DE2541667A1 - METHOD OF MANUFACTURING PRINTED CIRCUIT BOARDS - Google Patents

Description

P ATE N TA N WALTE

MANITZ, FINSTERWALD & CRÄMKOW

IS. SEP. 1975 Munich, the original / wf - N 2063

Northern Electric Company Limited 1600 Dorchester Boulevard West Montreal Que., Canada

Process for manufacturing printed circuit boards

The invention relates to a method of manufacturing printed circuit boards in multiple units.

Printed circuit boards are becoming very widespread and used in many industries used. The assembly of components on such boards can be done by hand, but the machine assembly with components preferred both because of the ejection speed and because of the

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Reduction in labor costs. This also avoids possible assembly errors.

While relatively large printed circuit boards individually economical can be handled, this is less economical with small boards. Thus a component insertion or placement machine is used as effectively as possible, ideally several small ones Boards assembled at the same time on the machine. However, this requires assembly or clamping devices or other devices that the Hold circuit boards and also the installation in the mounting devices is time consuming and relatively slow. The mounting fixtures are expensive and usually cannot accommodate as many boards as the one Machine could be processed, as retaining clips and other facilities required are.

After assembling the boards with components, the connection points usually wave soldered; While large boards can also be handled individually here, it would be more economical to use several smaller ones Handle boards at the same time. This in turn requires holders and workers who bring the circuit boards into the holders and moreover the brackets themselves cause problems.

The invention provides a method for producing printed Circuit boards created in which the circuit boards, after they have been printed or copied and also separated or cut out of a material plate have been in this material plate in their location without additional Holding or fastening devices are held in place while the assembly is being carried out with components and wave soldering is carried out. Preferably, the board material is a glass fiber reinforced synthetic resin and the resin can have the special property that it is nominally heat curable or thermosetting is that it is, however, at elevated temperatures in one

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limited area is thermoplastic to a small extent.

In the method according to the invention, the individual blanks, After the circuits have been produced on the individual boards, cut or separated from a sheet of material, then the Sinkers returned to the openings in the material plate, the material plate and the returned blanks are heated to a predetermined temperature and the plates are weighted or pressurized to reduce their flatness, i.e. maintain their flat shape while cooling. After cooling down, the components are assembled and the connection points, as required, wave soldered. Then the individual boards pushed or pushed out of the material plate.

The invention consists in that printed circuit boards according to the Printing and cutting out of a material plate are fed back into the material plate, the plate and the returned circuit boards are heated to a predetermined temperature and put under pressure while cooling or complained. The boards can then be provided with components by hand or by equipping them with a machine. Can also be a Wave soldering takes place before the individual boards are pressed out of the plate or -pressed. The material used is usually a fiber-reinforced synthetic resin and, in particular, a thermosetting resin is used. Thermosetting synthetic resin is used, which has the special property of being slightly thermoplastic in a limited area at elevated temperatures to be.

The invention is referred to below using an exemplary embodiment explained in more detail on the drawing; it shows:

Figure 1, a plan view of a material plate with punched manufacturing and Positioning holes as well as punched and returned individual

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printed circuit boards;

Figure 2 α and 2 b, cross sections through a plate along the line II II of Figure I, in which the successive positions of the sinkers shown after punching out of the plate and return into the plate are.

As shown in Figure 1, a plurality of individual printed Circuit boards 10 made from a plate made of glass fiber reinforced synthetic resin 11 shaped. Each circuit board 10 is provided with a printed circuit, which is shown schematically and denoted by the reference numeral 12. For more convenient Handling is usually an opening 13 punched in one end of each board. The edge of each board 10 is provided with the reference number 14 and this line also represents the shear line for punching out each board 10.

Manufacturing holes and positioning holes 15 are also in the Plate 11 stamped.

The method for producing the circuit boards 10 is shown in general below, it should be noted that modifications can be made to this method to meet changing requirements. Starting from the originally present glass fiber reinforced material, the plate 11 is cut to size. Then the holes will be 15 punched. This process is followed by punching out the windows or openings 13 if such openings are required. Then the printed Circuits formed in a conventional manner, such as by coating of the boards 10 with copper, covering or masking, and by a final etching process. Using the holes 15 as positioning means then turn the boards 10 punched out of the plate. The punch press is designed so that after the blanks in a, as in Fig. 2a

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The position shown were punched out, the spring-loaded pressure plate 16 below the material plate Π returns the plates 10 and presses them back into the openings remaining in the material plate. In the case of a sheet of material as shown in FIG. 1, the blanks 10 can be punched at one edge and returned in a first punching process and then the sheet of material turned around and the blanks punched and returned at the other edge. The number and arrangement of the blanks punched out at once largely depends on the performance of the press; but also on the size of the tool that one wishes to produce and that is required for the production of the blanks. After punching and returning the blanks, the material plate is curved or bent; this is due in part to stresses resulting from the stamping process. The sheets of material are then stacked on top of one another and placed in a heating furnace in which the stack is held at a predetermined temperature for a period of time sufficient to ensure that the stack is continuously heated. During the heating process, the material plates are put under pressure or weighted down in order to make them flat again. The stack is then removed from the oven and cooled while it remains under pressure or is weighted down.

After cooling, it is usually printed on the side on which the circuits are printed are, a coating of alcohol with tree resin or wood resin is applied to protect the copper circuit. The material plates with The boards sitting in their places then become the assembly stations

can

brought. The components / in the boards 10 by hand or by automatic Component insertion machines are installed. Both automatic insertion and manual assembly can also take place. On the Following assembly are the integral or one-piece material plates then forwarded to the wave soldering machines, in which the contacts between the component connections and the printed circuit are soldered will.

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After world soldering, further assembly or other processes can be carried out may or may not be performed on the boards. The boards are removed from the boards by means of a simple press that is applied to the boards while holding the surrounding frame or skeleton in place. The boards can be in a fully finished state, there however, further assembly or other work can also be carried out.

When the individual boards 10 are cut or looked out of the plate 11 a certain amount occurs because of the properties of the material Degree of crumbling or crumbling at the cutting or shearing lines of the So cut is not completely clean and sharp. When the sinkers are pushed back or returned to their previous positions in the plate, many of these crumbs are also pushed back into the shear line or cutting line. It is therefore believed that the slight softening of these Crumbs and resin during the heating of the plates and the boards helps to create an adhesion between the boards and the board frame or Creating skeleton. The term "liability" is used in the general sense, since there is no fusion or welding, but the slightly rough edges of the shear lines and the crumbs have a high degree of rubbing Create interaction and stickiness during softening.

The thickness of the starting material plate has a certain influence on the Strength of the bond between the returned or reinserted blanks. The thinner the material, the weaker the connection and it it has been found that thicknesses of 1.27 mm (0.05 inches) and greater give effective joints, although in some cases a thinner material is used can be achieved if minimal stress is applied to the boards after they have been reinserted.

As already stated, the special property of the synthetic resin seems to be one

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to have a beneficial influence on the effectiveness of the compounds. A Resin with a slight or low thermoplastic softening in a certain temperature range gives improved bonds, presumably This is because the slight softening causes a little movement or mixing of the rough edges, as well as compression Squeeze the loose crumbs into the gaps at the shear line. Although such a connection is strong enough to keep the boards in the board during assembly and other operations To carry, it can - if desired - be easily broken in order to take the circuit boards out of the material plate.

One particular synthetic resin that has been found to be suitable is a bis-chlorophenyl Α resin. This resin exhibits a slight softening ranging from about 145 to 180. In this temperature range, the printed and punched Heat-treated material sheets. A thickness of 1.58 mm (0.062 inches) - one of the standard thicknesses of starting plate material - is very effective and suitable, but thicker material is also very good; the thickness is also determined by the press performance, the strength requirements of the finished blank and the costs.

As an additional feature it should be mentioned that the alcohol tree sap or Wood resin coating that is applied to the circuit board to make the copper circuit Protecting against oxidation can also help improve the strength of the connection between the returned circuit board and the material plate to be improved in that some of the resin penetrates into the joint line and in this way acts to some extent like a glue.

Significant cost savings can be made by using the invention achieve. In special cases, savings have been made up to 30% of the cost of the populated and soldered boards achieved.

- patent claims -

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Claims (9)

5 <4! b b Claims Process for the production of printed circuit boards in multiple units, characterized in that individual blanks (10) are sheared from a material plate (11) that the sheared Sinkers (10) are fed back into the material plate (11) that the material plates (11) and the fed back plates (10) on a predetermined temperature are heated, and that the material plates (11) are kept under pressure during cooling, so their flat shape is maintained. 2. The method according to claim 1, characterized in that printed on the individual boards (10) before shearing the boards Circuits (12) are generated. . Method according to one of Claims 1 or 2, characterized in that, after cooling, components are applied to the individual Turn the boards (10) assembled. 4. The method according to claim 3, characterized in that the electrical connections of the components to the printed circuit (12) by wave soldering. 5. The method according to claim 4, characterized in that the ORIGINAL 6 0 9 8 15/0911 individual boards (10) after completion of the installation of the Components are pushed out into the circuit boards. 6. The method according to any one of the preceding claims, characterized in that g e k e η η draws that the Materia I plate consists of glass fiber reinforced synthetic resin. 7. The method according to claim 6, characterized in that the glass fiber reinforced synthetic resin material is a curable by heat Resin is thermoplastic in a limited range of elevated temperatures Has properties. 8. The method according to claim 7, characterized in that the MateriaIplatten (11) and the returned plates (10) in the limited In the area of elevated temperatures. 9. The method according to claim 2, characterized in that the material plate (11) and the returned blanks (10) on the side, on which the printed circuits (12) are arranged, are coated with a layer of alcohol tree resin. 609815/0911 Blank page