DE1665768C - Method for increasing the security of the electrical contact and for improving the solderability of the power supply lines present on electrical components - Google Patents

Description

6. The method according to claim 5, is applied thereby.

indicates that the molten metal from 1 to By the present proposal is thus

30 percent by weight indium and 70 to 99 Ge the lack of wettability and the tendency

is made of tin by weight. 35 to corrosion avoided by the fact that the material

7. The method according to claim 5, thereby defining coherent soldered connections beforehand indicates that the molten metal from 0.5 selected addition of a metal element with good up to 40 percent by weight indium and the remainder from diffusion properties and high wettability tin and lead in the eutectic mixture. speed, as is the case with indium, is supplied.

8. The method according to claim 5, characterized in that 40 The high diffusion rate and alloying characterizes that the molten metal from 80 ability of this element leads also under unfavorable weight percent indium and 20 weight percent conditions, e.g. B. in the absence of fluxes Tin is made. in hard-to-reach places, to remove all

9. The method according to claim 5, characterized by corrosion layers, whereby perfect soldering marks, that the molten metal from 5 to 45 bonds are guaranteed.

80 percent by weight indium and the remainder lead. Solders with added indium are known per se and

can be obtained commercially. this concerns

but not the present invention. A lowering of the melting point of solders by adding them 50 of indium, as is the case with the known solders

The invention relates to a method for increasing the addition of indium, is not intended here Security of the electrical contact and to the point. The invention is all about the safe Improving the solderability of the electrical construction. Degradation of corrosion layers on the elements to be soldered existing power supply. the surfaces of the components.

The failures of mechanical and electronic 55 The proposed method can be based on two things Devices are mainly due to the failure of the loading manner to be carried out. To always use an optin electrical switching components and their degree of paint wetting by breaking down the surface soldered joints traced back. to achieve corrosion layers on components are

The following ways are possible to achieve perfect material-to-material soldered connections:

to produce - this is particularly common in the mass production. . ,,, ...., _D

production of particular importance where high feed ^h _t ^D f ^{indium w 'rd} \ ^{n the z. u are} faced with deliberate building reliability requirements _, have to ^share ! ⁿ «™ ^ ™. ^b / ^{s TO l} ^ ^{m on} ^

applied to the vanic way on the surfaces of the components.

Corrosion layers are completely removed. a) To improve the soldering strength, you can use

This does not always succeed and it is also difficult to see through the galvanically deposited indium, where switching and components are covered with an additional layer of tin (Sn),

Space can be assembled tightly packed. There silver (Ag) or gold (Au) also on

This creates, among other things, the much feared galvanic way of being applied.

665 768

b) The galvanically applied indium layer d) indium 5 to 80 percent by weight, remainder lead;

but can also, because indium has a very strong influence on the bath temperature z. B. + 24O ⁰ C.

Alloy tends to be electroplated on the. . ,

Component produced layer of tin, silver · The under l, a) and b) listed galvanically or be gold-backed. 5 coated surfaces can be used particularly well

apply to all connecting wires of electrical

The strength of the additional, galvanically applied components, such as transistors, diodes, ^co- ed layers, is also in the size, complete electronic assemblies and order up to 1 μm. their soldered interconnection on conductor tracks and

ίο plates. Likewise, this procedure allows

2. The indium may also, in certain cases, namely industrial production of always well lotbaren Hch if galvanic processes ^un because of recom- surfaces of switching wires of copper ^{(J to} "the components are avoided sensitivity whose metals. Prepared Accordingly, connection ought, by The components to be soldered are immersed if they take place in indium-containing metal melts according to the proposal .

In the drawing is an embodiment for

a) 1 to 30 percent by weight indium; a component shown with connection wires that contain 70 to 99 percent by weight tin; Badtem- ao according to the present invention with an indium temperature z. B. 260 ⁰ C; ^l layer are provided. .

F i g. 1 shows the electrical component 1 with the

b) 0.5 to 40 percent by weight indium, the remainder tin both connecting wires 2..

and lead in the eutectic mixture; Badtem- F i g. 2 shows an enlargement of the section 11

temperature z. B. 260 ⁰ C; a ₅ in Fig. 1. The connecting wire 2 consists of the

actual wire 3, which is made of indium

c) indium 80 percent by weight; · Standing or at least containing indium Tin 20 percent by weight; Layer 4 is surrounded.

1 sheet of drawings

Claims (5)

ί 665 768 5 ι ^ i cold solder joints and contact breaks, the claims: possibly for. Failure of complex devices can lead to serious consequences 1. Procedure to increase the security of the cause. The technical soldering process, electrical contact and to improve the 5, irrespective of whether it is wave soldering or dip solderability of power connection elements, is associated with the lack of Bescher components due to the application of a thin wetting ability of the parts to be connected.
Metal layer on the connection elements, d a- To remedy these disadvantages, it is already characterized in that a little known to supply the so-called soldering flux, which is applied during the soldering process to the soldering point and which contains metal layer containing indium. This solder flow will. . agents have a slightly basic or acidic character 2. The method according to claim 1, characterized in character and therefore pickling at the soldering point indicates that the power supply lines are on existing corrosion layers away. Apart from that galvanic way with an indium layer of it that it is often difficult to get the flux about 1 μπι are provided. 15 to the soldering point even cause this 3. The method according to claim 2, characterized in the course of time an increased corrosion of the soldering, that on the indium layer on gall; they must therefore be used after the soldering process Vanisch way another layer of tin, remove again from the soldering point. Silver or gold also by electroplating. It is also known that the contacts to be soldered a thickness of about 1 μπι is applied. 20. Surfaces to be covered with a thin layer of precious metal 4. The method according to claim 2, thereby drawn. However, this procedure is very inherently indicates that before the galvanic charge. Both contacts to be soldered must also be worn the indium layer on the power supply surfaces be coated with precious metal those with an approximately 1 μπι thick layer of the present invention has the object zuZinn, silver or gold by electroplating 25 reasons, ^d: e to contact reliability of the solder joints on provided. Power connection elements of electrical components and 5. The method according to claim 1, characterized in that the solder joint itself is secure by application indicates that the at least indium be a thin metal layer on the connection elements standing layer on the power leads through to increase. Immersion in a bath of molten metal takes place, 30 This object is achieved according to the invention. which contains indium. solves that at least one indium-containing layer