Intel took us on a special visit to its advanced chip packaging, assembly, and testing facilities located on the island of Penang, and another one in the mainland city of Kulim, Malaysia and it was quite an experience.
During the tour, we visited two facilities. The Penang Assembly and Test (PGAT) facility is where the silicon dies are assembled, validated, and tested for errors. Then, the Intel Kulim Die Sort Die Prep (KMDSDP) facility is where the real magic happens. This facility processes silicon wafers and readies these silicon wafers for die preparation and categorization for packaging and testing at Intel facilities worldwide.
We’ve got the silicon, but now, what after that
Kulim Die Sort Die Prep (KMDSDP) facility has two main operations – die preparation and sorting. Nowadays, 300mm wafers are the standard size produced, and they are received at Kulim. Here, they undergo a series of processes that singulate them into individual chips.
Wafers are attached to flexible mylar sheets and go through various processes, such as grinding and thinning to an exact profile, to create individual chips. Using a vacuum and UV light, chips are separated and placed into trays before sorting. Intel uses huge sorting modules, as big as a bus, with 20 test cells weighing 1,000 pounds each, to test and sort the chips. It was so yellow in there that it felt like we were in the Mexico.
A specially designed lifting mechanism that hovers above the floor using a cushion of air manoeuvres these modules. Chips are loaded onto trays and distributed to various test cells.
One of the tests is to ensure that the chips are reliable and free from defects; each one undergoes testing using a probe card. The probe card consists of thousands of thin needles that are even thinner than human hair, which connect to the integrated circuit inside the test equipment. This allows for the measurement of the chip circuits’ electricity and analysis of any defects that may be present.
Then, there are automatic guided vehicles to transport these trays throughout the testing facility.
After a tray goes through the testing and characterization phase, it is returned to the area where the wafer was cut into individual chips. The chips that do not pass the test are separated, thrown away, or recycled. The trays with chips that have successfully passed all the tests are sorted and assigned a specific SKU. Each chip is removed from the tray and sealed between two film layers. The sealed chips are then rolled onto a reel to be transported to the Assembly and Test facilities located worldwide for further processing.
Intel also makes its own testing equipment
During the visit to Intel’s facility, we also visited the System Integration and Manufacturing Services (SIMS) facility, which manufactures testing equipment for CPUs.Some of the machines that are manufactured in this facility include the high–density Burn-In (HDBI) tester, the High-Density Modular Tester (HDMT) tester, and the System Level Tester (SLT). These equipment are used by Intel facilities in Malaysia and worldwide to test the CPUs.
A sneak peek into Intel’s testing practices
One of the Assembly and Test facilities is in Penang, where these chips are received and undergo further processing and testing before it reaches OEMs. Upon receiving the reels, the facility removes the die, and packages and conducts testing before the chips are distributed. PGAT’s assembly and test process has six stages.
The first is Chip Attach, where the chip is bonded to the substrate using the Foveros face-to-face (F2F) chip-on-chip bonding process. An extra layer of epoxy underfill is added to remove microscopic gaps. The next step is to attach the Integrated Heat Spreader (IHS) using thermal interface material and adhesive. This allows for efficient heat dissipation. Now, the CPU is ready, but there is one last step before it can be sent out to OEMs.
At the Design And Development Lab in Penang, the CPU undergoes burn-in, electrical, and PPV testing. The chips are exposed to high temperatures and voltages to identify defects. Once passed, all electrical traces and functionalities are tested. Then, these go through PPV testing, which is to confirm functionality in actual customer computer systems by simulating tests in controlled environments. Now, these CPUs are finally ready to be loaded up in the trucks and reach their destination.