DE102019129971A1 - Method for soldering a component onto a printed circuit board, electronic unit and field device in automation technology - Google Patents

Abstract

The invention relates to a method for soldering a component (1) onto a surface (OF) of a first printed circuit board (2), the method comprising the steps of: A) applying solder paste (3) comprising a first solder (L1) to a Plurality of contact surfaces (KF); B) providing preformed solder parts (LFT) having a second solder (L2), a preformed solder part (3) being applied to the contact surface for at least several of the contact surfaces (KF); Arranging the component (1) on the surface of the first printed circuit board (2) in such a way that the end face (SF) faces the surface (OF); C) soldering the connections (AS) of the component (1) to the contact surfaces (KF) in reflow soldering at a soldering temperature (LT) at which both the liquidus temperature of the first solder (L1) and the liquidus temperature of the second solder (L2) are exceeded, with the soldering between the connections (AS) and the contact surfaces (KF) in each case solder connections (4) are produced in such a way that a predetermined solder gap height (LSH) is present between the end face (SF) of the component and the surface (OF) of the first printed circuit board (2). The invention also relates to an electronics unit and a field device automation technology.

Description

The invention relates to a method for soldering a component onto a surface of a printed circuit board, an electronics unit and a field device in automation technology.

In automation technology, especially in process automation technology, field devices are often used to determine and / or monitor process variables. In principle, all devices that are used close to the process and deliver or process process-relevant information are referred to as field devices. These are, for example, level measuring devices, flow measuring devices, pressure and temperature measuring devices, pH redox potential measuring devices, conductivity measuring devices, etc., which record the corresponding process variables level, flow, pressure, temperature, pH value and conductivity. Field devices often have a sensor unit, in particular at least temporarily and / or at least in sections, which is in contact with a process medium and which is used to generate a signal that is dependent on the process variable. Furthermore, these often have an electronic unit arranged in a housing, the electronic unit serving to process and / or forward signals generated by the sensor unit, in particular electrical and / or electronic signals. For this purpose, the electronics unit often has a printed circuit board with components arranged thereon, which are soldered onto contact surfaces provided for this purpose.

A high quality of the soldered connections between the connections of the component and the contact surfaces provided for this is of great importance for the reliability of the electronics unit or the field device. The quality of the solder connections depends, among other things, on whether the distance between the component and the contact surface (the so-called solder gap height) is sufficiently large. If the height of the solder gap is too small, stress-induced cracks can occur in the solder joint due to temperature fluctuations over time. In the case of small solder gap heights, there is also the risk of undesired air inclusions (voids) occurring in the solder connections - this has been shown by investigations by the applicant. The reason for this is that for some of the solder connections not enough solder paste can be applied to the connection and / or flux residues remain. The latter applies in particular if the component has a large number of connections, in particular free of solder deposits, which are located under the component.

Solder deposits in the form of preformed solder parts in connection with a printed circuit board of an electronics unit of a field device in automation technology are, for example, in FIG DE 10 2006 021 335 , the DE 10 2012 200 021 , the DE 10 2006 017 978 , the DE 10 2005 043 279 , DE 10 201 209 , or the DE 10 344 745 disclosed.

The invention is therefore based on the object of specifying a method for soldering a component onto a printed circuit board, in which solder connections of high quality are achieved or to specify an electronic unit with a component soldered on a printed circuit board, in which solder connections of high quality are present.

The object is achieved by a method for soldering a component and an electronics unit.

• - das Bauelement eine Vielzahl von lotdepotfreien Anschlüssen aufweist, die auf einer Stirnfläche des Bauelements angeordnet ist, und
• - die Oberfläche der ersten Leiterplatte Kontaktflächen aufweist, die zum Auflöten der Anschlüsse vorgesehen sind und wobei das Verfahren die Schritte umfasst:
  1. A) Aufbringen von Lotpaste aufweisend ein erstes Lot auf die Vielzahl von Kontaktflächen;
  2. B) Bereitstellen von Lotformteilen aufweisend ein zweites Lot, wobei für zumindest mehrere der Kontaktflächen jeweils ein Lotformteil auf die Kontaktfläche aufgebracht wird;
  3. C) Anordnen des Bauelements auf der Oberfläche der ersten Leiterplatte derart, dass die Stirnfläche der Oberfläche zugewandt ist;
  4. D) Verlöten der Anschlüsse des Bauelements mit den Kontaktflächen in einem Reflow-Löten bei einer Löttemperatur, bei der sowohl die Liquidustemperatur der des ersten Lots als auch die Liquidustemperatur des zweiten Lots überschritten wird,

wobei beim dem Verlöten zwischen den Anschlüssen und den Kontaktflächen jeweils Lotverbindungen derart hergestellt werden, dass zwischen der Stirnfläche des Bauelements und der Oberfläche der ersten Leiterplatte eine vorgegebene Lotspalthöhe vorliegt.With regard to the method, the object is achieved by a method for soldering a component onto a surface of a first printed circuit board, wherein

• - The component has a plurality of solder depot-free connections, which is arranged on an end face of the component, and
• - The surface of the first printed circuit board has contact areas which are provided for soldering the connections and wherein the method comprises the steps:
  1. A) applying solder paste comprising a first solder to the plurality of contact surfaces;
  2. B) providing preformed solder parts having a second solder, a preformed solder part being applied to the contact surface for at least several of the contact surfaces;
  3. C) arranging the component on the surface of the first printed circuit board in such a way that the end face faces the surface;
  4. D) soldering the connections of the component to the contact surfaces in a reflow soldering process at a soldering temperature at which both the liquidus temperature of the first solder and the liquidus temperature of the second solder are exceeded,

wherein during the soldering between the connections and the contact surfaces, solder connections are made in each case in such a way that a predetermined solder gap height is present between the end face of the component and the surface of the first printed circuit board.

For some of the contact surfaces, a preformed solder part is therefore additionally fitted onto the solder paste that has already been applied thereon. The preformed solder parts are, in particular, preformed solderable parts that can be equipped with SMD components and that are applied simultaneously with a large number of other SMD-solderable components. SMD solderable components (short for “Surface Mounted Devices “ie surface-mountable components) are soldered with their contact elements directly to the connections provided for them. For this purpose, the SMD components are automatically placed on the contact surfaces provided with solder paste on the circuit board with automatic placement machines and soldered together with a so-called reflow soldering process in a reflow soldering oven. This means that a large number of SMD-solderable components can be soldered onto the circuit board at the same time. All steps A) - D) are therefore advantageously integrated into such an SMD grounding and reflow soldering process.

Since both the liquidus temperature of the first solder of the solder paste and that of the second solder of the solder preforms are exceeded during reflow soldering, the two soldering processes take place essentially simultaneously when the solder connections are made for these contact surfaces.

In one embodiment of the invention, a predetermined solder gap height of at least 60 μm (micrometers) is set.

• - Aufbringen von Flussmittel auf die Oberfläche der ersten Leiterplatte, nachfolgend zu Schritt A) und vor Schritt B).

According to one embodiment of the invention, flux-free preformed solder parts are provided, the method comprising the step:

• - Applying flux to the surface of the first printed circuit board, following step A) and before step B).

Advantageously, no additional flux is required for the preformed solder parts. The flux provided for the solder paste applied (e.g. by means of stencil printing) is completely sufficient. The flux for the first solder of the solder paste is then more or less used in the essentially simultaneously occurring soldering processes for the second solder of the solder preforms and is essentially completely used up, so that advantageously no flux residues remain.

In one embodiment of the invention, the component has on the end face an inner area with internal connections and an edge area delimiting the inner area with external connections, with preformed solder parts being applied to at least all contact surfaces that are provided for the internal connections.

In one embodiment of the invention, at least one preformed solder part is provided with at least one spacer element, the spacer element extending along the preformed solder part in a direction essentially perpendicular to the surface of the first printed circuit board, and wherein the liquidus temperature of the spacer element is undershot by the soldering temperature during reflow soldering becomes.

Of course, several preformed solder parts with spacer elements of this type can also be used. The direction indication “in the direction essentially perpendicular to the surface of the first printed circuit board” relates here to a preformed solder part arranged on the surface.

In one embodiment of the invention, a preformed solder part is provided, the second solder of which is lead-free and comprises at least Sn (tin) and Ag (silver)

In one embodiment of the invention, a preformed solder part is provided, the second solder of which has at least Cu (copper), In (indium) and / or Bi (bismuth).

According to one embodiment of the invention, the plurality of connections and contact areas is in each case at least ten connections and contact areas, a preformed solder part in each case being applied to at least half of the plurality of contact areas.

• - in einer zu der Oberfläche der ersten Leiterplatte im Wesentlichen senkrechten Richtung eine Höhe von 30 µm bis 400 µm und/oder
• - in einer zu der Oberfläche der ersten Leiterplatte im Wesentlichen parallelen Richtung eine Abmessung von 100 µm bis 400 µm aufweist.

In one embodiment of the invention, a preformed solder part is provided which

• a height of 30 μm to 400 μm and / or in a direction essentially perpendicular to the surface of the first printed circuit board
• - has a dimension of 100 μm to 400 μm in a direction essentially parallel to the surface of the first printed circuit board.

Here, too, the indication of direction (“in the direction essentially perpendicular to the surface of the first printed circuit board”) relates to a preformed solder part arranged on the surface.

• - ein Bauelement mit einer Vielzahl von Anschlüssen, die auf einer Stirnfläche des Bauelements angeordnet ist,
• - eine erste Leiterplatte mit einer Oberfläche und auf der Oberfläche angeordneten Kontaktflächen,

wobei das Bauelement derart auf der Oberfläche der ersten Leiterplatte angeordnet ist, dass die Stirnfläche der Oberfläche zugewandt ist und zwischen den Anschlüssen des Bauelements und den Kontaktflächen jeweils Lotverbindungen vorliegen,
und wobei zwischen der Stirnfläche des Bauelements und der Oberfläche der ersten Leiterplatte eine vorgegebene Lotspalthöhe vorliegt.With regard to the electronic unit, the object is achieved by an electronic unit which is produced in a method according to the invention, comprising:

• - a component with a plurality of connections, which is arranged on an end face of the component,
• - A first printed circuit board with a surface and contact areas arranged on the surface,

wherein the component is arranged on the surface of the first printed circuit board in such a way that the end face faces the surface and there are solder connections between the connections of the component and the contact surfaces,
and wherein there is a predetermined solder gap height between the end face of the component and the surface of the first printed circuit board.

The electronics unit thus comprises the arrangement of printed circuit board and component which is produced by the method according to the invention.

In one embodiment of the electronics unit, a solder stop is applied to an electrically insulating area of the surface of the first printed circuit board.

The solder stop serves initially to protect the conductor tracks from the liquid solder during the soldering of components onto the surface of the circuit board. The solder stop prevents the area of the surface of the printed circuit board covered with it from being wetted and thereby prevents the liquid solder from forming bridges on the insulating area. The solder stop is only present in the area of the surface of the printed circuit board that is used for electrical insulation, and therefore usually has to be applied selectively. Two types of solder masks are known in the prior art: a solder stop applied as a lacquer and a solder stop applied as a foil.

In one embodiment of the electronics unit, the component has a second printed circuit board with an integrated circuit arranged on the second printed circuit board, the end face being formed by the surface of the second printed circuit board and a solder stop being applied to an electrically insulating area of the end face, and the Connections of the component as a land grid array arranged on the front face ( LGA ) are executed.

In an alternative embodiment of the electronic unit, the component has an integrated circuit ( IC ) and the component is in particular as a Quad Flat No Leads Package ( QFN ) or a Dual Flat No-lead Package ( DFN ) executed.

The object is also achieved by a field device in automation technology with an electronic unit according to the invention.

The invention and further advantageous refinements are explained in more detail below on the basis of exemplary embodiments. The same parts are provided with the same reference symbols in all figures; if it requires clarity or if it appears otherwise sensible, the reference symbols already mentioned are dispensed with in the following figures.

• 1: Eine Ausgestaltung eines Bauelements, das in dem erfindungsgemäßen Verfahrens verwendet wird;
• 2a, 2b: Eine erste Ausgestaltung des erfindungsgemäßen Verfahrens;
• 3a, b Weitere Ausgestaltungen des Bauelements, für welche das erfindungsgemäße Verfahren vorteilhaft ist;
• 3c: Ein in einer Ausgestaltung des erfindungsgemäßen Verfahrens verwendetes Lotformteil;
• 4: Ein Feldgerät der Automatisierungstechnik mit einer erfindungsgemäßen Elektronikeinheit.

It shows:

• 1 : An embodiment of a component that is used in the method according to the invention;
• 2a , 2 B : A first embodiment of the method according to the invention;
• 3a, b Further configurations of the component for which the method according to the invention is advantageous;
• 3c : A solder preform used in one embodiment of the method according to the invention;
• 4th : A field device of automation technology with an electronic unit according to the invention.

1 shows an embodiment of a component 1 used in the method of the invention. The component 1 is in a plan view of that end face SF of the component 1 shown which when soldering onto a surface OF a first printed circuit board 2 this is facing. The component 1 is called a land grid array LGA designed.

The Land Grid Array LGA includes one on a second circuit board 8th arranged integrated circuit IC (not in 1 shown) and a multitude of connections arranged in a checkerboard shape AS on which on the whole face SF are arranged distributed. In particular, for a land grid array LGA an indoor area IB with internal connections ASI before which from an edge area RB with external connections ASA is limited. Basically it is due to the arrangement of the connections AS sophisticated for as a land grid array LGA designed components 1 reliable solder connections 4th of sufficiently high quality.

This is in the 2a , 2 B shown in more detail, which is a sectional view of the electronic unit according to the invention 10 comprised arrangement comprising the first printed circuit board 2 and the component arranged thereon 1 demonstrate. This in 2a , 2 B Land Grid Array shown LGA is shown here in a view that is related to that in already in 1 The view shown is rotated by 90 °, about an axis running horizontally along the plane of the paper.

In 2a is a section of the first printed circuit board 2 shown which on an insulating area of the surface OF the first circuit board 2 a solder stop 7th having. The connections AS are now as over the whole frontal area SF distributed below the component 1 recognizable. Furthermore, the contact surfaces Theatrical Version on the first circuit board 2 shown, which for soldering the connections AS of Component 1 are provided. In an in 2a The mass assembly process shown is initially solder paste in a process step A) 3 having a first solder L1 on the contact surfaces Theatrical Version upset. A stencil printing process with a thin stencil, ie with a thickness of <60 µm, is used for this. This is followed by a flux 5 through the template onto the contact surfaces Theatrical Version applied depots of solder paste 3 upset.

As both the second circuit board 8th of the Land Grid Array LGA as well as the first printed circuit board 2 a solder stop 7th have, arises when arranging the component 1 when populating the land grid array LGA in a process step C) following process step A) between the contact surfaces Theatrical Version the first circuit board 2 and the connections arranged like a checkerboard AS of the Land Grid Array LGA an additional gap. To make reliable solder connections 4th To get high quality, that needs to be between solder stops 7th present volume between the contact surfaces Theatrical Version the first circuit board 2 and the connections AS of the component 1 be filled with sufficient solder. This is particularly challenging because of the height of the solder stop 7th , e.g. a solder mask. is subject to strong fluctuations in terms of manufacturing technology.

About the reliability of the solder connections 4th To ensure that a predetermined, in particular sufficiently large, solder gap height should be used LSH be generated. Due to the different heights of the solder stops 7th is the achievement of a specified solder gap height LSH in the case of a solder paste applied only by means of stencil printing 3 very demanding, because due to current miniaturization requirements, thick printing stencils (> 120 µm) can often not be used. A thin template is therefore preferably used in step A) as mentioned above.

According to the invention, in a third method step C), the solder paste is then printed on 3 and applying the flux 5 additionally for at least some of the large number of contact surfaces Theatrical Version , especially several of the contact surfaces KF - for example at least half and / or at least five of the plurality of contact surfaces Theatrical Version - solder preforms LFT on the depots with solder paste 3 imprinted. Between the internal connections ASI and the contact surfaces provided for this Theatrical Version the risk of void formation is particularly high. Therefore are preferred at least for those contact areas Theatrical Version Solder preforms LFT provided, which for the internal connections ASI are provided.

The component is then in a method step D) in a reflow soldering process 1 Simultaneously with a large number of SMD components on the surface OF the first circuit board 2 at a soldering temperature LT soldered. All of the steps A) -D) according to the invention are preferably integrated into a mass assembly and reflow soldering process. Both the liquidus temperature of the first solder L1 as well as the liquidus temperature of the second lot L2 exceeded. The liquidus temperatures of the two solders L1 , L2 differ, for example, by a maximum of 20%, based on the liquidus temperature of the first lot L1 in ° C. This will make the two plumb bobs L1 , L2 melted at the same time during the reflow soldering process. If necessary, the first lot L1 and / the second lot L2 both be an alloy comprising copper

By means of the solder preforms LFT the solder volume is increased and a specified solder gap height LSH for the solder connections made during reflow soldering 4th set. The adjustment of the solder gap height LSH takes place over a height of the solder preforms LFT in one to the plane of the first printed circuit board 2 substantially perpendicular direction RS . According to the invention, a solder gap height is preferred LSH set of at least 60 µm.

Investigations by the applicant show that with such a solder gap height LSH the quality of the solder connections 4th is significantly increased, especially compared to the solder gap height LSH from 20 - 45 µm, which is the case with an otherwise comparable method for soldering the component 1 on the surface OF the first circuit board 2 without the use of solder preforms LFT are present. In the latter case, especially for many of the solder connections 4th Voids observed.

They are preferably lead-free and flux-free preformed solder parts LFT . As a result of the essentially simultaneous melting, any excess (ie not due to the first solder L1 completely used) flux from the second solder L2 used up. This will remove any flux residue 5 Favored formation of voids in the solder connections 4th effectively prevented.

That in the 1 and 2 The embodiment shown is in connection with a land grid array LGA designed component 1 explained. Of course, the invention does not apply to such components 1 limited. The method according to the invention is of great relevance for all components 1 showing a variety of connectors AS have (in particular at least ten), which on one of the first circuit board 2 facing face SF of the component 1 are arranged distributed (ie quasi below the component 1 as with the Land Grid Array LGA on one of the surface OF the second circuit board 8th ), especially in an internal area IB .

Examples of other such components 1 are in 3a and 3b shown. 3a shows a Quad Flat No Leads Package QFN designed component 1 and 3b one as a Dual Flat No-lead Package DFN executed component 1 . Like that LGA includes the Quad Flat No Leads Package QFN and the Dual Flat No-lead Package DFN an integrated circuit IC . In both cases, as with the land grid array LGA an indoor area IB with internal connections ASI and a border area RB with external connections ASA in front. All already related to 2 Explained features of the invention are mutatis mutandis also from the invention in connection with the in 3a , 3b shown components 1 includes.

It is preferred for at least one of the preformed solder parts LFT a solder preform LFT with a spacer 6th used. This is in 3c shown. The spacer 6th is made of a material whose liquidus temperature is reduced by the soldering temperature LT is not reached and therefore does not melt during reflow soldering. For example, is the spacer 6th made of copper, the melting temperature of which is significantly higher than a copper-containing solder alloy for the first solder L1 and the second plumb bob L2 . Such a solder preform LFT is sold by ALPHA under the name TrueHeight Preforms. When using at least one of the solder preforms LFT than this solder preform LFT can be the height of the soldering gap LSH on the design of the spacer element 6th can be set. Using this solder preform LFT can therefore be a distance between the first circuit board 2 and the component 1 can be set. In particular, in connection with the in 1 , 2 shown land grid array LGA this can be avoided, for example, that the solder mask of the LGA not on the solder mask on the first circuit board 2 rests. Through the use of solder preforms LFT with spacers 6th can be the height of the soldering gap LSH further significantly increased, as well as the differences in height between the connection partners (component 1 and first circuit board 2 ) be balanced. This further increase in the height of the solder gap LSH and the resulting reduction in voids, the reliability is further increased significantly.

In summary, the method according to the invention is used to create an electronic unit 10 with a high level of reliability, due to the reliable solder connections 4th with in particular an at least significantly reduced number of voids in the solder connections 4th .

The electronics unit 10 comprising the arrangement of component and printed circuit board is preferred in a field device 11 used in automation technology. Such a field device 11 automation technology is in 4th shown in more detail. The field device 11 has a sensor unit that is in contact, in particular, at least temporarily and / or at least in sections with a process medium 17th which is used to generate a measurement signal that represents the process variable, for example electrical and / or electronic.

The one in a transmitter housing 19th of the field device 11 arranged electronics unit 10 is used for processing and / or forwarding the from the sensor unit 17th generated measurement signals. The electronics unit 10 includes the circuit board 2 with the component arranged on it 1 .

In the in 4th The embodiment shown has the field device 11 another, as a display / input unit 20th designed electronics unit 10 on, with a (touch) display mounted on it. The electronic unit according to the invention 10 comprising the component 1 and the circuit board 2 can of course also be used as a display / input unit 20th be designed.

List of reference symbols

1

Component

2

first circuit board

3

Solder paste

4th

Solder connections

5

Flux

6th

Spacer

7th

Solder stop

8th

second circuit board

10

Electronics unit

11

Field device

17th

Sensor unit

19th

Transmitter housing

20th

Display / input unit

SF

Face

OF

surface

AS

connections

Theatrical Version

Contact surfaces

L1, L2

first / second lot

LFT

Solder preforms

LSH

Solder gap height

LT

Soldering temperature

IB

Indoor

RB

Edge area

ASI, ASA

internal / external connections

IC

integrated circuit

LGA

Land Grid Array

QFN

Quad Flat No Leads Package

DFN

Dual flat no-lead package

RS

perpendicular direction

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102006021335 [0004]
• DE 102012200021 [0004]
• DE 102006017978 [0004]
• DE 102005043279 [0004]
• DE 10201209 [0004]
• DE 10344745 [0004]

Claims (14)

Method for soldering a component (1) onto a surface (OF) of a first printed circuit board (2), wherein - The component (1) has a plurality of solder depot-free connections (AS) which is arranged on an end face (SF) of the component, and - The surface (OF) of the first printed circuit board (2) has contact areas (KF) which are provided for soldering the connections (AS) and wherein the method comprises the steps: A) applying solder paste (3) comprising a first solder (L1) to the plurality of contact surfaces (KF); B) providing preformed solder parts (LFT) having a second solder (L2), a preformed solder part (3) being applied to the contact surface for at least several of the contact surfaces (KF); C) arranging the component (1) on the surface of the first printed circuit board (2) in such a way that the end face (SF) faces the surface (OF); D) Soldering the connections (AS) of the component (1) with the contact surfaces (KF) in a reflow soldering at a soldering temperature (LT) at which both the liquidus temperature of the first solder (L1) and the liquidus temperature of the second solder (L2) is exceeded, whereby during the soldering between the connections (AS) and the contact surfaces (KF) in each case solder connections (4) are made in such a way that between the end face (SF) of the component and the surface (OF) of the first printed circuit board ( 2) there is a specified solder gap height (LSH). Procedure according to Claim 1 , whereby a predetermined solder gap height (LSH) of at least 60 µm is set. Method according to at least one of the preceding claims, wherein flux-free preformed solder parts (LFT) are provided, and wherein the method comprises the step: - Application of flux (5) to the surface (OF) of the first printed circuit board (2), following step A) and before step B). Method according to at least one of the preceding claims, wherein the component (1) on the end face (SF) has an inner area (IB) with inner connections (ASI) and an edge area (RB) delimiting the inner area (IB) with outer connections (ASA), and wherein preformed solder parts (LFT) are applied to at least all contact surfaces (KF) which are provided for the internal connections (ASI). Method according to at least one of the preceding claims, at least one preformed solder part (LFT) with at least one spacer element (6) being provided, wherein the spacer element (6) extends along the preformed solder part (LFT) in a direction (RS) which is essentially perpendicular to the surface (OF) of the first printed circuit board (2), and wherein the liquidus temperature of the spacer element (6) is undershot by the soldering temperature (LT) during reflow soldering. Method according to at least one of the preceding claims, wherein a preformed solder part (LFT) is provided, the second solder (L2) of which is lead-free and comprises at least Sn and Ag Procedure according to Claim 6 , wherein a preformed solder part (LFT) is provided, the second solder (L2) of which comprises at least Cu, In and / or Bi. Method according to at least one of the preceding claims, the multitude of connections (AS) and contact surfaces (KF) each being at least ten connections (AS) and contact surfaces (KF), and wherein in each case a preformed solder part (LFT) is applied to at least half of the plurality of contact surfaces (KF). The method according to at least one of the preceding claims, wherein a preformed solder part (LFT) is provided which - In a direction (RS) essentially perpendicular to the surface (OF) of the first printed circuit board (2), a height of 30 μm to 400 μm and / or - Has a dimension of 100 μm to 400 μm in a direction essentially parallel to the surface of the first printed circuit board (2). Electronic unit (10) produced in a method according to at least one of Claims 1 to 9 , comprising: - a component (1) with a plurality of connections (AS), which is arranged on an end face (SF) of the component (1), - a first printed circuit board (2) with a surface (OF) and on the surface (OF) arranged contact surfaces (KF), the component (1) being arranged on the surface (OF) of the first printed circuit board (2) in such a way that the end face (SF) faces the surface (OF) and between the connections (AS ) of the component (1) and the contact surfaces (KF) each have solder connections (4), and a predetermined solder gap height (LSH) is present between the end face (SF) of the component and the surface (OF) of the first printed circuit board (2). Electronics unit (10) Claim 10 , wherein a solder stop (7) is applied to an electrically insulating area of the surface (OF) of the first printed circuit board (2). Electronic unit (10) according to one of the Claims 10 to 11 wherein the component (1) has a second printed circuit board (8) with an integrated circuit (IC) arranged on the second printed circuit board (8), the end face (SF) being formed by a surface (OF) of the second printed circuit board (8) and a solder stop (7) is applied to an electrically insulating area of the surface (OF) of the second printed circuit board (8), and the connections (AS) of the component (1) as a land grid array arranged on the end face (SF) (LGA) are carried out. Electronic unit (10) according to one of the Claims 10 to 11 , wherein the component (1) has an integrated circuit (IC) and the component is designed in particular as a quad flat no-lead package (QFN) or a dual flat no-lead package (DFN). Field device (11) of automation technology with an electronics unit (10) according to one of the Claims 10 to 13th .

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