. EFFECT: improved quality and increased reliability of operations of printed circuit boards, decreased efforts and cost for their production.

Description

 The invention relates to the technology of manufacturing printed circuit boards and can be used in the manufacture of printed circuit boards, electronic equipment and in other industries.

 A known method of manufacturing printed circuit boards, French patent N 2385295, class. H 05 K 3/18, 1978, which includes the chemical deposition from aqueous copper-containing solutions of a thin layer of copper (about 3 μm) on the dielectric base and on the walls of the drilled holes, followed by obtaining a printed circuit board design from photoresist and galvanic build-up of conductors on the surface boards and in holes. After removal of the resist, a chemical etching of a thin film of copper is made from the blank spaces of the board. The adhesive ability of the surface of the dielectric is enhanced by special treatment with organosilicon compounds, using a dielectric with an enriched surface layer of epoxy resin and applying an adhesive to the dielectric.

 The disadvantages of this method is the low quality and reliability of the boards in operation, the high complexity and cost of their manufacture.

The closest, selected as a prototype of the proposed method for the manufacture of printed circuit boards, is a method of manufacturing printed circuit boards, ed. St. N 940323 cells H 05 K 3/18, priority dated 4.03.80, the USSR, including operations for drilling holes and a dielectric blank, preparing its surface, simultaneously depositing a metal sublayer on a dielectric base and on the walls of the holes, forming a printed circuit board pattern from photoresist, galvanic build-up of conductors on the surface of the printed circuit board and in the holes, removal of the resist and etching of the sublayer from the gaps, and the deposition of the metal sublayer is carried out by decomposition of nickel tetracarbonyl vapor at a pressure of 50-100 Pa and temperature the source of the vapor source is 20 - 35 ^o C on a dielectric base heated to 130 - 200 ^o C.

 The disadvantage of this method of manufacturing printed circuit boards is their low quality and reliability. Electrical conductors made of nickel and galvanic copper have poor electrical properties, are warped, and copper has a large porosity and poor purity. Such printed circuit boards are very expensive to manufacture and do not meet the modern requirements for them. Therefore, this method has not found application in industry.

 The aim of the proposed method for the manufacture of printed circuit boards is to increase their quality and reliability, as well as reduce the complexity and cost of manufacture.

The goal in the present invention is achieved by the fact that a method of manufacturing printed circuit boards, including the operation of drilling holes in the dielectric preform, preparing its surface, simultaneous deposition of metal on the dielectric base and on the walls of the holes, forming a printed circuit board from the photoresist, removing the resist and etching the metal from whitespace, characterized in that the deposition of metal on a dielectric base and on the walls of the holes is carried out by the decomposition of carbonyl metal vapors ervoy groups, such as the Cu ₂ (CO) _6; CuCO; Cu (CO) ₂ ; Cu (CO) ₃ and others of this group, based on their chemical properties, in a vacuum of 1 • 10 ^-1 mm Hg, or the process is carried out in hydrogen, nitrogen or argon, and these gases are used as carriers, and they are transferred from the evaporator to the reactor in which the blanks of the printed circuit boards are placed, and the technological process of deposition of metal on the dielectric base and the walls of the holes proceeds sequentially: the evaporation of the initial metal of the carbonyl of the first group, heated to the required temperature, the movement and supply of vapors to the heated printed circuit boards, at the temperature of which thermal vapor dissociation occurs, adsorption-desorption acts on the printed circuit boards blanks, nucleation and metal deposition to the required thickness.

 And this allows you to improve the quality and reliability of the printed circuit boards, reduce the complexity in their manufacture. To increase the choice of materials with which you can cover the blanks of printed circuit boards with copper.

 The introduction of this method in production will be a revolutionary leap not only in the production of printed circuit boards, but also in other industries. The speed of vapor-phase metallization is 20 times higher than the speed of electroplated coatings. And these copper coatings are of higher quality, it has less porosity and is cleaner in its chemical composition and has better adhesion compared to the electroplated coating.

 The proposed method for the manufacture of printed circuit boards gives a great economic effect when introduced into production and will find great application in the future for copper plating of parts in the radio, electronic, electrical and other industries.

Claims (1)

A method of manufacturing printed circuit boards, including the operation of drilling holes in a dielectric preform, preparing its surface, simultaneously depositing metal on a dielectric base and on the walls of the holes, forming a printed circuit board pattern from a photoresist, removing resist and etching metal from whitespace, characterized in that the metal deposition on the dielectric base and on the walls of the holes is produced by the decomposition of metal vapor of carbonyls of the first group, for example, such as Cu ₂ (CO) ₆ , CuCO, Cu (CO) ₂ , Cu (CO) ₃ and others from of this group, based on their chemical properties, in a vacuum of 1 • 10 ^-1 mm Hg or the process is carried out in hydrogen, nitrogen or argon, and these gases are used as carriers, and transferred from the evaporator to the reactor in which the blanks of the printed circuit boards are placed, while the process of deposition of metal on a dielectric base and on the walls of the holes proceeds sequentially: evaporation the initial carbonyl metal of the first group, heated to the temperature necessary for this, the movement and supply of vapors to the heated blanks of printed circuit boards, at the temperature of which thermal dissociation occurs vapor, adsorption-desorption acts on the blanks of printed circuit boards, nucleation and deposition of metal to the required thickness.