FI99169C - A method of making an aid for testing a semiconductor circuit - Google Patents

Description

99169

A method of making an aid for testing a semiconductor circuit

The invention relates to a method according to the preamble of claim 1 for manufacturing an aid for testing a semiconductor circuit.

5 -> According to the prior art, in semiconductor fabrication, the individual circuits on a semiconductor wafer (diodes, transistors, integrated circuits and the like) are tested before the circuits are sawn into separate semiconductor weights and before their expensive connection and encapsulation process. Increasing the degree of integration of semiconductor wafers and / or increasing the connection density is usually limited by the number of contact areas at the edges of the silicon, as they must be spaced far enough apart to facilitate rapid and automatic testing.

The testing uses contact pins 15 at the ends of the flexible arms mounted on the circuit board and positioned so that when the entire circuit board card (test card) is pressed against the semiconductor chip, the contact pins each make electrically conductive contact with their own contact area on the semiconductor chip. Such a test card is expensive and difficult to manufacture as well as susceptible to damage. Going to very large contact area densities, e.g. 50 to mid to center, this structure is practically almost technically and costly impossible to implement.

The object of the present invention is to obviate the drawbacks of the technique described above and to provide a completely new type of method for manufacturing an aid.

The method according to the invention is based on the fact that the contact cones are formed in the dry process by preventing the contact cone from etching in a suitable resist area.

More specifically, the method according to the invention is characterized by what is set forth in the characterizing part of claim 1.

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The invention provides considerable advantages.

• · ♦ / * j The method according to the invention reliably provides conical contact pins.

2 99169

Due to the structure and method of manufacture, a flexible test plate is inexpensive, so it is advisable to replace the test plate with a new one when testing long Saijas. Then the positioning of the alignment mark on the test plate speeds up repositioning. One possibility for automatic replacement in place of the worn one is to make a test plate in the form of a strip, in which case a new test plate with automatic targets is stepped in place of the worn one.

Compared to the effortlessly achievable mounting accuracy of the contact needles at the ends of the flexible (long) arms, the contact cones to be etched are inherently in the same plane, so that the resulting contact pressures are more evenly distributed. In this case, lateral displacements and the scratches caused by them are not created as a result of the various large elastic distances.

The invention will now be examined in more detail by means of exemplary embodiments according to the accompanying figures.

Figure 1 shows a cross-sectional side view of an aid made by the method according to the invention.

Fig. 2 shows a perspective view of the aid according to Fig. 1.

Figure 3 shows a perspective view of a first method step for manufacturing an aid according to the invention.

• «• ·· • ·« * · 1 Fig. 4 shows a perspective view of a product made by the method according to Fig. 3. , the end product.

• ♦ · • ♦ · · · • · · · 4

Figure 5 shows a side view of the etching step of the method according to the invention.

• · 30 According to Figures 1 and 2, a conductive pattern 2 is etched on a flexible circuit board made of a thin, flexible plastic film 1 so that the positions of their inner ends correspond to the positions of the contact areas 5 of the semiconductor chips to be tested. Of these, the conductors 2 are scattered 3 99169 as they progress to the edge regions of the circuit board 1, where they end up in relatively far apart contact belts 8. These are easily connected to the signal and drive electrical conductors required for testing.

5 Especially at the end of the semiconductor contact areas 5, the conductors 2 are narrow due to the high contact density and need support throughout which the plastic, typically polyimide or the like, which serves as the base material of the flexible circuit board 1. Thus, the geometry of the contact points 3 remains reasonably close to the geometry of the contact areas 5 of the semiconductor chip.

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Since, on the one hand, the surfaces of the contact areas 5 are usually in a recess formed by the passivation openings 7 and on the other hand reliable contact between the contact area 5 and the contact surface 3 requires high surface pressure. 10 mechanically against the semiconductor piece 6 or alternatively using pneumatic overpressure, the cones 3, like test needles, make contact with the contact areas 5.

To facilitate accurate mutual alignment, the alignment marks (not shown) on the chunks 6 and the test plate 1 can be automatically driven to the correct position by means of the pattern recognition ':: 20 according to the alignment marks 6 and the test plate 1.

• i i ···· The conductor pattern of the flexible test plate 1 is produced by known circuit board techniques [* according to Figs. 3 and 4, e.g. by etching on a polyimide film 1 la- • · «'· * * 25 from a mined metal layer 12. The conductors 12 thus obtained are formed. . for contact cone locations, e.g., a round etching shield, a resistor 14 having a diameter • · · • «· typically the same as the thickness of the metal layer 12.

• · · • · «

If the whole pattern is now etched with, for example, ferric chloride so that the packing of the conductors 12 thins in half, under the round resist spots 14 occurs laterally and. '· Depth-etching so that immediately below the resist the etching reaches the center and at deeper depth it has correspondingly less progress. The etching time 4 99169 should therefore be such that it corresponds to the etching time of the beam-thick layer of the resist spot 14.

As a result, according to Fig. 4, a pointed cone 3, 5 on the surface of the conductors 2 with a height of half the original thickness 12 of the conductor metal is coated.

Figure 5 shows in more detail the effect of the resistor 14 on the transformation of the metal layer 12 into a contact pin 3 on the plastic substrate 1 and a conductor 2. As can be seen, the metal layer 12 is etched by the radius of the resist spot 14.

Example dimensioning: lower limit upper limit typical value 15 substrate 1 thickness 35 pm 250 pm 125 pm substrate width 8 mm 35 mm conductors 2 thickness 18 pm 70 pm 35 pm conductors 2 width contact 25 pm 100 pm 35 pm tin pin 3 at the end

20 conductors 2 width contact- I 100 / tm I 1000 / tm I 250 / tm II

• '· at the end of the strips 8

* · I

·; The structure according to the invention is more compact than the prior art and has an advantageous effect on the testing of high-speed circuits. In functional testing, it is real that

• »I

J .:: A circuit simulating 25 final applications is easier to build around a compact flexible test board. If two-layer metallization is used in the circuit board, especially high-speed signal lines can be constructed on a precisely controlled impedance level for more accurate • · · V * measurement results.

• · 30 The materials of both the substrate 1, the conductors 2 and the resistor regions 14 can be chosen quite freely within the scope of the invention. In practice, the limitations are caused by the manufacturing process as well as the flexibility limitation of the substrate 1 and the conductivity and corrosion properties of the conductors 2.

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The following is a list of suitable materials for the above components:

Substrate: polyimide, polyester, fiberglass-reinforced epoxy 5 Conductors: copper <· 1 »• • Ml · • 4 • # · ♦ ·« • · · • · i 1 • · · t · * · i • · Λ • · < ·

Claims (2)

99169