High-power UV LEDs target UV-curing for industrial apps

I’ve seen UV disinfecting wands at Costco and wondered why they don’t use HB LEDs as their UV source. HB LEDs are more rugged and can be a more compact light source than lamps. What gives?

It turns out that to act as a disinfecting energy, UV radiation needs wavelengths in the 250nm range, and it’s very hard to make LEDs in that wavelength. Where UV LEDs are coming on strong, though, is for UV curing at 390 nm in industrial processes using UV-cured epoxies, inks, paints, laminates and adhesives. This is the market Luminus is targeting with its new UV CBT-120. UV curing requires lots of UV photons, and Luminus’s PhlatLight technology excels as a large-area LED light source. The UV CBT-120 has a power density of 1 W/mm² with a light energy output of 10W at 390 nm.

Apple ipad Day arrives

Chipworks is not normally in the business of blogging teardowns, we leave that to the guys at iFixit and PowerbookMedic, but after my previous speculation on an NXP chip being present next to Apple’s A4 processor chip, I thought it worth confirming. We got our sample this afternoon, and long weekend or not, our guys are in the lab pulling it apart. So first let’s look at the board:

Apple iPad Main Board Topside

Aside from the A4 chip, there are a couple of Samsung 64Gbit NAND flash parts, and next to the screen connectors, a duo of Broadcom parts (BCM 5973 and 5974) and a TI CD3240A. If we zoom in on the A4 we can indeed see that NXP got a design win - somewhat mysteriously marked L0614, it’s adjacent to the connector to the WiFi chip and the connector dock.

Close-up of the A4 Processor and NXP Chip

A bit of searching of the NXP site comes up with the CBLT06141 mux/demux part for DisplayPort and PCIe connections. My other speculation about the A4 was that it didn’t look like the Package-on-Package (PoP) structure used in the iPhones and iPod Touch. Turns out I was wrong - the K4X2G643GE marking on the package indicates the incorporation of 2Gbits of Samsung mobile DDR SDRAM. Whether it’s 2 x 1Gb or 1 x 2Gb chips in there we’ll see when we decapsulate the part. It’s possible it’s a multi-chip package, but it’s more likely PoP since this conformation gives Apple the flexibility to multisource the DRAM.

As an example, below is a package cross-section of the PoP out of the iPhone 3GS (click on the thumbnail image). This also had 2Gb of DRAM within, in the top part of the PoP. In this case the DRAM chips were sourced from Elpida, and the bondpad layout was such that all the bond wires are on one edge of the chip, so the two dies are offset to allow bonding. Another version of the PoP uses Samsung DRAM, with the bonds laid out at both ends of the die, so a different bonding set-up has to be used.

We’ll find out what’s in the A4 in the next few days - stay tuned! There will also be more details on the Chipworks website as our guys get into the iPad internals