DE102011011748A1 - Method for soldering components - Google Patents

Abstract

The invention relates to a 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, the solder stop layer (2) either being printed on or applied by means of an applicator which is guided along a solder stop line to be formed from the solder stop layer (2); c) A solder (5) is applied to the component (1) to be soldered before or after the solder stop layer (2) is applied; d) The components (1) to be soldered are soldered to one another with the solder (5) heated to at least its liquidus temperature.

Description

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.

By the WO 2005/043966 A1 It is known 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 the EP 0128386 A1 For example, 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 will be made in the DE 197 122 19 A1 made. Processing takes place at 200 to 400 ° C. In the US 3703386 For a printed circuit board, it is proposed to use a chemical barrier by means of a solder stop agent made 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.

The invention is therefore based on the object to show a method for soldering, in particular for high-temperature soldering of components, with which the order of Lötstoppmittels is considerably simplified and with which the order even in complex component structures, such as exhaust gas recirculation cooler, in mass production is possible.

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.

• a) Auf wenigstens einem der zu verlötenden Bauelemente wird eine Lotstoppschicht aufgebracht;
• b) Die Lotstoppschicht wird in flüssiger Form aufgetragen, wobei die Lotstoppschicht entweder aufgedruckt oder mittels eines Applikators aufgetragen wird, welcher entlang einer aus der Lotstoppschicht zu bildenden Lotstopplinie geführt wird;
• c) Anschließend erfolgt der Lötvorgang mittels eines Lotmittels, das vor oder nach dem Auftragen der Lotstoppschicht auf wenigstens eines der miteinander zu verlötenden Bauelemente aufgetragen wird.

The method according to the invention for soldering components comprises the following steps:

• a) On at least one of the components to be soldered, a Lotstoppschicht is applied;
• b) 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 Lotstopplinie 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 preferably printed in the form of a solder stop line, wherein different printing methods can be used to apply the chemical reaction layer which effects the solder stop. 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 solder stop layer can either promote this natural oxidation or be applied in liquid form. The liquid form of the solder stopper also comprises a viscous or pasty consistency.

The solder stop layer can be applied by screen printing, for example. Lotstoppmittel can be used in pasty or liquid form. Screen printing is suitable for flat structures, whereby a process from top to bottom is possible due to the process.

Alternatively, the so-called pad printing can be used. In this printing process pasty Lotstoppmittel be used. This printing process is not limited to an order from top to bottom and is well suited for flat components.

Alternatively, the Lotstoppmittel be applied by the stamping pressure. In this process, rather fluid Lötstoppmittellösungen are used, which are located in the stamp pad of the stamp. The wetted with the solder stopper stamp can be pivoted over the areas to be printed, so that unwinding takes place.

It is also conceivable to apply the Lotstoppmittel in the form of a liquid solution by 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.

Particularly advantageous is the application with an applicator in the form of a fiber pen is considered. About the fiber pen, for example, Ti ₂ O ₃ -containing pigments in a very flexible manner and high precision. 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 printing methods, it is possible to move the workpiece relative to the printing device (stamp, printhead, applicator) while the printing device is stationary during the printing process.

Suitable solder stop agents are considered to be substances which contain 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 are particularly useful in high temperature soldering, d. h at temperatures of more than 900 ° C.

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

1 an arrangement in which a Lotstoppschicht is applied by means of the printing process;

2 an arrangement in which a Lotstoppschicht is applied by the pad printing method and

3 a pin order of a Lotstoppmittels druch a dosing in isometric view.

1 shows a component 1 that with a solder stop layer 2 is provided. The solder stop layer 2 is located in a narrow local area. It is applied by means of the screen printing process. For this purpose, a sieve 3 on the component 1 positioned. The sieve 3 has in a manner not shown the function of a template and is permeable in some areas for the Lotstoppmittel to be applied and not in other areas. For the job, the Lotstoppmittel on the component 1 facing away from the screen 3 given and by means of a squeegee 4 that's over the sieve 3 is guided through the sieve 3 pressed. This results in the purely schematically shown applied Lotstoppschicht 2 in the desired arrangement. 2 also shows a solder stop layer 2 on a component 1 , In the picture to the left of the solder stop layer 2 there is a solder 5 , whose propagation in the liquid state through the solder stop layer 2 should be prevented. The surface of the device 1 is unlike the component 1 in 1 a bit uneven. Therefore, not the screen printing process is used, but the principle of so-called pad printing. This printing process is an indirect printing process. First, a cliché with the desired print image is created. The printed image is lower than the surface. In the recessed printed image Lotstoppmittel is introduced by means of a doctor blade. Excess Lotstoppmittel is removed cleanly by means of the doctor blade. Subsequently, a tampon, which is usually made of silicone rubber, lowered onto the printing plate and thus takes the printed image, ie the Lotstoppmittel from the cliché. Then the tampon lifts off the printed image and becomes the component 1 relocated. There, the tampon lowers and adapts to the surface contour 7 of the component 1 flexible. As a result, curved surfaces that are convex, concave or even irregular, can be printed. The tampon takes due to its elasticity, the surface contour 7 of the component to be printed 1 and so can the print image or the Lotstopplinien that of the Lotstoppschicht 2 be formed, exactly transferred. Due to its adaptability, this printing process can be adapted to different geometries.

LIST OF REFERENCE NUMBERS

1

module

2

solder resist layer

3

scree

4

doctor

5

Solder

6

surface

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2005/043966 A1 [0003]
• EP 0128386 A1 [0004]
• DE 19712219 A1 [0004]
• US 3703386 [0004]

Claims (8)

Method for soldering components ( 1 ) comprising the following steps: a) on at least one of the components to be soldered ( 1 ) a solder stop layer ( 2 ) applied; b) The solder stop layer ( 2 ) is applied in liquid form, wherein the solder stop layer ( 2 ) is either imprinted or applied by means of an applicator which extends along one of the solder stop layer ( 2 ) is guided to be formed Lotstopplinie; c) A solder ( 5 ) is applied before or after application of the solder stop layer ( 2 ) on the component to be soldered ( 1 ) applied; d) The components to be soldered ( 1 ) are heated with the at least to its liquidus temperature heated solder ( 5 ) soldered together. Method according to claim 1, characterized in that the solder stop layer ( 2 ) is applied by screen printing. Method according to claim 1, characterized in that the solder stop layer ( 2 ) is applied by pad printing. Method according to claim 1, characterized in that the solder stop layer ( 2 ) is applied by stamp printing. Method according to claim 1, characterized in that the solder stop layer ( 2 ) is applied according to the principle of inkjet printing. Method according to claim 1, characterized in that the solder stop layer ( 2 ) is applied by fiber stick application. Method according to one of claims 1 to 6, characterized in that the solder stop layer ( 2 ) comprises at least one member of the following group of substances: alumina, titania, zirconia, magnesia, chromia, boron nitride, calcium carbonate. Method according to one of claims 1 to 7, characterized in that the components ( 1 ) Are components of an exhaust gas recirculation cooler.

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