DE3316017A1 - Method of making electrical connections in multisubstrate circuits, and multisubstrate circuits produced thereby - Google Patents

Abstract

The invention relates to a method of making electrical connections between conductor tracks (or printed circuits) on the surfaces of substrates in multisubstrate circuits in which the conductor tracks to be electrically interconnected are in different levels. In order to provide greater freedom or flexibility in the choice of the position of the points to be connected in the different conductor tracks, the invention envisages that a solder metal is provided in the conductor track pattern of one level at the future point of connection to a conductor track in another level, that these solder metal points are fused by the action of heat to the end or ends, respectively, of a hole or holes which is/are electrically conducting and/or wettable by solder metal and which leads/lead to at least one contact point of at least one other conductor track or is/are itself/themselves a contact point of such a conductor track, the second substrate being provided with holes (18, 28) for electrically connecting the contact point(s) of the conductor track of a first substrate (1) with a conductor track of an adjacent second substrate (2), that said holes are internally metallised (17, 27) or rendered wettable by solder metal, and that the position of the holes is chosen so that on one side their ends are opposite the contact point or contact points of the conductor track of the first substrate. As a result of this, ... Original abstract incomplete. <IMAGE>

Description

"Process for making electrical connections

on multi-substrate circuits, as well as multi-substrate circuits manufactured according to this " The invention initially relates to a method according to the preamble of the claim 1. "Conductor tracks" also include printed circuits. Under Multi-substrate circuits are understood to mean the laying on of at least two substrates, each of which is provided with a conductor track on one or both surfaces. The task here is to find certain contact points of these conductor tracks, which are each located on surfaces of different substrates, electrically with one another to verbirlcien. To solve this problem, the procedure so far has been that several such substrates placed one on top of the other and connected to one another by pressing became.

Then you have these substrates at the point of contact with one another Track positions pierced, each of these holes all substrates penetrated. The inner surfaces of the holes were then each coated with a metallization (also called Uurchkntaktierung) coated. Each to such a hole Adjacent conductor track locations of different conductor tracks were over the metallic Coating of the inside of the bore conductively connected to one another. This resulted in but several disadvantages. First of all, it had to be ensured that each other to be contacted points of different conductor tracks of such a substrate package are exactly on top of each other, otherwise they will not have the associated hole come into the desired electrical contact. The practical implementation of this Demand is difficult, however. In particular, there is the problem, or the risk, that one of these holes penetrates a conductor track that is not in contact with bodies other conductor tracks may be brought. This can only be done through appropriate Avoid laying the electrically conductive parts of the conductor track in question. Apart from the amount of work required for this, this can also lead to a corresponding Lead to more space requirements. When making these holes, drilling dust is formed, which clog the contact surfaces of the conductor tracks and thus the desired electrical Impair or even prevent contact with the metallization coating carton. Another major disadvantage of this known method is that that - with the generally customary production of such substrates from ceramic - only used with a so-called green ceramic, i.e. a ceramic that has not yet been fired can be, because only such a relatively soft ceramic can with the mentioned Provide holes will. When using the aforementioned procedure the ceramic can only be fired after drilling and therefore only on that already assembled package of substrates take place. This in turn means that then only the outward facing surfaces of such a package can be equipped with capacitors, semiconductors and the like, as such Components cannot withstand the firing temperatures and therefore only on those that have already been fired Substrates can be applied.

The object of the invention is, first of all, a To improve the method according to the preamble of claim 1 in that a greater freedom or flexibility in the choice of the location of those to be contacted Places of the various conductor tracks, whereby the individual layers (substrates) the multi-substrate circuit even before it is put together and thus also before it is brought about the electrical connection can be burned.

To solve this problem, based on the preamble of the claim 1 first of all the procedural features of the characterizing part of claim 1. This does not apply the need to fabricate all layers of such circuitry Drilling. The associated disadvantages described above are avoided. The layers of such a circuit can already be put together before and before the melting of the solder joints must be fired. You can therefore also before they are assembled with electrical components (capacitors, semiconductors, etc.) on the surfaces that in one of several layers composite multi-substrate circuit are no longer accessible. Each substrate with sl ~ in conductor tracks or Printed circuits and any components must therefore be assembled before assembly with the other substrates individually controllable for any errors. At this Place it should be mentioned that the layers of a multi-substrate circuit, including their Conductor tracks, can be designed differently. This is how you can do it with the octopus technique provide an aluminum oxide ceramic with conductor tracks produced by screen printing. A ceramic material would also be used as the carrier (substrate) in thin-film technology or glass possible, with the conductor tracks carried thereby being vapor-deposited. Further is known as a substrate printed circuit boards made of organic carrier material, such as epoxy resin, in which the conductor tracks are pressed or etched (laminated). Usually substrates or layers of the same type will be connected to one another. There are multi-substrate circuits with thick-film circuits the preferred field of application of the invention. One can but also substrates or layers with different structures result in a multi-substrate circuit assemble and here proceed according to the invention. So you can do that on a The surface of the first substrate or the conductor track with the conductor track the surface of the second and possibly a third substrate facing away from it associate. The days of the holes in the second and possibly also the third substrate is selected according to the contacting desired in each case.

Through the bores of the respective outer substrates can with a two- or three-layer (see also claim 2) multi-substrate circuit with Help one Microscope to check the contacts any errors are carried out. With the invention, however, it is in principle also possible to create multi-substrate circuits that have more than three substrates exhibit.

You just have to make sure that through appropriate recesses (here the holes) of the respective outer substrates the quality of the next internal solder joints can be checked.

A particularly advantageous and efficient way of bringing about the soldering points are bulges according to claim 3. This can in detail depending on the circumstances in the variant according to claims 4 and 5 or in the embodiment according to the claims 4 and 6 take place. In the latter case, one and the same heating process is used both the formation of the bulge and the soldering with the respective mating contact at the metallized hole.

Furthermore, the variant according to claim 7 is also possible.

The features of claim 8 are recommended, on the one hand, to the substrates to keep at the desired distance from one another and to prevent the other, that when the substrates are in direct contact with one another, the bulges of the Soldering points are squeezed together and thus the liquid metal is pushed apart will. This could possibly cause unwanted contact with adjacent sections of the respective conductor tracks arise.

The object of the invention also includes the design of multi-substrate circuits, which are made according to the invention. There should be different variants of such Multi-substrate circuits can be created.

The possible according to the invention arrangements of the surfaces with the Conductor tracks to be contacted are part of claim 9, insofar as these surfaces towards each other it is sufficient if the holes of each outer substrate of the n.r. Sufficient control function and also on the inside These are at least partially wettable by> i # 'tn metal penetrating them is usually done by a metallization of the inner wall but surfaces facing away from one another are in contact with one another, so have the bores of the respective outer substrate both a control function and the function of a conductive connection between the surfaces to be contacted.

The three-layer multi-substrate circuit according to claim 10 is a preferred one Embodiment of the invention. Claim 12 ensures that with the compression of the substrates, no soldering moisture enters the area of the conductor tracks in an uncontrolled manner and cause damage there. The subject matter of claim 13 includes a particular advantageous design of the spacers, since the se at the same time with the production of the respective substrate can be created. Claim 15 relates to an embodiment of multisubstrate circuits, which are known when using the above-mentioned Procedure would not be possible.

Further advantages and features of the invention are the further subclaims, as well as the following statements and also the drawing of the invention Refer to exemplary embodiments. The drawing shows in longitudinal section: Fig. 1: a three-layer design, Fig. 2: a two-layer design, Fig. 3: a plan view of part of the surface of the embodiment of FIG.

Fig. 1 shows a three-layer multi-substrate circuit with the first Substrate 1, the second substrate 2 and the third substrate 3 in the final state. Fig. 2, on the other hand, shows an analogue structure, but only of two layers, namely, the multi-substrate circuit consisting of the first substrate 1 and the second substrate 2 before assembling and soldering the substrates. The surfaces 4 to 13 of these substrates resp.

Layers can be provided with applied conductor tracks. Instead of printed circuits can also be provided there for the conductor tracks.

It consists now the task of defining certain points of the conductor track a Surface with one point or several points of a conductor path of another To connect surface of another substrate. This is done in the exemplary embodiment 1 by soldering points 14 and 15.

The soldering point 14 connects a contact point 16 of the conductor track the surface 4 via a metallization 17 of a bore 18 of this substrate 2 with a conductor track 19 of the surface 6 of the substrate 1. From here the electrical one goes Contact continues via the metallization 20 of a bore 21 of the substrate 1 and from there via the conductor track 22 of the surface 7, the soldering point 15 and a metallization 23 of a bore 24 of the substrate 3 to a contact point 25 of a conductor track the surface '3. It should be mentioned at this point that the conductor tracks (or printed Circuits) in detail are not g # inet, because they are known per se.

In the exemplary embodiment in FIG. 2, the contact point 26 becomes the surface 10 via the metallization 27 of the bore 28 of the substrate 2, the soldering point 29, the conductor track 30 of the surface 12, the metallization 31 of a bore 32 of the The substrate 1 of a contact point 33 of the surface 13 of this substrate is lost. In addition, there is a connection between a point 34 on the surface 11 via a solder point 35 and the metallization 36 of a bore 37 in the substrate 1 to the contact point 38 of the surface 13.

The drawings show that the metallizations 17, 2327 and 36 of the Bores 13, 24, 28 and 37 of the substrates (these are called Innon metallizations also vias) can run out at the bore ends in collars.

These connections can be made in various ways: At the later contact points, solders in a curved or spherical shape (see Numbers 29, 35). You can either by melting an initially flat one Solder point are formed, which - by itself - in the side view of FIG Number 39 is shown. When it melts, it becomes drop-shaped and solidifies in the form of the above-mentioned convex solder points. The outward, i.e.

Curvature of the material directed away from the respective surface of the soldering points, e.g. tin, results from its surface tension. Man However, such solder points can also be applied to the corresponding points on the surfaces Apply the substrates in a known manner.

Then the substrates are moved and pressed against each other (see Arrows 40, 41) and the entire multi-substrate circuit is heated in an oven. The soldering points melt and penetrate the opposite hole of the a neighboring substrate and fill this completely or partially (see Fig.l). The rest of the solder remains between the surfaces (5, 6 or

7, 8 or 11, 12).

One can also proceed in such a way that one does not remove the curvature of the solder points before they merge with the respective opposite hole, rather, flat solder metal pads on the surfaces of the substrates provides that are located on or in the course of a conductor track. Then the individual substrates placed on top of one another and heated in the manner described This melting also results in a bulging of the soldering metal at these joints. The material then also completely or partially fills the interior of the bores (see Fig. 1).

Using the example of FIG. 2, it should be explained that both the surface 12 over the soldering point 29 with the surface 10 of the adjacent one facing away from it Substrate and also via the soldering point 35 with the surface 11 facing it of the adjacent substrate can connect electrically conductive. Basically the same applies to three-layer mu1ti: 3uhstratscha # tung according to Fig. 1.

(#le: cI # güiLig, how the spherical or curved plumb lines are made? "# cllt one can proceed according to the detail A in Fig. 'so that on the conductor track 30 a ring 42 is printed from a material that cannot be wetted by the solder metal is. The bulge 29 is electrical through the inner surface of the ring 42 conductively connected to the conductor track 30. This is the explained Squeeze of the substrates and heating avoided that the solder material of the bulge 29 on the surface 12 squeezes wide and arrives at the conductor track 30. Rather, penetrates this liquid solder material correspondingly deep into the bore 28. Uic: finZtllleit A is in Fig. 3 in plan view. d> rg #> stt'llÜ.

In order to be able to wash out the flux for the Lütverbi t # ci # jngen, it is advisable to maintain an end distance a between the individual substrates (see Fig. 1).

In cases in which the conductor tracks on their upper side do not have are provided with an insulating layer, this also creates an undesirable contact prevented between opposing conductor tracks. To such an end distance To achieve a between the individual substrates, spacers 43, 44 are which can either be loosely inserted (43), e.g. in the form of small sheet metal parts are removed from the gaps between the substrates after production is complete be pulled out. But they also run in a special production technology simple design with the associated substrate in one piece (44). The height of the spacers, which is equal to the distance a, should be smaller than that Height of the spherical plumb points (e.g. 29, 35). Otherwise there is a risk that insufficient fusion of the solder points with the opposite holes comes about.

The exemplary embodiments show that the conductor track can be selected here or corresponding contact points on a surface, e.g. 4, with a conductor track or Contact points of the opposite surface, e.g. 7, of the adjacent substrate, but ultimately also electrically with one of the surfaces of a further substrate can conductively connect.

The position of the holes in a substrate does not have to match the position of the Holes in the adjacent substrate: align, as shown in the exemplary embodiments. Essential Lich is in all of the aforementioned cases that you have the necessary Carry out checks for any manufacturing defects. As mentioned earlier, is this first of all for the individual substrates and before they are assembled with the other substrates possible. Since the solder points each penetrate into holes, their the other end is on an outer surface of the multi-substrate circuit is located (in the example in FIG. 1, these are the outer surfaces 4 and 9, as well as in the example 2, the outer surfaces 10 and 13), one can through the bore openings located on the outside Use a microscope to determine exactly whether the desired soldered connection is flawless was produced.

So you can do a wide variety of things with a relatively simple manufacturing process Meet the requirements or special wishes of the practice. it should be mentioned that d # the soldering points after they have fused with the opposite bore ends, not only the e refined electrical connection, but also an additional mechanical one Hold the substrates together.

Since here the substrates before their assembly and manufacture of the Once soldered connections have been burned, they can, as mentioned, with electrical components be provided. If these components are higher than that which is actually quite minor Distance a can be done in such a way that correspondingly large components 45 of a substrate surface in the assembled position in a recess or in a through-hole 40 of the benac # ibarten substrate.

- Expectations -

Claims (15)

Patent and protection claims Process for the production of electrical Connections between conductor tracks (or printed circuits) on surfaces of the substrates of multi-substrate circuits are provided, which are composed of at least two There are substrates, the conductor tracks to be electrically connected to one another lie in different planes, characterized in that on or in the course the conductor track of a level at the later contact point to a conductor track of a another level a solder metal is provided that fusing by the action of heat these solder metal points with the end or the ends of at least one contact point leading from at least one other conductor track, or a contact point itself such a conductor track forming, electrically conductive and / or from solder metal wettable bore or bores is produced, for electrical connection the contact point (s) of the conductor track of a first substrate (1) with a conductor track an adjacent second substrate (2) the second substrate with the Drilling (18, 28) is provided that these holes are metallized on the inside (17, 27) or be made wettable by the solder metal that the position of the holes is chosen so that their ends on one side of the contact point (s) of the conductor track of the first Substrates are opposite. 2. The method according to claim 1, characterized in that in analog Way a merging of one or more contact points of the further surface (7) of the first substrate with the metallized or from the solder metal wettable inner wall (23) of one or more bore (s) (24) of a third substrate (3) takes place with the first substrate placed between the second and third substrates will. 3. The method according to claim 1 or 2, characterized in that the Solder metal is brought into a curved or convex shape (29, 35), the curvature is directed away from the substrate (1, 2) of the associated conductor track. 4. The method according to claim 3, characterized in that the curvature is produced by melting a printed flat solder metal point (39), which is located on or in the course of a conductor track. 5. The method according to claim 4, characterized in i the melting of the flat solder metal parts before connecting the sulphide rate to a multi-substrate circuit takes place and that after this connection by again melting the solder metal parts their electrical and mechanical connection to the opposite bore ends will be produced. 6. The method according to claim 4, characterized in that the bulge the solder metal points and their fusing with the hole ends on the multi-substrate circuit takes place in one work step (elitz effect). 7. The method according to claim 3, characterized in that the curvature is prepared by dipping the individual substrates in a bath that afterwards these substrates are assembled to form a multi-substrate circuit and that afterwards by melting the solder metal points again, their electrical and mechanical points Connection to the opposite bore ends is made. 8. The method according to any one of claims 1 to 7, characterized in that that when melting for the purpose of establishing the electrical and mechanical connection of the solder metal points with the bore ends of the opposing substrates Substrates are held at a distance (a) from each other which is slightly less than is the height of the bulge of the solder metal points. 9. Multisubstrate circuit, which according to the method of one of the Claims 1 to 8 is made, characterized in that the conductor track (s) of the adjacent second or third substrate is on the surface (s) of this Substrate is or are located to the surface to be contacted of the facing the first substrate, and / or facing away from it, or is. 10. Multi-substrate circuit according to claim 9, characterized in that that a middle, first substrate (1) with bores metallized on the inside (21) (20) provided is and that these holes are part of an electrical Line run between conductor tracks of the surfaces (6, 7) of this substrate and Surfaces (4, 9) of this multi-substrate circuit (1, 2, 3) are, the two outer substrates (2, 3) of this multi-substrate circuit with the conductive Connection or wetting by the solder metal serving, metallized on the inside Bores (18, 24) are provided. 11. Multi-substrate circuit, which according to the method of one of the Claims 1 to 8 is produced, characterized in that two substrates (1, 2 in Fig. 2) and each with (27, 36) bores metallized on the inside (28, 37) are provided, which are part of the electrical cable run. 12. Multi-substrate circuit according to one of claims 9 to 11, characterized characterized in that between the edge of a convex or curved soldering metal point (29) and the underlying conductor track (30) or substrate surface (12) Circular ring (42) made of a material that cannot be wetted by solder metal is provided, a conductive connection from the solder metal through the inside of the circular ring to the conductor path. 13. Multi-substrate circuit according to one of claims 9 to 12, characterized characterized in that as spacers on the substrates (2) projections (44) are molded with the opposite surface (11, 12) of the adjacent substrate (1) and their löe the desired distance (a) between these substrates is equivalent to. 14. Multi-substrate circuit according to one of claims 9 to 13, characterized characterized in that the metallization of the holes at the ends of the holes in itself laterally collars extending therefrom and resting on the respective surface of the substrate expires. 15. Multi-substrate circuit according to one of claims 9 to 14, characterized characterized in that electrical components (45) on a surface of a substrate and these components receiving recesses (46) or bores of the opposite Substrates are provided.