WO2012110023A1

WO2012110023A1 - Method for soldering components

Info

Publication number: WO2012110023A1
Application number: PCT/DE2012/000132
Authority: WO
Inventors: Bianka Hoffmann; Marlene Lazar; Wilfried Schädel; Peter Ewers
Original assignee: Benteler Automobiltechnik Gmbh
Priority date: 2011-02-18
Filing date: 2012-02-15
Publication date: 2012-08-23
Also published as: DE102011011748A1

Abstract

The invention relates to a method for soldering components (1) comprising the following steps: a) a solder-stop layer (2) is applied to at least one of the components (1) to be soldered; b) the solder-stop layer (2) is applied in liquid form, either being printed according to the principle of inkjet printing, or applied, by means of fibre-tip application, using an applicator which is guided along a solder-stop line that is to be formed from the solder-stop layer (2); c) solder (5) is applied to the component (1) to be soldered before or after the solder-stop layer (2) has been applied, and; d) the components (1) to be soldered are soldered together using the solder (5) heated to at least its liquidus temperature.

Description

Method for soldering components

The invention relates to a method for soldering components according to the feature of patent claim 1.

When soldering, in particular high-temperature soldering, of metallic components, the problem arises that the liquid solder flows into areas in which the solder is not desired. This may be due to the low viscosity of the solder or to the soldering position. To prevent the spread of solder, it is known to use solder stop agents that either act chemically or provide a mechanical barrier.

It is known from WO 2005/043966 A1 to form a chemical barrier through a narrow oxide layer on a precoated nickel, copper or titanium layer by locally melting a protective layer.

In EP 0128386 A1, a chemical barrier is proposed by a solder-stop powder containing Al 2 O 3. Processing must be carried out at 350 to 400 ° C. A similar proposal is made in DE 197 122 19 A1. Processing takes place at 200 to 400 ° C. In US 3703386 is at a

| Confirmation copy | Printed circuit board proposed to use a chemical barrier by a Lotstoppmittel of 75% glass granules and 25% ceramic powder. Depending on the application, the Lotstoppmittel are only suitable for low temperature use, ie only when soldering printed circuit boards. In part, applying the Lotstoppmittels is very expensive. In particular, if previously a coating must be applied, which is then to be melted by means of a laser.

No. 3,110,102 A includes a method for soldering components to the state of the art, in which a solder-stop layer is applied to at least one of the components to be soldered. The solder stop layer is applied in liquid form, wherein the solder stop layer is either printed or applied by means of an applicator which is guided along a solder stop line to be formed from the solder stop layer. The solder stop layer can be applied by brush application or by spraying.

DE 101 38 042 A1 discloses a method for producing an electronic component, in which conductor track structures with connection contacts are provided on one side. There are solder balls used for making electrical contact with the circuit board. In order to control the solder propagation, at least one solder stop layer is provided, which can be applied, for example, by means of a printing process and patterned by means of photolithography.

The state of the art also includes an application device according to DE 297 03 356 U1 for applying solder resist on printed circuit boards. The solder resist is applied by screen printing.

In addition to screen printing, countless other graphic techniques are state of the art, as exemplified in Riat, M .: Graphische Techniques (v. 3.0), Version 3.0. Burriana, 2006.

On this basis, the invention is based on the object, a method for soldering, in particular for high-temperature soldering of components To show, with which the order of Lötstoppmittels is considerably simplified and with which the order is possible even in more complex component structures, such as exhaust gas recirculation cooling, in mass production.

This object is achieved in a method having the features of patent claim 1.

Advantageous developments of the invention are the subject of the dependent claims.

The method according to the invention for soldering components comprises the following steps: a) a solder stop layer is applied to at least one of the components to be soldered, b) the solder stop layer is applied in liquid form, the solder stop layer being printed either by the principle of ink jet printing or by an applicator Fiber pen order is applied, which is guided along a Lotstoppünie to be formed from the Lotstoppschicht; c) Subsequently, the soldering process is carried out by means of a solder which is applied before or after the application of the solder stop layer on at least one of the components to be soldered together.

In the method according to the invention, the solder stop layer is printed in the form of a Lotstopplinie preferably according to the principle of ink jet printing to apply the chemical reaction layer which causes the Lotstopp. The principle of ink-jet printing is understood to mean a matrix printing process in which individual liquid droplets are selectively shot off or deflected in order to produce a printed image. The solder stop agent is in particular an oxide layer in the form of titanium oxides, which is not formed by natural oxidation of active, metallic constituents of the surface of the component. The Lotstoppschicht can either promote this natural oxidation or applied in liquid form. The liquid form of the solder stopper also comprises a viscous or pasty consistency.

The solder stopper may be applied in the form of a liquid solution by the ink jet method. This can be done in vertical pressure from top to bottom. The highest precision is possible with this printing process. The print head itself can be guided on a robot arm, so that even complex structures can be printed. Both the CIJ process (CIJ - Continuous Inkjet) and the DOD process (DOD = Drop on Demand) can be used. While in the CU process an ink jet exits the nozzle of a printhead which breaks up into individual drops which are then deflected in the desired direction, in the DOD process only one drop is requested when needed.

Particularly advantageous is the application with an applicator in the form of a fiber pen is considered. For example, T12O3-containing pigments can be applied in a very flexible manner and with high precision via the fiber stick. The application process can be carried out via a relative movement of the Lotelements to the pin or by guiding the fiber pen by a robot. The advantage of this method is that a Lotstoppmittelauftrag is possible from all directions. The process can be highly automated.

In all application methods it is possible to move the workpiece relative to the printing device (printhead, applicator) while the printing device is stationary during the printing process.

Suitable solder stop agents are considered substances containing aluminum oxides, titanium oxides, zirconium oxides, magnesium oxides, chromium oxides, boron nitride or calcium carbonate. It is essential that the said oxides are present as high-temperature-stable barrier layers on the component and thus prevent the spreading of the solder. The solder stop means can be used in particular in high-temperature soldering, ie at temperatures of more than 900 ° C, in particular in a temperature range of 1000 ° C to 1200 ° C, preferably in a range of 1000 ° C to 1100 ° C.

The invention will be explained in more detail with reference to embodiments shown in the schematic drawings. It shows:

1 shows an arrangement in which a Lotstoppschicht means of

Inkjet printing method is applied;

Figure 2 shows an arrangement in which a Lotstoppschicht is applied to an uneven surface and

3 shows a pin order of a Lotstoppmittels by a metering system in isometric view.

FIG. 1 shows a component 1 which is provided with a solder stop layer 2. The solder stop layer 2 is located in a narrow local area. It is applied by the ink-jet printing method. An applicator 4 in the form of a print head injects the solder stop means 2 via an air gap 3 onto the component 1. This results in the purely schematically represented applied solder stop layer 2 in the desired arrangement.

FIG. 2 likewise shows a solder stop layer 2 on a component 1. In the illustration to the left of the solder stop layer 2 there is a solder 5 whose propagation in the liquid state is to be prevented by the solder stop layer 2. The surface of the component 1 is somewhat uneven, in contrast to the component 1 in FIG. But here, too, the inkjet printing process is suitable, because it can be overcome to a limited extent and bumps.

FIG. 3 shows a further advantageous embodiment of the invention. In an isometric view, the surface of a component 1 can be seen. A pin 7 is coupled to a dosing system 8, which comprises a reservoir 9. The pin 7 is intended to apply a solder stop layer 2 in a line adjacent to the solder 5. Of course it is also possible that Apply Lotmittel 5 subsequently. In both cases, a barrier is created when connecting to a second component not shown in a subsequent soldering process, which prevents the solder from flowing into undesirable areas.

The metering system is provided with valve means, not shown, which can be opened and closed for applying the Lotstoppschicht. In the system of the pen application, as shown in Figure 3, the pin 7 is held by an arrangement not shown and guided in the desired manner over the component 1 to provide the considered particularly advantageous continuous Lotstopplinien. In the case of highly viscous soldering agents, it is also possible to provide the lines with interruptions in order to save solder stopping means in this way.

REFERENCE CHARACTERS:

1 - component

2 - solder stop layer

3 - Air gap

4 - applicator

5 - Lotmittel

6 - surface

7 - pen

8 - dosing system

9 - Reservoir

Claims

claims

1 . Method for soldering components (1) with the following steps: a) a solder stop layer (2) is applied to at least one of the components (1) to be soldered; b) the solder stop layer (2) is applied in liquid form, wherein the solder stop layer (2) either printed on the principle of ink jet printing or applied by means of an applicator by fiber pin application, which is guided along a Lotstopplinie to be formed from the Lotstoppschicht (2); c) a solder (5) is applied before or after the application of the solder stop layer (2) on the component to be soldered (1); d) The components to be soldered (1) are soldered together with the at least heated to its liquidus solder (5).

2. The method of claim 1, characterized in that the solder stop layer (2) comprises at least one member from the following group of substances: aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide, chromium oxide, boron nitride, calcium carbonate.

3. The method according to claim 1, characterized in that the solder stop layer (2) is applied by fiber stick application, wherein a pin (7) which is connected to a dosing system (8) is used as the applicator.

4. The method according to any one of claims 1 to 3, characterized in that the solder stop layer (2) is applied linearly.

5. The method according to any one of claims 1 to 4, characterized in that the components (1) are components of an exhaust gas recirculation cooler.