NORTHBROOK, IL, July 28 -- Orders for rigid boards lagged in June, while demand for flex circuits remained strong, according to the latest three-month moving average of North American manufacturers.

For all board types, shipments rose 31.3% and bookings were up 13% vs. a year ago, said IPC, which administers the monthly poll. The figures may include some sales of products built offshore and brokered by the surveyed companies.

For the first time, data for flex circuits and rigid boards were broken out. In a statement, IPC said, "Due to divergent growth trends in the rigid PCB and flexible circuit segments of the industry, IPC will report separate monthly statistics for the two segments." The move seems to acknowledge calls by the media, including the publishers of Circuits Assembly, for better explanation of the data.

The June book-to-bill was 0.95 for rigid and 1.57 for flex. "[R]igid and flex shipments are rebounding and showing strong growth, but flex is growing at a faster rate," IPC said.

The book-to-bill ratio for all board types dropped to 1.06, down 0.05 points.

The ratio is calculated by averaging the number of orders booked over the past three months and dividing by the average sales billed during the same period. A ratio of 1.06 means that for every $100 in shipments, $106 worth of PCBs were booked. An increasing ratio is generally considered a sign of a market poised to rise.

Shipments are up 35.4% year-to-date, bookings 43.1%. Combined June shipments were up 5% sequentially, while bookings fell 19%.

June rigid shipments were up 28.4% and bookings 16.3% over last year. Year-to-date, rigid shipments are up 26.7% and bookings are up 23.6%. Among those surveyed, rigid shipments rose 6.4% sequentially and bookings rose 14.2%.

June flex shipments were up 76.9% but bookings were down 14.9% vs. last year. Year-to-date, flex shipments are up 79.1% and bookings 147%. Sequentially, flex shipments fell 1.4% and bookings dropped 69.7%.

Flex sales, which include some value-added services, make up about 17% of total PCB sales in the IPC poll.

The data come from a sample of North American rigid and flexible PCB manufacturers.

IPC did not publish June shipment or booking indices.