WO2015027266A1

WO2015027266A1 - Mechanical method for testing electronic components

Info

Publication number: WO2015027266A1
Application number: PCT/AT2014/050191
Authority: WO
Inventors: Khatibi GOLTA; Brigitte Weiss; Agnieszka Betzwar KOTAS
Original assignee: Golta Khatibi; Brigitte Weiss
Priority date: 2013-08-30
Filing date: 2014-08-29
Publication date: 2015-03-05
Also published as: EP3039396A1; DE102013109504A1; DE102013109504B4

Abstract

The invention relates to a device for testing microelectronic components (MK). Said type of device comprises an elongate sample holder for housing at least one electronic component which is to be tested and an ultrasonic actuator which comprises an ultrasonic transducer for generating ultrasonic waves and a coupling element which is mechanically joined thereto. Said coupling element transforms said ultrasonic waves into mechanical oscillations and mechanically couples the ultrasonic transducer to the sample holder. Said ultrasonic actuator is designed and coupled to the sample holder such that said sample holder is excited so as to generate a bending oscillation.

Description

Mechanical test method for components of electronics

The invention relates to the field of mechanical test methods for

Electronic components, in particular for so-called "microelectronic components" (MK).

Electronic components (in English also "electronic package Systems", EPS) experience stresses during their use, which their

Life and reliability can severely affect. In particular, stresses caused by the application of mechanical forces (e.g., compressive and tensile stresses due to thermal, thermo-mechanical or cyclic loads) can result in component damage. In particular, components composed of multiple parts (e.g., layers, chips, contacts, etc.) suffer from such stressors. This can cause delamination of layers and cracking that can damage the components and ultimately a complete failure of one

Component with it. It is therefore important to test electronic components that are subject to mechanical stress in their field of application, to test their load capacity and, as a result, the signs of fatigue in order to be able to take into account potential weaknesses in the development of new components.

Test methods for simulating such stress are e.g. Bending tests, in which the samples are clamped and then bent by means of a targeted application of force. However, such bending tests are not suitable for determining the fatigue behavior of the electronic components to be tested. In general, ultrasound test methods are known for simulating high frequency mechanical loading (which in reality is caused, for example, by thermal cycling) and determining the fatigue behavior of a sample as a function of the number of load changes. microelectronic

Components (MK) are known for their small dimensions (e.g.

Submillimeter range up to about 10 mm) but not for such

Test method suitable. The task is therefore a device or a Provide method with the / the small samples, specifically electrical

Components, stress tests can be subjected.

The object is achieved by a device according to claim 1 and a method according to claim 6.

According to one example of the invention, a device for testing microelectronic components (MK) comprises the following: an elongate sample holder for receiving at least one electronic component to be tested and an ultrasonic actuator having an ultrasonic transducer for generating ultrasonic waves and a mechanical coupling element connected thereto which transforms the ultrasonic waves into a mechanical vibration and mechanically couples the ultrasonic transducer to the sample holder. The ultrasound actuator is designed in such a way and coupled with the sample holder, that the sample holder is excited to a bending vibration.

Another example of the invention relates to a method for testing electronic components. In this case, an elongate sample holder with at least one electronic component to be tested is excited by means of an ultrasonic actuator to vibrate. The ultrasonic actuator is mechanically coupled to the sample holder via a coupling element in this way; that the sample holder is excited to a bending vibration. The invention will be explained in more detail with reference to the examples shown in the figures. The illustrations are not necessarily to scale and the invention is not limited to the aspects presented. Rather, emphasis is placed on representing the principles underlying the invention. In the pictures shows:

Figure 1 shows an embodiment of an electrical to be tested

Component in cross section, FIG. 2 shows an exemplary embodiment of the testing device in side view,

Figure 3 shows an embodiment of the sample holder with it

attached electronic components in side view,

FIG. 4 shows a bending mode of the ultrasonic mode generated by the ultrasonic actuator

Sample holder in side view,

FIGS. 5A-C show the first three possible vibration modes in the sample holder, and

Figur 6 Placement of the electronic components on the

Sample holder with consideration of the excited mode. In the figures, like reference characters designate like or similar components of like or similar meaning.

FIG. 1 shows as an illustrative example a microelectronic component as it is to be tested for fatigue phenomena in the context of the invention.

The microelectronic component (a MK) is a composite structure composed of different materials with different physical properties (eg, Young's modulus, shear modulus, coefficient of thermal expansion, texture, etc.) and shapes in the field of microelectronics and nanoelectronics. The exemplary embodiment in FIG. 1 in this case comprises a multilayer structure 50, ie a plurality of layers of different materials (multilayer) attached to one another and enclosed metallizations 56, vias 52 (also PTH, plated through-hole) and semiconductor chips 54 and 52, which may be integrated into the multilayer structure 50 (chip 54) or mounted on the surface of the multilayer structure 50 (flip-chip 52). In addition, SMD components 53 can be arranged on the surface. The multiplicity of layers result in a large number of interfaces (eg at the adhesive layer 55), which weak points in the electronic component with respect to mechanical Represent loads. The stresses occurring there can lead to the delamination of the layers. Furthermore, cracks can occur, which then spread as the stress increases and ultimately to the

Destruction of the electronic component (MK).

FIG. 2 shows an embodiment of a testing device according to the invention in a side view. The device 1 in this case comprises an ultrasonic actuator 20, which is used for generating the desired oscillation. The ultrasound actuator 20 in this case comprises an ultrasound transducer 21 which generates ultrasound waves of a specific selected frequency. The transducer 21 is, for example, a piezoelectric transducer in which mechanical vibrations are generated by an applied high-frequency AC voltage. The transducer is connected to a mechanical transducer 22, which performs a longitudinal oscillation, wherein the oscillation frequency corresponds to the ultrasonic frequency of the actuator. Connected to the mechanical transducer 22 is a mechanical coupling element 23 whose function is to connect the ultrasonic actuator 20 to an elongated sample holder 10 such that it is excited at the oscillation frequency-ideally resonant-to a bending oscillation. The coupling element is also referred to as sonotrode. This is designed in such a way that the applied oscillation frequency corresponds to its own resonance frequency. The sample holder 10 is indicated only schematically in this embodiment in order to clarify the connection between it and the ultrasound actuator. Figure 3 shows an embodiment of the sample holder 10. This is for

Simplification shown in abbreviated form. Within the device it is of elongated geometry (in relation to the thickness) to better perform bending vibrations. Essentially, it may be a (statically determined mounted) bending beam. The sample holder has a top 1 1 and a top side vertically opposite bottom 12. On the

Sample holder 10, at least one electronic component to be tested 15 is frictionally secured, which may be mounted both on the top 11 and on the bottom 12 of the sample holder 10. The attachment of the _

electronic components is carried out in a manner in which they follow the bending vibration of the sample holder. For example, the

electrical components are glued to the sample holder. On the sample holder 10 (bending beam) e.g. glued samples then experience an alternating ZugVDruckbelastung corresponding to the bending vibration of the sample holder.

Other variants of the fixed but damage-free attachment are not excluded here. In principle, the electronic components can be mounted at arbitrary positions on the two sample holder sides 11 and 12 and also on the two side surfaces 13 which run along the longitudinal direction of the sample holder and connect the sample holder sides 11 and 12 with certain positions being advantageous prove, as will be explained with reference to subsequent figures. An electronic component 15 ', which is attached to one of the side surfaces 13, is indicated schematically in FIG. The position of the excitation, i. the location at which the ultrasound actuator or its coupling element 23 (eg sonotrode) is connected to the sample holder 10 may also be arbitrary, wherein these are chosen and can be tuned with the vibration frequency that the sample holder at a natural frequency in a certain (matching the natural frequency) vibration mode oscillates.

Figure 4 shows the formation of the first mode of vibration of the possible

Bending vibrations in the (on both sides mounted) sample holder, wherein the

Coupling element 23 is approximately mechanically coupled in the middle of the sample holder 10. As will be explained with reference to FIGS. 5A-C, the first oscillation mode excited in this way has a maximum deflection in the middle of the sample holder, where excitation also occurs in this exemplary embodiment. The bending vibration of the sample holder and the consequent bending results on the surface of the sample holder in an alternating tensile / compressive load along the longitudinal axis of the sample holder. This is transmitted by the integral attachment of the electronic components 15 with the sample holder 10 on this. This even allows very small electronic Components 15 are exposed by the ultrasound system a variety of load cycles and thus tested effectively.

As already mentioned, the bending vibration produces an alternating tensile / compressive load in the sample holder and also in the samples attached thereto. The illustration in FIG. 4 thus shows only a snapshot at the time of maximum deflection in the direction of the upper side 11 of the sample holder.

Figures 5A-C show three possible modes of vibration in the sample holder.

Considering the sample holder 10, essentially decide two

Influencing factors over the wavelengths of the vibration modes forming in the resonance case. On the one hand, the type of clamping of the sample holder is fixed, where fixed predetermined nodes (places where the deflection of the sample holder is always zero) are located. Waves with such excellent locations are called standing waves. Consequently, standing waves in addition to the nodes 40 also have points of maximum deflection (so-called antinodes 41). It should be noted that at these points there is not always a maximum deflection, these points are also subject to the vibration and therefore take at certain times also the value zero. However, at these points, the displacement is extreme relative to all other points at certain times (i.e., maximum in both directions of oscillation). In all embodiments, these locations are the clamping at the two respective ends of the sample holder; so there is no deflection at these points. On the other hand, the length of the sample holder 10 determines the wavelength of the forming standing waves. Each wavelength of a wave in a medium (here the material of the sample holder) is beyond the physical

Relationship ο _Ρ = λ · ν assigned a (eigen-) frequency v. Decisive for this is the so-called phase velocity c _{P of} the wave within the medium. This size is material-specific and is thereby predetermined by the sample holder 10. Thus, by the sample holder 10 itself, its clamping and its length, the vibration modes (ie, their wavelength λ and thus also their resonance frequency) determined. Will the sample holder now with a

Stimulated frequency corresponding to one of its natural frequency, it forms in him a vibration mode that matches this natural frequency. It is thus possible, with knowledge of all relevant variables, to determine selectively both the points with node 40 and with the bulges 41 before the actually test method, which later still represents an important aspect for the actual method, since the samples are arranged at the points of maximum deflection can.

The introduction of the excitation is possible at any point of the sample holder, but are points at which the antinodes 41 are more efficient, since this ensures the greatest energy transfer to the sample holder 10 and thus the process is most efficient.

FIG. 5A shows the first possible oscillation mode 30 (or fundamental oscillation), the wavelength λ of the oscillation here being twice the length L of the specimen holder 10 (Ι_ = λ / 2). The (only) oscillation maximum 41 is located exactly in the middle of the sample holder, which is why the center is most sensible here as the excitation position.

FIG. 5B shows the second possible oscillation mode 31 (or also first

Harmonic). This fashion already owns another node 40 (in the middle of the sample holder) as well as two peaks 41 in each of ^_1/4 and% of the

Sample holder length L. It is therefore useful to encourage near these two points.

Analogously, FIG. 5C shows a further oscillation mode 32 (seventh harmonic oscillation). The targeted excitation of a resonant frequency can therefore over the

Adjusting the excitation frequency happen (ie the ultrasonic frequency). However, if one does not want to or can not vary these, it is possible to adjust the length of the sample holder 10 (to the frequency of the ultrasonic actuator) in order to set a specific resonance frequency of the system. One chooses the sample holder length so that the fixed excitation frequency corresponds exactly to a resonant frequency. FIG. 6 shows the sample holder 10 with its top side 1 1 and underside 12 and electronic components 15 'on both side surfaces 13 as well as a possible excited oscillation mode in the sample holder 10. For reasons of clarity, the ultrasonic actuator is not shown here. In addition to the maximum excitation energy and the maximum train or

To apply compressive stress to the applied electronic components 15, it is useful to attach those also at points with bellies, which can be done thanks to the fixed position of these points already before the test procedure.

Claims

claims

1 . Apparatus for testing components of electronics; the device comprises:

an elongate sample holder for receiving at least one electronic component to be tested;

an ultrasonic actuator comprising an ultrasonic transducer for generating ultrasonic waves and a mechanical coupling element connected thereto, which mechanically transposes the ultrasonic waves and mechanically couples the ultrasonic transducer to the sample holder, wherein the ultrasonic actuator is configured and coupled to the sample holder such that the sample holder a bending vibration is excited.

2. Device according to claim 1, wherein the ultrasonic actuator performs a resonant longitudinal vibration at an ultrasonic frequency, which is coupled into the sample holder, wherein the sample holder is geometrically configured and tuned to the ultrasonic frequency that it performs a resonant oscillation.

3. Apparatus according to claim 2, wherein the resonant vibration of the sample holder has a wavelength dependent on the ultrasonic frequency and the sample holder has a length which corresponds to a half wavelength or a wavelength or an integer multiple of one or one half wavelength.

4. Device according to claim 1, wherein the electronic component or components to be tested are (are) arranged on an upper side and / or a lower side and on both side surfaces 13 of the sample holder so that the ( n) electronic component (s) are exposed to substantially an oscillating train-pressure load.

5. The device according to claim 1 or 4, wherein the sample holder is excited at a natural frequency so that the sample holder oscillates in a natural frequency matching vibration mode.

6. Device according to one of claims 1 to 5, wherein the ultrasonic transducer is formed and connected to the coupling element, that forms in this a vibration along its longitudinal direction.

7. Apparatus according to claim 6, wherein the coupling element is a sonotrode whose resonant frequency corresponds to the ultrasonic frequency.

8. Method for testing electronic components; comprising the following steps:

Providing an elongate sample holder having at least one electronic component to be tested thereon,

Providing an ultrasonic actuator mechanically coupled to the sample holder via a coupling element;

wherein the ultrasonic waves generated by the ultrasonic actuator are converted into a mechanical vibration, which is transmitted by the coupling element to the sample holder, so that it is excited to a bending vibration.

9. The method of claim 8, wherein the exciting ultrasonic frequency corresponds to a resonant frequency of the sample holder.

10. The method of claim 9, wherein the length of the sample holder is selected such that a resonant frequency of the sample holder corresponds to the exciting ultrasonic frequency.

1 1. Method according to one of claims 8 to 10, wherein the coupling takes place at a position of maximum deflection of the sample holder.

12. The method according to any one of claims 8 to 1 1, wherein the electronic components are mounted at positions of maximum deflection of the sample holder on the sample holder.