The cumbersome process is filled with minutia and hiccups.

Rabbit Semiconductor has about 615 products on the market. Building these products uses almost 4,000 component manufacturer part numbers and over 1,400 internal component part numbers involving over 300 manufacturers.

This article addresses the components and materials aspects of converting existing products to comply with RoHS. It presents the magnitude of the task, details plans, explains changes to those plans and provides examples of what worked and what did not.

Although it would ultimately be necessary to convert all active component part numbers to RoHS compliance, it was decided to convert part numbers in a staged process.

Stage 1. The first stage was the creation of RoHS bills of material (BoM) for two specific high-volume products being used as test vehicles for choosing Pb-free solder paste and RoHS-compliant PCB material. We also had to develop a workable reflow oven profile for our five-zone reflow ovens. This effort covered 67 component part numbers and 268 manufacturer component part numbers. Starting with the existing BoM and associated approved manufacturer list (AML) the RoHS status of each part was researched in the following order:

Information Source	Success Rate
Manufacturer Website	<10%
Distributor contact	25%
Sales rep.	50%
Mfr. tech support	50%

The only component information requested for this effort was:

1. RoHS version status (to purchase).

2. RoHS unique part number.

3. Lead plating material.

At this stage we asked for lead plating materials because several RoHS seminars we had attended warned that bismuth plating could result in poor solder bonds that were likely to fail. It would be several months before we confirmed that as long as the amount of bismuth was limited to less than 10%, solder bonds were acceptably strong. Figure 1 shows typical examples of the compiled component RoHS data.

FIGURE 1: Typical stage 1 RoHS information, in spreadsheet format. (Click here to open 440KB PDF.)

Additionally, a process needed to be developed to manage Pb-free part numbers. Should we change internal component part numbers for Pb-free? Initially, a majority of component suppliers were not changing part numbers. Our decision was to add a "20-" prefix to all saleable products offered to customers. By adding this prefix our customers are assured that they will be shipped the right products per their wishes. We first planned to also add the "20-" prefix to component part numbers but ultimately we left them as is. The addition of a designator field to indicate RoHS compliance replaced the need for totally new RoHS component part numbers.

Three months into this stage we had identified and ordered 80% of the 67 components required to build these two products. Our primary contract manufacturer successfully built our first "nearly" RoHS-compliant products. An interesting sidebar to this build: two pin-header connectors and two ICs (one large QFP and one TSOP) passed the build with flying colors even though they were not rated for the higher reflow temperatures. Several months later we ran several lots of these products on our in-house five- and seven-zone reflow ovens - again, with complete success.

Stage 1 lessons learned.

1. Product yields, at our EMS companies and in our plant, did not degrade with Pb-free solder in spite of higher reflow temperatures.

2. In September 2004, very little useful information was available on the majority of the component manufacturer Websites.

3. Most manufacturers, although aware of RoHS, were only supplying rough estimates of availability dates.

4. Distributor contacts needed to be educated with respect to understanding the details of RoHS compliance. Sales personnel for our distributors had heard of RoHS regulations but had no knowledge of the details. The distributors themselves had no solid plans for how they would manage the logistics of warehousing and reliably delivering RoHS components.

5. Sales representatives and marketing executives for many component manufacturers did not yet understand the concept of homogeneous material with respect to banned substances.

6. The unique component part numbering system worked very well. It automatically isolated compliant parts from noncompliant via the ERP and warehouse stocking processes.

It was obvious that if our distributors were going to be our primary source for RoHS component information, they needed to be educated on RoHS requirements and the importance of material control. We used quarterly meetings with our primary distributors to present a detailed explanation of RoHS, provided them with the list of parameters that we required from each of the component manufacturers, and explained why that information was critical.

Stage 2. It was time to seriously pursue the component information that would be required to manufacture and document the majority of our top-selling products. We decided to identify all the components used on our 25 best-selling products plus an additional five products recently released or close to release. We decided to pursue only the primary source for each of these components - a decision we would definitely alter in hindsight.

Combining the BoMs for these products resulted in a list of 590 components requiring RoHS part numbers, documentation, etc. Limiting ourselves to only one manufacturer per part number kept the database down to 590 line items. The team looked at RoHS part availability, functionality, certification and declaration of conformance requirements and developed from that a list (below) of the information that would be required for each component:

1. RoHS family roadmap.

2. Confirm part is RoHS compliant.

3. If compliant - since when?

4. Is the part Pb-free?

5. RoHS compliant part number.

6. RoHS availability date (now, never or specific date).

7. Will RoHS compliant and noncompliant parts be available simultaneously?

8. Moisture sensitivity level (MSL).

9. Lead plating materials.

10. Material declaration form (MDF).

11. Numerical value of allowable peak reflow temperature.

12. Maximum allowable time at peak reflow temperature.

13. RoHS package qualification report.

14. Copy of new technical specification with RoHS information included.

15. Is the lead solderability backwards-compatible?

16. Precautions we need to be aware of.

17. Miscellaneous notes.

The 590 parts were categorized by distributor and an email was sent to each firm. Attached to these emails was the appropriate list of components in an excel spreadsheet with 17 columns identified for the information we were asking them to provide. The information supplied on these spreadsheets for each component was:

1. Rabbit Semiconductor part number.

2. Short description.

3. Primary manufacturer name.

4. Primary manufacturer part number for the current (noncompliant) part.

Stage 2 lessons learned. Our distributors, by and large, were stymied by the sheer volume of data requested. In most cases acknowledgment of the request was the only feedback we received. One distributor refused outright to supply any help, offering instead to supply access to a component database where we could look up our own information for approximately $20,000 per year.

Almost two months were lost in a fruitless effort to obtain more information than the industry was ready to supply.

Regrouping, the team contacted our distributors again and notified them that we would greatly appreciate anything they could do to provide at least basic RoHS information. The list of 17 data fields per component were trimmed to three required data fields and two others that would be helpful but not required. That list now consisted of:

1. When will a RoHS compliant version be available (now/never, date)?

2. RoHS part number.

3. Will it meet 260°C peak reflow temp?

This simplified request was relayed to the distributors and within a few weeks information started to flow back. Even the distributor that had initially refused to support us now offered the help of one of its more experienced inside sales representatives. The wall of resistance was brought down, we believe, by the confluence of two changes: the scaling back of requested information, and the beginning of meaningful dissemination of information from the manufacturers to their distributors and sales reps.

Feedback on 30% of the components came back from our distributors within the first four to six weeks but it took three months to accumulate RoHS part numbers for 50% of these 590 parts.

Stage 3. The company increased the scope of these component efforts to cover 127 additional products which then covered over 90% of our products. This brought the total number of parts requiring conversion to 825 and, as of July 2005, a total of 560 RoHS equivalent components (68%) had been identified. Most of the parts not yet converted are now miscellaneous hardware or sheet metal. Of PCB-related components 75% have been converted to RoHS.

Currently, Rabbit is moving from data-gathering to documentation and purchasing.

Stage 3 lessons learned.

1. Distributors are willing to research RoHS part numbers and provide details such as solder temperature capabilities for their strategic customers as long as the information requested is minimal and straightforward.

2. By July 2005, a great deal of useful RoHS related information was available on the majority of component manufacturer Websites. Most now have entire sections dedicated to RoHS and Green activities, status information and schedules for future RoHS production.

3. The semiconductor and connector industries are quickly making RoHS versions of most products available.

4. After reviewing many component datasheets it is evident that few parts have required form, fit or function changes due to the move to RoHS. Further, virtually every component is backwards compatible with respect to SnPb solder. In hindsight, it would have been worthwhile adding RoHS components to the AML immediately so that our Buyers could begin flushing non-RoHS components out of our stockrooms much sooner.

5. Approximately 25% of our PCB-mounted components lack a unique manufacturing part number for RoHS. We compensate by adding "RoHS Compliant" as a suffix to these manufacturers' part numbers on our AML and purchase orders to ensure that only RoHS compliant parts are delivered. Incoming inspection has been trained to confirm RoHS compliance via package markings.

6. It is unknown at this time if the majority of component manufacturers will comply with IPC-1751 and IPC-1752. It appears that most are currently only willing to supply a signed document that declares their products to be RoHS compliant.

7. A number of manufacturers will move transition dates up based on a request from a customer.

8. Large body (6 mm diameter and above) aluminum electrolytic surface-mount capacitors cannot yet meet the peak solder reflow temperatures expected with Pb-free solder paste. This requires redesign so that a different style cap can be used or a through-hole aluminum electrolytic substituted.

Cost Impact

To date we have seen very few component price increases due to RoHS conversion. This has, however, been an opportunity for the manufacturers to End of Life (EOL) low-volume components. We have experienced about 10 EOL situations but in most cases a more expensive replacement part has been made available. Because Rabbit tends to build a given product for many years, we still have a number of DIP packaged ICs. Almost across the board this package is being discontinued as the manufacturers move to RoHS compliant packages. At this time the cost associated with writing off parts containing lead will likely overshadow increased piece part costs.

Documentation and Material Purchase

As mentioned, we decided to create new Rabbit Semiconductor part numbers for RoHS-compliant components with semi-intelligent part numbers. Each RoHS compliant part number would be prefixed with a "20-". However, as we began to plan the progression of BoM documentation the complexity and extremely manual nature of the changes required for our ERP system became overwhelming and ultimately unmanageable.

Within the constraints of the ERP system an alternative material and documentation process was developed which did away with the semi-intelligent part numbering system. The existing component part numbers and associated AML were retained as-is, but an additional designator for qualification status was added to each manufacturer part number.

1. At the manufacturer part number level (multiple manufacturer part numbers per Rabbit component part number):

• APR - approved for general use and is RoHS compliant.

• RDQ - RoHS disqualified. Part is not RoHS compliant (and may be purchased only if APR version is not available)

2. At the Rabbit component, subassembly and assembly levels:

• RHY - RoHS yes. Part is RoHS compliant. If a purchased part, at least one source is APR. If an assembly or subassembly, all sub-parts are RHY.

• RHN - RoHS no. Part is not RoHS compliant. If a purchased part, no sources are APR. If an assembly, one or more sub-parts are RHN.

• RHX - RoHS excluded. Part is documented with a RoHS exclusion.

• N/A - Not applicable.

BoMs. All BoMs indicate RHY/RHN/RHX status for each component.

Component level examples.

1) 241-0101 - some resistor - RHY

a) Meritec P/N ABC-123 -APR

b) Koa P/N DEF-456 - RDQ

2) 241-0101 - some resistor -RHN

a) Meritec P/N ABC-123 - RDQ

b) Koa P/N DEF-456 -RDQ

Assembly level examples. Each assembly has a qualifier indicating Rabbit's evaluation of RoHS status for each sub-component on the BOM.

3) 101-0520 - RCM3200 - RHY

a) 241-0101 - some resistor - RHY

b) 341-0202 - some capacitor - RHY

4) 101-0520 - RCM3200 -RHN

a) 241-0101 - some resistor -RHN

b) 341-0202 - some capacitor - RHY

Purchasing screens in ERP system. Buyers see all manufacturer part numbers along with their associated qualification designator (i.e. APR or RDQ) and must choose a specific manufacturer's part number which then shows up on the purchase order.

Inventory control. Because unique component part numbers were no longer an option, a method for receiving, managing and separating RoHS from non-RoHS components was critical. This was solved in an innovative and functional way.

• All existing components in stock were marked with large red tags (at both the innermost and outmost packaging levels). Also, all existing components were identified within the ERP system as existing within the "Red" warehouse.

• Incoming inspection identifies new product with appropriate red or green tags.

• Incoming inspection assigns a stock location within the "Green" warehouse for RoHS-compliant parts and within the "Red" warehouse for non-RoHS parts.

• Manufacturing personnel are trained to pull inventory from the Red warehouse first. This allows us to flush out non-RoHS components as quickly as possible.

• The Red and Green warehouses are ERP system locations. The actual physical location is the same regardless of whether a component is labeled Red or Green.

Documentation. Products will be offered for sale as RoHS compliant only when every component, subassembly and final assembly is identified with a "RHY" designator and sufficient component inventory is available. At that time the Documentation group will re-identify that product with a unique product part number that indicates RoHS compliance.

Component qualification. The Engineering group identified specific commodities which require engineering testing before RoHS versions can be added to the AML. Examples of these categories include custom ICs, resonators, magnetics and aluminum electrolytic capacitors. All other commodities will be added directly to the AML based on similarity to current parts. Examples of commodities that will be added directly are resistors, logic ICs, memory ICs and small value capacitors.

Rabbit Semiconductor is moving to the point where the majority of new component purchase orders are for RoHS-compliant parts. At the same time our production floor is working its way through the remaining noncompliant stock. As individual noncompliant components are fully depleted we update the AML so that only RoHS-compliant manufacturer part numbers remain.

At the end-product level we follow a tight RoHS Product Roadmap. Our plan is now to begin Pb-free production of our 25 best-selling products during the second quarter of 2006. Approximately half these products will be built by EMS companies and half internally. We are also expanding RoHS production to our 100 best-selling products. Remaining products will be transitioned based on part availability and customer needs.

Component manufacturers continue to improve their RoHS offerings, documentation and delivery schedules. Even now, however, it is still difficult to obtain much more than an updated specification and a simplified material declaration form. We are collecting MDFs for inclusion in internal component documentation.

Finally, a number of our distributors have expressed concern about their ability to track compliant versus noncompliant components because so many of them are rolling RoHS-compliant product in without part number control. Our plan to handle this potential problem is internal training and well-controlled purchasing and receiving processes.

• Buyers specifically request RoHS compliancy on purchase orders.

• Incoming material inspectors are trained to recognize RoHS markings (or lack thereof) and to double check against POs.

• Stockroom personnel are trained to recognize RoHS markings and follow carefully crafted stocking and kitting processes that specifically address RoHS.

• Production personnel are also trained to recognize RoHS-related components and material.

• Implementation of an automated barcoding system for material tracking throughout the manufacturing process. This system will improve process controls to keep leaded and Pb-free materials segregated.

 

Ed.: This article has been updated from a paper presented at SMTA International in September 2005 and is used with permission of the author.

Gary Schulte is a component engineer at Rabbit Semiconductor (rabbit.com); gary_schulte@rabbit.com.