|The new Twin Placement Robot for the A-Series machine. |
The electrical connections between a semiconductor die and its package — and hence the outside world — are today made using wire (or flip-chip) bonders. Because of the repeatability accuracy needed for this operation — down to 10µ — the machines are expensive and have fairly low throughput: between 5,000 and 8,000 components per hour. So, multiple machines are usually needed to keep pace with semiconductor production lines.
Once packaged, the ICs then have to be placed on printed circuit boards. This is a much faster process, but is generally less accurate. The gantry-based systems that dominate the SMT industry use sequential placement — picking and placing one component at a time. The single exception is the A-Series pick-and-place equipment from Assembléon (a 100 percent Philips subsidiary), which uses up to 20 robot heads to place a maximum of 20 components at a time. For the same throughput, that gives up to 20 times the length of time available to pick a component and transport it, calculate its trajectory, allow it to settle, place it with controlled force, and check the placement.
|Modular A-Series machine, from chip shooting to IC and die shooting. |
This smooth placement process cuts accelerations, decelerations and rotations, which in turn greatly reduces the number of components twisted or thrown off. The machines are designed for six-sigma repeatability, with automatic calibration maintaining repeatability even with changing environmental variables like temperature. High- resolution laser alignment brings placement repeatability of 40µ. Working as a pure chip-shooter (placing components like micro- miniature 01005 chips), the A-Series works at up to 165,000 components per hour with an industry benchmark quality figure of below 10 defects per million components placed. That quality not only improves overall predictability and quality of end products, it helps reduce overall end-product waste and its associated rework and disposal costs. And, unlike most other equipment in the industry these are "real-life" placement speeds — higher than the 121,000 cph rated to the IPC 9850 measurement standard.
30,000 Die per Hour
Another key feature of the A-Series is its modularity, and Assembléon has recently developed a new Twin Placement Robot head that allows an A-Series machine to work as a combined chip and IC shooter. The new TPR has also already improved the speed of die and Package on Package placements to 16,000 components per hour. It has simultaneously improved the placement repeatability to 25µ and to 17µ — both at 3 sigma, CpK>1 — when aligned by camera. Adding multiple TPRs and reducing the individual robot speeds to give more time for the components to settle will soon allow the A-Series machines to achieve die bonding outputs of 30,000 die per hour and above at a repeatability of 10µ at 3 sigma.
A single A-Series machine will therefore match the output of four to six existing die bonding machines, but at only twice the price. That also eliminates all the running costs that come with multiple machines — maintenance, operation, parts, air, power, floor- space. That in itself promises to transform the back-end semiconductor industry.
Package manufacturing and PCB assembly have, until now, been quite widely separated. Both industries have equipment that can pick and place devices, but both have different specialties and
specifications. Package manufacturers have slower but ultra stable and accurate die and flip chip bonders, while PCB assemblies have faster but less accurate SMD mounters. However, boards are now taking smaller and thinner components with tighter component interspacings and, from the other side, modules (e.g. SIPs) are now integrating SMD components. So, repeatability requirements have been tightening for SMD mounters, and with this increase in repeatability both segments are moving closer to each other, and rapidly. As functionality increases, the number of I/Os increase with it, but with the same (or smaller) package size as before. Bump sizes and bump pitches are therefore decreasing. For bonding, this means that SMD mounters are having to move beyond the traditional placement in paste with its advantage of self-aligning. Moving from PCB assembly to die bonding moves from paste to (e.g.) conductive adhesive. With no more self alignment, the device must be placed precisely. Repeatability and repeatability are therefore absolute requirements.
Born a high-end chip and small-IC shooter, and in use at large module manufacturers since 1997, the A-Series has been dealing with large components to very small ones like die and 01005 (0.4 by 0.2mm) chips. It has been evolving ever since. The single head/single pick parallel placement architecture allows each device to be processed individually using its optimum process parameters, with fully controlled and monitored placement force.
|Continual miniaturization is making chip components vanishingly small with tighter component interspacings. |
At 30,000 components an hour and 10µ repeatability, Assembléon's new linear TPR provides a single-machine solution, particularly for back-end manufacturers who need to cut costs while improving output, repeatability and the ability to handle die products.
For memory modules with high IC count, such as DRAM memory modules, costs can also be reduced by combining chip shooting with IC shooting. The same applies to modules — System In Package (SIP), with multiple die, Package on Package (PoP) technologies, and 0201 and 01005 chips.
This is also exciting for Assembléon's existing board assembly customers since it shows the ease with which new technologies can be added using the modular parallel robot system approach. The future- proof design means there is no need to invest in new pick-and-place equipment when technology moves forward.
The equipment is also ready for future component trends like thinner (half-height) components, and chips that will be half the size of even the 01005 component: the 0201 metric. All these need the finely controlled closed-loop pick-and-place process that is already incorporated into the company's A-Series equipment.
Packaging Bare Die
Then what is the best way to package bare die products for this die- shooter, especially when their size is so very small (less than 1mm2)? The most cost-effective method is to feed pre-sorted known good dies continuously to the system. Sorting and placing known good dies into carriers is done by die-sorters (which can also pre-test the die).
|The trend is from single die in package to SIP and DDR3. |
Die are most efficiently fed to pick-and-place equipment on tape. This is usually tape-and-reel and/or Surftape® although specialized feeding methods are also available. Regardless of the die size, tape allows the known good die to be presented to the pick-and-place equipment at high speed and makes them no longer subject to (relatively slow) wafer exchange, wafer yield or die extraction time.
With the TPR's present IC and die shooting capabilities of up to 16,000 components per hour, the AX-501 (Assembléon's "Flagship" A-Series machine) has a combined chip and IC output that can be scaled up to 111,000 components per hour (output to IPC 9850 and, in most applications, also the real output). The modular equipment design also means that Assembléon's established "True Capacity on Demand" is available for the AX-501 with TPR robots. Customers who foresee future growth can order a machine with low capacity and later increase output, while customers with seasonal sales patterns can rent extra capacity as required.
The combined chip and IC output of the AX-301 machine can be increased from 40,000 to 64,000 components per hour, while that of the AX-501 can be increased from 64,000 to 111,000 components per hour. By simply replacing robots with more compact versions, this increase in output comes from the same machine; there is no disruption of existing line layout that would occur if extra machines were added. This saves enormously on initial investment as well as running costs.
It is not only the output of pick-and-place machines that is important. Delivery commitments must be fulfilled, so forecasts and schedules must be accurate and tightly controlled. Assembléon's equipment is supported by a full set of NPI and MES solutions that ensure optimum setup, fast ramp-up and continuous operation. MES solutions also include traceability data storage, viewing and reporting. That helps integrate A-Series machines seamlessly into the user's factories.
Contact: Assembléon America, Inc., 5110 McGinnis Ferry Rd., Alpharetta, GA 30005 800-474-4547 or 770-751-4420 fax: 770-751- 4450 E-mail: firstname.lastname@example.org Web: http://www.assembleon.com