Die design with integrated assembly aid

Methods and systems for inserting and replacing swaged probe pins in a lower die portion of a head having an array of micro-holes for receiving the probe pins are disclosed. The methods and systems include the following: swaged probe pins including substantially cylindrical ends and a swaged center portion; and an assembly aid film including an array of slotted holes, each of the slotted holes including a substantially round portion for receiving the substantially cylindrical ends of the swaged probe pins and slot portions for receiving the swaged center portion of the swaged probe pins. The array of slotted holes is configured to properly align the swaged probe pins with the array of micro-holes.

BACKGROUND

U.S. Pat. Nos. 6,297,657, 6,633,175, and 7,282,936illustrate vertical pin probing devices and are incorporated by reference as if fully disclosed in their entireties herein.

One type of vertical pin probing devices utilizes a buckling beam die design. As described in U.S. Pat. No. 6,297,657, an integrated circuit or other device under test is supported on a movable chuck. The integrated circuit typically has a pattern or matrix of contact pads to be simultaneously probed by a vertical-pin integrated circuit probing device, such as the probe head sold under the brand name COBRA® by Wentworth Laboratories of Brookfield, Conn. The probing device includes a lower die with a group of holes and an upper die with a group of holes separated by a spacer and carrying multiple vertical pin probes. The die materials are typically made of a plastic insulating material such as those sold under the brand name Delrin®, an acetal resin that is a registered trademark E.I. duPont de Nemours & Co of Wilmington, Del., a low expansion metal such as those sold under the brand name Invar®, a nickel alloy that is a registered trademark of Imphy, S.A., or a ceramic such as silicon nitride.

Each probe pin has a probe tip that protrudes from a hole in the lower face of the lower die and an exposed head that protrudes from holes in the upper side of upper die. Holes containing opposing ends of the vertical probe pins are slightly offset from one another and the probe pins are curved in a snake-like configuration to promote buckling, to create substantially uniform contact pressure on the integrated circuit pads despite any slight vertical unevenness or misalignment.

With reference toFIG. 1, a partially-assembled portion of a buckling beam die10as known in the prior art includes of a lower die12, probe pins14, and an assembly aid film16. Lower die12contains an array of micro-holes18into which probe tips20are inserted. Assembly aid film16contains a matching pattern of micro-holes22punched into the film. One edge24of a small piece of assembly aid film16is adhered, e.g., using tape or similar, to top26of lower die12so that it is approximately positioned over micro-holes18. Each probe tip20is inserted into one of lower die micro-hole18, and then probe head28is inserted up through a corresponding micro-hole22in assembly aid film16to hold probe pin14in position. This process is continued until each of probe pins14are in place. Insertion of probe heads28requires lifting assembly aid film16to provide sufficient clearance to slip each probe head under the film and up through the proper one of micro-holes18. As the assembly proceeds, it is necessary to tie down assembly aid film16periodically to prevent it from lifting up off probe heads28of the contacts that have already been installed. Regardless, assembly aid film16occasionally lifts off probe heads28resulting in the need for a partial or complete re-assembly. The process of fitting probe heads28up through micro-holes22in assembly aid film16also presents opportunities for each of probe pins14to be inadvertently bent.

After each of probe pins14have been loaded into lower die12and assembly aid film16, it is necessary to cut the film so that it fits entirely inside an upper die cavity, and to remove the tie-down wires. This process often results in assembly aid film16lifting off one or more of probe heads28, again requiring a partial or complete re-build of the assembly. After assembly aid film16has been cut and the wires removed, it is necessary to install an upper die30. As shown inFIG. 2, this requires aligning upper die30, which has an array of micro-holes32matching the pattern of micro-holes18and22in lower die12and assembly aid film16, respectively, over array of probe pins14such that each of probe heads28lines up with a respective one of the micro-holes in the upper die. This is a delicate operation, as typically each of thousands of probe pins14must pass through one of micro-holes32simultaneously in order to avoid bending probe pins. Consequently, each of micro-holes32in upper die30are larger than those in lower die12and in assembly aid film16to facilitate assembly. Also, still referring toFIG. 2, upper die30is conventionally made by starting with a round disk of polyimide material of approximately 0.1 inch thickness, and milling out a cavity34leaving a thin “web” on the order of 0.010″ thick through which the pattern defining array of micro-holes32is drilled. It is often difficult to keep such a thin web of material flat across the array due to unbalanced internal stresses in the material after milling, moisture absorption, etc., and may result in a relatively low yield rate for upper dies.

After upper die30is installed, alignment pins (not shown) are inserted to correctly align the upper die with lower die12dies, and screws (not shown) are installed to hold the upper and lower dies together. Probe heads28are then lapped in order to arrive at a consistent over-all probe pin length throughout the array. One consequence of the lapping process is that lapping debris passes through over-sized micro-holes32in upper die30and collects on assembly aid film16inside the head assembly. This debris is conductive and must be removed to avoid electrical shorting between contacts. It is therefore necessary to remove upper die30after lapping in order to adequately remove the debris. The removal of upper die30presents a further opportunity for assembly aid film16to lift off probe heads28, requiring a partial or full re-build of the assembly. It also requires upper die30alignment and assembly to be repeated, presenting another opportunity for bending probe pins14if alignment is not perfect.

One of the advantages of buckling beam technology is repair-ability. Since the probe pins are not permanently bonded to the test electronics, it is possible to replace damaged probe pins rather than discard the entire assembly. The repair process with the conventional design as illustrated inFIG. 2may be problematic. The repair process requires removal of upper die30to gain access to probe pins14. A damaged one of probe pins14is then extracted by pulling it through assembly aid film16, and re-inserting a new probe pin through the same assembly aid film hole. There are several problems that may arise when using this technique. First, the removal of upper die30may cause assembly aid film16to lift off one or more of probe heads. Static electricity sometimes results in assembly aid film16adhering to the underside of upper die30and coming completely off the array, resulting in the need for a complete re-build.

Assuming upper die30is successfully removed, any of probe pins14that are damaged must then be withdrawn through assembly aid film16. Since micro-holes22in assembly aid film16are “tight”, e.g., with a diameter on the order of 0.0001 inch larger than the diameter of typical probe pin14, the assembly aid film must be slightly torn in order for the probe pin “swage” to pass through the film. This “tugging” on assembly aid film16presents another opportunity for the film to lift off of one or more of probe pins14.

Assuming a damaged one of probe pins14is successfully removed and another probe pin inserted, the particular one of micro-holes22in assembly aid film16is now enlarged, causing potential difficulties in aligning the new probe pin with its associate micro-hole32in upper die30. Also, enlarged one of micro-holes22in assembly aid film16allows probe pin14more freedom of movement, which may allow it to contact a neighboring probe pin in tight tolerance applications resulting in an electrical short circuit.

SUMMARY

A system for inserting and replacing swaged probe pins in a lower die portion of a head having an array of micro-holes for receiving the probe pins is disclosed. In some embodiments, the system includes the following: swaged probe pins including substantially cylindrical ends and a swaged center portion; and an assembly aid film including an array of slotted holes, each of the slotted holes including a substantially round portion for receiving the substantially cylindrical ends of the swaged probe pins and slot portions for receiving the swaged center portion of the swaged probe pins; wherein the array of slotted holes is configured to properly align the swaged probe pins with the array of micro-holes.

An upper die portion of a die head for aligning swaged probe pins in an array of micro-holes formed in a lower die portion of the die head is disclosed. In some embodiments, the upper die portion includes the following: a spacer portion including first and second surfaces, the first surface adapted to contact the lower die portion; a first support frame positioned above the second surface; an assembly aid film having an array of slotted holes adapted to receive the swaged probe pins; a second support frame positioned above the first support frame and the assembly aid film; and a sheet joined with the second support frame and having an array of micro-holes adapted to receive the swaged probe pins.

An upper die portion of a die head for aligning swaged probe pins in an array of micro-holes formed in a lower die portion of the die head is disclosed. In some embodiments, the upper die portion includes the following: a spacer portion including first and second surfaces, the first surface adapted to contact the lower die portion; a support frame; and an assembly aid film attached with the second surface of the spacer portion and having an array of slotted holes adapted to receive the swaged probe pins.

A die head including alignment mechanisms for aligning probe pins having substantially cylindrical ends and a swaged center portion in the die head is disclosed. In some embodiments, the die head includes the following: a lower die portion having multiple surfaces, at least one of the multiple surfaces having an array of micro-holes adapted to receive the cylindrical ends of the probe pins; and an upper die portion having a spacer portion and an assembly aid film, the spacer portion including first and second surfaces, the first surface in contact with at least one of the multiple surfaces of the lower die portion, the assembly aid film positioned adjacent with the second surface, the assembly aid film having an array of slotted holes adapted to receive both the cylindrical ends and the swaged center portion of one of the probe pins.

A method of aligning swaged probe pins in an array of micro-holes formed in a lower die portion of a die head assembly is disclosed. In some embodiments, the method includes the following: stacking an assembly aid sheet having slotted holes in a first position on top of the lower die portion so that round portions of the slotted holes are axially aligned with the array of micro-holes; inserting swaged probe pins having cylindrical end portions and a swaged center portion through the slotted holes in the assembly aid film and the array of micro-holes in the lower die portion; and lifting the assembly aid film to a second position by lifting it upwardly over the cylindrical end portion closest to the lower die portion and over the swaged center portion of each of the swaged probe pins; and wherein in the second position, each of the slotted holes are offset from each of array of micro-holes of lower die portion.

DETAILED DESCRIPTION

Referring now toFIGS. 3-5, some embodiments of the disclosed subject matter include a system40for inserting and replacing swaged probe pins42in a die head having a lower die portion44with an array of micro-holes46for receiving the swaged probe pins. System40includes swaged probe pins42. Each of swaged probe pins42typically, but not always, includes substantially cylindrical ends48,50and a swaged center portion52. As best shown inFIGS. 4B and 4C, ends48and50of each of swaged probe pins42are typically laterally offset from one another by a distance D to promote buckling of the pins so that they are spring-like. System40includes an assembly aid film54that has an array of slotted holes56. Array of slotted holes56is configured to properly align swaged probe pins42with array of micro-holes46. To account for the offset between ends48and50of swaged probe pins42, array of slotted holes56is typically offset from array of micro-holes46. Assembly aid film54is typically, but not always, at least semi-transparent. Each slotted hole of array of slotted holes56includes a substantially round portion58for receiving substantially cylindrical ends48,50of swaged probe pins42and slot portions60,62for receiving swaged center portion52of the swaged probe pins. Array of slotted holes56is typically, but not always, configured so that a first one48of the substantially cylindrical ends of each of swaged probe pins42is releasably retained within a micro-hole64of array of micro-holes46and a second one50of the substantially cylindrical ends of each of the swaged probe pins is releasably retained within substantially round portion58of a slotted hole66of the array of slotted holes.

As defined herein, the swaged probe pins can include a center portion that has a non-rectangular cross-section such as a D-shaped cross-section or star-shaped cross-section. As follows, the slotted holes of the assembly aid film are defined to include holes that allow the entire probe pin to pass through, regardless of their shape. For example, the disclosed subject matter contemplates the use of any cross-sectional shape for the center portion of the probe pin providing the slotted holes of the assembly aid film are fabricated and sized to allow the passage of the center portion and both cylindrical end portions of the probe pin without damaging the assembly aid film.

Referring now toFIGS. 6-8, some embodiments include an upper die portion70of a die head72for aligning swaged probe pins42′ in an array of micro-holes76formed in a lower die portion78of the die head.FIGS. 6 and 7show a side section view from the front of swaged probe pins42′ andFIG. 8shows a side section view from the side of the swaged probe pins. Upper die portion70generally includes a spacer portion80, a first support frame82, an assembly aid film84, a second support frame86, and a sheet88.

Spacer portion80includes first and second surfaces90and92, respectively. First surface90is adapted to contact lower die portion78. Spacer portion80is typically an annular configuration having a square or rectangular cross-section and may be formed from any materials known to be suitable as a die portion, e.g., a fiber-filled epoxy, a low expansion metal, or a ceramic. Spacer portion80can have varying thicknesses in varying embodiments.

First support frame82is positioned above second surface92of spacer portion80and typically holds assembly aid film84taut. First support frame82is typically formed from a metal foil such as a low expansion nickel alloy for higher temperature applications, e.g., sold under the brand name Invar® or similar, or stainless steel for lower temperature applications, e.g., near room temperature. First support frame82is typically similar in shape to spacer portion80but with a smaller dimension with respect to the longitude of each of swaged probe pins42′. Some embodiments of the disclosed subject matter may not include a support frame.

Assembly aid film84is typically positioned between first support frame82and second support frame86and includes an array of slotted holes94adapted to receive swaged probe pins42′. Each of the round portions58′ in array of slotted holes94of assembly aid film84can be over-sized, e.g., typically having a diameter approximately 0.5 mil (0.0005 inch) larger than the diameter of ends48′ and50′ of swaged probe pins42′, which is smaller than micro-holes22in upper die16of the prior art. Each of the micro-holes in array of micro-holes102of second assembly aid film100are generally smaller than round portions58′ in array of slotted holes94of assembly aid film84, e.g., typically having a diameter about 0.1 mil (0.0001 inch) larger than the diameter of each of ends48′ and50′ of swaged probe pins42′ so that the probe pins can be held in close relative alignment to each other and that each of the micro-holes is effectively sealed to prevent debris from entering the die head. Slot portions60′ of swaged probe pins42′ are sized so that a swaged center portion52′ of swaged probe pins42′ can pass through without tearing assembly aid film84. Assembly aid film84is generally at least semi-transparent. Assembly aid film84may also include alignment holes96, which are intended to engage a dowel or similar structure (not shown) for aligning the components of upper die portion70with lower die portion78. Additional structural rigidity may be provided to upper die portion70by bonding assembly aid film84to support frame86and spacer portion80using commercially available adhesives, e.g., 3M 2290 Structural Adhesive (3M, St. Paul, Minn.) or similar.

As mentioned above, spacer portion80can have varying thicknesses in varying embodiments. The thickness of spacer portion80will generally determine what portion of each of swaged probe pins42′ is surrounded by each of array of slotted holes94when the die head is assembled. For example, in some embodiments, a thickness of spacer portion80is selected so each of array of slotted holes94of assembly aid film84surround one of ends48′ of swaged probe pins42′. In some embodiments, a thickness of spacer portion80is selected so each of array of slotted holes94of assembly aid film84surround one of swaged center portion52′ of swaged probe pins42′.

Second support frame86is positioned above first support frame82and assembly aid film84. Sheet88is typically joined with second support frame86and includes an array of micro-holes98adapted to receive swaged probe pins42′. Sheet88is typically formed from a polyimide having a thickness of about 4-12 mils. In some embodiments, sheet88has a thickness of about 6 mils. Array of slotted holes94and array of micro-holes98are typically aligned with one another and adapted to be offset from array of micro-holes76formed in lower die portion78of the die head.

Additional embodiments include variations to those illustrated inFIGS. 6-8. For example, referring now toFIG. 9, some embodiments are substantially the same as those illustrated inFIGS. 6-8, but do not include second support frame86and sheet88.

Referring now toFIG. 10, some embodiments are the same as those illustrated inFIG. 9, but include a second assembly aid film100positioned proximal to assembly aid film84and having an array of micro-holes102adapted to receive swaged probe pins42′. Second assembly aid film100generally is in contact or close proximity to assembly aid film84. Array of micro-holes102in second assembly aid film100and array of slotted holes94in assembly aid film84are adapted to be offset from array of micro-holes76formed in lower die portion78of the die head. The amount of offset is determined by the offset of each of swaged probe pins42′, i.e., the lateral distance between ends48′ and50′.

Referring now toFIG. 11, some embodiments are substantially similar to those inFIG. 10, but further include a second support frame86′ and a sheet88′. Second support frame86′ includes a top surface108and a bottom surface110. Sheet88′ is positioned on top surface108and bottom surface110is positioned on top of assembly aid film84so that second assembly aid film100is positioned between assembly aid film84and sheet88′. In some embodiments, assembly aid84and second assembly aid film100are at least semi-transparent. Assembly aid films84and100may be any suitable polymer film, e.g., of the type formed from a polyimide. Assembly aid film84typically has a thickness of about 0.5 to 4 mils. In some embodiments, assembly aid film84has a thickness of 2 mils. Assembly aid film100typically has a thickness of 1 to 3 mills. In some embodiments, assembly aid film100has a thickness of 1 mil. Sheets88and88′ are typically substantially not transparent. Assembly aid film84generally creates a taut “drum skin” across an aperture114that includes a perimeter116, which is defined within the die head and first support frame82, thereby eliminating the non-flatness problem inherent in conventional designs. Second assembly aid film100is generally smaller in diameter than assembly aid film84and has an outer perimeter118that is smaller than perimeter116of aperture114. As a result, second assembly aid film100is typically not connected with first support frame82and instead may float on top of assembly aid film84.

Referring now toFIGS. 12A and 12B, some embodiments include a method of aligning swaged probe pins42″ in an array of micro-holes46′ formed in a lower die portion44′ a die head assembly. As shown inFIG. 12A, in a first position, an assembly aid sheet54′ having slotted holes56′ is stacked on top of lower die portion44′. Round portions58′ of slotted holes56′ are axially aligned with each of array of micro-holes46′. Swaged probe pins42″, which each include cylindrical end portions48″,50″ and a swaged center portion52″, are inserted through slotted holes56′ in assembly aid film54′ and array of micro-holes46′ in lower die portion44′. As shown inFIG. 12B, assembly aid film54′ is moved to a second position by lifting it upwardly over one cylindrical end portion50″ and over swaged center portion52″ of each of swaged probe pins42″. In doing so, each one of round portions58′ of slotted holes56′ is lifted over one of cylindrical end portions48″,50″ and each one of a slot portion60′,62′ of the slotted holes is lifted over one swaged center portion52″. In the second position, each of slotted holes56′ are offset from each of array of micro-holes46′ of lower die portion44′. Although not shown, spacer portions and support frames can be configured and can be removed and inserted as required.

The disclosed subject matter offers a plurality of benefits and advantages over prior art designs. For example, the disclosed subject matter design enhances the repair-ability of the die head. Repairs can be performed by simply removing the second assembly aid film and/or polyimide sheet, withdrawing a damaged probe pin through the slotted holes in the assembly aid film, re-inserting a new probe pin, and re-installing the second assembly aid film. There is no need to remove the upper die, no possibility for the assembly aid film to lift off the probe heads, and no tearing of the film.

The assembly process of the disclosed subject matter described above offers several benefits over prior art assembly processes. First, it generally can be completed in less time than for conventional assembly. Next, because there is no longer any need to tie down the assembly aid film, there is no possibility for the film to lift off the probe heads. Also, it greatly reduces the likelihood of bending the probe pins, since the probe heads no longer have to be bent down and inserted upwards through the assembly aid film.

As described above for some embodiments of the disclosed subject matter, after all of the probe pins have been loaded, the second assembly aid film having an array of smaller diameter micro-holes is aligned over the probe heads and lowered onto the surface of the assembly aid film. The smaller micro-holes allow the probe pins to be held in close relative alignment to each other. In addition, since the second assembly aid film is generally not fixed to the die assembly, it allows free motion of the probe pins during probe pin compression while still maintaining their relative positions. The alignment of the second assembly aid film to the probe pins is much simpler than the upper die alignment of a conventional design because a) the second assembly aid film is preferably at least semi-transparent so the probe pins are always visible and b) it is not necessary that all the probe pins pass through all the micro-holes of the array simultaneously, but rather the second assembly aid film can be applied to sections of the array in stages.

A further advantage of the second assembly array film is evident in the lapping process. As described earlier, the lapping process generates debris. Since the second assembly aid film has a small diameter, i.e., “tight,” micro-holes, the lapping debris collects on the top of this film, rather than passing into the head assembly. As the debris is on the outside of the assembly, it may be removed easily without requiring removal of the upper die. The second assembly aid film may even be removed entirely and replaced with a clean film.

The drilling process of the disclosed subject matter also offers improvements over prior art processes. The drilling of conventional upper dies is time consuming because the drilling process requires controlled feed rates and multiple passes in order to achieve good quality micro-holes and avoid drill breakage. In contrast, the assembly aid films according to the disclosed subject matter can be punched or laser drilled at low cost and low lead time. Also, the films of the disclosed subject matter offer opportunities for slotted holes, which provide advantages in very tight pitch applications, whereas conventional drilling processes are typically limited to round holes.

Although the invention has been described and illustrated with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the disclosed subject matter.