DE102004048434A1 - Electronic component, useful for mounting at a disk of a motor vehicle, comprises a housing for soluble mounting (made of optical coupling medium comprising silicon gel) at a disk of vehicle - Google Patents

Abstract

Electronic component (A) comprises a housing for soluble mounting (made of optical coupling medium) at a disk of a motor vehicle, where the disk is placed on the medium, and the optical coupling medium comprises at least one silicone gel, which is obtained by the reaction of at least one vinyl organosiloxane with at least one hydraulic organosiloxane. An independent claim is also included for a preparation of silicon gel pads for the use in an electronic component comprising making a two-component material from starting substances necessary for silicone gel, whose components (A) and (B) are separated itself and are storable, and later producing a compound from these components in a certain mixing proportion.

Description

The The present invention relates to an electronic component comprising a housing for releasable Attachment to a window of a motor vehicle, the attachment of the housing on the vehicle window over an optical coupling medium takes place, which on the vehicle window is applied, wherein the optical coupling medium at least one silicone gel includes.

An electronic component of the type mentioned is, for example, in the DE 101 19 219 A1 described. Electronic components of this type serve as sensors for different applications, for example. For example, it may be rain / light sensors. In these rain / light sensors, an optical measuring principle is applied, which is based on the fact that light falls through the windshield of a motor vehicle on the sensor and infrared light from the sensor at the outer interface of the windscreen is totally reflected, if there is no wetting of the vehicle window by raindrops. With the help of this information, for example, the windshield wiper system or lighting of the motor vehicle can be switched on and / or off.

In order to the light rays through a good coupling through these components can go through, An optically clear gel is poured onto the sensor optics, which is when mounting the rain / light sensor Good on the windscreen and reserves after a short time no bubbles inclusion. In the previously mentioned document from the prior art is hereby used a silicone-based gel.

Of the Sensor can be attached for example by means of a retaining ring, the by means of a structural adhesive on the windshield is glued. The retaining ring, for example, by resilient brackets held and pressed with the gel become. The sensor should be mounted on the disc and disassembled can be. For this purpose, in the prior art windscreens with previously glued Retaining rings available posed. So that the joining forces are not get too big The gel should only have a module of a certain height.

at Dismantling experiments using the prior art known silicone gel was found that dismantling only comparatively short time, for example hours or days successful possible is. If successfully disassembled, the gel must be on the sensor side without replacement or injury to the gel pad. Indeed However, already after the gel is comparatively short Time on the vehicle window is a cohesive rupture of the Gels on, or later on adhesive Failure on the sensor side. Then the gelpad is on the Vehicle window and the sensor can not as required to a new disk provided with retaining ring can be applied.

There Windshields during the operation of a motor vehicle, for example, by scratching damaged be damaged or damaged by stone chipping or accident an exchange of the vehicle window may be possible. In these cases is It makes sense to use high quality electronic components such as Disassemble sensors of the aforementioned type and on the new vehicle window to mount.

The Object of the present invention is an electronic Component with a housing for Attachment to a disc of a motor vehicle of the aforementioned Genus available to provide a smooth even after a long period of time Dismantling of the component without damage is possible.

ADVANTAGES OF INVENTION

The solution This object is achieved by an electronic component of the aforementioned Genus with the characterizing features of the main claim.

The silicone gel used as the coupling medium of the type according to the invention is an optically clear gel which should be transparent in the visible and near infrared light range and preferably has good transparency in the wavelength range between approximately λ = 380 nm and 1320 nm. During processing, the material, which is usually liquid at first, should spread well and vent gas bubbles quickly. The Viscosity in the initial state of the silicone gel is preferably comparatively low. The assembly of the component should be possible with a comparatively low counterpressure in order not to overload the fixing adhesive and if possible to allow a small adhesive surface. The gel pad of the component should preferably be easily detachable even after long-term storage of heat from a glass surface, so that the gel pad rests undamaged after a separation operation on the sensor, which has a plastic housing in the rule.

According to the invention will be different as in the previous known solutions, so to speak, a "solid" of the gel material on the glass surface prevented. A one-sided increase the adhesion on the other hand, the plastic material of the sensor housing is not enough because the internal strength of the gel is low and in the separation operation tear through the gel pad would. The silicone gel pads used so far have turned into a good one Solve Disassembly probably prevented by the silicone gel pad chemically combines with the glass in some form.

Around the rheological behavior regarding the silicone gel according to the invention to be able to judge you look at the dynamic-mechanical spectroscopy. The measured Sizes say about the characteristic relaxation times of a material. Becomes For example, a macromolecular material using this method examined, receives one the shear modulus | G * | as a complex entity whose decomposition into the (elastic) real part the memory module G ', the (viscous) imaginary part the Loss modulus G "results.

In a single phase elastomeric material that is above its glass transition, the storage modulus G ' _{o is} proportional to the network node density of the macromolecular network. If the module G 'is plotted as a function of the measurement frequency, it will be noted that there is a region along the frequency axis in which the memory module is independent of the frequency. In this range, G ' _o corresponds to the network node density in the material. At high frequencies, other short chain segments will no longer be able to follow the imposed oscillatory motion and result in an increase in G '. If the area of G ' _o on the frequency axis is large, a relatively uniform network exists. If the region between the G ' _o and the high-frequency region of G' is characterized by a broad transition region, then this is an inhomogeneous network whose internal relaxation times are distributed between the network nodes and free chain ends according to the number of different chain lengths.

In order to evaluate the wetting and wetting behavior in terms of the rheological properties, extensive work has been carried out by various authors in the past. The properties of pressure-sensitive adhesives and their behavior has been described, for example, by Dahlquist [Proc. Nottingham Conf. On Adhesion, in Adhesion: Fundamentals and Practice. McLaren, London 1966]. Accordingly, a material must have a certain flexibility to be able to wet a substrate when pressed. This Dahlquist criterion can be estimated as a modulus value of about 1 × 10 ⁵ Pa. At the same time, however, in the relevant joining time range, the wetting of the substrate takes place irreversibly when the viscous portions in the coating material exceed the elasticity. This is true if the loss modulus G "is> storage modulus G '. This relationship is reflected in the loss factor tan (δ) = G "/ G 'again. Consequently, in addition to the Dahlquist criterion, a flow criterion tan (δ)> 1 is required in order to achieve a permanent adhesion from the flow behavior during the joining process. In addition, the surface energies of the substrate should be greater than those of the coating material, so that a spontaneous wetting occurs.

• – Das Modul G' muss klein genug bleiben, damit der Sensor ohne große Kräfte bei der Fügung komprimiert werden kann,
• – die Benetzung muss gegeben bleiben, damit keine Blasen im optischen Weg entstehen oder bestehen bleiben.

In the case of consciously induced dewetting, mutatis mutandis, the contrary applies. However, since a good connection of the surfaces is to be achieved in use, so that the optical coupling between the glass and gel pad is given, not all three of these criteria can be moved into the dewetting friendly area.

• - The module G 'must remain small enough so that the sensor can be compressed without great forces in the joining,
• - The wetting must be maintained, so that no bubbles in the optical path arise or remain.

As a result, indicates a material with a tan (δ) <1 especially preferred rheological dandruff behavior.

Particularly preferred raw materials according to the invention are polyfunctional alkenyl-polydimethylsiloxanes and hydro-siloxanes of the general formula:

Or:

mit d = 0...28; bevorzugt 1 oder 0
mit e = 0...4; bevorzugt 0 oder 1In formula (I), R ^x or R ^{y are} :

with d = 0 ... 28; preferably 1 or 0
with e = 0 ... 4; preferably 0 or 1

mit d = 0...28; bevorzugt 1 oder 0
mit e = 0...4; bevorzugt 0 oder 1 ist.In formulas (I) and (III), R ^a or R ^{b are} : -CH = CH ₂ or:
-C _f H _{2f + 1}
with f = 0 ... 28; preferably 1 or 0 or:
phenyl
and: n = 1 ... 5000; preferably 2 ... 2000
or: m = 3 ... 1000; preferably 3 ... 10
or
In formula (III), R ^a or R ^{b are} :

with d = 0 ... 28; preferably 1 or 0
with e = 0 ... 4; preferably 0 or 1.

In formula (II), Y:
Remainders of the formula

Where a = 0 ... 20
b = 0 ... 12
c = 0 ... 12
d = 0 ... 8
with R = R ^a or R ^b , R ^x or R ^y
and where R '; R '' may be equal to R;
and X = R ^a or R ^b , R ^x or R ^y .

In The literature describes the suitable catalysts.

DESCRIPTION THE EMBODIMENTS

following the present invention will be described in more detail by means of exemplary embodiments.

Embodiment 1

Successively 249.0 g of a material of the formula (III)
with mean m = 4; 6 × R ^a with d = 2; e = 1 and 2 × R ^a where d = 1; e = 0 and 698.0 g according to formula (I) with R ^y = R ^x with d = 0; R ^a = R ^b with d = 1 as well
53.0 g according to formula (I) with an average of 19 × R ^a with f = 0; on average 231 × R ^b with f = 1; R ^x = R ^y with d = 1; e = 0 and on average 212 × R ^a with f = 1 with a mean n = 231
with 0.80 g of a Karstedt catalyst mixture with a 20 ‰ Pt (0) content in a vinyl-terminated polydimethylsiloxane having a viscosity of 412 mPas at 25 ° C. with a shear rate D = 10 / s,
mixed in a 2 liter planetary mixer with scraper at atmospheric pressure for 8 minutes and evacuated at p = 0.008 bar, T = 19 ° C, for 5 minutes. Then emptying the mixer and dividing the batch to examine a sample in the dynamic mechanical spectrometer and the remaining material coated 59 sensor optics.

These Optics are forced in a level position in a convection oven hardening exposed, for 15 minutes at T = 90 ° C. After that lets to cool, covers the sensors against dust and waits approx. 40 hours. Then the sensors are mounted on the inside of windscreens. The windshield is subjected to a thermal cycle with 16h RT, 8h T = 80 ° C and 80 cycles.

First, be 3 × all 8 hours, 3 × 24 Hours and then every 3 days a sensor from the cooled to RT disc solved. The separation result is evaluated, after deletion the glass (desired) or cohesive Failure or adhesive Failure on the plastic of the optical sensor.

Before mixing, the ratio was mol _(Si-vinyl) / mol _(Si-H) = 5.16. In the cured state, the material has a damping _factor tan (δ) _{(w = 1..10 / s)} = 0.021 ... 0.128. The modulus G ' ₀ is 3094 Pa.

Embodiment 2:

Component A:

One after another, 249.0 g of a material of the formula (III) with an average of m = 4; 6 × R ^a with d = 2; e = 1 and 2 × R ^a where d = 1; e = 0 and 0.80 g of a Karstedt catalyst mixture with 20 ‰ Pt (0) content in a vinyl-terminated polydimethylsiloxane having a viscosity of 412 mPas at 25 ° C. at a shear rate D = 10 / s, mixed in a 2 liter planetary mixer with stripper at normal pressure for 8 minutes and evacuated at p = 0.008 bar, T = 19 ° C, for 5 minutes. Then empty the mixer into a storage vessel.

Component B:

698.0 g according to formula (I) with R ^y = R ^x with d = 0; R ^a = R ^b with d = 1 and 53.0 g according to formula (I) with an average of 19 × R ^a with f = 0; on average 231 × R ^b with f = 1; R ^x = R ^y with d = 1; e = 0 and mixed medium 212 × R ^a with f = 1 with an average n = 231 in a 2 liter planetary mixer with scraper at atmospheric pressure for 8 minutes and evacuated at p = 0.008 bar, T = 19 ° C, for 5 minutes. Then empty the mixer into a storage vessel.

Production of ready-to-use compounds:

The Components A and B are for over storable for several months at RT and can as desired in a dynamic mixer, static mixing tube or manually with subsequent Degassing mixed under reduced pressure and filled in the sensor. The mixing ratio of the compound is 1 part A and 3 parts B.

Comparative Example 1

Besides, a comparative example was mixed whose resulting molar ratio is mol _(Si-vinyl) / mol _(Si-H) = 1.67.

To A.) a vinyl-terminated polydimethylsiloxane (Vt-PDMS) of about 35000g / mol to 29.8 g; another Vt-PDMS with about 27500g / mol to 59.6g and 9.9 g of a Vt-PDMS at about 156,000 g / mol with 0.6 g of a Pt (0) catalyst mixture after Karstedt in Vt-PDMS dispersed. The content of the catalyst is 29.8 ppm Pt (0).

In another vessel B.) 19.0 g of a Vt-PDMS with about 35000g / mol. 38.1 g of a Vt-PDMS at about 27500 g / mol and 7.0 g of a Vt-PDMS at about 156000 g / mol with 27.5 g of a Si (CH ₃ ) ₂ H-terminated PDMS (Ht-PDMS) with about 17000g / mol and 4.2g of a multi-Si-H-PDMS (Hm-PDMS) at about 17000g / mol mixed with 19mol _(Si-H) / mol _(polymer) .

Around the reactivity adjust the component B.) is still 4.2 g of a freshly homogenized Mixture of 5% ethynylcyclohexanol in Vt-PDMS at about 27500 g / mol added.

The Components A.) and B.) are divided equally before use mixed, as the embodiment 1 degassed and tested.

In the cured state, the material has a damping _factor tan (δ) _{(w = 1..10 / s)} = 0.124 ... 0.387. The modulus G ' ₀ is 2567 Pa.

Comparative Example 2:

A commercially available material of an addition-crosslinking gel was mixed so that the resulting ratio is mol _(Si-vinyl) / mol _(Si-H) = 0.44. The viscosity of the components is for A.) η (D = 10 / s) = 0.88 Pas; B.) η (D = 10 / s) = 0.97 Pas. In degassed, cured state G ' _o = 1096Pa. The damping _factor is tan (δ) _{(w = 1..10 / s)} = 0.32..0.64.

Results:

Tabelle 1:

• Symbol + entspricht Lösung vom Glas, Gelpad intakt.
• Symbol –S entspricht Lösung vom optischen Sensor.
• Symbol –K entspricht kohäsivem Versagen.

Table 1 shows the results of the storage test. The behavior "solution from the glass" is desirable The values were determined at RT after storage in the temperature cycle.

Table 1:

• Symbol + corresponds to solution from the glass, Gelpad intact.
• Symbol -S corresponds to solution of the optical sensor.
• Symbol -K corresponds to cohesive failure.

The embodiment 1 shows the desired one Behavior and thus represents the inventive solution to the problem.

following the invention will be with reference to the accompanying drawings explained in more detail. there demonstrate:

1 the cure curves of the embodiments and the comparative examples;

2 the storage modulus of the viscoelastic spectrum of the working and comparative examples after curing;

3 the loss factor of the viscoelastic spectrum of the experimental and comparative examples after curing.

The processing is also determined by the pot life. The cure curves of the comparative and comparative examples show the 1 , Comparative Example 2 shows a sufficiently long pot life, but Embodiment 1 is of improved performance. The curing takes place for 30 minutes at 120 ° C.

By the measurement is shown to have less elastic components in the material according to the invention are present, thereby the wetting of the substrates is improved and the vent of gas bubbles when pouring onto the optical sensor can be included facilitated.

2 shows the storage modulus of the viscoelastic spectrum of the working and comparative examples after curing. The storage modulus G 'indicates, as a function of the measurement frequency, an indication of the distribution of the relaxation times in the material. As a result, it is like 2 Comparative Example 2 is the most unreliable of the network design and varies greatly with the strain rate at which the material is acted upon in the measurement.

The Spectrum of the embodiment points to a very uniform network with a homogeneous one Distribution of net arc lengths out.

3 shows the loss factor of the viscoelastic spectrum of the working and comparative examples after curing.

The in 3 reported loss factor shows that the comparison materials are high values, and there having viskosirreversible portions in the time range relevant to a separation operation. This easily leads to cracking and sticking on the substrate. Optimal separation results can be expected with minimum values of tan (δ).

Claims (11)

An electronic component comprising a housing for releasable attachment to a window of a motor vehicle, wherein the attachment of the housing to the vehicle window via an optical coupling medium is applied, which rests against the vehicle window, wherein the optical coupling medium comprises at least one silicone gel, characterized in that the silicone gel produced is starting from at least one vinyl-organosiloxane, which is reacted with at least one hydro-organosiloxane. Electronic component according to claim 1, characterized in that the silicone gel can be prepared by reacting at least one compound of formula I given below

in which R ^x or R ^{y is} a radical of the formula given below:

with d = 0 ... 28; preferably 1 or 0 with e = 0 ... 4; preferably 0 or 1, in which R ^a or R ^{b is} vinyl, alkyl or phenyl, and in which n = 1 to 5000, preferably 2 to 2000, with at least one compound of formula III given below

in which R ^a or R ^{b is} vinyl, alkyl or phenyl and m = 3 to 1000, preferably 3 to 10, or in which R ^a or R ^{b is} a radical of the following formula:

with d = 0 ... 28; preferably 1 or 0 with e = 0 ... 4; preferably 0 or 1 in the presence of a catalyst or a catalyst mixture. Electronic component according to claim 1 or 2, characterized in that it comprises at least one silicone gel which can be prepared by reacting at least one compound of formula II given below

in which Y is a radical of the formula given below

in which a = 0 to 20 b = 0 to 12 c = 0 to 12 d = 0 to 8 and in the R = R ^a or R ^b , R ^x or R ^y , where R ', R "= R can be and X = R ^a or R ^b , R ^x or R ^y . Electronic component according to one of claims 1 to 3, characterized in that the silicone gel is made by Implementation of at least two different compounds selected from the above-represented formulas I, II and III, wherein in the silicone gel the content of diene groups in excess of that Content of hydrosiloxane is present, preferably in an excess ratio of 1.80 to 100, more preferably in an excess ratio of between 2 and 10. Electronic component according to the preamble of the claim 1 or according to one of the claims 1 to 4, characterized in that this at least one silicone gel contains comprising a polysiloxane, which by addition hardening per Hydrosilylation was crosslinked. Electronic component according to one of claims 1 to 5, characterized in that the silicone gel in the cured state a damping factor tan (δ) at ω = 10 l / s of less than 2, preferably less than 0.3. Electronic component according to one of claims 1 to 6, characterized in that it comprises at least one silicone gel, which in the cured state has a G ' ₀ of 500 to 25,000, preferably 1000 to 5000 Pa, at an angular frequency of w = 0.05 l / s determined. Electronic component according to one of claims 1 to 7, characterized in that the silicone gel pad after solidification and joining on a substrate, preferably a glass sheet, even after a long period of time without damage of the gel pad leaves. Electronic component according to one of claims 1 to 8, characterized in that the silicone gel pad on a plastic housing of a optical sensor is applied and also when loosening a substrate, preferably a glass sheet with the plastic material the optical sensor remains permanently connected. Electronic component according to one of claims 1 to 9, characterized in that this one optical sensor, preferably a rain / light sensor for motor vehicles. Process for the preparation of a silicone gel pad for use in an electronic component according to the claims 1 to 10, characterized in that one first of the starting materials required for the silicone gel produces a two-component material whose components A and B for yourself separately storable are and later from these components in a certain mixing ratio Compound manufactures.