Preparation method of inner layer of thick copper thin circuit board of printed circuit board

Abstract

The invention provides a preparation method of an inner layer of a thick copper thin circuit board of a printed circuit board. The technical scheme of the preparation method includes that plating grinding and chemical micro-etching are carried out in preliminary treatment, secondary printing ink is coated in coating, exposure is carried out with a semi-automatic exposure machine of a brand Chuanbao and a model E2100-7KMD, and an encrypted nozzle is adopted and compensation etching is carried out on the line width of a film. The preparation method has the advantages that the reject rate due to open circuits and gaps can be reduced to be 1.5%; the value of the line width is within + / - 10%; and exposure foreign matters and image distortion are reduced. The defects that the reject rate of an existing thin circuit board caused by open circuits and gaps is high, edges of circuits after etching are not regular, thicknesses of the circuits are not uniform and the range of line widths is large are overcome.

Description

technical field [0001] The invention relates to an inner layer preparation technology of a printed circuit board, in particular to an inner layer preparation method of a thick copper thin circuit board of a printed circuit board. Background technique [0002] Printed circuit boards are rapidly developing towards the combination of soft and hard, high-rise, and thin lines. Thick copper thin circuit boards have been widely used in the fields of automobiles, communications, ships, and military industries. Higher requirements are put forward for the inner layer preparation of thick copper thin circuit boards. requirements. At present, the inner layer preparation methods of thick copper thin circuit boards are as follows: ① pre-treatment using grinding plate; ② applying ink once when coating; ③ manual exposure machine exposure; ④ acid etching line etching. The following defects exist: [0003] (1) Grinding plate is used for pretreatment, and the defects are: the roughness of th...

AI Technical Summary

Problems solved by technology

[0003] (1) Grinding plate is used for pretreatment, and the defects are: the roughness of the copper surface after grinding is extremely uneven, the adhesion of the resist is poor, and the resist is easy to fall off during the development and etching process;

[0004] (2) The ink is applied once during coating. The disadvantage is that the thickness of the ink resist layer is only 10-14um. Because the thick copper plate has a relatively long etching time, the ink film is too thin and the resist is easy to fall off during the etching process;

[0005] (3) Manual exposure machine exposure, the disadvantages are: ①The film of manual exposure machine is not easy to clean, and it is easy to produce debris and foreign objects during the operation; ②The energy uniformity of manual exposure machine is poor, and it is easy to appear out of shape and distortion of local circuit graphics after exposure ;

[0006] (4) Acidic etching line etching, the defects are: there is a pool effect during the etching process, the etching uniformity is lower than 85%, the lines after etching are irregular, the line thickness is uneven, and the line width is very poor