JPH05503815A - Method for manufacturing a printed circuit board or multilayer circuit board with connections through multiple layers - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method for manufacturing a printed circuit board or multilayer circuit board with connections through multiple layers The drill holes produced are cleaned by the following method steps: a) immersion in a treatment liquid; b) Rinse; C) Oxidation treatment with permanganate solution.

Electronic printed circuit boards, in particular so-called "multilayer circuit boards", contain several electrically conductive structures. It has layers. To make the connection through the latter, the entire printed circuit board, i.e. A double hole xvi must be drilled and then the cylindrical surface of the hole must be covered with a conductive layer. stomach. There are high demands on the reliability of such printed circuit boards and multilayer circuit boards. In this case, it is very important to connect various conductive structures of different layers. this Especially when drill holes are made, they become contaminated, especially drill holes contaminated with resin. A careful cleaning of the cylindrical surface is a prerequisite.

Drill hole circle, also known as the "desmearing" method This type of cleaning method for cylindrical surfaces is described in DE-O33638630. The present invention is based on this. In this case cleaning is done by immersion, i.e. printed circuit boards. Alternatively, it begins by treating the multilayer circuit board with a treatment solution. This processing solution is generally used in various The immersion liquid containing organic abrasions is then removed in a rinsing step. Then the actual cleaning , caused by oxidation treatment with permanganate solution, and then the excess oxidation solution is no longer used. Rinse once and remove. So-called r/r3 decontamination n) J is the standard (in this case, reducing and removing the manganese dioxide generated in the oxidation treatment, This is followed by further rinsing.

The printed circuit board pretreated in this way is then, as known per se, DE-O No. 3,363,8630, the cylindrical surface of the drill hole is coated with gold in a manner not further described in Cover the genus. of known methods for cleaning drill holes and metallization of cylindrical surfaces. Mere juxtaposition would result in a very large number of steps in the method, and a large number of processing solutions and equipment. A large number of individual equipment units (apparatus modules) for implementation regarding s) is required.

The object of the invention is to provide step-by-step methods for producing a conductive layer on the cylindrical surface of a drilled hole. The aim is to supplement methods of the type described above in the most economical way possible.

This purpose is to ensure that, immediately after step C of the method, neither a neutralization step nor an additional treatment or soaking step is carried out. The following steps involve the currentless formation of a conductive layer on the cylindrical surface of the drilled hole without leaving d) oxidation treatment with permanganate; e) Rinse; f) precipitate a layer of these monomers from the organic monomer solution; g) precipitate the monomers; The polymer is polymerized to form a conductive layer.

The present invention utilizes the method of "sewage removal" known per se (DE-PS 38 06 8). 84) A special current-free method of forming a conductive layer on the cylindrical surface of the drill hole and especially This is based on the discovery that they can be conveniently combined. In particular, the present invention In the proposed combination of these two methods, some of the steps of each can be "omitted". ', i.e. the printed circuit board or multilayer circuit board must be treated with a treatment liquid. The number of process steps can be reduced and the associated rinsing operation can be omitted. . In particular, in the present invention, after the oxidation treatment in the "stain removal" method, "stain removal" ``removal'', thus removing the formed manganese dioxide before the monomer precipitation. What is excluded is that this manganese dioxide has a favorable effect on oxidation pretreatment. And it's no longer necessary. Furthermore, those mentioned in DE-PS 38 06 884 The method still uses current-free precipitation of a conductive layer on the cylindrical surface of the drill hole. This eliminates any additional processing or soaking that would otherwise have been required.

The chemical reaction that occurs during the oxidation process in the "stain removal" process is the result of currentless deposition of a conductive layer. Since the oxidation process before the oxidation process is not the same as the It is recommended to do this in the bath. By rinsing these two baths There is no need to separate them further.

According to a special aspect of the invention, in some cases this can be confirmed by testing. However, steps C and d of the above process, i.e. acid with permanganate solution. It is also conceivable to combine the method steps for performing the conversion process into a single method step.

1M of the present invention will be described in detail below with reference to the drawings. Here, Figure 1 shows DE-O Diagrammatically showing the "stain removal" method known from S 36 38 630; Figure 2 shows the cylindrical surface of the drill hole known from DE-PS 3B 06 884. schematically shows a method for currentless deposition of a conductive layer on; FIG. 3 partially uses the method steps of the partial method shown in FIGS. 1 and 2. A method according to the invention.

In order to better understand the proposed means of the present invention, DE-〇S36　38　63 In the known method described in No. 0, printed circuit boards or cites Figure 1 to explain how to clean the drilled holes in a multilayer circuit board. Let me explain briefly first.

For more information on this method, please refer to this printed specification.

Before the method steps shown in FIG. 1, this printed circuit board or multilayer circuit board has already been A drill hole is provided. The pores are connected to conductive structures placed in different layers. This is what you intend to use to establish a connection through. This hole was formed In some cases, the pore walls are contaminated. Especially when resin dirt or worthless impurities accumulate . To remove these, the printed circuit board is introduced into a first treatment solution (the first step in the method). step), in which the cylindrical surface of the hole is immersed. This is done using various organic solvents and sodium hydroxide. Performed in a mixture with thorium. After rinsing (second step of this method), the printed circuit The substrate is subjected to an oxidation treatment bath, preferably a potassium permanganate bath (third step of the method) guided by. The actual removal of impurities on the drill hole occurs here. What happens in this case? In the chemical reaction, manganese dioxide is also formed by the reduction of potassium permanganate. There is. This must be removed in order to successfully metallize the cylindrical surface of the hole. This was basically believed. Therefore, it was known from DE-○S36 38 630 In the method (Fig. 1), after rerinsing (fourth stage 'Fr1 of the method), the so-called ``After the decontamination process (the sixth step of this method), this printed circuit The plate cleans the cleaned cylindrical surface of the drill hole by a method not shown in detail. reaches the point where it is coated with a metal layer.

In combination with the method shown in Figure 1, a conductive coating can be formed on the cylindrical surface of the drill hole. Among the various known methods for determining the amount of data, the present invention chooses a very specific method. This method is It is described in DE-PS 3B 06 884, and it is briefly explained below by quoting Figure 2. explain. For further details see the printed specification mentioned above.

The pretreated printed circuit board is first immersed in an organic solvent (related steps Since the details are not known, it would be more accurate to say "processing" in general. cormorant). This is the seventh step in the method of FIG. Rinsing (step 8 of this method) Afterwards, the printed circuit board is passed through a permanganate solution (step 9 of the method), Here, an oxidation pretreatment of the cylindrical surface of the drill hole to be subsequently coated is carried out. be exposed. In this case, the foreign matter does not disappear completely after passing through this stage; It is desirable that some amount of manganese dioxide generated during reduction of the ganochloride solution remains. I found out something new.

The thus pretreated printed circuit board is rinsed (step 10 of this method), and then (step 11 of the process). These A layer of on-machine material is thus deposited on the cylindrical surface of the drill hole. Intervention of rinsing In the next twelfth step of the process, which is carried out in the In this case, a conductive layer is formed. Scouring and rinsing module (Modulξ) in which excess polymerization product and residual process liquor from stages 11 and 12 of the process are is removed, whereby the printed circuit board is subjected to further steps of depositing a conductive layer, e.g. Supplied to the electrolytic process.

According to the invention, the two aforementioned methods are combined with each other. This is shown in FIG. figure 3, the steps of the method adopted from the known method according to FIGS. , identified by the same quotation number. Comparing FIG. 3 with FIGS. 1 and 2, it is clear that the present invention It is important to note that not all steps of known methods may be adopted. Ru. On the contrary, the decontamination step 5 and the subsequent rinsing step 6 are omitted from FIG. The soaking operation 7 and subsequent rinsing step 8 are omitted from the method shown in Figure 2. It is. The printed circuit board is thus directly transferred from the oxidizing bath 3 of FIG. 1 to the oxidizing bath of FIG. introduced in 9. This method saves four steps, which means it saves two processing solutions. Not only does it mean: in terms of equipment, it means a saving of 4 equipment modules. , this results in considerable cost savings.

This can be ascertained in a few tests in each individual case, but under favorable conditions Below, the third and ninth stages of the method in Fig. It can also be integrated at the legal level. This clearly results in further cost savings.

abstract A method for manufacturing a multilayer circuit board or printed circuit board with through-holes, known in the art. The first method combines two methods: soaking (1), rinsing (2) and overmanning. Clean the connecting through holes by oxidation (3) with ganoic acid salts. This known The method further comprises that after an additional rinsing step there is a so-called decontamination step and then a further rinsing step. Although there are steps, according to the invention these last steps are omitted. Second known The method includes a conditioning or soaking step, a rinsing step, and a permanganate solution. an oxidation step (9), a further rinsing step (lO) and Depositing (11) and then polymerizing it (to form a 12L conductive layer) Then, the outer surface of the through hole is electrically plated with a conductive layer. Additional rinse or After the enching step (13), the printed circuit board or multilayer circuit board is subjected to further fabrication processes. However, this does not fall within the scope of the present invention. The method disclosed is as mentioned at the beginning. Conditioning or soaking of the last-mentioned known methods in conjunction with the method step and subsequent rinsing step can be omitted. Overall, the processing fluid At least two stages applied to the board or multilayer circuit board and a corresponding rinsing stage is omitted.

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Claims (2)

[Claims] 1. Drill holes made to penetrate each layer and form connections in the following directions a) to c). Printed circuit boards or polygons with connections through each layer, including cleaning at In the method for manufacturing a layered circuit board: a) immersion in a treatment liquid; b) rinsing; c) oxidizing treatment with a permanganate solution, immediately after method step c a neutralization step; onto the cylindrical surface of the drilled hole without intervening any additional treatment or dipping operations. A method characterized in that the currentless formation of the conductive layer is carried out according to the following steps: d) oxidizing with permanganate solution; e) rinsing; f) depositing a layer of organic monomers from a solution of these monomers; g) depositing Polymerizing monomers to form a conductive layer. 2. The method according to claim 1, characterized in that steps c and d are combined into one method step. Law.