DE102005040685A1 - Design for electrical resistor with positive temperature coefficient, includes belt around ceramic material with electrical end contacts, suitable for surface mounting - Google Patents

Abstract

It is an electrical component (1) with a main body (2) indicated that a belt area (3) largest lateral Expansion and next to the belt area having applied electrical contact body (4), wherein the body a cross-shaped longitudinal section Has. In the process for the production of electrical components (1) a surface substrate (5) using material removal on two opposite surfaces with a trench structure and the surface of the surface substrate with electrical Contact bodies (4) and provided with electrical contact bodies surface substrate isolated into individual electrical components.

Description

It is an electrical component and a method of manufacture of electrical components, in particular of PTC components.

Out US 6,285,275 B1 For example, a PTC resistance element having terrace-like planar surfaces is known.

A to be solved The object is to provide an electrical component which in big Quantities with tight electrical tolerances can be produced.

A Another object is to provide an electrical component, which in large quantities can be produced with minimal costs.

It an electrical component is specified with a basic body, whose lateral extent is greatest in a belt area, being next to the belt area electrical contact body on the main body are applied.

Of the Area of the body, which is next to the belt area is compared to the belt area narrower in the lateral direction. Thus, the main body and the electrical component characterized by a cross-shaped longitudinal section.

The electrical component can according to a SMD construction lying on a support plate, which preferably has electrically conductive areas, are mounted. The electrical component is preferably by means of his belt area with the carrier plate connected. However, it is also possible that the device by means of its contact body areas on a Lot a carrier plate is mounted.

To an embodiment the electrical component has a cuboid shape at at least one point, so that the device has a plurality of planar surfaces through which the Component orientation independent SMD mountability is offered.

It is cheap, when the electrical contact body realized with sputtered metallizations. This results the advantage that the electrical component is monolithic, So, for example, without separately applied contact caps constructed can be. The contact bodies can However, also be realized as electrically conductive outer layers.

Of the body of the electrical component preferably contains ceramic material, so that the electrical component in particular as a thermistor, NTC or PTC device, Varistor or can be designed as a capacitor.

The described electrical component may advantageously be particularly simple, inexpensive and produced as a series product.

• – ein Flächensubstrat anhand von Materialabtragung auf zwei sich gegenüberliegenden Oberflächen mit einer Grabenstruktur versehen wird,
• – die Oberflächen des Flächensubstrats mit elektrischen Kontaktkörpern versehen werden,
• – das mit elektrischen Kontaktkörpern versehene Flächensubstrat in einzelne elektrische Bauelemente vereinzelt wird.

A suitable manufacturing method is that:

• A surface substrate is provided with a trench structure on the basis of material removal on two surfaces lying opposite one another,
• The surfaces of the surface substrate are provided with electrical contact bodies,
• - The provided with electrical contact bodies surface substrate is separated into individual electrical components.

With The creation of a trench structure arise next to the trenches as well tabular Elevations, so the surface of the surface substrate can also be understood as a mesa structure. The isolation of the surface substrate is preferably carried out on the basis of a central transection of the surface substrate in the trenches.

With At the same time, a plurality of such a production method can be used electrical components with absolute and mutually small Differences in their electrical properties are produced, because on a single, structured surface substrate continuous electrical Contact body can be generated and only then the surface substrate is severed. Across from a method in which individual electrical components after the Singulation of the surface substrate with contact bodies, for example, by immersion in a metal bath, be provided have to, Another advantage is that at least one step is saved in the production of the electrical component.

It it is preferred that the electrical contact bodies in the form of metallizations on the basis of a kinetic exchange on the surface substrate applied, metallic material with the surface material of the surface substrate in the trenches be incorporated. For application, sputtering methods are preferred. When sputtering there is the advantage that forming a metallization in no time Time can be done and the electrical and mechanical properties the metallization can be kept in very tight tolerances.

It it is preferred that the surface substrate be ceramic material contains. In this case, the surface substrate one piece be educated. However, it is also possible that the surface substrate from several, one above the other stacked, green Ceramic films, which are then sintered. The sintered surface substrate can be separated monolithically into individual multilayer ceramic bodies after structuring be such. in multilayer ceramic capacitors (MLCCs) or multilayer varistors.

The Material removal can be done by sawing, milling or etching, depending on from which materials the surface substrate consists. In the case of sawing the use of a diamond saw is preferred, in particular then when the surface substrate Contains ceramic material.

The described objects will be apparent from the following embodiments explained in more detail.

there shows:

1 a perspective view of an electrical component having a belt region having base body,

2a a side view of the electrical component with geometric dimensions,

2 B a cross-sectional view of the electrical component with geometric dimensions,

3a a side view of a structured surface substrate,

3b a plan view of a provided with a mesa structure surface substrate.

1 shows an electrical component 1 , In particular, a PTC component, which has a substantially cuboid, sintered ceramic body 2 includes. The base body can contain a resistance-forming PTC ceramic material, preferably barium titanate. The end regions up to the end faces of the component are metallized by sputtering, preferably with nickel and chromium radiation. Between the metallized areas 4 of the component protrudes centrally a ceramic area 3 out of the base body, which is executed with its enlarged cross-section or its lateral extent as a belt or as a corset in relation to the remaining areas of the body. This results in a total of a cross-shaped longitudinal section of the device.

The metallized areas 4 can reach down to the belt area 3 extend. The belt 3 The device is preferably free of metallization and may be connected to a circuit board on a planar surface side. The belt 3 should have at least two opposite planar surfaces, whereby a good handling, for example, with a vacuum pipette, is offered for mounting the device on a circuit board. It is thus favored by the planar surface, in particular by a cuboid shape, which has a planar surface result, a so-called "pick and place" method for mounting on a circuit board.

The electrical component is preferably constructed monolithically, ie, it consists for example only of a base body made of a suitable ceramic powder 2 and on the surface of the body incorporated or applied electrical contact bodies 4 ,

• – eine Länge 1 zwischen einem und 2 mm, vorzugsweise aber eine Länge von 1.56 mm,
• – eine Breite b und eine Höhe h zwischen 0.5 mm und einem mm, vorzugsweise aber 0.88 mm.

The 2a and 2 B together show an electrical component 1 , whose basic body 2 which has the dimensions length 1, width b and height h. For example, the following dimensions are possible for a typical electrical component:

• A length 1 between one and 2 mm, but preferably a length of 1.56 mm,
• A width b and a height h between 0.5 mm and one mm, but preferably 0.88 mm.

Between the front sides of the component and the belt 3 of the main body is the basic body between k = 0.2 mm and 0.7 mm, but preferably 0.5 mm, long. The length k corresponds to the depth of the trenches generated during structuring 7 , The metallized areas 4 of the basic body 2 can therefore each have these lengths k. The height of the belt 3 exceeds the remaining component by a value x of between 0.02 mm and 0.08 mm, but preferably by 0.05 mm. Depending on the size and material properties of the component, the electrical resistance of the body 2 preferably set between 30 and 33 Ω, in particular to about 31.5 Ω .. Also, the length k of the metallized region 4 of the basic body 2 because of with the 3 exactly described manufacturing process to exactly 0.01 mm adjustable. The length of the belt area is thus about 1-2k.

3a is an edge view of a structured, sintered surface substrate 5 , By means of a material removal process, for example by double-sided sawing with a diamond saw 6 , become ditches 7 incorporated into the surface substrate. The trenches are preferred wise with a depth of k = 0.2 mm and 0.7 mm, but preferably 0.5 mm and a width of about 200 microns created. In the trenches, nickel and / or chrome can be fired during sputtering, to metallizations 4 to produce, which after the separation of the surface substrate as a contact body 4 to serve for the electrical components. A nickel-chromium double layer is favorable as reinforced metallization. After the separation of the surface substrate, the depth k of the trenches corresponds 7 the length of a metallized area 4 an electrical component, as in 2 shown. However, it is also possible to lay conductor tracks, for example in the form of conductive layers, in the trenches. Next to the trenches 7 When surveying surveys or Mesas arise 8th , whose width after separating the to the 2 said width b of each electrical component results.

The separation of the surface substrate 5 done by a separation along with the other saw 9 and the dashed line shown line. The further saw 9 or another cutting tool is narrower than the saw 6 , z. B. 150 microns. After the separation or separation of the component body, areas of the base body protruding beyond the dividing line remain. After separation of the electrical components by separating the surface substrate corresponding to these protruding areas, the belt areas 3 the electrical components, preferably with heights x according to 2 , With the example dimensions mentioned, x is about 0.25 μm to 0.5 μm.

The surface substrate can consist of several sintered ceramic layers or ceramic green sheets consist. Between these films can also internal electrodes present be, for example, the main body of a ceramic multilayer component or to form varistors. A trench structuring according to the mentioned Manufacturing process is still possible.

In 3b For example, the surface structure of the surface substrate is shown by a plan view. The surface substrate 5 is sawn on both sides, creating a regular pattern of straight, regular trenches 7 and intervening surveys. The surveys or Mesas are in the Ausführungsbeispeile the 3 rectangular, but can also be like in 2 be square. The surface substrate is then separated by means of a central, the course of the trenches corresponding cut with a suitable tool. This is done with a dashed and with a saw 9 marked line shown.

After the separation of the surface substrate into a plurality of electrical components, these are preferably nickel-plated and tinned around the metallized regions 4 to make the component as flat as possible and to reinforce it. This favors a stable pick and place assembly.

By the high precision in the geometric dimensions parallel producible electrical Components, which can be reached by said production methods are, can tight electrical specifications are met. The tolerance of Resistance values (R25 value) of the electrical components produced is for example +/- 10%.

1

electrical module

2

body

3

girdle of the basic body

4

electrical Contact body

5

surface substrate

6

saw

7

dig of the surface substrate

8th

survey of the surface substrate

Claims (16)

Electrical component with a basic body ( 2 ), one - belt area ( 3 ) largest lateral extent and adjacent to the belt area applied electrical contact body ( 4 ), wherein - the base body has a cross-shaped longitudinal section. Electrical component according to Claim 1, in which the basic body ( 2 ) has a cuboid cross-section. Electrical component according to one of Claims 1 or 2, in which the electrical contact bodies ( 4 ) metallized areas of the body ( 2 ) are. Electrical component according to Claim 3, in which the metallised regions ( 4 ) are sputtered. Electrical component according to one of the preceding claims, in which the main body ( 2 ) Contains ceramic material. An electrical component according to claim 5, wherein the ceramic material is a PTC ceramic material. An electrical component according to claim 6, wherein the ceramic material contains barium titanate. An electrical component according to claim 5, wherein the ceramic material is NTC ceramic material. Electrical component according to one of Claims 1 to 5, in which the basic body ( 2 ) contains a varistor ceramic. Electrical component according to one of the preceding claims, in which the belt region ( 3 ) of the basic body ( 2 ) has a planar surface. Method for producing electrical components ( 1 ), in which - a surface substrate ( 5 ) is provided with a trench structure on two opposite surfaces by means of material removal, - the surfaces of the surface substrate for the production of electrical contact bodies ( 4 ) are provided with a metallization, - provided with electrical contact bodies surface substrate is separated into individual electrical components. Method according to Claim 11, in which the electrical contact bodies ( 4 ) are generated by sputtering. The method of claim 12, wherein sputtering with irradiation of chromium and nickel. Method according to one of claims 11 to 13, wherein the Material removal Sawing and milling includes. Method according to one of claims 11 to 14, in which the separation into a plurality of electrical components ( 1 ) by means of a transection of the surface substrate ( 5 ) along the trenches ( 7 ) of the trench structure. Method according to one of claims 11 to 15, wherein the individual electrical components are nickel-plated and tin-plated.