EP3610705A1

EP3610705A1 - Printed circuit board assembly and method for producing a printed circuit board assembly

Info

Publication number: EP3610705A1
Application number: EP18712599.2A
Authority: EP
Inventors: Kay STENZEL
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2017-04-10
Filing date: 2018-03-21
Publication date: 2020-02-19
Also published as: DE102017206099A1; CN110463359A; WO2018188918A1

Abstract

The invention relates to a printed circuit board assembly (1) for an electronic circuit. The printed circuit board assembly (100) comprises a first printed circuit board (110) having one or more electrically conductive first contact points (111) on a front side (114) of the first printed circuit board (110). In addition, the printed circuit board assembly (100) comprises a second printed circuit board (120) having one or more electrically conductive second contact points (121) on a rear side (123) of the second printed circuit board (120). The printed circuit board assembly (100) also comprises a spacer element (130) having one or more conductor tracks (134) on a rear side of the spacer element (130) and having one or more conductor tracks (134) on a front side of the spacer element (130). The one or more conductor tracks (134) on the rear side is/are connected to the one or more conductor tracks (134) on the front side in an electrically conductive manner. Furthermore, the one or more conductor tracks (134) on the rear side is/are soldered to the one or more first contact points (111). In addition, the one or more conductor tracks (134) on the front side is/are soldered to the one or more second contact points (121).

Description

Circuit board arrangement and method for producing a

Circuit board assembly

The invention relates to a printed circuit board assembly having a plurality of printed circuit boards, which are electrically conductively connected to each other. Furthermore, the invention relates to a method for producing a printed circuit board assembly.

The electronics of an electrical device, in particular a domestic appliance or a household appliance, may be implemented on a plurality of different printed circuit boards, wherein the printed circuit boards are electrically conductively connected to each other. For example, a first circuit board, e.g. a base circuit board having a relatively low number (e.g., 2) of conductor layers (e.g., copper layers). The first circuit board can be used to provide a basic function. Furthermore, a second circuit board, e.g. a module circuit board having a relatively high number (e.g., 4 or more) of conductor layers. In addition, the second circuit board may be of higher and / or higher quality circuit board technology (e.g., HDI circuit board technology) than the first circuit board. The second circuit board may be used to provide an expansion function. Possibly. For example, the second circuit board may be used in different types of electrical devices.

Different circuit boards can be used to provide different functions in each cost and space optimal manner. The different printed circuit boards can be interconnected via board-to-board (B2B) connectors. Two different printed circuit boards are typically manufactured and tested separately. The circuit boards can then be connected to each other during assembly by hand or by machine, in particular plugged. Furthermore, a mechanical fixation is typically used (e.g., a support frame or a screw) to permanently and securely connect the various circuit boards.

The use of connectors and mechanical fixings is typically costly and labor intensive. This document deals with the technical task of electrically and mechanically interconnecting different circuit boards in an efficient manner.

The object is solved by the subject matter of the independent patent claims. Advantageous embodiments are defined in particular in the dependent claims, described in the following description or illustrated in the accompanying drawings.

In accordance with one aspect of the invention, a printed circuit board assembly for an electronic circuit is described. The electronic circuit can be used in an electrical device, e.g. in a domestic appliance or in a household appliance, are used. The printed circuit board assembly includes a first circuit board having one or more electrically conductive first contact pads on a front side of the first circuit board. The first printed circuit board is typically populated with one or more electronic components (e.g., at least one electrical resistor, at least one capacitor, at least one coil, at least one integrated circuit (IC) component, etc.). In this case, the front side and possibly also the rear side of the first printed circuit board can each be equipped with one or more electronic components.

In addition, the printed circuit board assembly comprises a second printed circuit board with one or more electrically conductive second contact points on a back side of the second printed circuit board. The second circuit board is typically populated with one or more electronic components (e.g., at least one electrical resistor, at least one capacitor, at least one coil, at least one IC device, etc.). In this case, the rear side and possibly also the front side of the second printed circuit board can each be equipped with one or more electronic components.

Typically, the first circuit board is larger than the second circuit board. By way of example, the second printed circuit board may have an area that is smaller than the area of the first printed circuit board by a specific factor. The factor may e.g. 1 .5, 2, 3 or more.

The first circuit board and the second circuit board each typically include one or more conductor layers (eg, copper) that may be used to To provide strip conductors between the one or more components of the respective printed circuit board. In this case, at least one conductor layer may be located on the front side of the first printed circuit board and a conductor layer on the rear side of the second printed circuit board. In addition, the first conductor layer typically also has a conductor layer on the rear side and the second conductor layer has a conductor layer on the front side. In addition, the first circuit board and the second circuit board may comprise one or more conductor layers, which are each arranged as an intermediate layer between the front side and the back side of the respective circuit board. Overall, the second circuit board may have a higher number of conductor layers than the first circuit board.

The printed circuit board arrangement further comprises at least one spacer element with one or more conductor tracks on the rear side of the spacer element and with one or more conductor tracks on the front side of the spacer element. In this case, the one or more conductor tracks of the rear side are electrically conductively connected to the one or more conductor tracks of the front side. The spacer element thus has conductor tracks, which electrically connect the rear side of the spacer element to the front side of the spacer element. The spacer element can be designed as a coherent component. In particular, the front side and the rear side of the spacer element can be firmly and / or inseparably or not detachably connected to one another. For example, the spacer may be formed as a plate having one or more tracks on the front and one or more tracks on the back. It can thus be used a cost-efficient and mechanically stable spacer. The one or more traces of the back of the spacer are soldered to the one or more first pads (eg, solder pads) on the front of the first circuit board. In addition, the one or more tracks of the front of the spacer are soldered to the one or more second pads (eg, solder pads) of the back of the second circuit board. Thus, a printed circuit board assembly of at least two printed circuit boards can be provided which are connected together in a cost-effective and mechanically stable manner. The spacer may include one or more vias. The vias connect the front and the back of the spacer. In particular, the one or more interconnects of the rear side of the spacer element can be electrically conductively connected to the one or more interconnects of the front side of the spacer element via the one or more plated-through holes. The one or more vias can be permanently installed and / or inseparable or not be solvable. For example, the one or more plated-through holes can be formed by bores in the spacer element. Alternatively or additionally, the one or more plated-through holes can extend on at least one edge of the spacer element. It can thus be made possible a cost-effective contacting of the tracks on the front with the tracks on the back of the spacer.

The spacer may comprise a spacer printed circuit board or the spacer may be formed as a spacer printed circuit board. The circuit board may be made of a circuit board material (e.g., a fiber reinforced plastic). Furthermore, the spacer printed circuit board may include a first conductor layer for the one or more traces of the rear of the spacer. Furthermore, the spacer printed circuit board may comprise a second conductor layer for the one or more tracks of the front of the spacer. The printed conductors can thereby be replaced by a typical printed circuit board manufacturing process, such as e.g. be created by an etching process. This enables the provision of a cost-effective spacer element.

The spacer element preferably has a height that makes it possible, in a gap between the back of the second circuit board and the front of the first circuit board, one or more electronic components at least on the back of the second circuit board, in particular both on the back of the second circuit board and on the front of the first circuit board, to place. Thus, a particularly cost-effective printed circuit board assembly is provided.

The spacer element may be formed as a cuboid. Furthermore, the spacer may have a certain height, by which the distance between the first circuit board and the second circuit board is defined. Furthermore, that can Distance element have a certain width and a certain length, wherein the width and the length of the spacer form a base surface, with which the spacer member contacts the front side of the first circuit board.

The spacer element can be arranged on an edge of the second printed circuit board. In this case, the spacer can at least partially overlap with the second circuit board. That is, a part of the base of the spacer may be disposed below the second circuit board, and contact the back side of the second circuit board. Furthermore, the spacer element may protrude at least partially beyond the edge of the second printed circuit board. For example, the spacer may overlap with 50% or more and / or 10% or more with the second circuit board. Furthermore, the spacer may project 50% or less and / or 10% or more beyond the edge of the second circuit board. Thus, an efficient automatic optical inspection of the solder joints in the manufacture of the printed circuit board assembly is made possible.

Typically, the circuit board assembly has at least two spacers on at least two different (e.g., opposing) edges of the second circuit board. This enables a particularly stable fixation of the printed circuit boards. In another aspect, an electronic circuit is described that includes the printed circuit board assembly described in this document.

According to a further aspect, an electrical device, in particular a domestic appliance or a household appliance, is described which comprises the printed circuit board arrangement described in this document.

In another aspect, a method of making a printed circuit board assembly for an electronic circuit is described. The method includes creating one or more solder joints between one or more tracks on a front side of a spacer with one or more electrically conductive second pads (eg, solder pads) on a back side of a second circuit board. It can thus be made a sub-assembly in which the Distance element electrically conductive and mechanically stable on the second circuit board is fixed.

In addition, the method includes creating one or more solder joints between one or more tracks on a back side of the spacer with one or more electrically conductive first pads on a front side of a first circuit board. In particular, the subassembly can be fixed by means of soldered connections to the first printed circuit board in an electrically conductive and mechanically stable manner.

The one or more interconnects of the rear side of the spacer element are electrically conductively connected to the one or more interconnects of the front side of the spacer element. It can thus be provided in an efficient manner, a printed circuit board assembly in which two circuit boards are connected via one or more electrically conductive connections of a spacer both electrically conductive and mechanically stable.

The one or more solder joints can be created as part of an automatic assembly, in particular a SMT, Surface Mounted Technology, assembly. In this case, the spacer element can be treated like an electronic component in the automatic assembly of the second printed circuit board. Alternatively or additionally, the subassembly of the second printed circuit board and the soldered spacer can be treated like an electronic component in the automatic assembly of the first printed circuit board. In particular, the spacer element and / or the subassembly can be fed to a placement machine for the automatic assembly of the second printed circuit board and / or the first printed circuit board in a tray or on a belt, in particular a blister strip. Thus, the production of a printed circuit board arrangement is made possible in a particularly efficient manner.

The method may include performing an automatic optical inspection of the one or more solder joints. Thus, the reliability of a circuit board assembly can be increased efficiently.

It should be noted that any aspects of the printed circuit board assembly described in this document or the method described in this document are incorporated herein by reference various ways can be combined. In particular, the features of the claims can be combined in a variety of ways.

Furthermore, the invention will be described with reference to embodiments illustrated in the accompanying drawings. Show

FIG. 1 shows an exemplary printed circuit board arrangement with two printed circuit boards;

Figure 2 shows an exemplary circuit board with a spacer element; FIG. 3 shows an exemplary spacer element; and

FIG. 4 shows a flow diagram of an exemplary method for connecting printed circuit boards. As stated above, the present document is concerned with the efficient connection of multiple printed circuit boards to produce a printed circuit board assembly. 1 shows a printed circuit board arrangement 100 having a first printed circuit board 110 and a second printed circuit board 120. The printed circuit boards 110, 120 may each have one or more electronic components 101, the components 101 on the front side 14, 124 and / or. or on the back of 1 13, 123 of the respective circuit board 1 10, 120 may be arranged. For example, the first circuit board 110 may be a relatively large and a relatively inexpensive circuit board having a relatively low number of conductor layers (eg, two conductor layers on the two surfaces of the circuit board 110). On the other hand, the second circuit board 120 may be relatively small and relatively expensive. For example, the second circuit board 120 may include one or more additional conductor layers inside the circuit board 120. The second circuit board 120 may be used to implement highly integrated switching devices. The use of different printed circuit boards 1 10, 120 may, for example, due to the requirements of certain components 101 to certain printed circuit board technologies, for example, multilayer printed circuit boards, conditional. A complete implementation on a costly printed circuit board technology is typically at a relatively high cost connected. Furthermore, mechanical and / or design-related conditions may require a certain geometry or size of the electronics of an electrical device. In addition, by using different printed circuit boards 1 10, 120 a modular concept can be realized, since thus parts of the electronics of an electrical device (eg the part implemented on the second printed circuit board 120) can be used for several different types of electrical devices.

As shown in FIG. 1, the second circuit board 120 is mounted on the first circuit board 110. In this case, there is preferably a certain intermediate space 103 between the first printed circuit board 110 and the second printed circuit board 120, which makes it possible to equip the rear side 123 of the second printed circuit board 120 and possibly the front side of the first printed circuit board 110 with one or more components 101. Thus, the cost and the area of the circuit board assembly 100 can be reduced. The first printed circuit board 1 10 and the second printed circuit board 120 are interconnected via two spacers 130 (also referred to in this document as spacers). In this case, a spacer 130 is electrically conductively and mechanically connected to the rear side 123 of the second printed circuit board, in particular soldered. Furthermore, a spacer 130 with the front side 1 14 of the first circuit board 1 10 electrically conductively and mechanically connected, in particular soldered.

Fig. 3 shows details of a spacer 130. The spacer 130 comprises a printed circuit board, referred to in this document as a spacer printed circuit board. The spacer printed circuit board has a certain thickness, wherein the thickness of the spacer printed circuit board is preferably so large that the gap 103 between the first printed circuit board 1 10 and the second printed circuit board 120, the inclusion of components 101 on the Rear side 123 of the second circuit board 120 allows.

The spacer printed circuit board has a first conductor layer 131 (see Fig. 2), which faces in the installed state of the first circuit board 1 10 and which can be used to electrically contact the first circuit board 1 10. Furthermore, the spacer printed circuit board has a second conductor layer 132 (see FIG installed state of the second circuit board 120 faces and which can be used to electrically contact the second circuit board 120.

The first conductor layer 131 and the second conductor layer 132 may each be segmented into one or more tracks 134 to provide one or more electrically conductive connections between the first circuit board 110 on the one hand and the second circuit board 120 on the other. The individual tracks 134 of the first conductor layer 131 and the second conductor layer 132 may be connected via vias 135, i. in pairs, be electrically connected to each other.

In a first step, one or more spacers 130 may be affixed to the back 123 of the second circuit board 120 (e.g., two spacers 130 on two different edges of the second circuit board 120). This is exemplified in Fig. 2. The one or more interconnects 134 of the second conductor layer 132 may be electrically conductively connected, in particular soldered, to contact points (in particular solder joints) 122 on the rear side 123 of the second circuit board 120 for this purpose. By the production of solder joints between the second circuit board 120 and the second conductor layer 132 of the spacer 130, a mechanical fixation between the second circuit board 120 and the spacer 130 is achieved.

In a second step, the subassembly of the second circuit board 120 and one or more spacers 130 on the front side 1 14 of the first circuit board 1 10 are attached. In particular, the one or more interconnects 134 of the first conductor layer 131 of the one or more spacers 130 with contact points (in particular with solder joints) 1 12 on the front side 1 14 of the first circuit board 1 10 electrically connected, in particular soldered, are. By producing solder joints between the first circuit board 110 and the first conductor layer 131 of the one or more spacers 130, a mechanical fixation between the first circuit board 110 and the one or more spacers 130 is achieved. In total, an electrically conductive and mechanically fixing connection between the first printed circuit board 110 and the second printed circuit board 120 is thus effected. As shown in FIG. 1, a spacer 130 may be arranged such that the spacer 130 has an overlapping area with the second circuit board 120 and a non-overlapping area with the second circuit board 120. Thus, an efficient inspection of the connection, in particular of the solder joints, between the spacer 130 and the respective printed circuit board 1 10, 120 take place. In particular, after the first production step (see FIG. 2), a check (for example an optical check) of the connection sites between the second conductor layer 132 of the spacer 130 and the second circuit board 120 can take place. After the second production step, a check of the connection points between the first conductor layer 131 of the spacer 130 and the first circuit board 110 can then take place.

The two or more circuit boards 1 10, 120 are thus not plugged together, but soldered together. In this case, one or more spacers 130 are used, which are soldered between each two printed circuit boards 1 10, 120.

The spacers 130 are made of printed circuit board material and preferably have a height so that components 101 between the circuit boards 1 10, 120 can be installed. The one or more spacers 130 are equipped with the assembly of the lower or rear side 123 of the second (smaller) circuit board 120. The equipment can be done automatically. In particular, a spacer 130 may be "strapped" as a component or placed in a tray to populate the second circuit board 120 with the spacer 130. Thus, an efficient manufacturing process of the subassembly of the second circuit board 120 and the one or more spacers 130 is enabled ,

On the one or more spacers 130 may each be provided a two-layered copper layout connecting solder pads on top of a spacer 130 to solder pads 121 on the underside of the second circuit board 120 (in a 1: 1 relationship), and / or which solder pads on the bottom of a spacer 130 with solder pads 1 1 1 on the front side of the first circuit board 1 10 connects (in a 1: 1 relationship) The second circuit board 120 with one or more populated spacers 130 may be tested separately prior to assembly on the first circuit board 110. In this case, an automatic optical inspection (AOI) of the solder joints of the one or more spacers 130 can be performed. The subassembly of the second circuit board 120 and the one or more spacers 130 may be handled in a further process such as an electronic component 101 to be placed on the front side 1 14 of the first circuit board 1 10. The subassembly can be strapped or placed in a tray and fed to another SMT process, in which the subassembly is soldered to solder pads 1 1 1 of the first circuit board 1 10 and thus joined to the first circuit board 1 10.

The solder joints between the spacer 130 and the front side 1 14 of the first printed circuit board 110 can also be checked by AOI since the spacers 130 protrude beyond the edge of the second printed circuit board 120 (e.g., to about 1/3 of the base of the spacer 130).

4 shows a flowchart of an exemplary method 400 for manufacturing an electronic circuit board assembly 100. The method 400 includes creating 401 one or more solder joints between one or more tracks 134 on the front of a spacer 130 having one or more electrically conductive second pads 121 on the back 123 of a second circuit board 120. Thus, in a first step, a Partial arrangement of a second circuit board 120 and at least one spacer element 130 are formed. Typically, at least two spacers 130 are fixed to different edges of the second circuit board 120 by soldering.

In addition, the method 400 includes creating 402 one or more solder joints between one or more traces 134 on the back of the at least one spacer 130 having one or more electrically conductive first pads 1 1 1 on the front surface 124 of a first circuit board 120 Step can thus be soldered to the subassembly of the second circuit board 120 and the one or more spacer elements 130 on the first circuit board 1 10. By soldering second printed circuit boards 1 10, 120 via a spacer element 130, in particular via a spacer printed circuit board, can be dispensed with an additional mechanical fixation. The printed circuit boards 1 10, 120 can be fully automatically loaded in an SMT process and connected to each other. Furthermore, both circuit boards 1 10, 120 can be equipped on both sides. It can be installed in the overlap region 103 between the two circuit boards 1 10, 120 components 101. In particular, no recess in the first printed circuit board 110 is required for components 101 on the rear side 123 of the second printed circuit board 120. This increases the stability of the printed circuit board assembly 100. In addition, so closed copper (screen) surfaces can be made possible. Furthermore, the available area on the first printed circuit board 110 can be used to provide printed conductors.

By soldering a solid mechanical connection is created. Quality problems due to loose or detachable plug connections can be ruled out. It also eliminates the cost of a connector, mechanical fixation and assembly.

The spacers 130 described in this document may be manufactured in standard processes by an electronics manufacturer. In particular, the required traces 134 may be fabricated on the spacer 130 by standard processes for making a printed circuit board.

The present invention is not limited to the embodiments shown. In particular, it should be understood that the description and figures are intended to illustrate only the principle of the described printed circuit board assembly 100 and method 400 described.

Claims

Printed circuit board arrangement (100) for an electronic circuit, wherein the printed circuit board arrangement (100) comprises

a first printed circuit board (1 10) having one or more electrically conductive first contact points (1 1 1) on a front side (1 14) of the first printed circuit board (1 10);

a second circuit board (120) having one or more electrically conductive second contact pads (121) on a back side (123) of the second circuit board (120);

a spacer (130) having one or more tracks (134) on a back side of the spacer (130) and one or more tracks (134) on a front side of the spacer (130); wherein the one or more conductive traces (134) of the back side are electrically connected to the one or more conductive traces (134) of the front surface; wherein the one or more tracks (134) of the back side are soldered to the one or more first pads (1 1 1); and wherein the one or more conductive tracks (134) of the front side are soldered to the one or more second contact pads (121).

A printed circuit board assembly (100) according to claim 1, wherein

the spacer (130) comprises one or more vias (135); and

the one or more interconnects (134) of the rear side of the spacer element (130) are electrically conductively connected to the one or more interconnects (134) of the front side of the spacer element (130) via the one or more vias (135).

Circuit board arrangement (100) according to one of the preceding claims, wherein

the spacer element (130) comprises a spacer printed circuit board;

the spacer board has a first conductor layer (131) for the one or more

Conductor tracks (134) of the rear side of the spacer element (130) comprises; and the spacer board comprises a second conductor layer (132) for the one or more tracks (134) of the front of the spacer (130).

A printed circuit board assembly (100) according to any one of the preceding claims, wherein the spacer (130) has a height enabling it to be interposed in a gap (103) between the back side of the second circuit board (120) and the front side of the first circuit board (120). one or more electronic components (101) at least on the back of the second circuit board (120), in particular both on the back of the second circuit board (120) and on the front side of the first circuit board (1 10) to place.

Circuit board arrangement (100) according to one of the preceding claims, wherein the spacing element (130)

is disposed on an edge of the second circuit board (120); and

at least partially beyond the edge of the second circuit board (120) protrudes.

A printed circuit board assembly (100) according to any one of the preceding claims, wherein the circuit board assembly (100) comprises at least two spacers (130) on at least two different edges of the second circuit board (120).

A method (400) of making an electronic circuit board assembly (100), the method comprising (400)

Creating (401) one or more solder joints between one or more tracks (134) on a front side of a spacer (130) having one or more electrically conductive second pads (121) on a back side (123) of a second circuit board (120); and

Creating (402) one or more solder joints between one or more tracks (134) on a back side of the spacer (130) having one or more electrically conductive first pads (11) on a front side (124) of a first board (120). ; wherein the one or more interconnects (134) of the rear side of the spacer element (130) are electrically conductively connected to the one or more interconnects (134) of the front side of the spacer element (130).

8. The method (400) according to claim 7, wherein

- The one or more solder joints in the context of an automatic assembly, in particular an SMT, Surface Mounted Technology, assembly, created;

- The spacer (130) as an electronic component (101) in the automatic assembly of the second circuit board (120) is treated; and

- A subassembly of the second circuit board and the soldered spacer element (130) as an electronic component (101) in the automatic assembly of the first circuit board (1 10) is treated.

9. The method (400) according to claim 8, wherein the spacer element (130) and / or the subassembly is fed to a placement machine for automatic placement in a tray or on a belt.

The method (400) of any one of claims 7 to 9, wherein the method (400) comprises performing an automatic optical inspection of the one or more solder joints.