DE102015216417A1 - Printed circuit board and method for producing such a printed circuit board - Google Patents

Abstract

It is a printed circuit board (10) with an insulating layer (45) and a conductor track (40) indicated. The circuit board (10) has a first portion (15), a second portion (20) and a third portion (25) wherein the second portion (20) between the first portion (15) and the third portion (25) is arranged and the first portion (15) mechanically and electrically connected to the third portion (25) such that a main extension plane of the first portion (15) is arranged inclined to a main extension plane of the third portion (25). The conductor track (40) has a conductor layer (41) extending over the sections (15, 20, 25) and is guided arcuately in the second section (20). At least in the second section (20), the conductor track (40) has an electrically conductive solder layer (85) which covers the conductor layer (41) at least in sections. Furthermore, a method for producing the printed circuit board (10) is given.

Description

The invention relates to a printed circuit board according to claim 1 and a method for producing such a printed circuit board.

From the EP 2 728 982 A1 For example, a printed circuit board with a main section, a connection section and a connection section is known, wherein the connection section has a reduced thickness with respect to the main section and the connection section.

It is an object of the invention to provide an improved circuit board and an improved method of manufacturing such a circuit board.

The object is achieved by means of a printed circuit board and a method according to the independent patent claims. Advantageous embodiments are specified in the respective dependent claims.

It is a printed circuit board specified. The printed circuit board has an insulating layer and at least one conductor track arranged on the insulating layer. The circuit board has a first portion, a second portion, and a third portion, wherein the second portion is disposed between the first portion and the third portion and mechanically and electrically connects the first portion to the third portion such that a main extension plane of the first portion is inclined is arranged to a main extension plane of the third section.

The conductor track has a conductor layer extending over the sections. In other words, the conductor layer extends, in particular in one piece, from the first section into the second section and further into the third section. In the second section, the track is guided arcuately. At least in the second section, the conductor track has an electrically conductive solder layer which covers the conductor layer at least in sections.

In this way, the conductor track in the second section can have an enlarged cross section with respect to the cross section in the first and / or third section, so that a current carrying capacity of the conductor track in the second section can be improved.

In a further embodiment, the printed circuit board has a smaller thickness in the second section than in the first section or in the third section. As a result, the circuit board can be bent very easily. The insulating layer is in particular a main body of the printed circuit board or is a part of the main body. In an advantageous embodiment of the body is dimensionally stable, i. especially self-supporting. Preferably, the insulating layer of the circuit board is integrally formed extending over the first, second and third sections of the circuit board.

The main body is provided, for example, for forming the second portion with a trench which extends in particular transversely to the conductor track. In an advantageous embodiment, the printed circuit board-in particular by means of the second section-is semiflexible. In this way, advantageously, in particular, the inclined arranged third portion of the arcuately guided second section are held cantilevered.

In a further embodiment, the solder layer is designed to run without interruption over the second section. In this way, an electrical resistance of the conductor in the second section can be kept particularly low and a particularly high current carrying capacity can be achieved in the second section for the conductor.

In a further embodiment, the solder layer extends over a first region and over a second region of the second region. In the first region and in the second region, the solder layer covers the conductor layer on the outside, i. in particular on the side facing away from the insulating layer side. Between the first region and the second region, the solder layer has an interruption. At the interruption, the outside of the conductor layer is covered or free with a layer of varnish. The one covered by the lacquer layer or free, i. in particular exposed, conductor layer is uncovered in particular by the solder layer.

In a further embodiment, the solder layer has at least one further interruption, wherein the outside of the conductor layer is covered or exposed at the further interruption with the varnish layer. A distance of the interruption to the further interruption may expediently be selected as a function of a bending radius of the second section. In particular, the smaller the bending radius, the smaller the distance.

In a further embodiment, the printed circuit board has a further printed conductor. The further conductor track is preferably arranged on the insulating layer on the outside, ie in particular, it is not embedded in the insulating layer. However, in addition to or as an alternative to the further printed conductor, the printed circuit board can also have printed conductors embedded in the insulating layer. The insulating layer electrically insulates the trace from the other trace. The further conductor extends over the sections; ie in particular it extends from the first section into the second section into and far into the third section. The further conductor track is on the outside - ie in particular on its side remote from the insulating layer side - covered with a further lacquer layer or is exposed on the outside. By means of the further conductor track, for example, signal pulses can be transmitted electrically over the sections.

In particular, the further conductor track in the region of the second section is completely uncovered by the solder layer. For example, for the occurring during the signal transmission small currents is increased by the solder layer current carrying capacity of the other conductor is not required. By means of the uncovered by the solder layer further conductor track so a particularly cost-effective production of the circuit board can be achieved.

In a further embodiment, the conductor track covered at least in sections by the solder layer is designed to transmit a current having a value which is in a range from 0.7 A to 50 A, preferably in a range from 0.7 A to 25 A, in particular in a range of 0.7 A to 8 A, and for example in a range of 1 A to 5.5 A, is located. The boundaries are included.

Furthermore, a method for producing a printed circuit board according to at least one of the embodiments described above is given. In the method, the circuit board is provided with the insulating layer and at least the conductor layer. In the insulating layer, a recess is formed in the second section on a side of the printed circuit board opposite the printed circuit, for example by means of milling of the insulating layer.

The solder layer is applied to the conductor layer before or, preferably, after the recess has been formed. The printed circuit board is subsequently heated in such a way that the solder layer melts and forms a material connection with the conductor layer. Subsequently, the circuit board is cooled.

The first section is-in particular following the application of the solder layer and preferably also subsequent to the cooling of the printed circuit board-inclined with respect to the third section in such a way that the second section is curved. This is done in particular by bending the second section.

Advantageously, this allows a particularly high current to be transmitted between the first section and the third section via the second section of the conductor track.

In a further embodiment, at least in sections, before the application of the conductor layer with the solder layer, a lacquer layer is applied at least to the conductor layer in order to form an interruption in the solder layer. This ensures that when tilting the first portion relative to the third portion, the solder layer remains crack-free and splintering of the solder layer is avoided by the conductor layer.

Further advantages and advantageous refinements and developments of the printed circuit board and the method will become apparent from the following, in connection with the figures illustrated embodiments.

Show it:

1 a cross section through a printed circuit board according to the invention;

2 a flow diagram of a method according to the invention for the preparation of in 1 shown printed circuit board;

3 a sectional view of the circuit board in a first method step;

4 a sectional view of the circuit board after a second method step;

5 a sectional view of the circuit board after a third process step;

6 a plan view of a variant of in 5 shown circuit board after the third process step;

7 a sectional view through the in 6 shown circuit board along a in 6 shown section plane AA; and

8th a plan view of a circuit board according to a development.

1 shows a cross section through a printed circuit board 10 according to an embodiment of the invention.

The circuit board 10 has a first trace 40 , a second track 50 , a third track 60 , a fourth trace 75 and a first insulating layer 45 , a second insulating layer 55 and a third insulating layer 65 , The insulating layers 45 . 55 . 65 form together in particular a dimensionally stable body of the circuit board 10 ,

The first trace 40 is on the first insulating layer 45 on the outside of the first insulating layer 45 arranged. The second track 50 is between the first insulating layer 40 and the second insulating layer 55 arranged. The third track 60 is between the third insulating layer 65 and the second insulating layer 55 arranged. The fourth trace 75 is arranged on the outside of the third insulating layer. The insulating layers 45 . 55 . 60 and the tracks 40 . 50 . 60 . 75 form the circuit board in a stack-like composite 10 as a multilayer printed circuit board. Of course, also a different number of tracks 40 . 50 . 60 . 75 and insulating layers 45 . 55 . 60 conceivable.

The circuit board 10 has a first section 15 , a second section 20 and a third section 25 , The second section 20 connects the first section 15 with the third section 25 electrically and mechanically. The first paragraph 15 has a first main extension plane and the third section 25 has a second main extension plane. The second main extension plane of the third section 25 is inclined, in the embodiment by way of example at right angles, to the first main extension plane of the first section 15 arranged. Of course, it is also conceivable that the third section 25 another than in 1 has shown alignment and thus another second main extension plane. It is also conceivable that the second main extension plane of the third section 25 obliquely to the first main extension plane of the first section 15 is arranged. In the area of the second section 20 are in the present embodiment, the first conductor track 40 and the first insulating layer 50 arcuate on a partial cylindrical shell around a bending axis 30 guided. Of course, other arcuate guides in the region of the second section 20 conceivable.

The first trace 40 is on a first outside 35 the circuit board 10 arranged. The first outside 35 is one of the bending axis 30 opposite side of the conductor plate 10 , The first trace 40 is electrically conductive and may, for example, serve to flow between the first and third sections 15 . 25 over the second section 20 transferred to.

The circuit board 10 points to one of the bending axis 30 facing the second outer side 70 the circuit board 10 a recess 80 on that the second section 20 Are defined. The recess 80 is as a trench in the second insulating layer 55 formed from the second outside 70 forth in the second insulating layer 55 penetrates, but this does not penetrate completely. The first paragraph 15 has a first thickness d ₁ . The second section 20 has a second thickness d ₂ . The third section 25 has a third thickness d ₃ . The first thickness d ₁ and the third thickness d ₃ are, for example, the same size. The second thickness d ₂ is smaller than the first thickness d ₁ and the third thickness d ₃ . Due to the reduced second thickness d ₂ , the circuit board 10 in the second section 20 be bent particularly easily. Here is the circuit board 10 by means of the second section 20 remaining remainder of the second insulating layer 55 semi-flexible trained.

The first trace 40 has a conductor layer 41 on. The conductor layer 41 extends uninterrupted over all sections 15 . 20 . 25 and, in this and other embodiments, preferably comprises copper as a major constituent.

At the first outside 35 the circuit board 10 has the first trace 40 in the area of the second section 20 an uninterrupted solder layer 85 on. The solder layer 85 has in this and other embodiments, for example, as the main component tin on.

The solder layer 85 is by means of a material connection 42 with the conductor layer 41 connected and covered on one of the first insulating layer 45 opposite side of the conductor layer 41 Completely. The cohesive connection 42 can be made for example by means of a reflow soldering process.

Additionally, at the first section 15 by means of an outside of the conductor layer 41 on the conductor layer 41 applied further solder layer 90 at least one electrical component 95 mechanically and electrically with the conductor layer 41 be connected. The solder layer 85 and the further solder layer 90 be in one embodiment in the same process step on the conductor layer 41 applied.

Due to the arcuate course of the first conductor track 40 in the second section 20 can be at the first track 40 in the second section 20 no electrical component 95 to be ordered. The third section 25 the first trace 40 can serve as a connecting section, for example, to the circuit board 10 electrically connected to another circuit board or a connector (not shown). For example, pins of the connector are in the third section 25 pressed or soldered with this.

Through the solder layer 85 becomes a thickness d _{4 of} the first trace 40 in the second section 20 (hereinafter also referred to as "fourth thickness") with respect to a thickness d _{5 of} the first conductor track 40 in the first and / or third section 15 . 25 (hereinafter also referred to as "fifth thickness") enlarged. The fifth thickness d ₅ is in particular the thickness of the conductor layer 41 , It may have a value which is in a range of 30 μm to 50 μm, in particular in a range of 35 μm to 45 μm. The solder layer 85 advantageously has a sixth thickness d ₆ , which has a value which is in a range of 60 microns to 90 microns, in particular in a range of 70 microns to 90 microns. The fourth thickness is in particular the sum of fifth and sixth thickness: d ₄ = d ₅ + d ₆ . It is advantageous if the sixth thickness d _{6 of} the solder layer 85 is about twice as thick as the fifth thickness d _{5 of} the conductor layer 41 , As a result, a current carrying capacity of the first conductor track 40 in the area of the second section 20 total tripled compared to the conductor layer 41 in the first and / or third section 15 . 25 become. At the same time is also an electrical resistance of the first conductor 40 in the area of the second section 20 reduced. The first trace 40 is designed to transmit a current having a value in the range of 0.7 A to 50 A, in particular in a range of 0.7 A to 25 A, in particular in a range of 0.7 A to 8 A. , Particularly advantageously in a range of 1 A to 5.5 A.

2 shows a flowchart of a method for producing the in 1 shown circuit board 10 , 3 shows a sectional view of the circuit board 10 in a first process step 200 , 4 shows a sectional view through the circuit board 10 after a second process step 205 , 5 shows a sectional view through the circuit board 10 after a third process step 210 ,

In the first process step 200 becomes the circuit board 10 provided. Here is the circuit board 10 , as in 1 described, designed as a multilayer printed circuit board and has a layered stack of the conductor tracks 40 . 50 . 60 . 75 placed between or adjacent to the insulating layers 45 . 55 . 65 are arranged on. The circuit board 10 is prior to deployment in the first process step 200 by known manufacturing methods such as etching the tracks 40 . 50 . 60 . 75 and / or pressing the insulating layers 45 . 55 . 65 with the tracks 40 . 50 . 60 . 75 produced. The circuit board 10 is essentially in the first process step 200 plan, ie in particular are the main extension planes of the first and third sections 15 . 25 coplanar (cf. 3 ).

In the second process step 205 who is at the first procedural stage 200 follows, the recess becomes 80 by means of a cutting manufacturing process, in particular by means of a milling process, in the circuit board 10 introduced (cf. 4 ). As the circuit board 10 unbent and thus formed straight, the recess 80 be formed rectangular in the second step. As a result, the milling tool for producing the recess 80 especially inexpensive. Of course, other cross sections of the recess 80 conceivable.

In the third process step 210 (see. 5 ) becomes the solder layer 85 in the second section 20 on the conductor layer 41 applied. Of course, it is also conceivable that a further layer of solder 90 in the first / or third section 15 . 25 on the conductor layer 41 is applied to the further process, the electrical component 95 by means of the further solder layer 90 with the conductor layer 41 electrically and mechanically connect. This can be done for example by means of a printing process, in particular by means of a screen printing process.

In a fourth process step 215 , the third step 210 follows, the circuit board becomes 10 for example, with the first section 15 the first trace 40 fixed electrical component 95 stocked.

In a fifth process step 220 , the fourth step 215 follows, the circuit board becomes 10 along with the electrical components 95 and the solder layers 85 . 90 heated so that the solder layers 85 . 90 melt on the outside and a cohesive connection 42 , in particular a solder joint, with the conductor layer 41 received. This can be done in particular in a reflow process.

In a sixth process step 225 , the fifth step 220 follows, the circuit board becomes 10 along with the electrical components 95 cooled.

In a seventh process step 230 , the sixth procedural step 225 follows, becomes the second main extension direction of the third section 25 by bending the second section 20 opposite the first main extension direction of the first section 25 changed so that the second section 20 arcuate runs. Due to the reduced second thickness d ₂ in the second section 20 ensures that the first insulating layer 45 in the second section 20 is free of cracks.

6 shows a plan view of the second section 20 a variant of in 5 shown circuit board 10 after the third process step 210 , 7 shows a sectional view through the in 6 shown circuit board 10 along an in 6 shown section plane AA. For easier understanding is in 6 a rectangular coordinate system 250 represented by an x-axis, a y-axis and a z-axis.

The circuit board 10 is essentially identical to the one in 5 shown and related to 1 described circuit board 10 , Deviating from this are several first tracks 40 provided, which are arranged parallel to each other. In this case, each of the first interconnects 40 the conductor layer 41 and the solder layer 85 on. The conductor layer 41 is outside with the solder layer 85 completely covered. The solder layer 85 is formed without interruption. In the embodiment, the solder layer covers 85 in an entire width (y-direction) the conductor layer 41 , Of course, it is also conceivable that the solder layer 85 is narrower in the y direction than the conductor layer 41 , The y-direction is in particular parallel to the bending axis 30 running direction. In other words, the y-direction is transverse - in particular perpendicular - to the direction in which the tracks from the first to the third section 15 . 25 over the second section. In this case, the y-direction is in particular parallel to the main extension planes of the first and third sections 15 . 25 ,

Furthermore, several are on the first outside 35 arranged further tracks 300 provided, which in the y direction narrower than the first conductor track 40 are formed. The other tracks 300 are on the first insulating layer 45 on the first outside 35 the circuit board 10 arranged. This isolates the first insulating layer 45 the other tracks 300 electrically to each other and to the first conductor track 40 , The other tracks 300 extend over the sections 15 . 20 . 25 time. Here are the other tracks 300 configured to transmit signals, in particular control signals, with a current having a value which is in a range of 10 mA to 200 mA. The other tracks 300 can - without damaging and / or overheating - so only transmit a current that is at least an order of magnitude smaller than that over the first conductor track 40 transferable electricity.

The other tracks 300 are on the first outside 35 in the second section 20 free from the solder layer 85 ie from the solder layer 85 uncovered. In addition, it can be provided that on the other interconnects 300 in one between the second and third process steps 205 . 210 additional process step to be performed 208 (in 2 shown in dashed lines) a lacquer layer 305 on the other tracks 300 is applied. This protects the paint layer 305 the other tracks 300 before oxidation. Furthermore, the paint layer prevents 305 a flow of possibly on the other tracks 300 applied further solder layer 90 and / or a material connection 42 between erroneously on another trace 300 passed solder and the other conductor track 300 ,

By applying the solder layer 85 on the first track 40 is the current-carrying cross section of the first conductor track 40 greater than before the application of the solder layer 85 on the conductor layer 41 , This can cause a heating of the first conductor track 40 be avoided even at high currents.

8th shows a plan view of a development of in 6 and 7 shown circuit board 10 , The circuit board 10 is essentially identical to that in the 6 and 7 shown circuit board 10 educated.

Deviating from this, the solder layer comprises 85 in the 8th shown in plan view second section 20 the circuit board 10 a first area 400 , a second area 405 and a third area 410 , Between the first area 400 and the second area 405 is a first interruption 415 and between the second area 405 and the third area 410 is a second interruption 420 intended.

The first interruption 415 and the second interruption 420 are the same length formed in the x direction. The x-direction is in the stretched, unbent state of the circuit board 10 the direction of the first section 15 to the third section 25 out. Here is a distance of the first interruption 415 to the second interruption 420 depending on a bending radius r of the second section 20 , in particular the first conductor track 40 in the second section 20 , chosen. The dimension of the interruptions 415 . 420 along the x-direction are smaller than the dimensions of the areas 400 . 405 . 410 in this direction. They reduce in the eighth step 235 performed alignment change of the third section 25 opposite the first section 15 and the consequent bending of the second section 20 the danger that the solder layer 85 tears.

To corrosion or flow when heating the solder layer 85 over the melting temperature of the solder layer 85 into the break 415 . 420 can prevent the interruption 415 . 420 - For example, in the additional process step 208 - with another coat of paint 425 to be covered. Alternatively, it is also conceivable that the further lacquer layer 425 is omitted and outside the conductor layer 41 free is.

Through the interruptions 415 . 420 is an electrical resistance of the first trace 40 at the break 415 . 420 locally higher than in the areas 400 . 405 . 410 , This causes the first trace 40 at the respective interruption 415 . 420 warmed up more than in the areas 400 . 405 . 410 , Due to the thermal conductivity of the conductor layer 41 The heat from the interruption 415 . 420 to the interruption 415 . 420 adjacent areas 400 . 405 . 410 the first trace 40 derived. The solder layer arranged there 85 forms a heat sink for the dissipated heat. This will make the conductor layer 41 at the break 415 . 420 cooled and a local overheating of the conductor layer 41 at the break 415 . 420 avoided. Of course, it is also conceivable that the further lacquer layer 425 also in the first and / or third section 15 . 25 on the outside of the conductor layer 41 is provided (dashed in 3 to 5 shown).

The invention is not limited by the description based on the embodiments of these. Rather, the invention includes every new feature and every combination of features, which in particular includes any combination of features in the embodiments and claims.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2728982 A1 [0002]

Claims (10)

Printed circuit board ( 10 ) - comprising an insulating layer ( 45 ) and at least one on the insulating layer ( 45 ) arranged conductor track ( 40 ), - whereby the printed circuit board ( 10 ) a first section ( 15 ), a second section ( 20 ) and a third section ( 25 ), the second section ( 20 ) between the first section ( 15 ) and the third section ( 25 ) and the first section ( 15 ) with the third section ( 25 ) connects mechanically and electrically such that a main extension plane of the first section ( 15 ) inclined to a main extension plane of the third section ( 25 ) is arranged, - wherein the conductor track ( 40 ) one over the sections ( 15 . 20 . 25 ) running conductor layer ( 41 ), wherein the conductor track ( 40 ) in the second section ( 20 ) is arcuately guided, characterized in that - at least in the second section ( 20 ) the conductor track ( 40 ) an electrically conductive solder layer ( 85 ), wherein the solder layer ( 85 ) at least in sections, the conductor layer ( 41 ) covered. Printed circuit board ( 10 ) according to the preceding claim, wherein in the second section ( 20 ) the printed circuit board ( 10 ) has a smaller thickness (d ₂ ) than in the first section ( 15 ) and / or in the third section ( 25 ). Printed circuit board ( 10 ) according to one of the preceding claims, wherein the solder layer ( 85 ) on the second section ( 20 ) is designed to run without interruption. Printed circuit board ( 10 ) according to one of the preceding claims, - wherein the solder layer ( 85 ) over a first area ( 400 ) and a second area ( 405 . 410 ) of the second section ( 20 ), - in the first area ( 400 ) and in the second area ( 405 . 410 ) the solder layer ( 85 ) outside the conductor layer ( 41 ), wherein the solder layer ( 85 ) between the first area ( 400 ) and the second area ( 405 . 410 ) a break ( 415 . 420 ), whereas at the interruption ( 415 . 420 ) outside the conductor layer ( 41 ) with a paint layer ( 425 ) is covered or exposed. Printed circuit board ( 10 ) according to the preceding claim, - wherein the solder layer ( 85 ) at least one further interruption ( 420 ), wherein the outside of the conductor layer ( 41 ) at the further interruption ( 420 ) with the paint layer ( 425 ) is covered or free, and - in particular, a distance of the interruption ( 415 ) to the further interruption ( 420 ) as a function of a bending radius (r) of the second section ( 20 ) is selected. Printed circuit board ( 10 ) according to one of the preceding claims, - comprising a further conductor track ( 300 ), - wherein the further conductor track ( 300 ) on the insulating layer ( 45 ) is arranged on the outside, - wherein the insulating layer ( 45 ) the conductor track ( 40 ) electrically from the further conductor track ( 300 ), - wherein the further interconnect ( 300 ) over the sections ( 15 . 20 . 25 ), whereby the further conductor track (on the outside) 300 ) with another paint layer ( 305 ) is covered or exposed, and in particular in the area of the second section ( 20 ) of the solder layer ( 85 ) is uncovered. Printed circuit board ( 10 ) according to one of the preceding claims, wherein the conductor track ( 40 ) is adapted to transmit a current having a value in a range of 0.7 A to 50 A, preferably in a range of 0.7 A to 25 A, in particular in a range of 0.7 A to 8 A. , for example in a range of 1 A to 5.5 A. Printed circuit board ( 10 ) according to one of the preceding claims, which is designed to be semiflexible such that the inclined third section (FIG. 25 ) of the arcuately guided second section ( 20 ) can be kept cantilevered. Method for producing a printed circuit board ( 10 ) according to one of the preceding claims, - wherein a printed circuit board ( 10 ) with the insulating layer ( 45 ) and at least the conductor layer ( 41 ), - wherein in the insulating layer ( 45 ) in the second section ( 20 ) a recess ( 80 ) on one of the conductor layers ( 41 ) opposite side of the circuit board ( 10 ), - the solder layer ( 85 ) on the conductor layer ( 41 ) is applied, - wherein the circuit board ( 10 ) is heated so that the solder layer ( 85 ) melts and a cohesive connection ( 42 ) with the conductor layer ( 41 ), - the circuit board ( 10 ), wherein, in particular by means of bending of the second section ( 20 ), the first paragraph ( 15 ) compared to the third section ( 25 ) is inclined so that the second section ( 20 ) is arcuate. Method according to the preceding claim, wherein prior to the application of the conductor layer ( 41 ) with the solder layer ( 85 ) at least in sections a lacquer layer ( 305 ) at least on the Conductor layer ( 41 ) for the formation of an interruption ( 415 . 420 ) in the solder layer ( 85 ) is applied.

Images