--0__=XxlU8Dr0kF46esV9233SPUZR2jGiEsidG4yzQz5zUdhj1FVoCYvFFUDn Content-type: text/plain; charset=us-ascii Content-Disposition: inline Putting vias in the pads can cause the solder to wick into the holes during reflow, thus screwing up the solder joint. I found it best to put the vias next to the pads, and use solder mask as a dam to prevent the wicking. Via's add less than 1nh of inductance (rule of thumb I found somewhere...) and if 1nh can be tolerated go ahead and use a via.. Multiple vias will lower inductance and resistance. |--------+-----------------------------> | | Simon Gerblich | | | | | | | | | 01/18/01 01:08 AM | | | Please respond to | | | pic microcontroller| | | discussion list | | | | |--------+-----------------------------> >----------------------------------------------------------------------------| | | | To: PICLIST@MITVMA.MIT.EDU | | cc: (bcc: Scott Touchton/US/UNIPHASE) | | Subject: [EE]: Surface mount components to PCB internal planes? | >----------------------------------------------------------------------------| What is the best method of attaching surface mount bypass capacitors, etc, to internal ground and power planes on a multilayer PCB? Can you put a few small vias on the component pad or will this make the pad difficult to solder to? Another idea is a small track from the pad to a via. What would normally be used for a noise sensitive ADC PCB? Simon -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics --0__=XxlU8Dr0kF46esV9233SPUZR2jGiEsidG4yzQz5zUdhj1FVoCYvFFUDn Content-type: application/octet-stream; name="att1.eml" Content-Disposition: attachment; filename="att1.eml" Content-transfer-encoding: base64 UmVjZWl2ZWQ6IGZyb20gbnRzajEudW5pcGhhc2UuY29tIChbMTAuMTAuNDkuMjQ4XSkgYnkgc2pu b3Rlcy51bmlwaGFzZS5jb20gKExvdHVzIFNNVFAgTVRBIHY0LjYuNyAgKDkzNC4xIDEyLTMwLTE5 OTkpKSB3aXRoIFNNVFAgaWQgODgyNTY5RDguMDAyMEJDMzg7IFdlZCwgMTcgSmFuIDIwMDEgMjE6 NTc6MzMgLTA4MDANClJlY2VpdmVkOiBGUk9NIGNoZXJyeS5lYXNlLmxzb2Z0LmNvbSBCWSBudHNq MS51bmlwaGFzZS5jb20gOyBXZWQgSmFuIDE3IDIxOjU3OjQ3IDIwMDEgLTA4MDANClJlY2VpdmVk OiBmcm9tIGdyYXBlLmVhc2UubHNvZnQuY29tICgyMDkuMTE5LjAuMzQpIGJ5IGNoZXJyeS5lYXNl Lmxzb2Z0LmNvbSAoTFNNVFAgZm9yIERpZ2l0YWwgVW5peCB2MS4xYikgd2l0aCBTTVRQIGlkIDwy MC4wMDI1NUZFQUBjaGVycnkuZWFzZS5sc29mdC5jb20+OyBUaHUsIDE4IEphbiAyMDAxIDA6NTc6 NDYgLTA1MDANClJlY2VpdmVkOiBmcm9tIE1JVFZNQS5NSVQuRURVIGJ5IE1JVFZNQS5NSVQuRURV IChMSVNUU0VSVi1UQ1AvSVAgcmVsZWFzZSAxLjhkKQ0KICAgICAgICAgIHdpdGggc3Bvb2wgaWQg MTI5OCBmb3IgUElDTElTVEBNSVRWTUEuTUlULkVEVTsgVGh1LCAxOCBKYW4gMjAwMQ0KICAgICAg ICAgIDAwOjU1OjQ0IC0wNTAwDQpSZWNlaXZlZDogZnJvbSBNSVRWTUEgKE5KRSBvcmlnaW4gU01U UEBNSVRWTUEpIGJ5IE1JVFZNQS5NSVQuRURVIChMTWFpbA0KICAgICAgICAgIFYxLjJjLzEuOGMp IHdpdGggQlNNVFAgaWQgNTM1NjsgVGh1LCAxOCBKYW4gMjAwMSAwMDowOTowMCAtMDUwMA0KUmVj ZWl2ZWQ6IGZyb20gYnJ1Y2Uuc3lkYWMuY29tLmF1IFsyMDIuNi44MS42XSBieSBtaXR2bWEubWl0 LmVkdSAoSUJNIFZNIFNNVFANCiAgICAgICAgICBMZXZlbCAzMjApIHZpYSBUQ1Agd2l0aCBFU01U UCA7IFRodSwgMTggSmFuIDIwMDEgMDA6MDg6NDcgRVNUDQpYLUNvbW1lbnQ6IG1pdHZtYS5taXQu ZWR1OiBNYWlsIHdhcyBzZW50IGJ5IGJydWNlLnN5ZGFjLmNvbS5hdQ0KUmVjZWl2ZWQ6IGJ5IGJy dWNlLnN5ZGFjLmNvbS5hdSB3aXRoIEludGVybmV0IE1haWwgU2VydmljZSAoNS41LjI2NTAuMjEp IGlkDQogICAgICAgICAgPFlYRlk0OVJGPjsgVGh1LCAxOCBKYW4gMjAwMSAxNTozODo0OSArMDkz MA0KTUlNRS1WZXJzaW9uOiAxLjANClgtTWFpbGVyOiBJbnRlcm5ldCBNYWlsIFNlcnZpY2UgKDUu NS4yNjUwLjIxKQ0KQ29udGVudC1UeXBlOiB0ZXh0L3BsYWluOyBjaGFyc2V0PSJpc28tODg1OS0x Ig0KTWVzc2FnZS1JRDogIDwxNjVEODEyMEJERjNEMzExOEVDNDAwMDBGODdBNkI5QTAzNUI3RkBi cnVjZS5zeWRhYy5jb20uYXU+DQpEYXRlOiAgICAgICAgIFRodSwgMTggSmFuIDIwMDEgMTU6Mzg6 NDMgKzA5MzANClJlcGx5LVRvOiAgICAgcGljIG1pY3JvY29udHJvbGxlciBkaXNjdXNzaW9uIGxp c3QgPFBJQ0xJU1RATUlUVk1BLk1JVC5FRFU+DQpTZW5kZXI6ICAgICAgIHBpYyBtaWNyb2NvbnRy b2xsZXIgZGlzY3Vzc2lvbiBsaXN0IDxQSUNMSVNUQE1JVFZNQS5NSVQuRURVPg0KRnJvbTogICAg ICAgICBTaW1vbiBHZXJibGljaCA8c2ltb24uZ2VyYmxpY2hAU1lEQUMuQ09NLkFVPg0KU3ViamVj dDogICAgICBbRUVdOiBTdXJmYWNlIG1vdW50IGNvbXBvbmVudHMgdG8gUENCIGludGVybmFsIHBs YW5lcz8NClRvOiAgICAgICAgICAgUElDTElTVEBNSVRWTUEuTUlULkVEVQ0KDQpXaGF0IGlzIHRo ZSBiZXN0IG1ldGhvZCBvZiBhdHRhY2hpbmcgc3VyZmFjZSBtb3VudA0KYnlwYXNzIGNhcGFjaXRv cnMsIGV0YywgdG8gaW50ZXJuYWwgZ3JvdW5kIGFuZCBwb3dlcg0KcGxhbmVzIG9uIGEgbXVsdGls YXllciBQQ0I/DQoNCkNhbiB5b3UgcHV0IGEgZmV3IHNtYWxsIHZpYXMgb24gdGhlIGNvbXBvbmVu dCBwYWQgb3INCndpbGwgdGhpcyBtYWtlIHRoZSBwYWQgZGlmZmljdWx0IHRvIHNvbGRlciB0bz8N Cg0KQW5vdGhlciBpZGVhIGlzIGEgc21hbGwgdHJhY2sgZnJvbSB0aGUgcGFkIHRvIGEgdmlhLg0K DQpXaGF0IHdvdWxkIG5vcm1hbGx5IGJlIHVzZWQgZm9yIGEgbm9pc2Ugc2Vuc2l0aXZlDQpBREMg UENCPw0KDQpTaW1vbg0KDQotLQ0KaHR0cDovL3d3dy5waWNsaXN0LmNvbSBoaW50OiBUaGUgbGlz dCBzZXJ2ZXIgY2FuIGZpbHRlciBvdXQgc3VidG9waWNzDQoobGlrZSBhZHMgb3Igb2ZmIHRvcGlj cykgZm9yIHlvdS4gU2VlIGh0dHA6Ly93d3cucGljbGlzdC5jb20vI3RvcGljcw0KDQoNCg== --0__=XxlU8Dr0kF46esV9233SPUZR2jGiEsidG4yzQz5zUdhj1FVoCYvFFUDn-- -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics