Printed circuit board assembly, and method for mounting an electronic component on a printed circuit board

Abstract

The invention relates to a printed circuit board assembly (1) comprising: a printed circuit board (4) having a top side (2) and a bottom side (3); and at least one electronic component (5), wherein the component (5) has at least one connection element (6), wherein the printed circuit board has at least one conductor track (7) and at least one contact hole (8) for receiving and electrically contacting the connection element (6) of the electronic component (5), wherein the contact hole (8) is at least partially lined with a solderable, electrically conductive material (10), specifically one which forms a soldering surface (9), and wherein the at least one conductor track (7) is in electrically conductive contact with the soldering surface (9), wherein the connection element (6) of the electronic component (5) is guided through the contact hole (8) from the top side (2) of the printed circuit board (4) and is electrically conductively connected to the soldering surface (9), and thus to the at least one conductor track (7), by means of a solder connection (11), characterised in that: a stabilisation hole (12) for stabilising the electronic component (5) is provided adjacent to the contact hole (8); the stabilisation hole (12) is lined with a solderable material (13); the connection element (6) of the electronic component (5) is bent towards the stabilisation hole (12) at least on the top side (2) of the printed circuit board (4); and the connection element (6) of the electronic component (5) is additionally connected, at least mechanically, to the solderable material (13) in the component stabilisation hole (12) by means of a solder connection (14).

Description

[0001] Printed circuit board assembly and method for assembling a printed circuit board with an electronic component

[0002] The invention relates to a printed circuit board arrangement with a printed circuit board having a top side and a bottom side and at least one electronic component, wherein the component has at least one connection element, wherein the printed circuit board has at least one conductor track and at least one contact hole for receiving and electrically contacting the connection element of the electronic component, wherein the contact hole is at least partially lined with a solderable material, namely an electrically conductive material forming a soldering surface, and wherein the at least one conductor track is in electrically conductive contact with the soldering surface, wherein the connection element of the electronic component is guided from the top side of the printed circuit board through the contact hole and is electrically conductively connected to the soldering surface and thus to the at least one conductor track via a solder.

[0003] The printed circuit board arrangements in question find a wide variety of applications in almost every field of technology. The top side of the circuit board is the side on which the components are arranged. The back of the circuit board is the side of the circuit board facing away from the components. Circuit boards can be assembled in different ways. The assembly technology in which the connection element - usually a connecting wire - of the electronic component is inserted into a contact hole and soldered from the underside of the circuit board is called THT assembly (Through-Hole Technology). In contrast, SMD assembly (Surface Mounted Device) is used, in which the electronic components are soldered directly onto solder pads on the top side of the circuit board. THT assembly is preferred for assembling circuit boards with larger components.SMD assembly requires significantly less space and is ideal for the production of populated circuit boards with high packing density.

[0004] The present invention relates to a printed circuit board assembly comprising a printed circuit board and at least one electronic component that is soldered using THT assembly. However, this does not preclude the possibility of SMD-assembled components being arranged on the printed circuit board.

[0005] The connection elements of electronic components are implemented, for example, as connecting pins or connecting wires. When it is mentioned that the contact hole is at least partially lined with a solderable material, solderable material in this context means that the material is wettable with solder. The solderable material therefore forms a soldering surface.

[0006] Many electronic components are coated with a protective varnish. In this case, the protective varnish may not only cover the component itself, but also at least partially cover the connection element(s) of the component, particularly in the area of ​​the connection element adjacent to the component body. If a connection element covered with protective varnish is inserted through a via and soldered there, the protective varnish may lead to poor wetting with the solder and thus to an inadequate solder connection between the component and the circuit board. It is therefore known from the prior art to create the solder connections in an area of ​​the connection element further away from the component body. To prevent the components from protruding unnecessarily far from the circuit board, it is common practice to bend the connection elements.This ensures, on the one hand, that the soldering point is not realized in an area of ​​the connection element coated with protective varnish and, on the other hand, that the component is arranged close to the circuit board.

[0007] The disadvantage, however, is that bending at the bending points weakens the material of the connection element. This makes the connection elements more susceptible to breakage in the area of ​​the bending points when the components are subjected to mechanical stress. This mechanical stress arises, for example, from vibrations in the devices and systems in which the circuit boards are installed.

[0008] The object of the present invention is therefore to provide a printed circuit board assembly in which the disadvantages known from the prior art are reduced, namely to provide a printed circuit board assembly that is more stable, particularly with respect to mechanical stress. Furthermore, the object of the present invention is to provide a method for assembling a printed circuit board.

[0009] The object is achieved according to the invention in the printed circuit board arrangement initially and essentially in that a stabilizing bore for stabilizing the electronic component is formed adjacent to the contact bore, that the stabilizing bore is lined with a solderable material, that the connection element of the electronic component is bent towards the stabilizing bore at least on the upper side of the printed circuit board and that the connection element of the electronic component is additionally at least mechanically connected to the solderable material in the component stabilizing bore via a solder.

[0010] According to the invention, it has been recognized that mechanical stabilization of the soldered electronic component can be achieved by means of an additional soldering point. Particularly given that the components in question are soldered using THT assembly, the implementation of an additional hole in the form of a stabilizing hole, into which solder can flow during the soldering process, has proven advantageous. The stabilizing hole is preferably largely lined with solderable material.

[0011] However, a particularly preferred embodiment is characterized by the stabilizing hole being completely lined with solderable material. Solder applied from the underside is drawn to the top side of the circuit board due to the capillary effect.

[0012] Preferably, the connection element extends at least partially over the stabilizing hole. However, this is not absolutely necessary, as the solder can also spread into the surrounding area of ​​the stabilizing hole and thus mechanically contact the connection element. However, this requires that the solderable material of the stabilizing hole extends at least partially onto the top side of the circuit board.

[0013] A particularly preferred embodiment of the printed circuit board arrangement according to the invention is therefore characterized in that the material lining the stabilizing bore and which can be soldered extends at least partially to the upper side of the printed circuit board, in particular extends to the contact bore.

[0014] Particularly preferably, the material forming the soldering surface of the contact hole and the solderable material of the stabilizing hole together form a continuous soldering surface on the top side of the circuit board. More preferably, they are the same material. The continuous soldering surface is preferably implemented on the top side of the circuit board in such a way that the contact hole and / or the stabilizing hole is / are surrounded by the soldering surface. In one variant, the soldering surface completely surrounds the contact hole and / or the stabilizing hole. The contact hole and / or the stabilizing hole is / are thus arranged in the region of the soldering surface.

[0015] The soldering surface formed on the top side of the circuit board can have various basic shapes. The soldering surface is particularly preferably round, oval, or square.

[0016] A further preferred embodiment of the printed circuit board assembly according to the invention is characterized in that the at least one conductor track is electrically connected to the wettable material of the stabilizing bore. This electrically contacts the connecting element in the area of ​​the contact bore and in the area of ​​the stabilizing bore.

[0017] In a particularly preferred embodiment of the printed circuit board assembly according to the invention, the stabilizing hole is designed such that the stabilizing hole has a smaller diameter than the contact hole. In a further preferred variant, the contact hole has a diameter of 0.3 mm to 0.6 mm. The diameter of the stabilizing hole is selected such that solder applied from the underside of the printed circuit board is preferably drawn to the top side of the printed circuit board via the capillary effect, thus mechanically fixing the connection element of the electronic component when cooled.

[0018] As previously explained, it is known to bend the connection elements of electronic components in order to prevent areas of the connection elements coated with protective varnish from being soldered. A particularly preferred embodiment of the printed circuit board arrangement according to the invention is characterized in that the at least one connection element of the electronic component is bent at least twice, namely that a first bending point and a second bending point are realized on the upper side of the printed circuit board arrangement. The two bending points divide the connection element into three subsections: a first subsection of the connection element extends from the end of the connection element facing away from the component body to the first bending point, a second subsection of the connection element extends from the first bending point to the second bending point and a third subsection extends from the second bending point to the component body.The first subsection and the second subsection are bent relative to each other at a first bending angle α, and the second subsection and the third subsection are bent relative to each other at a second bending angle β. Particularly preferably, the second subsection and the third subsection are bent relative to each other in an L-shape or V-shape.

[0019] Particularly preferably, the first bending point is located above the contact hole. Further preferably, the second bending point is located above the stabilizing hole.

[0020] In one variant of the printed circuit board assembly according to the invention, the additional solder in the stabilizing hole reinforces the connection element in the area of ​​the second bending point. This not only stabilizes the electronic component itself, but also significantly reduces the likelihood of breakage in the area of ​​the bending point due to mechanical influences. As described above, the printed circuit board assembly according to the invention reinforces the connection element of the soldered electronic component with additional solder, thus mechanically stabilizing it. As also explained, the material has been weakened, particularly in the area of ​​the bending points, creating unwanted "predetermined breaking points."To further increase the stability of a component soldered to a circuit board, in the described variant of the invention, the connecting element is reinforced with additional solder in the area of ​​a bending point, particularly in the area of ​​the second bending point. Particularly preferably, the bending point is completely embedded in solder and thus reinforced. This can be achieved in particular when the bending point is located directly above or near the stabilizing hole.

[0021] In addition to the printed circuit board assembly, the invention also relates to a method for assembling a printed circuit board having at least one conductor track with at least one electronic component. The electronic component has at least one connection element. The printed circuit board has at least one contact hole for receiving the at least one connection element, which is lined with a solderable material, namely an electrically conductive material forming a soldering surface, wherein the at least one conductor track is in electrically conductive contact with the soldering surface. In addition, the printed circuit board further has at least one stabilizing hole formed adjacent to the contact hole and lined with a solderable material.In the method according to the invention, the object is achieved in that in a provision step an electronic component with at least one bent connection element is provided, in that in a mounting step the printed circuit board is mounted with the at least one component by the at least one bent connection element being inserted into the contact hole from the top side of the printed circuit board in such a way that the at least one bending point is arranged on the top side of the printed circuit board and the connection element is bent towards the stabilizing hole and in that in a soldering step solder is applied from the underside of the printed circuit board in such a way that the connection element is connected in an electrically conductive manner to the soldering surface and thus to the at least one conductor track in the region of the contact hole via solder and is also additionally at least mechanically connected via solder to the solderable material in the stabilizing hole.Particularly preferably, in the soldering step, the circuit board loosely populated with the electronic component is guided over a soldering wave, whereby the component is wetted with solder from the underside of the circuit board and solder passes through both the contact hole and the stabilizing hole to the top of the circuit board.

[0022] As explained in the introduction, it is entirely possible to carry out the method according to the invention on printed circuit boards that have previously been populated with SMD components. For example, it is conceivable that an unpopulated circuit board is first printed with solder paste and then populated with SMD components.

[0023] In a particularly preferred embodiment, the connection element of the electronic component is bent such that it has a first bending point and a second bending point. The circuit board is preferably loaded with the component such that the second bending point is located directly above or near the stabilizing hole. The solder applied during the soldering step is then located in particular in the area of ​​the bending point and stabilizes it. Preferably, such a quantity of solder is applied that the bending point is completely surrounded by solder.

[0024] All embodiments explained in connection with the printed circuit board arrangement according to the invention, together with their advantages, can be transferred analogously to the method according to the invention and apply accordingly.

[0025] In detail, there are now numerous possibilities for designing and developing the circuit board arrangement according to the invention and the method for assembling a circuit board according to the invention. Reference is made to the claims subordinate to the independent claims and to the description of preferred embodiments in conjunction with the drawing. The drawing shows

[0026] Fig. 1 is a schematic representation of a cross section through a printed circuit board arrangement with a printed circuit board and an electronic component in a first embodiment,

[0027] Fig. 2a is a schematic representation of a cross section through a printed circuit board in a first variant,

[0028] Fig. 2b is a schematic representation of a cross-section through a printed circuit board in a second variant,

[0029] Fig. 3a-3e schematic representations of top views of a partial section of a printed circuit board in various designs,

[0030] Fig. 4a is a schematic representation of a cross section through a printed circuit board arrangement with a printed circuit board and an electronic component in a second embodiment,

[0031] Fig. 4b is a schematic representation of a cross section through a printed circuit board arrangement with a printed circuit board and an electronic component in a third embodiment,

[0032] Fig. 5 is a block diagram of a method for assembling a printed circuit board with an electronic component.

[0033] Fig. 1 shows a schematic sectional view through a printed circuit board arrangement 1 with a printed circuit board 4 having a top side 2 and a bottom side 3 and with an electronic component 5. The electronic component 5 has at least one connection element 6. The printed circuit board has at least one conductor track 7. In addition, a contact hole 8 is realized in the printed circuit board 4, which serves to receive and electrically contact the connection element 6 of the electronic component 5. For this purpose, the contact hole 8 is at least partially lined with a solderable material 10, namely an electrically conductive material 10 forming a soldering surface 9. In addition, the conductor track 7 is in electrically conductive contact with the soldering surface 9. The connection element 6 of the electronic component 5 is inserted from the top side 2 of the printed circuit board 4 into the contact hole 8 and is electrically conductively connected to the soldering surface 9 via a solder 11.This connection also creates an electrically conductive connection between the connection element 6 of the component 5 and the conductor track 7.

[0034] As can be seen from Fig. 1, a stabilizing hole 12 is formed in the circuit board 4 adjacent to the contact hole 8. The stabilizing hole 12 serves to mechanically stabilize the electronic component 5. For this purpose, the stabilizing hole 12 is at least partially lined with a solderable material 13. In the illustrated embodiment, the stabilizing hole 12 is completely lined with solderable material 13. The connection element 6 of the component 5 is bent towards the stabilizing hole 12 and mechanically connected, namely soldered, to the solderable material 13 of the stabilizing hole 12 via a solder 14. The connection element 6 of the component 5 is thus mechanically connected to the circuit board 4 in the area of ​​the contact hole 8 on the one hand and mechanically connected to the circuit board 4 in the area of ​​the stabilizing hole 12 on the other.Overall, this reduces the sensitivity of the arrangement to mechanical stress - for example in the form of vibrations.

[0035] The electronic component 5 shown in Fig. 1 has two connection elements 6, wherein the electrical and mechanical contacting of the two connection elements 6 is implemented identically in this case. Accordingly, two contact holes 8 and two stabilizing holes 12 are implemented. However, it is also conceivable to mechanically stabilize only one of the connection elements 6 via an additional stabilizing hole 12. In the embodiment shown, both connection elements 6 are bent symmetrically inwards towards the component center. In other embodiments, which are not shown but are nevertheless inventive, the two connection elements are bent symmetrically outwards away from the component center or bent at an angle away from a longitudinal axis of the component.Asymmetric configurations can also be realized, for example where the length of the connecting elements is different or where the bending directions of the respective connecting elements are different.

[0036] Figures 2a and 2b show two different variants for implementing the circuit board assembly. The figures show only a partial cross-section of the circuit board; for clarity, the component itself has been omitted.

[0037] Fig. 2a shows an embodiment in which the solderable material 13 of the stabilizing hole 12 extends to the top side 2 of the circuit board 4, but does not reach the contact hole 8. Fig. 2b shows an embodiment in which the solderable material 13 of the stabilizing hole 12 and the electrically conductive material 10 of the contact hole 8 are made of the same material and form a continuous soldering surface 15 on the top side 2 of the circuit board 4.

[0038] Fig. 3a to 3e show various representations, each of a partial section of the circuit board in a top view, also without a component and without a conductor track. Shown in each case are a contact hole 8 and a stabilizing hole 12 realized adjacent to the contact hole 8. In the representations in Fig. 3a to 3c, the electrically conductive material 10 of the contact hole 8 and the solderable material 13 of the stabilizing hole 12 together form a soldering surface 15 on the top side of the circuit board 4. In Fig. 3a, the soldering surface 15 is rectangular, in Fig. 3b the soldering surface 15 is oval, and in Fig. 3c the soldering surface 15 is round. The soldering surface 15 completely surrounds both the contact hole 8 and the stabilizing hole 12.

[0039] Figs. 3d and 3e show embodiments in which the electrically conductive material 10 of the contact hole 8 and the solderable material 13 of the stabilizing hole 12 each form separate soldering pads 9, 16. In Fig. 3d, the separate soldering pads 9, 16 are round, while in Fig. 3e, the separate soldering pads are rectangular. The soldering pad 9 completely surrounds the contact hole 8. The soldering pad 16, on the other hand, completely surrounds the stabilizing hole 12.

[0040] As explained in connection with Fig. 1, the printed circuit board 4 has at least one conductor track 7, which is realized in electrically conductive contact with the soldering surface 9 of the contact hole 8. Fig. 2a shows an embodiment in which the conductor track 7 is also electrically conductively connected to the solderable material 13 in the stabilizing hole 12.

[0041] All illustrations show that the diameter d sthe stabilizing hole 12 is smaller than the diameter d K the contact hole. In the embodiments shown in Fig. 3a to Fig. 3e, the stabilizing hole 12 has a diameter of d s =0.5 mm.

[0042] Fig. 4a shows a further schematic representation of a section through a printed circuit board assembly 1. The electronic component 5 shown has two connection elements 6, each of which is inserted from the top side 2 of the printed circuit board 4 through a contact hole 8 and soldered there. As can be seen from Fig. 4a, each of the connection elements 6 is bent twice. Each of the two connection elements 6 thus has a first bending point 17 and a second bending point 18, which are located on the top side 2 of the printed circuit board assembly 1.The two bending points 17, 18 divide the connecting element 6 into three sub-sections: a first sub-section 21 of the connecting element 6 extends from the end 20 of the connecting element 6 facing away from the component body 19 to the first bending point 17, a second sub-section 22 of the connecting element 6 extends from the first bending point 17 to the second bending point 18, and a third sub-section 23 extends from the second bending point 18 to the component body 19. The first sub-section 21 and the second sub-section 22 are bent towards one another at a first bending angle α, and the second sub-section 22 and the third sub-section 23 are bent towards one another at a second bending angle β. In the variant shown in Fig. 4a, the second sub-section 22 and the third sub-section 23 are bent towards one another in an L-shape; the bending angle β in this case is 90°.

[0043] Fig. 4b shows a further variant in which the second section 22 and the third section 23 are bent toward each other in a V-shape. The bending angle ß is less than 90°.

[0044] In Figs. 4a and 4b, it is particularly clearly visible that the additional solder 14 reinforces the connecting element 6 in the region of the second bending point 18 and completely encloses the bending point 18. The second bending point 18 is realized directly above the stabilizing bore 12. The bending angles α and β are selected such that the bending point 18 is completely enclosed by solder 14.

[0045] Fig. 5 shows a block diagram of a method 100 for populating a printed circuit board with an electronic component. The electronic component has at least one connection element. The printed circuit board has at least one contact hole for receiving the at least one connection element, which is lined with a solderable material, namely an electrically conductive material forming a soldering surface, wherein the at least one conductor track is in electrically conductive contact with the soldering surface. In addition, the printed circuit board further has at least one stabilizing hole formed adjacent to the contact hole, which is lined with a solderable material. In a provision step 101, an electronic component with at least one bent connection element is provided. In a placement step 102, the printed circuit board is populated with the at least one component.For this purpose, the at least one bent connection element is inserted from the top side of the circuit board into the contact hole in such a way that the at least one bending point is located on the top side of the circuit board and the connection element is bent toward the stabilizing hole. In a soldering step 103, solder is applied from the underside of the circuit board in such a way that the connection element is both electrically connected to the soldering surface and thus to the at least one conductor track in the region of the contact hole via solder and is also additionally at least mechanically connected via solder to the solderable component in the stabilizing hole.

[0046] Reference symbol

[0047] 1 PCB layout

[0048] 2 Top of the circuit board

[0049] 3 Bottom of the circuit board

[0050] 4 circuit board

[0051] 5 electronic component

[0052] 6 Connection element of the electronic component

[0053] 7 Conductor track

[0054] 8 contact holes

[0055] 9 Soldering surface

[0056] 10 electrically conductive material

[0057] 11 lots

[0058] 12 stabilization boreholes

[0059] 13 solderable material

[0060] 14 lots

[0061] 15 Soldering surface

[0062] 16 soldering surface

[0063] 17 first bending point

[0064] 18 second bending point

[0065] 19 component bodies

[0066] 20 end of the connecting element remote from the component body

[0067] 21 first section

[0068] 22 second section

[0069] 23 third section

[0070] 24 a first bending angle ß second bending angle d s Diameter of stabilization hole d K Diameter of contact hole

[0071] 100 procedures

[0072] 101 Provisioning step

[0073] 102 Assembly step 103 Soldering step

Claims

Patent claims 1. Printed circuit board arrangement (1) with a printed circuit board (4) having a top side (2) and a bottom side (3) and at least one electronic component (5), wherein the component (5) has at least one connection element (6), wherein the printed circuit board (4) has at least one conductor track (7) and at least one contact hole (8) for receiving and electrically contacting the connection element (6) of the electronic component (5), wherein the contact hole (8) is at least partially lined with a solderable material (10), namely an electrically conductive material (10) forming a soldering surface (9), and wherein the at least one conductor track (7) is in electrically conductive contact with the soldering surface (9), wherein the connection element (6) of the electronic component (5) is guided from the top side (2) of the printed circuit board (4) through the contact hole (8) and is electrically connected to the soldering surface (9) and thus to the at least one conductor track via a solder (11) (7), characterized in that a stabilizing bore (12) for stabilizing the electronic component (5) is formed adjacent to the contact bore (8), that the stabilizing bore (12) is lined with a solderable material (13), that the connection element (6) of the electronic component (5) is bent towards the stabilizing bore (12) at least on the upper side (2) of the printed circuit board (4), and that the connection element (6) of the electronic component (5) is additionally at least mechanically connected to the solderable material (13) in the stabilizing bore (12) via a solder (14).

2. Printed circuit board arrangement (1) according to claim 1, characterized in that the solderable material (13) lining the stabilizing bore (12) extends at least partially onto the upper side (2) of the printed circuit board (4), in particular extends as far as the contact bore (8).

3. Printed circuit board arrangement (1) according to claim 2, characterized in that the solderable material (13) of the stabilizing bore (12) and the solderable material (10) forming the soldering surface (9) of the contact bore (8) together form a soldering surface (15) on the upper side (2) of the printed circuit board (4), in particular wherein the contact bore (8) and the stabilizing bore (12) are surrounded by the soldering surface (15), further in particular wherein the soldering surface (15) is round, oval or square.

4. Printed circuit board arrangement (1) according to one of claims 1 to 3, characterized in that the at least one conductor track (7) is electrically conductively connected to the solderable material (13) of the stabilizing bore (12).

5. Printed circuit board arrangement (1) according to one of claims 1 to 4, characterized in that the stabilizing bore (12) has a smaller diameter (d s ) than the contact hole (8), in particular a diameter (d s ) from 0.3mm to 0.6mm.

6. Printed circuit board arrangement (1) according to one of claims 1 to 5, characterized in that the at least one connection element (6) of the electronic component (5) is bent at least twice, namely that a first bending point (17) and a second bending point (18) are realized on the upper side (2) of the printed circuit board arrangement (1).

7. Printed circuit board arrangement (1) according to claim 6, characterized in that the first bending point (17) and the second bending point (18) successively divide the connection element (6) of the electronic component (5) from the end (20) of the connection element (6) remote from the component body (19) to the component body (19) into a first partial section (21), a second partial section (22) and a third partial section (23) and that the second partial section (22) and the third partial section (23) are preferably bent towards one another in an L-shape or a V-shape.

8. Printed circuit board arrangement (1) according to one of claims 1 to 7, characterized in that the additional solder (14) of the stabilizing bore (12) reinforces the connection element (6) in the region of at least one bending point, preferably the second bending point (18), in particular completely envelops the bending point and that preferably the second bending point (18) is arranged directly above the stabilizing bore (12) 9. Method (100) for assembling a printed circuit board having at least one conductor track with at least one electronic component, wherein the electronic component has at least one connection element and wherein the printed circuit board has at least one contact hole for receiving the at least one connection element, which is lined with a solderable, electrically conductive material forming a soldering surface, wherein the at least one conductor track is in electrically conductive contact with the soldering surface and that the printed circuit board further has at least one adjacent to the con- contact hole formed stabilization hole, which is lined with a solderable material, characterized in that in a provision step (101) an electronic component with at least one bent connection element is provided, that in a mounting step (102) the printed circuit board is equipped with the at least one component by the at least one bent connection element being inserted from the top side of the printed circuit board into the contact hole in such a way that the at least one bending point is arranged on the top side of the printed circuit board and the connection element is bent towards the stabilization hole in such a way that in a soldering step (103) solder is applied from the underside of the printed circuit board,that the connecting element is electrically connected to the soldering surface and thus to the at least one conductor track via solder in the area of the contact hole and is also at least mechanically connected to the solderable material in the stabilizing hole via solder.

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