DE102016216377A1 - A method of providing a wiring pattern on a support substrate to form a resistive element - Google Patents

Abstract

A method is proposed for providing a conductor track structure (1) on a carrier substrate (12) for forming a resistance element (8) with joining zone (3) having at least one strip conductor (5) and connecting sections (7) arranged outside the joining zone (3), wherein the conductor tracks (5) are formed by means of a printing method and the conductor tracks (5) are formed in the region of the terminal sections (7) with a larger track width (bLB) than in the area spaced from the terminal sections (7).

Description

The present invention relates to a method for providing a printed conductor structure on a carrier substrate for forming a resistor element with at least one interconnect joining zone and arranged outside the joining zone connecting portions, wherein the conductor tracks are formed by a printing method, according to the preamble of claim 1.

A generic method is unpublished in the assignee's name German Patent Application No. 10 2015 205 656 described. In such a method in which heat is introduced via a resistance element into a component arrangement having two plastic components in order to join or weld the two plastic components together in order to produce a cohesive, high-strength connection between the two plastic components, compliance with certain heat input via the interconnect arrangement of great relevance.

The components are supplied with heat via the conductor element arrangement forming a resistance element, which is intended to ensure a local reaching of the melting temperature of the components. The printed conductor arrangement is produced by means of a printing process and the printed conductors should transfer the heat in the area of contact with the components. Accurate adherence to the control of the printing process for forming the printed conductors is therefore essential in order, for example, to avoid local overheating of the components and local burn-through of printed conductors and also to achieve a sufficient heat input at the edge regions of the joining zone or the welding region.

The present invention is therefore based on the object, the generic method such that on the one hand burn through individual traces is prevented and on the other hand, the circumstances of a homogenous in the joining zone heat transfer from the trace arrangement is taken into account the components.

The invention has to solve this problem, the features specified in claim 1, advantageous embodiments thereof are described in the further claims.

The invention provides a method for providing a conductor track structure on a carrier substrate for forming a resistive element with at least one interconnect joining zone and connecting sections arranged outside the joining zone, wherein the interconnects are formed by a printing process and the interconnects are formed in the area of the terminal sections with a larger interconnect width as in the area spaced from the terminal sections.

The heat transfer takes place in the region of the joining zone from the resistance element to the plastic components to be melted, one of which can also form the carrier substrate on which the printed conductor arrangement for forming the resistance element is formed by means of the printing method. In the joining zone or the welding area, the area in which the components are welded together should be heated homogeneously to the melting temperature.

An increased heat dissipation takes place at the edge regions of the welding region and thus the joining zone compared to the inner region of the joint zone, which must be compensated for by increasing the power density, that is to say the power per unit of the joining surface. For this purpose, it has already been described to reduce the distance of the interconnects from each other in the edge region of the joint zone in order to increase the power density.

The inventors of the subject application have achieved a surprising and significant improvement in the adaptation of the power density in that the conductor tracks are formed in the region of the terminal sections with a larger track width than in the area spaced from the terminal sections.

The area spaced from the connection sections may be the joining zone and the inventive construction of the method for providing the conductor track structure homogenization of the temperature distribution in the welding area is achieved such that the measured in the joining zone minimum and maximum temperature are close to each other, so that the entire joining zone is heated almost homogeneously to the melting temperature of the plastic and thus a complete welding of the plastic components is achieved.

It is provided according to a development of the method according to the invention that the conductor track width increases linearly or non-linearly from a region between the connection sections to the connection sections. In other words, this means that the strip conductors in the region out of the joining zone have an increasing width in the direction of the two connection sections and the width of the strip conductors can change linearly or nonlinearly, this being matched to the respective application.

It is provided according to a development of the invention that the distance between the conductor tracks in the region of the terminal sections is determined as a function of the width of the conductor tracks on the terminal section and a distance factor. As a result, the distance between the tracks outside the welding area, ie outside the joining zone and thus in the free area can be determined.

It is also provided according to a development of the invention that the distance between the interconnects and the width between the terminal sections is determined such that a free of conductor tracks surface of the joint zone is at least 60 percent of the surface of the joint zone. The interconnect arrangement is thus designed such that the free area of the joint zone is at least 60 percent of the total area of the joint zone, ie at least 60 percent of the total area of the joint zone is formed without interconnects. As a result, a homogeneous heat input is achieved within the joining zone and reduces the risk of overheating of the interconnects in the free area, ie outside the joining zone and it can be a uniformly heating conductor track structure is achieved, which leads to a homogeneous welding of the joint partners and enough area in the Joining zone for cohesive connection of molten material of the joining partners is provided.

It is also provided according to a development of the invention that the interconnects of the interconnect arrangement are formed by applying an electrically conductive ink on the carrier substrate and the ink dried after a first order and ink is thermally removed from ink-covered areas.

By removing ink from areas covered with ink, ink can be removed where it was applied by the printing process, but ink coverage was undesirable in these areas, ie unwanted amounts of ink were applied. This may be the case, for example, when ink has run along edges of areas where it has been desirably applied, or at the edge regions of the desired ink-deposited structures, flat flank angles have been formed which result in broadening of the structures have and thus to a distance between adjacent tracks, which does not correspond to the desired distance.

By thermal removal of the ink from areas of unwanted coverage or at the edges of desired coverage with ink, for example by means of a laser, the printed image can be post-treated and it can defined track geometries are created with a predetermined width of the tracks.

By the aftertreatment of the printed structures by means of the laser, the flank angle of the edge regions of the structures can be formed significantly steeper and it can be achieved a conductor track cross-sectional shape, which adapts or approximates an ideal rectangle of the cross-sectional shape.

After the thermal aftertreatment of the printed structure, ink can be applied to the treated structure by means of a further printing operation and thus the thickness of the printed conductor structure can be increased, for example doubled. This also includes the only local increase of the conductor track thickness for the purposeful adjustment of a thickness profile of the conductor tracks. After any further thermal aftertreatment of the conductor track structure obtained in this way, a further repetition of the print job of ink can take place on the structure obtained, and this process can be repeated, for example, until the desired thickness of the printed conductor structure has been achieved by the multiple printing.

It is therefore also provided according to a development of the invention that the printing process comprises the formation of printed conductors with a print job of ink, followed by drying of the ink applied and at least one further print job of ink after drying. Between the individual printing operations, a thermal aftertreatment of the conductor track structure thus obtained can take place, but it is also provided by the method according to the invention that such a thermal aftertreatment takes place, for example, by means of a laser only after the first print job and thus a desired edge angle of the first layer or position of the conductive ink is set or achieved.

It is also provided according to a development of the invention that the joining zone is provided with conductor tracks such that the free surface is 70 percent of the surface of the joint zone and the conductor width b _LB in the central region of the joint zone and the distance factor f _a for reinforced plastic and unreinforced plastic following table corresponds to: b _LB in μm f _a reinforced Kst f _a unreinforced Kst 200 1.25 to 1.7 1.2-1.5 250 1.32 to 1.6 1.3-1.4 300 1.37 to 1.6 1.3-1.45 350 1.3-1.7 1.3 400 1.5 1.2

The strip width is given in micrometers and corresponds to the width of the strip conductors in the middle region of the joint zone and the distance factor f _a , which is given in the table for a plastic provided with reinforcing fibers in the form of carbon fibers or glass fibers and also for an unreinforced plastic , which may be, for example, a polyamide 6 (PA6), the layout geometry of the tracks in the joint zone can be determined, the minimum distance between the tracks over an open joining surface of 70 percent is defined and the maximum distance is limited in that in the free area, ie in the area adjacent to the connection sections, no overheating may occur.

The invention will be explained in more detail below with reference to the drawing. This shows in:

1 a plan view of a schematic representation of a conductor track structure with two contact areas, a welding area and two free areas;

2 a representation of the right half of the 1 with highlighted areas; and

3 a schematic sectional view of a conductor tracks for explaining the flank angle.

1 The drawing shows a conductor track structure 1 with two contact areas 2 , one of the joining zone 3 trained welding area 4 with a plurality of parallel conductor tracks 5 and two each transition areas or free areas 6 between the joining zone 3 and the contact areas 2 ,

The contact areas 2 serve to form the connection sections 7 , to which in each case an unillustrated electrical conductor can be connected, with which the conductor tracks 5 can be supplied with electrical energy for melting the plastic of the joining partners.

The tracks 5 form a resistance element 8th from, which at the in 3 illustrated carrier substrate 12 is arranged, which may be, for example, a first plastic component, which by the heat input via the resistance element 8th with a second plastic component, not shown, in the region of the joining zone 3 should be welded.

2 The drawing shows the right half of the joining zone 3 to 1 and the right transition area or free area 6 as well as the right contact area 2 ,

As is readily apparent from the circular area marked "A", the spacing of the tracks decreases 5 to the edge area 9 the joining zone 3 down to increase the power density, the increased heat dissipation at the edge region 9 the joining zone 3 Take into account.

In contrast, the area marked with an ellipse "B" shows that in the inner or middle area of the joint zone 3 the tracks 5 have a constant interconnect distance to one another, to a homogeneous heat distribution in this region of the joint zone 3 Take into account.

The area marked with the circle "C" shows that the tracks 5 in the area 10 adjacent to the terminal sections 7 are formed with an increasing track width b _LB , which in the detail "C" corresponding enlarged representation can be seen and can be determined for example via a spline function or as an interpolated curve between nodes. As a result, the width b _{LB of} the conductor tracks 5 towards the area 10 In turn, the fact is taken into account that even at the edge regions of the joining zone 3 , the connecting sections 7 are facing, the heat dissipation increases and therefore the power density must be increased as power in watts per joining surface in the edge region. In addition, it is achieved by the broadening of the tracks at this point that the tracks do not burn, since they are not covered here by the joining partner and thus also no conductive heat dissipation takes place.

The distance s _{a of} the conductor tracks 5 to each other in the transition area of the joining zone 3 to the connection section 7 arises as a function of the above-mentioned and shown in the table below distance factor f _a and the width b _{a of} the conductor tracks 5 directly at the base, ie the width of the tracks directly at the connection section 7 according to the formula s _a = f _a · b _a . b _LB in μm f _a reinforced Kst f _a unreinforced Kst 200 1.25 to 1.7 1.2-1.5 250 1.32 to 1.6 1.3-1.4 300 1.37 to 1.6 1.3-1.45 350 1.3-1.7 1.3 400 1.5 1.2

The table shows that the distance factor f _a increases as _a function of the track width b _LB.

The open joining surface in the area of the joining zone 3 is at the in 1 and 2 The example shown in the drawing 74 percent.

The thickness of the sample on which the structure of the printed conductor structure shown in the drawings 1 is arranged, is 2 mm and the fiber volume fraction of the sample is 50 percent, it is in the unspecified sample to a plastic polyamide 6 (PA6).

3 The drawing shows a on the carrier substrate 12 in cross-section, by application of a conductive ink 11 Traced conductor 5 whose flank angle α relative to the carrier substrate 12 can be significantly increased by a laser, not shown, by ink in the tapered area 13 is thermally removed and thus the flank angle α is increased in the direction of the arrow P, and thus a conductor track structure 5 is formed, which approximates in cross-section to an ideal rectangle.

At the in 1 the drawing illustrated embodiment of the resistive element 8th is assumed that a preferred track width b _LB of 250 microns, which was applied to a carrier substrate of the already mentioned carbon fiber reinforced polyamide 6. Investigations have shown that with the method according to the invention it is also possible to form interconnect structures to form a resistive element on a unidirectional polyamide 6 reinforced with glass fiber, a quasi-isotropic carbon fiber reinforced polyamide 6 or an unreinforced polyamide 6.

By using a multiple printing of conductive ink and the thermal aftertreatment by means of a laser, any conductor track geometries can be formed on a flat printing with high-precision printed conductor structures and high fineness, even below a printed conductor width of 200 μm. The possibility of the post-treatment of the printed image by means of a laser also results in the advantage of a very high repeat accuracy of the printed image, which is a great advantage in the formation of the printed conductor structure by multiple printing and the inventive method also increases the reproducibility of the printed image and thus achieves a reduction the danger of burning through conductor tracks of the resistor element.

Due to the significant increase in the flank angle conductor tracks structures can be created, which have large open spaces in the space between the individual tracks that the passage of melt and thus for unimpeded melt exchange between the joining partners is available.

The inventive method is suitable for the formation of resistive elements on fiber-reinforced or unreinforced plastics, which is independent of the nature of the reinforcing fibers and for different laminate structures, such as quasi-isotropic or unidirectional structures and also for different joining partners made of different materials, in which also one of Partner may have reinforcing fibers, while the other joining partner is free of reinforcing fibers.

With regard to features of the invention which are not explained in greater detail above, reference is expressly made to the claims and the drawings.

LIST OF REFERENCE NUMBERS

1

Conductor structure

2

contact area

3

joint zone

4

welding area

5

conductor path

6

free area, transition area

7

connecting section

8th

resistive element

9

border area

10

Area

11

ink

12

carrier substrate

13

triangular, bevelled area

P

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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

• DE 102015205656 [0002]

Claims (10)

Method for providing a printed conductor structure ( 1 ) on a carrier substrate ( 12 ) for forming a resistance element ( 8th ) with at least one conductor tracks ( 5 ) joining zone ( 3 ) and outside the joining zone ( 3 ) arranged connecting sections ( 7 ), wherein the conductor tracks ( 5 ) are formed by means of a printing method, characterized in that the conductor tracks ( 5 ) in the region of the connecting sections ( 7 ) are formed with a larger track width (b _LB ) than in the area spaced from the terminal sections ( 7 ). A method according to claim 1, characterized in that to the end sections ( 7 ) spaced area from the joining zone ( 3 ) is formed. A method according to claim 1 or 2, characterized in that the conductor track width (b _LB ) of a region between the connecting portions ( 7 ) to the connecting sections ( 7 ) increases linearly or nonlinearly. Method according to one of the preceding claims, characterized in that the spacing of the conductor tracks in the region of the connecting sections ( 7 ) depending on the width (b _a ) of the tracks ( 5 ) at the connection section ( 7 ) and a distance factor (f _a ). Method according to one of the preceding claims, characterized in that the spacing of the strip conductors and their width between the connecting sections ( 7 ) is determined such that one of tracks ( 5 ) free area of the joining zone ( 3 ) at least 60 percent of the area of the joining zone ( 3 ) is. Method according to one of the preceding claims, characterized in that the conductor tracks ( 5 ) by applying an electrically conductive ink ( 11 ) on the carrier substrate ( 12 ) and the ink ( 11 ) is dried after a first application and ink is thermally ablated from ink-covered areas. A method according to claim 6, characterized in that for the removal of ink, a laser beam is used such that a flank angle (α) of a portion of the conductor track ( 5 ) before removal from the flank angle (α) after the removal differs. Method according to one of the preceding claims, characterized in that the printing method, the formation of printed conductors ( 5 ) with a print job of ink ( 11 ), followed by drying of the applied ink ( 11 ) and at least one more print job of ink ( 11 ) after drying. Method according to one of the preceding claims, characterized in that as carrier substrate ( 12 ) One of the components to be welded is used. Method according to one of the preceding claims 4 to 9, characterized in that the joining zone ( 3 ) with conductor tracks ( 5 ) is provided such that the free area 70 percent of the area of the joint zone ( 3 ) and the conductor track width (b _LB ) in the middle region of the joining zone ( 3 ) and the distance factor (f _a ) for reinforced plastic (Kst) and unreinforced plastic correspond to the following table: b _LB in μm f _a reinforced Kst f _a unreinforced Kst 200 1.25 to 1.7 1.2-1.5 250 1.32 to 1.6 1.3-1.4 300 1.37 to 1.6 1.3-1.45 350 1.3-1.7 1.3 400 1.5 1.2

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