Global chip sales grew 7.5% in May, once again defying expectations that economic troubles would crimp the industry.

According to the Semiconductor Industry Association, an industry group, worldwide chip sales totaled $21.8 billion in May, vs. $20.8 billion during the same period last year.

The sequential increase, with sales in May up 2.8% from April, represents the strongest month-over-month growth in the past five years.

SIA President George Scalise said the figures reflect strong sales of consumer electronic products, which account for more than half of all semiconductor sales.

"Despite reports of declining consumer confidence in the U.S., both disposable income and consumer spending rose in May," Scalise said in a statement. "It is likely that the distribution of tax rebate checks to millions of Americans was a factor in increased consumer spending."

And he said the increasing importance of consumers in emerging markets means that "a slowdown in the U.S. today would not have the same impact it had in the past."

The Philadelphia Stock Exchange Semiconductor Sector Index, which is comprised of 18 semiconductor stocks, was up 1.1% in midday trading Monday.

The SOX has slipped about 12.5% since its most recent peak in mid-May, compared to a 13.2% decline in the

Dow Jones Industrial Average

during the same period, and an 8.8% dip in the

Nasdaq

.

In a note to investors Monday, JPMorgan analyst Chris Danely ascribed the better-than-expected chip sales in May to healthy unit shipments of the microprocessors made by companies like

Intel

(INTC) - Get Report

and

Advanced Micro Devices

(AMD) - Get Report

, and of digital signal processors made by firms like

Texas Instruments

(TXN) - Get Report

.

And revenue increased across virtually all chip categories, including troubled memory chips, Danely wrote.

Indeed, according to the SIA, sales of DRAM memory chips, the main type of memory used in PCs, increased 6.4% sequentially in May, but declined 20% year-over-year.

The data seems in keeping with last week's earnings report from

Micron

(MU) - Get Report

, the top U.S. memory chip maker. Micron

posted its sixth consecutive quarterly loss

, as the overcapacity of memory chips flooding the market ate away at its profit margin. But Micron noted that average selling prices for DRAM chips used in PCs, was beginning to strengthen, having increased 35% from February.

Sales of NAND flash chips increased 1.4% sequentially in May, and 25.5% year over year, the SIA said.

Excluding sales of memory chips, the SIA said that global semiconductor sales were up 12.3% year over year.

Despite May's better-than-expected chip sales, JPMorgan's Danely was not convinced that the semiconductor industry is out of the woods.

"We remain cautious on the group due to our belief of a slowdown driven by softening end demand and macroeconomic uncertainty," Danely wrote.