... The nearer the deadline draws to the compulsory implementation of lead-free regulations (ROHS), the greater the attempts to achieve lead-free solutions that are comparable | MULTILAYER BOARDS PROTOTYPING | to the “all-purpose answer” SnPb in terms of technology and cost. Two systems are particularly predominant: tin/silver/copper (SnAgCu) and, more recently, stabilised tin/copper (SnCuNi). Although | MULTILAYER BOARDS PROTOTYPING | the level of efficiency of both systems is not yet completely clear, the following presents the latest information: SnAgCu There is more experience in the | MULTILAYER BOARDS PROTOTYPING | field of silver systems. Here, differentiation is made between the Sn-3.5Ag-0.7Cu, Sn-4Ag-0.5Cu and Sn-3Ag- 0.5Cu systems which vary in use from continent to continent. However, | MULTILAYER BOARDS PROTOTYPING | the agreed expert opinion (IPC/Soldertech-Conference Brussels 2003) is that the technological differences between the three systems are negligible. Sn-3.5Ag- 0.7Cu is the most common alloy | MULTILAYER BOARDS PROTOTYPING | in Europe. SnCuNi Although there are even fewer field results for the stabilised tin/copper system ...
[ Multilayer Boards Prototyping ]


... soldermask flaking. Spacing between the drills is just right. You hand the data set to the fabricator, and voila! No unexpected phone calls, no | MULTILAYER BOARDS PROTOTYPING | changes in the layout, and the fabricator happily sends back a good set of boards on time. Our recommendations for the correct storage of PCBs | MULTILAYER BOARDS PROTOTYPING | and MLBs A.1 ) Brief desricption of the problem: PCB`s, especially Multilayer boards are extremly sensitive towards moisture The microscopic structure of the Multilayer material | MULTILAYER BOARDS PROTOTYPING | develops a strong capillary power that soaks up the humidity of the surrounding air. Even under very dry conditions it is a question of time | MULTILAYER BOARDS PROTOTYPING | that water accumulates in the stored PCB`s. For example: At storage conditions of 20 C° and 35 % of humidity the weight of the epoxyraisin | MULTILAYER BOARDS PROTOTYPING | of the Multilayer PCB`s rises 0,12 % due to the accumulation of moisture. If the capillary effect leads to an increase of more than 0,17 | MULTILAYER BOARDS PROTOTYPING | % a gas pressure of 8-10 bar can be reached, causing delamination Even if delamination tests are made after ...
[ Multilayer Boards Prototyping ]


... a manner similar to that used for imaging the circuitry. Phototools containing black areas where the solder mask is to be removed are placed | MULTILAYER BOARDS PROTOTYPING | in direct contact with both sides of the panel. The panel is then exposed to UV light. The amount of light used is controlled by | MULTILAYER BOARDS PROTOTYPING | an integrator. Printing is done with a semi-automatic dual drawer printer. While one drawer is being loaded with a panel and phototools, the other is | MULTILAYER BOARDS PROTOTYPING | inside the machine being exposed. This dual drawer printing system runs at the same rate as the screen printer to insure continuous flow. Develop LPI | MULTILAYER BOARDS PROTOTYPING | Mask After the panel has been exposed, it is placed in a vertical developer. The unexposed solder mask is dissolved in a high pressure spray | MULTILAYER BOARDS PROTOTYPING | of developing solution. The solution temperature, concentration and conveyor speed control the development process. The developer solution concentration is maintained by a feed and bleed | MULTILAYER BOARDS PROTOTYPING | system controlled by pH. After development, the panels are rinsed and dried. Cure LPI Mask As ...
[ Multilayer Boards Prototyping ]