JP2008536141A - Test head with vertical probe for semiconductor integrated electronic devices - Google Patents

Abstract

A test head contact probe (20) of the type in which a plurality of probes are inserted into guide holes realized in each plate-like holder or die, said probes being corresponding contact pads of the integrated electronic device to be tested And a rod-like body (21) having at least a contact tip at the end, and the rod-like body (21) has a non-uniform cross section. To do. According to the test head contact probe, it is possible to appropriately approach the probe, to minimize the probe pitch, and to reduce the risk of the probe coming out of the guide hole.
FIG. 11A

Description

The present invention relates to a contact probe for a test head having a vertical probe effective for testing a plurality of semiconductor integrated electronic devices including a plurality of so-called contact pads.
More particularly, the present invention relates to a contact probe for a test head of the type in which a plurality of probes are inserted into guide holes realized in each plate-like holder or die, which probe is an integrated electronic device to be tested. It is effective to ensure mechanical and electrical connection with the corresponding contact pad, and includes a rod-like body having at least a contact tip at the end.

The present invention also relates to a method for obtaining the contact probe and a test head comprising the plurality of probes.
The present invention relates to, but is not limited to, a test head having a vertical probe for testing semiconductor integrated electronic devices, and the following description is merely for convenience of explanation in the field of the present application. Absent.

  As is well known, a test head is essentially a device that is useful for making electrical connections to a plurality of contact pads of a semiconductor integrated electronic device that corresponds to the channel of the test machine performing those tests. .

  Tests performed on integrated electronic devices detect and isolate defective devices that already exist in the manufacturing process. Thus, test heads are typically used to electrically test electronic devices integrated on a semiconductor or silicon wafer before they are cut and assembled into a chip package.

  A test head with a vertical probe includes at least a pair of parallel plates or plate-like holders spaced apart from each other and a plurality of contact elements suitable for movement to maintain an air gap.

  Each plate is referred to as a die in the related arts and in the following description and is individually provided with a plurality of through guide holes, each hole of the plate being a separate contact element or contact probe (which elements are described and claimed below). Corresponds to holes in other plates that are slidably engaged and guided. Contact probes usually consist of wires made of special metals with good electrical and mechanical properties.

  A good electrical connection between the test head probe and the contact pad of the integrated electronic device being tested ensures that each contact probe is propelled to each contact pad, and the mobile contact pads have two It bends elastically in the air gap between the dies.

These test heads are commonly referred to in English as “vertical probes”.
In short, the known test head has an air gap in which the probe bends, as schematically shown in FIG. 1, and this bending is facilitated by the probe itself or the appropriate contour of the dies.

In FIG. 1, the test head 1 includes at least an upper die 2 and a lower die 3 having upper and lower through guide holes 4 and 5 into which a contact probe 6 is slidably engaged.
The contact probe 6 has at least a contact end or tip 7. In particular, the contact chip 7 is mechanically connected to the contact pad 8 of the integrated electronic device to be tested, which at the same time is electrically connected to a test device (not shown) which is a terminal element of this test head. Connected.

  The upper and lower dies 2 and 3 are spaced by an air gap 9 so that during normal operation of the test head, that is, when the test head contacts the integrated electronic device to be tested, the probe 6 is deformed or tilted. enable. Further, the upper and lower guide holes 4 and 5 have a size for guiding the contact probe 6.

  FIG. 1 shows a test head with a probe that is unblocked, ie slidable within each upper and lower guide hole 4, 5, with a microcontact strip or space transformer generally indicated at 10. .

  In this case, the contact probe 6 has further contact tips directed to the plurality of contact pads 11 of the space transformer 10, and good electrical connection between the probe and the space transformer 10 causes the contact probe 6 to be connected to the space transformer 10. Propulsion over the contact pads 11 ensures a connection similar to the integrated electronic device being tested.

  In particular, according to a technique known as Cobra, as shown schematically in FIG. 2, the contact pad 6 is at the end in contact with the contact pad 11 of the space transformer 10 and on the contact pad 8 of the integrated electronic device to be tested. It has an external shape deformed in advance with an offset d between the contact chip 7.

  Further, the external shape before deformation is such that the test head 1 can be accurately bent during its operation, that is, during contact with the integrated electronic device to be tested, when the test head 1 is not connected to the integrated electronic device to be tested. Help.

  In addition, a thin and flexible insulator film 12, typically implemented with polyimide, is interposed between the upper and lower dies 2, 3 so that the upper end of the contact probe 6 can be held in place during the assembly process.

In particular, the assembly process of the test head 1 realized by the cobra technology is very delicate and includes the following processes.
Each contact probe 6 is inserted into the hole of the lower die 3 from the side corresponding to the contact probe 7, as schematically shown in FIG.
As shown schematically in FIG. 4, the other end of the contact probe 6 is gently pushed into the appropriately perforated flexible material film 12 so that it is held by the material film 12 without risk of escaping therefrom. ,
As shown schematically in FIG. 5, once all the contact probes 6 have been inserted into the flexible material film 12 as described above, the upper die 2 is covered, and all the contact probes 6 are put on the upper die 2 with excellent skill. Center in the corresponding hole formed.

  This assembly mode required by the probe realized by the Cobra technology is very time consuming, there is a risk to the possibility of the probe being deformed, and very unstable until locking on the upper die 2.

  Furthermore, when the task of keeping the probe 6 end in place during the assembly process is complete, the film 12 is still trapped inside the test head 1 so that normal operation of the test head 1 is achieved. In the meantime, there is a risk of mechanical interference between the flexible material film 12 and the contact probe 6, which is mainly referred to as a slide of the probe itself for a large size test head having a large number of adjacent probes. May cause serious problems.

  As schematically shown in FIG. 6 (though components that are structurally and functionally identical to the test head 1 of FIG. 1 are indicated by the same reference numbers), a technique called “shift plate” is used. It is also known to realize a test head.

In this case, the contact probe 6 has not been deformed in advance, has a constant circular cross section over the entire length thereof, and only has a straight outer shape with a sharp sharp end.
In order to achieve an accurate operation of the contact probe 6, the upper and lower dies 2, 3 are shifted from each other, allowing the probe 6 to bend selectively in the same direction.

  The assembly of the probe 6 in the test head realized by the shift plate technology is very simple, can be done in a short time and does not require the use of any flexible material film. In particular, the upper die 2 is sufficiently aligned with the lower die 3 in order to align the corresponding guide holes 4, 5 and then insert the contact probe 6 into the guide holes 4, 5 and shift the appropriate length between the dies. Then block them in place.

However, this technique also has drawbacks. Especially it is
It is difficult to hold the contact probe 6 in their housing, ie in the die guide hole. In fact, despite the relative shift between the upper and lower dies 2, 3, it causes friction between the contact probe 6 and the corresponding guide holes 4, 5, which is always sufficient to hold the probe in place. Don't be.

  In particular, during the maintenance and cleaning work of the test head 1, there is a considerable risk of the contact probe 6 coming out, which work is usually done with ventilation or ultrasound and is therefore suitable for it coming out of the guide hole. This causes mechanical stress in the contact probe 6.

The distance between two adjacent probes of the test head 1 is limited due to the circular cross section of the wire realizing the contact probe 6;
In particular, the test head has an intrinsic distance limit between two adjacent probes and thus between the centers of the two contact pads of the integrated electronic device to be tested (known in this field as the English term “pitch”). Have In particular, the minimum “pitch” depends on the geometrical shape and size of the probe. In order to avoid contact of adjacent probes, the test head 1 must satisfy the following relationship.

P> ΦF + G1
(P is the pitch of the device to be tested, that is, the distance between the centers of two adjacent contact pads, ΦF is the diameter of the contact probe 6, and G1 is the safe distance between adjacent contact probes 6.)
The condition Gl = 0, that is, the absence of the safety distance corresponds to a probe collision.

  In the case of a circular probe, as shown in FIG. 7, the minimum pitch P1 is indicated by the probe diameter ΦF corresponding to the diameter of the guide hole that increases with the wall thickness G1 separating two adjacent holes.

  The need to ensure a minimum distance pitch value between probes thus contrasts with the needs of the current market, and the devices are designed with higher density, thus a very large number of devices for testing these devices. A test head with a contact probe is required.

  The fundamental technical problem of the present invention is to provide a contact probe having a configuration that effectively reduces the minimum pitch required by the device being tested, while the contact probe exits from the guide hole. There is danger.

  The fundamental solution of the present invention is to provide a contact probe with a non-constant cross section, which can ensure that the probe is properly approached while at the same time reducing the risk of the probe coming out of the guide hole.

Based on this solution, the technical problem is solved by the contact probe as described above and as defined in the characterizing part of claim 1.
The technical problem is also solved by the test head as described above and in the characterizing part of claim 7.

Furthermore, the problem is solved by a method for obtaining a contact probe as defined in the characterizing part of claim 15.
The features and advantages of the contact probe and test head of the present invention will become apparent from the following description of those embodiments, illustrated by non-limiting examples, with reference to the accompanying drawings.

1 schematically shows a first embodiment of a test head described in the prior art. It is the schematic of the test head of FIG. 2 schematically shows an assembly process of the test head of FIG. 2 schematically shows an assembly process of the test head of FIG. 2 schematically shows an assembly process of the test head of FIG. 2 schematically illustrates another embodiment of the test head of FIG. FIG. 7 schematically shows important dimensions of the test head of FIG. A to D schematically show a first embodiment of the contact probe of the present invention. A to 9 schematically show a second embodiment of the contact probe of the present invention. A to D schematically show a third embodiment of the contact probe of the present invention. A and B schematically show details of the test head of the present invention. A and B schematically show configurations of the conventional example and the test head of the present invention. A and B schematically show different assembly steps of the test head of the present invention.

Referring to these figures, and in particular FIGS. 8A-8D, a contact probe of the present invention is indicated at 20. FIG.
The contact probe 20 includes a rod 21 having at least a contact end or tip 22. In particular, as found in the prior art, the contact chip 22 is in mechanical contact with the contact pads of the integrated electronic device to be tested, while the integrated electronic device is a test device (where the test head is a terminal element). (Not shown).

  Further, for example, in the case of a test head probe having an unblocked probe, it is accompanied by a micro contact strip or a space transformer, and the contact probe 20 has a second contact tip 23 directed to a plurality of contact pads of the space transformer. .

An advantage of the present invention is that the rod-like body 21 of the contact probe 20 has a non-identical cross section with respect to its main development line LL.
In particular, the rod-shaped body 21 of the contact probe 20 has at least a first portion 21A and a second portion 21B having cross sections S1 and S2 having different outer shapes, as shown in the enlarged view of FIG. 8B.

  An advantage of the present invention is that, as will be shown below, the first cross section S1 is at least larger than the size corresponding to the second cross section S2 and prevents the contact probe 20 from slipping out of the guide hole realized by the die.

  In particular, as shown in FIG. 8B, the first section S1 of the portion 21A has a longitudinal dimension X1 that is longer than the corresponding longitudinal dimension X2 of the second section S1 (X1> X2). Furthermore, the first cross section S1 has a vertical dimension Y1 shorter than the corresponding vertical dimension Y2 of the second cross section S2 (Y1 <Y2).

  Further, as shown in FIGS. 8C and 8D, the contact probe 20 has a portion 21B close to the contact tip shorter than the corresponding vertical dimension X2 of the second cross section S2 in light of the probes shown in FIGS. 8A and 8B. It can also be considered to have a longitudinal dimension Y1 (Y1> Y2) that is longer than the corresponding longitudinal dimension Y2 of the first section S1 (X1 <X2) and the second section S2 having the longitudinal dimension X1.

  An advantage of the present invention is that it is possible to obtain a contact probe 20 having a non-constant cross-section from a probe realized in a conventional manner with a circular cross-section wire. This circular cross-section wire is flattened in two different thicknesses corresponding to the portions 21A and 21B of the rod 21 of the contact probe 20, and thus a substantially rectangular first cross-section with rounded corners. A contact probe 20 having S1 and a second cross section S2 is obtained.

  Also, as schematically shown in FIGS. 9A and 9B, only a part of the wire corresponding to one of the portions 21A or 21B of the rod-like body 21 (for example, the portion corresponding to the first portion 21A) is flattened. Is also possible, so that a first rectangular cross-section S1 and a second circular cross-section S2 with rounded corners are obtained. Similarly, as shown in FIGS. 9C and 9D, it is also possible to flatten only a part of the wire corresponding to the portion 21B, and thus the first circular cross section S1 and the second having a rounded angle. A rectangular cross section S2 is obtained.

  Similarly, it is possible to obtain a contact probe 20 having a non-constant cross-section of the present invention from a probe having a rectangular cross-section and flattening that portion, and thus FIGS. 10A and 10B and FIGS. 10C and 10C. As shown in 10D, a contact probe 20 having a first cross section S1 and a second rectangular cross section S2 is obtained.

  However, in particular, the cross section of the contact probe 20 corresponding to the contact tip 23 toward the space transformer is at least larger than the corresponding dimension of the outer shape of the cross section of the contact probe 20 corresponding to the contact chip 22 toward the device to be tested. It has an outer shape.

  In fact, as shown in FIG. 10B, the horizontal dimension X1 of the first cross section S1 is larger than the horizontal dimension X2 of the second cross section S2, and as shown in FIG. 10D, the vertical dimension Y1 of the first cross section S1 is , Larger than the longitudinal dimension Y2 of the second cross section S2.

Further, in general, the contact probe 20 of the present invention has two or more cross-sections of any shape, but different from each other, obtained with several currently available techniques.
In a preferred embodiment of the present invention, the contact probe 20 is obtained by a method including the following steps.

-Preparing a wire that effectively realizes the rod 21 of the contact probe 20;
In order to obtain in this part a cross-section having a different profile relative to the profile of the wire cross-section, this wire corresponding to at least part 21A or 21B is deformed, for example flattened, and thus a contact probe of non-constant cross-section Get 20.

Furthermore, the method of the present invention may include a step of planarizing a further part of the rod-shaped body 21 of the contact probe 20.
An advantage of the present invention is that the non-constant cross-section contact probe 20 can solve the problem of probe dropout that affects the known shift plate vertical technology.

  In fact, referring to the prior art, this shift plate technique is usually given a contact probe with a circular guide hole realized with upper and lower dies. Therefore, it is not certain that these contact holes hold the contact probe in the test head. Especially during cleaning operations, the probe tends to slide out of each guide hole due to the usual ventilation or ultrasonic cleaning of the solution.

  An advantage of the present invention is that the contact probe 20 with a non-constant cross section is associated with a suitable hole having different profiles between the upper die 24 and the lower die 25 of the test head, as schematically shown in FIGS. 11A and 11B. ing. In particular, the lower die 25 includes a hole having a cross-section SF2 with an outer shape substantially corresponding to the outer shape of the cross-section S2 of the second portion 21B of the contact probe 20, while the upper die 24 includes the portion 21A of the probe 20 and A hole having a cross-section SF1 of the outer shape corresponding to the combination of the outer shapes of the cross-sections S1 and S2 of 21B is provided.

  In this way, the contact probe 20 is guaranteed to be held inside the die of the test head that includes these dies and the plurality of contact probes 20. In fact, each contact probe 20 cannot move because the hole of the lower die 25 has a cross section with a dimension that is smaller than the corresponding dimension of the cross section of at least one portion of the contact probe 20.

  In other words, the test head thus obtained has a preferred exit direction of the contact probe 20, in particular from the lower die 25 to the upper die 24, and any reverse movement is appropriately shaped, This is prevented by the guide hole of the lower die 24 having a dimension that is at least smaller than the corresponding dimension of the cross-sectional outer shape of the probe portion 21A.

  Furthermore, a reliable test head is obtained that allows cleaning and cleaning that prevents the contact probe 20 from slipping out of the test head itself. For this purpose, it is sufficient to use a gas jet that pushes the contact probe 20 towards the lower die 25 and they do not escape from it. Alternatively, by blocking the probe from escaping from the upper die with a suitable cap, both cleaning and cleaning can be performed without any risk of the probe escaping in either of the two directions.

An advantage of the present invention is that the non-constant cross-section contact probe 20 solves problems associated with assembling a test head including them.
In particular, it is sufficient that the upper die 24 and the lower die 25 overlap with the corresponding guide holes, and it is sufficient that the contact probe 20 is simply inserted from the upper die 24 toward the lower die 25 into the overlapping guide hole. It is.

Thus, it is sufficient that the upper and lower dies are spaced apart, and the contact probe 20 can slide in the guide hole of the upper die 24.
The test head assembly of the present invention consists of blocking the upper and lower dies 24, 25 in a position with space provided that they are shifted together and the spacers 26 are inserted between the dies before the blocks. Completed.

It can easily be recognized that this assembly technique is faster and safer than, for example, the assembly technique known as the Cobra technique.
In fact, the above-described assembly of a test head including a plurality of contact probes 20 with non-constant cross-sections reduces the implementation time considerably, and is simpler and more reliable.

Finally, an advantage of the present invention is that the non-constant cross-section contact probe 20 can solve the problems associated with the minimum pitch required for the device being tested.
As described above for existing technology, the minimum pitch of the device being tested is constrained by the fact that the cross section of the wire that implements the contact probe is circular. In fact, the minimum pitch value is indicated by the guide hole diameter, which is increased by the separation wall thickness G1 between two adjacent holes, as schematically shown in FIG. 12A for a contact probe realized in the prior art.

  The advantage of the present invention is that, as schematically shown in FIG. 12B, the contact probe 20 having a non-constant cross section has a minimum pitch value up to the same length as the reduction of the cross section between the cross sections S1 and S2 of the rod 21 of the contact probe 20. Can be reduced.

13A and 13B show a test head 30 that is implemented in shift plate technology and includes a plurality of contact probes 20 of the present invention as an example.
In particular, after assembling the contact probe 20 between the upper die 24 and the lower die 25, the probes can be bent by shifting these dies as shown by arrow F in FIG. 13A. In this way, the contact probe 20 has a preferred bending direction.

  Further, as schematically shown in FIG. 13B, a spacer 26, sometimes shown as a housing or spacer, can be provided with a variable height to allow force in the bending process to be adjusted appropriately. It is.

  A preferred embodiment of the test head according to the invention is that the die, in particular at least the lower die 25, has a very long guide hole. These guide holes can be made by increasing the thickness of the die itself, or, in a simpler way, by using two or more thin dies that overlap each other, or two very thin dies ( Therefore, it can be obtained by using a very easy to make hole. In this way, long guide holes that are substantially aligned with each other can be obtained.

  In the case of the shift plate technique, it is also possible to utilize a guide hole obtained with an offset drill to help bend the contact probe 20 in a preferred direction. Also in this case, the guide hole can be obtained by using two or more dies that are overlapped or spaced apart from each other, where the holes are slightly offset from each other and perforated. .

In conclusion, the advantages of the present invention are that the non-constant cross-section contact probe 20 has the following problems:
-As mentioned with reference to the known shift plate vertical technology,
An assembly, as can be seen with reference to the known “cobra” technology,
-The minimum allowable pitch and good electrical connection can be solved.

Claims (20)

A plurality of probes are contact probes (20) for a test head of the type inserted into a guide hole realized by each plate-like holder or die,
The probe is effective to ensure mechanical and electrical connection with a corresponding contact pad of the integrated electronic device to be tested and includes a rod (21) with at least a contact tip at the end;
The rod-like body (21) has a non-constant cross-section, and is a test head contact probe.   The contact according to claim 1, characterized in that the rod (21) comprises first and second parts (21A, 21B) having first and second cross sections (S1, S2) of different outlines, respectively. Probe (20).   The contact probe (20) according to claim 2, wherein the first cross section (S1) has at least a dimension larger than the corresponding dimension of the second cross section (S2).   The contact probe (20) according to claim 2, characterized in that the first and second cross sections (S1, S2) are rectangular with rounded corners.   Contact probe (20) according to claim 2, characterized in that the first cross section (S1) is circular and the second cross section (S2) is a rectangle with rounded corners.   Contact probe (20) according to claim 2, characterized in that the first and second sections (S1, S2) are rectangular. A test head (30) comprising a plurality of contact probes inserted into guide holes realized in an upper die (24) and a lower die (25),
A test head (30), characterized in that the contact probe (20) is realized by any one of claims 1-6.   8. The test head according to claim 7, wherein the lower die (25) has a cross-sectional hole (SF2) having an outer shape substantially corresponding to the outer shape of the cross-section (S2) of the contact probe (20). (30).   8. The test head (30) according to claim 7, wherein the upper die (24) has a cross-sectional hole (SF1) having an outer shape corresponding to a combination of outer shapes of different cross-sections of the contact probe (20). .   10. Test head (30) according to claim 9, characterized in that the profile of the hole cross section (SF1) is given by a combination of two rectangular profiles with rounded corners.   10. Test head (30) according to claim 9, characterized in that the profile of the hole cross section (SF1) is given by a combination of a circular profile and two rectangles with rounded corners.   Test head (30) according to claim 9, characterized in that the profile of the hole cross-section (SF1) is given by the combination of two rectangular profiles.   The test head (30) according to claim 7, wherein the upper and lower dies (24, 25) are appropriately offset.   8. The test head (30) according to claim 7, wherein a spacer (26) is provided between the upper and lower dies (24, 25). -Preparing a wire having a predetermined cross-section that effectively realizes the rod-like body (21) of the contact probe (20);
A contact probe (20) having a non-constant cross-section comprising deforming a wire corresponding to at least a portion (21A, 21B) of the rod-like body (21) to obtain a portion of a different shape for a wire having a predetermined cross-section How to get.   The method according to claim 15, wherein the deforming step includes at least a flattening step of the wire portion.   The method of claim 16, wherein the planarization step is performed on another portion of the wire.   The test head (30) according to claim 7, wherein the die (24, 25) is provided with a slot.   19. The test head (30) according to claim 18, characterized in that the dies (24, 25) are realized by a plurality of thin dies overlapping or a pair of thin dies suitably spaced from each other. ).   20. The test head (30) according to claim 19, wherein the dies (24, 25) have guide holes that are offset from each other.

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