Component placement.

1. One principle of international diplomacy is "trust but verify," which also applies to selecting and qualifying placement equipment. Talk to users of the equipment to compare their experience against what the salesperson tells you. Write into the contract what the supplier will do and when to remedy any failures to meet guarantees. Also, document how any disputes will be settled.

2. Commonly, a machine will not meet its published specifications for placement accuracy. Check this specification using glass parts or other appropriate methods before accepting a machine.

3. Check the amount of time required for routine maintenance operations and at what interval these are required, which can add up to considerable time and cost. Be sure to look at feeder cost and capability of those that are offered. Find out what maintenance the feeders require and how often.

--Glenn Robertson, Process Sciences, [e-mail]

4. When you design your next board, do not forget the fiducial marks. Surprisingly, a lot of boards still have no fiducial marks, and, without them, consistent placements are almost impossible. Fiducial marks are especially important for boards with fine-pitch components.

5. Make sure the board has sufficient support and is fixed correctly. If a board is warped in a conveyor or board holder, a good placement result is impossible. This support is very important with fine-pitch components and ball grid arrays (BGAs). Spending a little more time to secure the board with the correct bottom support and side fixtures will save you a lot of time fixing placement errors.

--Eric Bach, Manncorp, [e-mail]

6. Mechanical stress (MS) is the enemy. MS can cause breakage in the component body, Sometimes, the damage is internal and not severe enough to cause an open but will cause a deviation of performance. At times, cracks are not visible until soldering, but they can be visually detected with proper investigation. Some recommendations include:

* Determine the optimal location to put board support systems to avoid warps, especially in double reflow or reflow plus adhesive boards. In double-sided assemblies the components that undergo a higher stress are those on the opposite side to the one being mounted, since they are submitted to surface traction on their electrodes.

* Measure the MS in your printing and pick-and-place systems. Values over 1.000 [micro][epsilon] are not recommended.

* If MS is suspected but visual examination is not successful, retouch by hand soldering the suspicious components. Surface tension during solder reflow may be enough to make the crack apparent. Be careful not to touch the component's body with the soldering iron tip; otherwise, a thermal crack could result.

--Miguel Castilla, FUJITSU MANUFACTURING ESPANA, S.A.U., [e-mail]

7. Improve the skills and capabilities of your operators. Is everybody well trained and up to date? Have some operators been trained in-house by colleagues who were also trained by colleagues? This practice may perpetuate slipshod habits, leave operators with knowledge gaps and an outdated approach, and gradually reduce production efficiency. Training by the equipment supplier may help ensure that operators make the most of their capabilities and of potential machine/line performance.

8. Optimize your machine/line. Asking your equipment supplier for a performance audit typically costs nothing. If the audit yields recommendations for improving line performance, you can choose only those solutions with a worthwhile return on investment and direct boost to your bottom line.

--Paul Gerits, Assembleon, [e-mail]

9. Check material quality. One of the most essential aspects of surface-mount component placement occurs outside of the placement process itself. Component vendor selection and strict incoming material inspection are critical for a successful surface mount assembly process. Component vendors must supply components manufactured to consistent tolerances and feed media that are reliable at machine level. Incoming material inspection then verifies the parts' conformance to both dimensional and electrical specifications, as well as the quality of the media.

--Mark Campbell and Chris Lambrecht, Siemens Dematic; [e-mail]; [e-mail]

10. The number one reason for lost productivity is a lack of supervision at the surface-mount assembly line. Guidance and leadership on the production floor are fire keys to quick changeovers, good utilization and high efficiency on surface mount assembly equipment.

--Scott Wischoffer, Fuji America Corp., [e-mail]

Have a tip for our next Ten timely Tips on Controlling and Avoiding ESD? Submit 75 words to lhamburg @upmediagroup. corn by October 24. Those tip authors selected will have their names, company names and e-mail addresses printed.