DD297539A5 - METHOD FOR PRODUCING WIRING SUPPORT SIMILAR TO PCB - Google Patents

Abstract

The invention aims at the production of electronic assemblies, which serve as carriers and connecting elements of electronic components. Since the production of known printed circuit boards is expensive, the invention has the goal of avoiding the expense of Naszverfahren for the production of printed circuit boards, including those with wires (multiwire method), and to reduce the number of Prozeszschritte. The object of the invention is to find a method in which wires are laid, held and connected to the components in such a way that plated-through holes and galvanic processes are avoided. This object is achieved according to the invention in that the contact points to which the components are connected by means of solder or conductive adhesive are formed by the laid wires without intermediate elements. The specific advantages of the stated solution are that the layout effort is avoided and chemical process steps are almost completely avoided, but that they can form finer structures than conventional printed circuit boards. Fig. 1 {printed circuit board; Wire; components; to contact; Contact points}

Description

For this 7 pages drawings

Field of application of the invention

The invention relates to a method for producing wiring substrates similar to printed circuit boards and finds application for the production of wiring that perform the same functions as circuit boards, namely the holding of components and making electrical connections between their connection points. The field of application can be found everywhere, where printed circuit boards can be used, thus the field of development and production of electronic assemblies is detected.

Characteristic of the known state of the art

Electronic components must be mechanically held and electrically connected to provide a functioning circuit. It is known prior art to solve both tasks by means of a printed circuit board, to which the components are soldered and on the plated and etched conductor tracks make the electrical connections between the connection points of the components.

Well-known is the production of printed circuit boards by means of chemical etching combined with galvanic and physical application processes in many detail variants (Hermann, G. et al.: Printed circuit boards - production and processing. - Leuze Verlag Saulgau). A disadvantage of these ancestors

- the large number of very precisely executed process steps,

- The necessary high expenditure on equipment, which allows a production usually only with specialized manufacturers,

the relatively long time, or the high cost, that a user needs to get to a pattern blank,

- environmentally hazardous process steps causing high costs for the exclusion of hazards and waste disposal,

- the high water consumption, which requires extensive reprocessing ..

the high space requirements for the apparatuses for the execution of the many method steps,

the very high level of precision and cleanliness required for the manufacture of fine circuit boards and multilayer circuit boards,

- the high expenditure for the production of the delivery documents (routing, layout, films, data media, etc.).

Methods are known which are intended to more or less eliminate these disadvantages. Mention may be made of the milling methods (eg brochures of the company LPKF Seebach) and the wire laying methods (eg multiwire method [see ao in Herrmann, G. et al.] And description of the KOVO Aritma machine for laying printed wire conductors ARITMA1601). The disadvantages are overcome only partially and conditionally. In addition, the milling processes and some wire-laying processes require the plating of holes, which removes all or part of their advantages of simplicity and speed. Other wire laying methods require mechanical intermediate elements to make the connection between the wire and the component. In addition, these methods are slow and usually ineffective due to the not small number of process steps. Known is the SMD (surface mounted devices) method (Schraft, RD; Bleicher, M .: surface mounting electronic components.- Hüthig Verlag Heidelberg 1987.), is applied to the solder paste on conductor tracks of the circuit board, placed on the solder paste components and then the solder paste is heated and melted, creating a strong bond.

The SMD method has led to an effectiviation of the Leiterplatterhorstellung. Vieio drilling can be avoided. However, the production of the circuit board itself shows the already criticized effort for their production. It is also known from SMD technology, instead of using solder paste conductive adhesive for the production of the connections between conductor and component connection.

Numerous other connection methods are known from microelectronics (Hacke, H.-J .: Monta -je Integrated Circuits.-Springer Verlag 1987.), but by the manufacture of the actual wiring substrate (conductor}, latte) will not affect. In the wire laying technique in its known method design following steps are necessary:

- On an insulating plate wires are laid, which are thereby fixed in an adhesive layer. The wires are then baked in another, overcoated adhesive layer.

- The wires are to be connected to the component terminals, which is done by soldering additionally produced vias. The preparation of the vias requires drilling and numerous galvanic processes, or it must be mechanical intermediate elements to enable the connection between wire and component.

Wires are laid by hand individually for repairs or changes to printed circuit boards.

A disadvantage of the known method of high production costs, which is also and precisely due to the required galvanic steps.

Object of the invention

The aim of the invention is a solution for a method for producing a wiring substrate, which avoids all the disadvantages of the known wet process, is less expensive than known Drahtlegeverfahren and more powerful than milling process. Thus, the method should be suitable to produce even complicated wiring of components on carriers quickly, with little effort and cost in a few process steps. The advantages of the methods are to be combined without taking over their disadvantages.

Explanation of the essence of the invention

The Erfindufng has the task of specifying a method in which wires are laid and connected to the components that vias and galvanic processes or mechanical intermediate elements in the production of wiring substrates similar PCBs are avoided and the laying process is carried out automatically at high speed.

According to the invention the object is achieved in that a continuous wire is laid, which is at the future connection points, which produce the connections to the components, molded and stripped, and the wire in one of the downstream process steps by separation into sections that the individual potentials correspond to the circuit to be produced, is disassembled. The connection between, formed by the wire formed and stripped connection points and the component connections is carried out without further intermediate elements by soldering solder paste or conductive adhesive.

The embodiment of the invention is carried out by various solutions for the process steps laying the wire, fixing the wire, forming the wire at the connection points, stripping at the connection points and separating into sections.

The illustrated invention has the following specific advantages:

- Simplest layout of the wiring, no time-consuming routing,

- no expensive means of production (films, masks) required,

- no chemical process steps, so no worries with waste, etc.,

- no cleanroom required,

- In some embodiments, no drilling of the circuit board required to required holes are not made the high quality requirements as in chemical vias, therefore executable by laser or punching,

- simplified requirements for the base material, usable material spectrum expands,

- Three-dimensional design possible,

- high PCB density relatively easy to reach, many connections in one plane possible,

- The laid in the manner of the invention wires can be continued for further device wiring outside the circuit board, whereby the connection costs can be reduced,

- small footprint for the manufacturing facilities,

- much fewer process steps than in the wet production of printed circuit boards,

- with thin wires, z. B. diameter 0.150mm, despite the same space requirements significantly larger cross-sections achieved than with conductor tracks. Assuming the wire thickness d equal to the conductor width b and the copper of the circuit board has the strength s, the area ratio is

f = (pi-d) / (4-s).

The cross-sectional enlargement has advantages, in particular for the dynamic behavior of the circuit (recharging operations during switching), because the voltage drops on the connections are reduced. Coupling capacities remain small at intersections.

- An adhesive layer can be kept so thick and adjusted in terms of curing, that they thrust movements

can absorb by thermal rotation, thereby eliminating related problems with large SMD components. - Before the continuous wire is separated, all connection points are connected to one another at a potential. This allows a simplification of the test and new test methods.

embodiments The invention will be explained in more detail below with reference to seven embodiments with associated figures 1 to 7. Ausführungsbeisplel 1 (see Fig. 1):

Fig. 1 shows a plate P which is covered with an adhesive layer K. As an adhesive can z. Acrona MV from DuPont. The wire D is laid in or on the adhesive layer K and fixed by this. At the connection points to be formed, the wire is formed into a projection B. The hump stands out of the adhesive layer hjraus. By targeted action z. B. by means of laser radiation, any existing insulation can be removed on the hump. On the hump solder paste or conductive adhesive L is applied. Since the wire is not yet separated, it can be an electrical contact test between the solder or adhesive applicator, wherein an electrode is immersed in the solder paste or in the conductive adhesive, and the wire. After placing the device BE with its component connection BA on the solder paste is then followed by soldering (reflow or infrared method). In a further method step, the separation of the wire takes place at the separation points T for the purpose of decomposition into the individual potentials. The separation can be done mechanically or by laser.

Ausführungsbelsplel 2 (see Fig.2):

Fig. 2 illustrates a plate P on which the wire D is laid in an adhesive layer K. The connection points to be formed are formed in a projection B. By special action z. B. of laser radiation, the wire is melted after laying on the hump B and thereby separated. At the same time the terminal is formed by the convergence of the wire end to a ball Ku. Solder paste or conductive adhesive L is applied to this connection point and the component BE is attached to its component connection BA. Then the soldering can be done.

Ausführungsbelsplel 3 (see Fig.3):

Fig. 3 shows a plate P, on which an adhesive layer K is applied. In the adhesive layer K depressions V are pressed, over which the wire D is laid. The application of the solder paste or the conductive adhesive takes place in the recess V, a separation point T is outside the wells. It is made mechanically or by laser. On the solder paste or the conductive adhesive, the component BE is placed with its component terminals BA.

Embodiment 4 (see FIG. 4):

Fig. 4 shows a plate P, on one side of an adhesive layer K is applied. The plate has bores Bo, through which the wire, which is laid on the adhesive layer, is inserted. The inserted piece of wire can be formed into a loop S or other shape, which is adapted to the specific nature of the aufzusetzenden device. The loop S is stripped, z. B. by heat (micro-flame) and covered with solder paste or conductive adhesive L. In the solder paste or the conductive adhesive L of the component connection BA of the component BE is set. The component connection BA can protrude into the bore Bo. A separation point T breaks down the wire again into the necessary sections.

Ausführungsbelsplel 5 (see Figures 5a and 5b): Fig. 5a presents a variant that can be executed without adhesive. The wire D is passed through at a connection point to be formed

a slot Sch inserted into the support plate P and held in a non-positive fit in this slot, including the slot at least some points in one direction has a smaller degree than the wire diameter. When laying the wire this is printed by means of a tool in the slot. It can then terminate with the plate surface (component side) or project beyond it, and also above the plate in addition, e.g. be formed into a loop. An adhesive layer on the

Components facing away from side can support. The slot may be laid or misplaced during installation

be formed. The impressions can be combined with the separation.

Figure 5b illustrates the top view of a threaded wire slot from the component side. The total visible area

The wire is available for connecting the device via solder paste or conductive adhesive available. By appropriate

Forming the slot and tools, the pad can be made oblong or punctiform. Such Pad can also be used as a bonding pad for welding connection wires. The embodiment of Fig. 5 can be changed by a slot which is slightly larger in all dimensions than that Wire diameter. Upon insertion of the wire into the slot, plastic deformation of the slot environment will occur

connected, whereby a positive and positive fixing of the wire takes place.

Exemplary embodiment 6 (see FIG. 6):

Fig. 6 illustrates the carrier plate P with the adhesive layer K. The plate P has a cutout A, which has larger dimensions than the wire diameter on all sides. The wire D is laid in or on the adhesive layer and deformed by the cutout on the other side of the plate, the component side. Other wires can be routed equally in the same section. Their distance is in the smallest case equal to the wire diameter. Forming the wire in the form of F1 or F2 can provide improved conditions for the placement of the component BE with its component connection BA. The form F2 can be used for potted components. Oas donated device BE1 has a contact pin BA1, which engages in the wire form F2. The wire is replaced by targeted action z. B. a laser beam stripped only at one point on the component side or in the vicinity of the center of the molds F1 or F2. The connection to the component produces solder paste or conductive adhesive L. The embodiment of Figure 6 has the advantage that a very high connection density can be achieved. Connection points can have a distance equal to the wire diameter.

Embodiment 7 (see FIG. 7)

Fig. 7 illustrates the direct connection with a set on the wire D chip C. Between the hump of the wire D and the pad Dl of the chip is conductive adhesive L, are contacted via the wire and chip. The plate P and the adhesive layer K correspond to the above. The wire hump can, but does not have to tower over the surface of the component side.

Claims (3)

1. A method for producing wiring substrates similar to printed circuit boards, in which in process steps wires on plates, also adhesive or adhesive coated, laid for the purpose of making electrical connections of components and thereby fixed, and contacted the devices by means of solder or conductive adhesive at the contact points of the wiring substrate and be held, characterized in that the contact points of the wiring substrate are formed by method steps without further intermediate elements solely by the wires. 2. The method according to claim 1, characterized in that the following process steps are passed - laying a continuous wire, - forming the contact points, - separating the wire into individual sections, wherein test steps can be inserted in which the contact points of the continuous wire can be checked for electrical continuity against another point of the wire. 3. The method according to claim 1, characterized in that the wires are fixed to contact points by inserting the wire into slots or holes or similarly shaped openings of the plate in which the wire is held non-positively after it has been pressed or pressed into this.