Thanks, John. As a reminder, in addition to using GAAP results when evaluating PDF's business, we believe it is also useful to consider our results using other non-GAAP measures. For internal purposes, the company focuses on non-GAAP net income and EBITDAR.
Non-GAAP net income excludes from nonrecurring items -- sorry, excludes nonrecurring items, stock-based compensation expenses and amortization of expenses related to acquired technology and other intangible assets, their related tax effects, as applicable. Additionally, the income tax provision has been adjusted in our non-GAAP net income to reflect cash tax expenses only.
EBITDAR is equal to earnings before income tax adjusted to exclude nonrecurring items, depreciation, amortization and stock-based compensation. You can access the earnings press release that contains a reconciliation of EBITDAR and non-GAAP net income to GAAP results in the Investors section of our website located at pdf.com.
Now let's turn over to the financial results. Total GAAP revenues for the quarter were $26.7 million, resulting in GAAP net income of $2.2 million and GAAP EPS of $0.07 per fully diluted share. Revenues on a non-GAAP basis also totaled $26.7 million, with non-GAAP net income of $5.3 million and $0.17 per fully diluted share. Cost of sales and operating expenses together were $22.9 million on a GAAP basis and $20.4 million on a non-GAAP basis.
Moving on to the revenue details. As stated earlier, total GAAP revenues for the quarter were $26.7 million. This was higher than the previous quarter by approximately $1.6 million. Total non-GAAP revenues were also $26.7 million and were approximately $1.5 million higher than in Q1. Total non-GAAP revenues were comprised of design-to-silicon-yield solutions or solutions revenue of $20.6 million and gainshare performance incentive or gainshare revenues of $6.1 million.
Our top 10 customers represented 86% of total revenues in the quarter. Two of these customers contributed revenues of 10% or greater for a total of 52% as compared to 2 customers and 64% in the prior quarter.
Looking at solutions revenue in more detail. 15 project-based engagements contributed at least $100,000 of solutions revenue in the quarter, 2 more than in the previous quarter. This increase in the number of product engagements was driven by the addition of a major Taiwanese foundry and a leading Chinese fabless customer. Q2 solutions revenue at $20.6 million was $1.9 million higher than in Q1.
Gainshare revenue for the quarter was $6.1 million, a decrease of approximately $400,000 from the prior quarter. The total number of node sites, which we define as an individual fab and process node combination, contributing to gainshare revenue was 13, down 2 from the previous quarter, as some older nodes continued to shrink down below our cutoff levels.
On a geographic basis, North America accounted for 36% of total revenues, which is down 13% from the previous quarter. Europe accounted for 21% of total revenues, an increase of 4% from the prior quarter, and Asia accounted for the remaining 43% of total revenues, an increase of 9% over the prior quarter.
As you can see from both the geographic revenue data and the top 10 data, our efforts to both expand our customer base and focus on the Asia markets are being reflected in our actual revenue results.
Moving to expenses. Cost of sales for the quarter was $10.7 million on a GAAP basis, which was approximately $500,000 higher than in the previous quarter. This increase in GAAP cost of sales was primarily driven by higher salaries and benefits due to our annual worldwide merit increases, hiring in Asia and higher travel expenses during the quarter, partially being offset by lower stock compensation expense. GAAP gross margin was 60% in the quarter as compared to 59% in the previous quarter.
On a non-GAAP basis, cost of sales was $9.6 million, which was approximately $600,000 higher than in the previous quarter. This increase in non-GAAP cost of sales was driven by the same factors as in GAAP cost of sales. However, there was no offset for the lower stock compensation expense. Non-GAAP gross margin was 64% in the quarter, the same as in the previous quarter.
Total GAAP operating expenses at $12.3 million were approximately $700,000 higher than the last quarter and 46% of total revenues, the same as last quarter.
R&D expenses totaled $7 million, approximately $700,000 higher than the prior quarter. R&D expense as a percent of revenue was 26% in the quarter, up 1% from the prior quarter.
SG&A expenses totaled $5.2 million or 20% of total revenues compared to $5.2 million, the same as in last quarter, and 21% of total revenues in the prior quarter.
The overall GAAP operating expense increase was primarily driven by a ramp-up in the development activity related to our DFI solution, which includes R&D hiring and increases in the use of third-party contractors. Also contributing to the increase was the previously mentioned worldwide merit increases and higher travel expense. Lower stock compensation expenses once again partially offset these increases.
On a non-GAAP basis, looking at operating expenses and cost of sales together, total spending was $20.4 million, which was $1.5 million higher when compared to the prior quarter. As previously mentioned, this increase was primarily driven by the development activity related to our DFI program, higher compensation expenses related to merit increases and finally, additional hiring in Asia.
The GAAP income tax provision for the quarter was $1.5 million, which represents an effective tax rate of 40% compared to 33% in the prior quarter. This rate increase is primarily due to having fewer discrete reserve reversals in Q2 as opposed to Q1.
Cash tax liabilities for the quarter were approximately $1 million. This represents an effective cash tax rate for the quarter of 26% of pretax GAAP income. As we have stated before, our cash taxes are primarily comprised of foreign withholding taxes.
GAAP net income of $2.2 million for the quarter resulted in GAAP EPS of $0.07 per fully diluted share compared to $2.1 million and also $0.07 per fully diluted share in the prior quarter.
EBITDAR, which I defined earlier and is also defined in our press release, was $7.1 million in the quarter as compared to $6.8 million for the prior quarter.
On a non-GAAP basis, net income was $5.3 million and non-GAAP EPS was $0.17 per share for the quarter compared to $5.4 million and $0.17 in the prior quarter.
Total cash at the end of the quarter was $122.2 million, a decrease of $7.2 million when compared to cash on March 31. Cash used in operations during the quarter was $2.7 million. The cash impact of fixed asset purchases during the quarter was $3.3 million, which were used primarily related to our DFI program.
The company also repurchased $1.8 million or 129,500 shares of stock during the quarter related to our board-approved stock repurchase program. Additionally, the company also repurchased $1.1 million worth of shares related to employee tax liabilities on RSU grants.
Trade accounts receivable DSO was 66 days for the quarter compared to 72 days in the previous quarter. The trade accounts receivable balance at the end of the quarter was $19.4 million, a decrease of approximately $600,000 from the previous quarter. The unbilled accounts receivable balance, including long-term, was $23.3 million, an increase of approximately $7.1 million over the prior quarter. This increase in unbilled receivables was primarily driven by the company meeting previously established yield targets and other milestones on multiple solutions projects ahead of scheduled invoicing dates. This also resulted, by the way, in a positive impact on solutions gross margins in the quarter.
Of the $42.7 million of total current and long-term receivables, approximately $2.6 million or 6% was aged greater than 30 days. Since the end of the quarter, an additional $3.4 million has been collected. Total DSO for the quarter, including unbilled receivables, was 146 days compared to 129 days in the prior quarter.
Headcount at the end of the quarter was 412 compared to 395 at the end of last quarter. And as I stated earlier, it was primarily increased in Asia.
Now let's discuss the remainder of 2016. As we previously stated, we've been very cautious with regards to 28-nanometer volumes for this year. Given what we saw in Q2 and the expansion of capacity at new 28-nanometer customers, we are a bit more optimistic than in that we may have seen the trough on 28-nanometer volumes in Q1. Offsetting this good news on 28-nanometer, we saw the impact of industry inventory corrections and product transition at the 14-nanometer node. Looking at the combined effect of these 2 variances, we expect total gainshare for the year to be flat to slightly down as compared to 2015.
In respect to solutions revenue for 2016, due to the incremental strength in our solutions bookings as well as some upside in our DFI program, we expect solutions revenue to grow in the mid- to upper-teens range versus our prior estimates of low teens. Therefore, our overall revenue outlook is to outpace the logic semiconductor market and grow at a rate in the high single digits for the year.
In regards to spending, as John stated earlier, growing demand for our eProbe 150 system and accelerating development on our eProbe 250 system are requiring increased investment levels in R&D and cost of sales from both an expense and cash standpoint. We would expect R&D expense to grow by approximately 3% per quarter for the remainder of the year. Finally, we expect our capital spending to increase by $10 million as compared to 2015, once again, driven by the DFI program.
Finally, as you may or may not be aware, the SEC has recently provided updated interpretations related to disclosure of non-GAAP financial information. In order to comply with this guidance, we will be changing our methodology for calculating non-GAAP financial results. The most significant impact of this change will be that non-GAAP net income will be calculated on a full tax basis as opposed to our current methodology, in which it is calculated on a cash tax basis only. As we have stated previously, we expect our full effective tax rate for the year to be 38% to 40% of pretax income. We will fully implement this change in the reconciliation of GAAP to non-GAAP table included in our Q3 earnings release, and I will discuss the impact of this change in detail on the methodology on our next call.
Now I will turn the call back over to the operator for Q&A. Operator?