JPH1174405A - Test fixture for leadless chip carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a test fixture for a leadless chip carrier with which stable high-frequency measurement can be performed, by forming transmission lines in contact with a dielectric substrate. SOLUTION: Line conductors 4 and a ground conductor 5 are respectively formed on both surfaces of a dielectric substrate 2, and another ground conductor 5b is formed on one surface of another dielectric substrate 3. The line conductors 4 and the ground conductors 5a and 5b are formed by using gold- plated copper plates having a thickness of 35 μm. Strip lines which are a structure suitable for high-frequency transmission lines are formed by holding the line conductors 4 between the substrates 2 and 3, and arranging the ground conductors 5a and 5b on the outsides of the substrates 2 and 3. When the strip lines are used as transmission lines, the occurrence of losses and reflection between a matching circuit and an object to be measured is reduced and accurate high-frequency measurement can be performed, because the matching circuit can be formed near the object to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test fixture for measuring high-frequency electrical characteristics of a leadless chip carrier on which a semiconductor device or the like is mounted. The test fixture for measuring high-frequency electrical characteristics makes it easy to attach and detach the DUT, and electrically connects the external circuit such as a measuring device to the DUT with good reproducibility. Is a device that enables measurement of

[0002]

2. Description of the Related Art A test fixture for measuring high-frequency electric characteristics includes a transmission line for guiding an electric signal from an external circuit to an object to be measured, a contact electrode for connecting the transmission line to an electrode of the object to be measured, a contact electrode and a contact electrode. It comprises a positioning mechanism for accurately adjusting the position of the electrode of the object to be measured, an elastic body for bringing the contact electrode into elastic contact with the electrode of the object to be measured, a presser for fixing the object to be measured, and the like.

In a conventional test fixture, a coaxial line 20 is used as a transmission line as shown in FIG.
The end of the 0 line conductor is exposed to form a contact electrode 21. Further, the positioning mechanism 22 and the presser 23 are formed of an insulator such as a resin, and the elastic body 24 is provided immediately below the contact electrode.

[0004]

In the measurement of high-frequency electric characteristics, a matching circuit is provided between an external circuit and an object to be measured so as to prevent loss or reflection of high-frequency power in order to perform the measurement accurately. There is. However, if high-frequency power loss or reflection occurs between the matching circuit and the device under test, it becomes difficult to design the matching circuit, and it becomes very difficult to perform accurate measurement. Therefore, it is better to provide the matching circuit as close as possible to the device under test so as to minimize the loss and reflection on the transmission line along the way.

[0005] In the conventional test fixture, the coaxial line 20 is used as a transmission line. A general coaxial line has a cross-sectional shape as shown in FIG.
It is composed of a dielectric 26 surrounding the line conductor 25 and a ground electrode 27 further surrounding the outside. In such a line, it is difficult to change the characteristic impedance of the line or to branch the line, thus forming a matching circuit. Hard to do. For this reason, a connector is connected to the coaxial line 20 and connected to an external matching circuit via the connector, or the coaxial line 20 is directly connected to a matching circuit formed on a printed circuit board or the like. However, in such a configuration, the matching circuit is separated from the device under test, which hinders accurate measurement for the above-described reason.

As a contact electrode, there is a method of using a metal pin having a built-in metal spring, but it is not suitable as a high-frequency transmission line. The electrode 21 is used.
The positioning mechanism 22 and the presser 2 are made of an insulator such as resin.
3 and an elastic body 24 is provided immediately below the contact electrode.

Further, if a microstrip line having a sectional shape as shown in FIG. 8 or a strip line as shown in FIG. 9 is used as a transmission line, there is an advantage that a matching circuit can be easily formed. However, in measurement of a leadless chip carrier having a plurality of electrodes on the same surface, contact electrodes are arranged on one dielectric substrate, and it is difficult to elastically deform each contact electrode. Therefore, the unevenness between the electrodes of the object to be measured cannot be absorbed, and a connection with good reproducibility cannot be obtained by repeated attachment and detachment.

The present invention has been made to solve the above problems. In other words, the present invention provides a structure of a test fixture capable of performing stable high-frequency measurement in a test fixture for a leadless chip carrier.

[0009]

A test fixture for a leadless chip carrier according to the present invention (claim 1) has a leadless chip carrier mounted thereon and extends from an electrode of the leadless chip carrier to a connector of an external device. The above object is achieved by providing a test fixture for a leadless chip carrier, wherein the transmission line is formed in contact with a dielectric substrate, wherein the test line is electrically connected through at least one transmission line. I do.

[0010] In the test fixture for a leadless chip carrier according to the present invention (claim 2), the above object is achieved because the transmission line is a strip line or a microstrip line.

By using a strip line or a microstrip line having a ground electrode, it is possible to withstand use at a higher frequency.

A test fixture for a leadless chip carrier according to the present invention (claim 3) achieves the above object by forming a matching circuit on the dielectric substrate.

The provision of the matching circuit makes the device suitable as a test fixture for a device operated at a higher frequency.

In a test fixture for a leadless chip carrier according to the present invention (claim 4), a plurality of the dielectric substrates are laminated, the transmission line is formed between the substrates, and one of the substrates is formed. The above object is attained by exposing the transmission line by notching the portion and electrically connecting the exposed portion to the leadless chip carrier.

By providing a step by shifting the edge of the overlapping dielectric substrate and exposing the tip of the transmission line, it is possible to obtain a more stable contact than by using a pin to contact a device as in the related art. .

A test fixture for a leadless chip carrier according to the present invention (claim 5) achieves the above object by forming an elastic body in contact with the dielectric substrate.

An elastic body is brought into contact with the dielectric substrate, and the dielectric substrate is elastically deformed by using the deflection of the elastic body, so that not only the device whose characteristics are to be measured and the transmission line but also the ground electrode are stable. It is possible to obtain a contact state.

In the test fixture for a leadless chip carrier according to the present invention (claim 6), a plurality of transmission lines are formed in the dielectric substrate, and a cut is formed in the dielectric substrate between the transmission lines. By achieving the above, the above object is achieved.

By making a cut between the transmission lines of the dielectric substrate, the dielectric substrate bends more appropriately, and the device whose characteristics are to be measured and the transmission line can be more reliably brought into contact.

Hereinafter, the operation of the present invention will be described.

If a strip line is used as a transmission line, a matching circuit can be formed in the immediate vicinity of the device under test, so that loss and reflection hardly occur between the matching circuit and the device under test, enabling accurate measurement. Becomes In addition, by making a cut between each contact electrode, each contact electrode is individually elastically deformed, and it becomes possible to absorb the unevenness of the electrodes of the DUT. Even if it is attached and detached, connection can be made with good reproducibility. Furthermore, since the object to be measured can be positioned by the step formed by shifting the edges of the dielectric substrate and superposing them, a positioning mechanism using metal pins or resin is not required, and a low-cost test fixture can be produced.

[0022]

FIG. 1 shows an embodiment of a test fixture for a leadless chip carrier according to the present invention,
FIG. 2 shows a state where the leadless chip carrier 9 is mounted thereon.

The dielectric substrates 2 and 3 are preferably formed of a material that easily forms a transmission line and has a small loss. In this embodiment, the PPO
Although a (PolyPhenylene Oxide) substrate is used, a glass epoxy substrate or the like may be used.
It is preferable that the dielectric substrates 2 and 3 have the same thickness for ease of design. However, if the dielectric substrate 2 is thicker than the leadless chip carrier 9, it is difficult to take out the dielectric substrate 2. The thickness of the chip carrier 9 was 0.62 mm, which was slightly smaller than 1.0 mm.

The dielectric substrate 2 has a line conductor 4 on one side,
A ground conductor 5a is formed on the opposite surface, and a ground conductor 5b is formed on one surface of the dielectric substrate 3. Gold plated 35 μm thick copper is used for the line conductor 4 and the ground conductors 5a and 5b. The line conductor 4 is sandwiched between the dielectric substrate 2 and the dielectric substrate 3, and the outside thereof is sandwiched between the ground conductors 5 a and 5 b to form a strip line having a structure suitable for a high-frequency transmission line. doing. The width of the line conductor 4 is set to 0. 0 so that the characteristic impedance becomes 50Ω to facilitate matching with peripheral devices.
39 mm. If the impedance of the peripheral device is not 50Ω, the characteristic impedance can be adjusted to the impedance of the peripheral device by changing the line width of the line conductor. Further, by forming an arbitrary pattern on the dielectric substrate 2, a matching circuit can be formed.

A hole 14 is formed in the dielectric substrate 3.
Since the hole 14 has a function as a positioning mechanism when the leadless chip carrier is mounted, the hole 14 is slightly larger than the leadless chip carrier 9. In this embodiment, the size of the leadless chip carrier 9 is 6.3.
Since it was 5 mm square, the hole 14 was 6.50 mm.

A hole 12 is formed in the dielectric substrate 2.
Since the contact electrode and the positioning mechanism are formed by shifting the edges of the dielectric substrate 2 and the dielectric substrate 3, the hole 12 is slightly smaller than the leadless chip carrier 9. Also, the contact electrode 13 is determined by the amount of shift of the edge between the dielectric substrate 2 and the dielectric substrate 3.
Since the size of the electrode 15 is determined, the amount of shift is determined by the electrode 15 formed on the back surface of the leadless chip carrier 9 as shown in FIG.
Size. In this embodiment, since the size of the electrode 15 of the leadless chip carrier 9 is 1.0 mm square, the hole 12 is 4.5 mm smaller than the hole 14 by 2.0 mm.
And

As shown in FIG. 4, the dielectric substrate 2 and the dielectric substrate 3
Are overlapped, the tip of the line conductor 4 seen when the hole 14 is viewed from the dielectric substrate 3 side becomes the contact electrode 13. If durability is required, a metal piece may be attached to the tip of the line conductor 4.

Cuts 16 each having a length of about 4.0 mm are made between the contact electrodes 13 so as to be individually elastically deformed, so that the unevenness between the electrodes of the leadless chip carrier 9 can be absorbed.

Instead of making a cut, the dielectric substrate 2 may be cut off to form a plurality of substrates.

The base metal 1 is formed with a protrusion 10 and a groove 11 surrounding the protrusion at a position in contact with the back surface of the leadless chip carrier 9.

Since the projection 10 functions as a ground electrode, and it is desirable that the upper surface be flat and the contact area be large, a conductive rubber plate or the like may be placed. In addition, a metal plate or the like that is soft and easily deformed may be placed because it also functions as a heat radiation path. The shape of the projection 10 is the shape of the line conductor 4.
Dielectric substrate 2 from base metal 1 so as to be flush with
And a 4.0 mm square cross section large enough to pass through the hole 12 of the dielectric substrate 2 with a margin.

The groove 11 is for inserting the elastic body 7 which makes the contact electrode 13 elastically contact the electrode 15 of the leadless chip carrier 9. When the groove 11 is deeper, the heat radiation path becomes longer and the thermal resistance becomes higher. If it is too shallow, the elastic body 7 becomes thin, and it is difficult to reliably connect the contact electrode 13 and the electrode 15. In this embodiment, the elastic body 7 is made of rubber having a thickness of 1.0 mm, and the depth of the groove 11 is set to 0.9 mm. Groove 11
Is made slightly shallower than the elastic body 7 so that the contact electrode 13 is lightly pushed up so as to be surely in contact with the electrode 15. In order to stabilize the contact of the contact electrode, an elastic body 7 is required.
It is better to be located directly below the contact electrode 13, but the heat radiation is improved by separating the groove 11 from the protrusion 10 and as shown in FIG. Since the effect cannot be expected even if the groove is separated more than the depth of the groove 11, an interval of 1.0 mm is provided in this embodiment.

Then, the dielectric substrate 2 and the dielectric substrate 3 are fixed on the base metal 1 in an overlapping manner, as shown in FIG.
When the leadless chip carrier 9 is dropped into the hole 14 formed in the above, the leadless chip carrier 9 is positioned by the hole 14 formed in the dielectric substrate 3, and the contact electrode 13 is accurately connected to the electrode 15 of the leadless chip carrier 9. it can. Then, when the leadless chip carrier 9 is pushed in using the presser 6 until the back surface hits the projection 10, the contact electrode 13 and the electrode 15 are elastically contacted by the action of the elastic body 7, and an electrical connection is obtained. Further, since the leadless chip carrier 9 is pressed against the protrusion 10, the protrusion 10 functions as a heat radiation path to the base metal 1.

Further, a connector 8 having a characteristic impedance of 50Ω is connected to the transmission line 4 so that connection with an external device is possible.

[0035]

According to the present invention, the following effects can be obtained.

1. Since a transmission line is formed using a dielectric substrate, a matching circuit or the like can be easily formed in the middle of the line, and accurate electrical characteristics can be measured even at a high frequency.

2. Even an object to be measured having a plurality of electrodes on the same plane can absorb irregularities between the electrodes, so that measurement with good reproducibility can be performed even when the object is repeatedly attached and detached.

3. Since the mechanism for positioning the object to be measured can be made with a simple structure, a low-cost test fixture can be made.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of the present invention.

FIG. 2 is a partially broken perspective view showing a state where a leadless chip carrier is mounted on the test fixture of the present invention.

FIG. 3 is a partially enlarged view of a leadless chip carrier mounting portion of a base metal.

FIG. 4 is a partially enlarged view of a leadless chip carrier mounting portion.

FIG. 5 is a view showing an electrode formation surface of a leadless chip carrier.

FIG. 6 is an enlarged cutaway view of a conventional technique.

FIG. 7 is a sectional view of a coaxial line.

FIG. 8 is a sectional view of a microstrip line.

FIG. 9 is a sectional view of a strip line.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base metal 2, 3 dielectric substrate 4 line conductor 5, 27 ground electrode 6, 23 retainer 7, 24 elastic body 8 coaxial connector 9 leadless chip carrier 10 protrusion 11 groove 12, 14 hole 13, 21 contact electrode 15 electrode 16 Notch 20 Coaxial line 22 Positioning mechanism 25 Line conductor 26 Dielectric

Claims (6)

[Claims] 1. A leadless chip carrier having a leadless chip carrier mounted thereon and electrically connected from an electrode of the leadless chip carrier to a connector of an external device via at least one transmission line. A test fixture for a leadless chip carrier, wherein the transmission line is formed in contact with a dielectric substrate. 2. The test fixture according to claim 1, wherein the transmission line is a strip line or a microstrip line. 3. The test fixture for a leadless chip carrier according to claim 1, wherein a matching circuit is formed on the dielectric substrate. 4. A method comprising: laminating a plurality of said dielectric substrates, forming said transmission line between said substrates, and exposing said transmission line by cutting out a part of said substrate; The test fixture for a leadless chip carrier according to claim 1, wherein the test fixture is in electrical contact with the leadless chip carrier. 5. The test fixture for a leadless chip carrier according to claim 1, wherein an elastic body is formed in contact with the dielectric substrate. . 6. The dielectric substrate according to claim 1, wherein a plurality of transmission lines are formed in the dielectric substrate, and cuts are formed in the dielectric substrate between the transmission lines. The test fixture for a leadless chip carrier according to any one of the above.