DE9101284U1 - Electrical resistance - Google Patents

Description

SAMSON & BÜLOW

PATENT ATTORNEYS O/A.lVlO\Jl> (JL J-Jl^-A-ZV-/ VV WIOENMAYERSTR.

FR. von SAMSON-HIMMELSTJERNA '. D-8000 MUNICH

DIPL-PHYS. D.TCwTuntfAiTcii.wvici TELEPHONE; 089/229461

DR. TAM AXEL von BÜLOW KAItNlAINWALIbKA[NzLLtI TELEGRAM: SAMPAT

DIPL - ING., OIPL. -WIRTSCH. - ING. TELEX: 521 4940 egsa d

Fax: 089/29 94

SAMSON S BÜLOW ■ PATENT LAW FIRM WIDENMAYERSTFt 5 D-8000 MUNICH 22

Applicant :
Wilhelm Ruf KG
Schwanthalerstrasse 18

Munich 2

YOUR SIGN/YOUFt REF: OUR SIGN/OUR REF.: DATE/OATE;

R10-108-B 91 G 5 February 1991

vB/lo

Electrical resistance

Description

The innovation relates to an electrical resistor according to the generic term of claim 1. Such electrical resistors, which are also known as thick-film resistors or thick-film resistor networks and are commercially available, usually have a ceramic carrier onto which resistors made of electrically conductive paste are printed using screen printing technology.

To contact the individual resistors, the thick-film resistors available on the market have clamps that are attached from the underside of the carrier and enclose the end sections of the side surfaces in a U-shape and also have protruding clamps from the underside of the carrier.

Have solder lugs with which the resistors are then soldered onto a circuit board. To better fix these clamps to the carrier, they are also soldered onto the resistors.

These known resistance networks are due to the

Clamps are complex to manufacture, have a relatively high construction height and poor handling properties. Viewed from the front, the known resistors ,Q have a T-shaped cross-section with an unfavourable centre of gravity distribution, so that these resistors have poor stability properties when not soldered in, which makes assembly more difficult. This disadvantage is further exacerbated by the connection lugs, which increase the construction height.

The aim of the innovation is to improve the electrical resistance of the type mentioned above so that it is easier to manufacture and easier to handle and has good stability, especially with a low installation height.

According to the innovation, this task is solved in that the connection contacts consist of a flat layer, which is applied to the same side surface as the associated resistor and that the connection contacts extend from the associated resistor to the edge between the side surface and the underside of the carrier.

In contrast to the current state of the art, the connection contacts no longer protrude from the underside of the carrier, which reduces the overall height and provides better stability. Manufacturing is also simplified, as the clamps with the soldering tabs no longer have to be mounted and the almost smooth, cuboid shape of the component prevents mutual snagging, which makes handling easier.

Advantageous embodiments and further developments of the innovation can be found in the subclaims.

The innovation is explained in more detail below using two examples in conjunction with the drawing. It shows:

Fig.l A side view of an electrical resistor with four individual resistors according to the first ^q embodiment of the innovation;

Fig.2 A perspective view of a resistor network with eight resistors and nine terminals; and

Fig.3 A perspective side view of the resistance network of Fig.2 with additionally applied

insulating layer.

All three figures are in a greatly enlarged scale. In a practical embodiment for the grid size
1.27 mm the following dimensions are provided: length 12 mm, height 2.54 mm and width 2 mm.

Identical or corresponding parts in the individual figures have the same reference numerals.

A carrier 1 made of electrically insulating material, in particular ceramic, has a cuboid shape. Its six sides are provided with the following reference symbols in the drawing for clarity: top side 2, bottom side 3, side surfaces 4 and 5, end faces 6 and 7. These designations refer to the normal installation position, in which the bottom side 3 rests on another component such as a circuit board.

In the embodiment of Figure 1, a total of four resistors 8 made of conductive paste are printed on the side surface 4, whereby these resistors extend in the longitudinal direction of the carrier and are arranged one behind the other in a line

are arranged. The respective ends of the resistors 8 cover L-shaped connection contacts 9, which extend from the resistors in the direction of the underside 3 of the carrier 1 and, in the embodiment shown, end at the edge between the side surface 4 and the underside 3. The horizontal legs of the L-shaped connection contacts 9 are thickened in order to form a sufficiently large area for later soldering.

IQ In the embodiment of Figure 1, the resistors 8 are independent of each other in terms of circuitry and can each be connected via the associated connection contact pair.

,,- Line 12 in Figure 1 illustrates a calibration cut, which is applied with a laser beam in order to precisely adjust the electrical resistance value.

Although not shown in Figure 1, the side surface 4 including the resistors 8 and the vertical 0

Legs of the connection contacts 9 are covered with an insulating varnish, so that essentially only the horizontal legs of the connection contacts are exposed (see insulating layer 13 of Fig. 3)

Figure 2 shows another variant in which a total of eight electrical resistors 8 are connected in the form of a resistor network. The individual resistors 8 are each arranged as elongated, rectangular strips

parallel to each other, with their sides pointing to the top 2-30

the ends contact a common conductor track 10. One end of this conductor track 10 is led to a connection contact 11 in the direction of the bottom 3. The ends of the resistors 8 pointing towards the bottom 3 each contact

an associated connection contact 9, which essentially 35

is rectangular and extends to the edge between the side surface 4 and the bottom 3. On one of the resistors, the line 12

7
Again, the adjustment is shown using laser cutting.

Figure 3 shows the resistor network of Figure 2 with an additional insulating layer 13, which essentially covers the entire side surface 4 and in particular the resistors 8 and the conductor track 10 and has recesses only in the area of the connection contacts 9 and 11, which are formed here by projecting webs 14 that extend into the space between two adjacent connection contacts. These webs in particular prevent unwanted solder bridges from forming between adjacent connection contacts when the finished component is soldered on.

•,c Although not shown in the drawing, it is readily apparent that both side surfaces 4 and 5 can be used to apply resistors, possibly conductor tracks and connecting contacts. It is also readily apparent that any configuration in the arrangement of the resistors and possibly conductor tracks can be provided within the scope of the available area. It is important that the connecting contacts are brought up to the underside 3 of the carrier 1 in order to create a hybrid circuit when the carrier 1 is placed on a circuit board.

etc. soldering the connection contacts 9 or 11 to 25

A small distance between the downward-pointing end of the connection contacts and the edge between the side surface 4 or 5 and the underside 3 of the carrier can be present, provided that this enables solderability. The connection contacts and possibly conductor tracks are preferably made of silver and in particular platinum silver, which is applied using a screen printing process. To improve solderability, the connection contacts are also dipped in a bath.

to tin, which after printing the insulating varnish-35

layer 13. The resistors 8 can also be applied using screen printing or other application techniques from resistance lacquer or paste.

Claims (5)

PATENT ATTORNEYS O A-JV IS O JN 0£ O L^ .L; C_J YV WIDENMAYERSTR. FR by SAMSON-HIMMELSTJERNA _: : D-8000 MUNICH DIPL-PHYS datcmtawu/ai tcv AM7I CT TELEPHONE: 0 89/22 94 DR.TAMAXELvonBÜLOW PATENT LAW FIRM TELEGRAM: SAMPAT DIPL-ING, DIPL-WIRTSCH-ING. TELEX: 521 4940 egsa d Fax: 089/29 94 SAMSON & BULOW PATENT LAW FIRM WIDENMAYERSTR 5 D-8000 MUNICH 22 Applicant: Wilhelm Ruf KG
Schwanthalerstrasse 18 Munich 2 YOUR REF.: OUR REF. DATE: R10-108-B 91 G 5 February 1991 vB/lo Electrical resistance Protection claims 1. Electrical resistor with a cuboid-shaped carrier made of electrically insulating material, which in relation to its installation position has a bottom, a top, two side surfaces and two end surfaces, wherein at least one electrical resistor in the form of a layer of resistance material is applied to at least one of the side surfaces, which is connected to connection contacts made of electrically conductive material, characterized in that that the connection contacts (9, 11) consist of a flat layer which is applied to the same side surface as the associated resistor (8) and that the connection contacts (9, 11) extend from the associated resistor (8) to the edge between the side surface (4, 5) and the bottom (3) of the carrier (1). 2. Electrical resistance according to claim 1, characterized in that the connecting contacts (9, 11) are made of platinum silver. 3. Electrical resistance according to claim 2, characterized in that that the connecting contacts (9, 11) are additionally tinned. 4. Electrical resistance according to one of the claims
,c 1-3, characterized in that that a covering layer (13) made of electrically insulating material is applied to the side surfaces (4, 5), which completely _covers the at least one electrical resistor and possibly conductor tracks (10) and which in the area of the connection contacts (9, 11) has recesses. 5. Electrical resistance according to one of claims 1-4, characterized in _oc that several resistors (8) on one or both side surfaces (4 and/or 5).