Automated SMT assembly line

01

Balance the line to its slowest step

Yamaha's specification for its YSM20R (now discontinued) gives 95,000 CPH with two beams and two high-speed heads, and a mounting accuracy of ±0.035 mm (±0.025 mm) at Cpk ≥ 1.0 (3σ), both under optimum conditions as defined by Yamaha Motor, the accuracy with standard evaluation materials. It takes boards from L50 × W50 to L810 × W490 mm and up to 140 component types (8 mm tape feeder equivalent) on a fixed plate. [1]

The reflow oven also sets a pace. Kester's profile guidance says to measure the heated tunnel and divide its length by 3.5 and by 4 minutes; the result is the conveyor speed range that lets the profile end in the last zone at 3.5–4 minutes and uses the whole oven. [2]

Editorial calculation: a board with 600 placements takes 600 ÷ 95,000 h ≈ 22.7 s on that mounter at its rated speed. An oven with a 3.0 m heated tunnel runs at 0.75–0.86 m/min under the Kester rule; with boards at 0.3 m pitch that is 2.5–2.9 boards per minute, or about 21–24 s per board. Here the rated mounter and the oven are about even, so a mounter running below its optimum rating would become the bottleneck; ask suppliers to simulate your boards. [1] [2]

Give the supplier your board sizes and panelisation, placements per board and component mix (smallest chip, largest part, odd-form parts), number of feeder slots needed, target boards per hour, product changeovers per shift, solder alloy, inspection needs, floor space, power and air supply.

02

Check that the paste printer keeps pace with placement

The solder paste printer is the first process step and can pace the whole line. ASMPT's page for its DEK TQ XL large-format stencil printer gives the figures a line plan needs: boards up to 850 × 610 mm, up to 8 mm thick and up to 12 kg, warpage compensation up to 4 mm, a wet print accuracy of ±20 µm at 2.0 Cpk, and a core cycle time of 12 s with a full cycle time of 22.4 s. ASMPT states that cleaning processes and motion sequences are coordinated to keep the cycle stable. [4]

Editorial calculation: a full cycle of 22.4 s is 3,600 ÷ 22.4 ≈ 161 boards per hour. Against the example above, where a 600-placement board takes about 22.7 s on the mounter at its rated speed, the printer is only 0.3 s faster, so any stencil cleaning beyond the stated cycle would make the printer the bottleneck. The printer's 850 × 610 mm board limit also exceeds the 810 × 490 mm maximum of the Yamaha mounter, so the smallest board limit in the line sets the panel size. [4] [1]

03

Link board flow, changeover and profiling between machines

The Hermes Standard (IPC-HERMES-9852) is an open, non-proprietary protocol based on TCP/IP and XML for machine-to-machine communication in SMT lines. Its initiative describes it as the next-generation successor to IPC-SMEMA-9851 board handover, passing board data such as dimensions and IDs along mixed-vendor lines so barcodes need not be read again at each machine; version 1.0 was released in April 2017 and it can be implemented without licence fees. [3]

Yamaha lists optional compatibility with the SEMI SMT-ELS communication standards for its mounter, giving automatic program changeover with other companies' machines. [1] Editorial note: if the line mixes vendors, write the protocol (SMEMA, Hermes, SMT-ELS) and the data each machine must exchange into the order.

For the oven, Kester lists a calibrated profiler with at least four thermocouple ports and a populated board representative of production, with thermocouples at the board's leading and trailing edges and at its largest and smallest thermal masses. Its chart puts a lead-free profile peak at 235–255 °C against a 217 °C liquidus, compared with 205–215 °C and 183 °C for leaded paste. [2]

04

Compare what suppliers offer

Suppliers linked to this page list SMT line equipment; each card links to the page reviewed.

Listings include complete SMT line configurations, desktop and production pick-and-place machines with printers and reflow ovens, and board loaders, unloaders and conveyors.

05

Trace the line components

This is a functional reference built from the sources cited; it is not one maker's specification.

06

Fill the specification fields with values for your boards

An SMT line quotation needs values for your boards and output. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the board, output and integration data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Boards: [sizes; panels; sides]
Components: [placements per board; smallest and largest parts; feeder count]
Output: [boards per hour; changeovers per shift]
Soldering: [alloy; oven length; nitrogen or air]
Inspection: [SPI; AOI; positions]
Integration: [handover protocol; data to exchange; MES]

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