Thanks, Bob. Net revenues for the quarter ended March 31, 2013, of $9.0 million increased 9% from fourth quarter revenues of $8.3 million and decreased when compared with first quarter 2012 net revenues of $10.7 million. First quarter 2013 end user net revenues were $8.1 million, or 90% of net revenues, compared with fourth quarter end user net revenues of $7.0 million. OEM net revenues were $845,000, or 10% of net revenues, compared with fourth quarter OEM net revenues of $1.3 million. Net revenues from markets outside of semiconductor test were $1.7 million, or 19% of net revenues, compared with $1.3 million, or 15% of net revenues in the fourth quarter.
The Company's overall gross margin for the first quarter was $4.1 million, or 46%, as compared with $3.5 million, or 42%, in the fourth quarter of 2012. The improvement in the gross margin was primarily driven by a more favorable absorption of our fixed manufacturing cost in the first quarter of 2013, which decreased from 20% of revenues in the fourth quarter to 16% of revenues in the first quarter. In addition, our fixed manufacturing cost decreased in absolute dollar terms from $1.6 million in Q4 to $1.5 million in Q1. The decrease in our fixed manufacturing cost as a percentage of net revenues in the fourth quarter was partially offset by an increase in our consolidated material cost, which increased from 32.4% in the fourth quarter to 34.2% in the first quarter.
All three of our product segments experienced increases in their component material costs quarter-over-quarter, with our Electrical Products segment increasing the largest increase, going from 37.3% of revenues in Q4 to 41.5% of revenues in Q1. The increase was driven by changes in both our product and customer mix in our Electrical Products segment, as well as our other two product segments. Our Thermal Products segment's component material cost increased from 30.3% in Q4 to 30.8% in Q1, while our Mechanical Products product segment increased from 36.8% in Q4 to 39.7% in Q1.
I'll now talk about operating expenses for the quarter. Selling expense for the first quarter was $1.2 million, or 13% of net revenues, compared with $1.1 million, or 14% of net revenues, for the fourth quarter, an increase of $168,000 or 10%. The increase was primarily due to increased sales commission expense on higher levels of revenue, as well as increased accruals for product warranty costs. Engineering and product development expense is relatively unchanged quarter-over-quarter, coming in at $996,000 for Q1 compared to $985,000 for Q4. Reductions in spending on various product development initiatives was offset by increased patent legal costs.
General and administrative expense for the first quarter was $1.6 million, or 17% of net revenues, compared with $1.3 million, or 16% of net revenues, in the fourth quarter, an increase of $227,000 or 17%. The increase was primarily the result of increased salary and benefits, largely driven by higher levels of payroll taxes. In addition, there were increases in professional fees paid and directors' fees.
Other income for the first quarter was $6,000 compared to $21,000 in the fourth quarter, and we accrued income tax expense of $78,000 during the first quarter compared to a tax benefit of $83,000 booked in the fourth quarter. The income tax benefit booked in the fourth quarter was driven by year-end true-up of our deferred tax assets. Our effective tax rate in the first quarter was 21% compared to 70% in the fourth quarter. The reduced tax rate in the first quarter was driven by the impact of booking, the impact of the benefit of the research and development tax credit and these benefits finally being enacted during the first quarter. We expect our effective tax rate will be in the low to mid-30% range during the balance of 2013, and at March 31, 2013, we had total deferred tax assets of approximately $2.0 million.
First quarter net income was $292,000, or $0.03 per diluted share, compared to fourth quarter net income of $201,000, or $0.02 per diluted share. Average shares outstanding were 10,366,000 at March 31, up 22,000 shares from the level at December 31, 2012. Amortization and depreciation expense were $248,000 for the first quarter and EBITDA was $590,000 for the first quarter. Consolidated headcount at the end of December, which includes temporary staff, was 133, a decrease of nine individuals during the first quarter, primarily in our Thermal Products segment. As we have noted before, we closely monitor our resource levels and will adjust as needed when we see any prolonged softness in demand levels.
I'll now turn to our balance sheet. Cash and cash equivalents at the end of the fourth quarter were $15.4 million, down 1% from December 31, 2012. We currently expect cash and cash equivalents to increase sequentially throughout the balance of 2013. Accounts receivable at the end of the fourth quarter was $5.8 million, which increased $283,000 during the quarter. The increase was driven by higher levels of net revenues in the first quarter compared to the fourth. And inventory increased by approximately $283,000 to $3.4 million at the end of March. This increase was primarily in our Mechanical and Thermal Products segments in response to improved demand we are seeing late in the first quarter, which has continued into the first month of the second quarter.
Capital expenditures during the first quarter were $44,000, down from $148,000 in the fourth quarter. Bob previously provided the consolidated and segment booking data in the call. The backlog at the end of March was $2.9 million, down from $4.2 million at the end of December.
In terms of our financial outlook, as noted in our earnings release, due to improved business trends, we expect the net revenue for the quarter ended June 30, 2013, will be in the range of $9.5 to $10.5 million, with net earnings ranging from $0.05 to $0.09 per diluted share. We currently expect that our Q2 2013 material costs as a percentage of revenue will range from 33 to 35%, similar to what we guided last quarter. Please note that our outlook is based upon the Company's current views with respect to operating and market conditions and customer forecasts, which are subject to change.
Operator, that concludes our formal remarks. We can now take questions.