Preparation of through hole printed circuit boards and compositions useful therefor
Abstract
Abstract THIS INVENTION CONCERNS AN IMPROVEMENT IN THE PROCESS FOR RENDERING ELECTRICALLY CONDUCTIVE THE NON-CONDUCTIVE WALLS OF THE HOLES IN THE INSULATING BOARDS OR BASE IN THE PREPARATION OF THROUGH HOLE PRINTED CIRCUIT BOARDS, WHEREBY THE FORMATION OF A WEAKLY ADHERENT COPPER LAYER ON THE COPPER-CLAD SURFACE PORTIONS OF THE BOARD IS INHIBITED WITH ATTENDANT ELIMINATION OF THE PRIOR REQUIREMENT OF A SANDING REMOVAL OF THE WEAKLY ADHERENT ELECTROLESS COPPER PRIOR TO THE ELECTROPLATING. THE IMPROVEMENT IS PROVIDED BY HAVING PRESENT IN AN ACIDIC LIQUID SOLUTION UTILIZED TO TREAT THE BOARD INCLUDING THE WALLS OF THE THROUGH HOLES PRIOR TO THE ACTIVATING AND ELECTROLESS COPPER PLATING, AN EFFECTIVE AMOUNT OF A LOWER ALKYL THIOUREA. THE ACIDIC LIQUID SOLUTION CONTAINING THE ALKYL THIOUREA CAN BE, FOR EXAMPLE, AN ACIDIC NEUTRALIZING SOLUTION UTILIZED TO NEUTRALIZE ALKALINE MATERIAL (DERIVED FROM AN ALKALINE CLEANER) PRESENT ON THE BOARD SURFACE, OR AN ACIDIC SENSITIZER SOLUTION FOR SENSITIZING THE BOARD SURFACES FOR THE ACTIVATING STEP.
Inventors
- 👤 E Saubestre
- 👤 L Durney
Bibliographic Details
Claims Analysis
Total Claims: 0References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |